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IDENTIFYING COST SAVINGS THROUGH ENERGY CONSERVATION MEASURES IN
MECHANICALLY AERATED ACTIVATED SLUDGE TREATMENT PROCESSES IN SOUTHEAST
FLORIDA
by
Eric Stanley
A Thesis Submitted to the Faculty of
The College of Engineering and Computer Science
in Partial Fulfillment of the Requirements for the Degree of
Master of Science
Florida Atlantic University
Boca Raton, FL
May 2012
IDENTIFYING COST SAVINGS THROUGH ENERGY CONSERVATION l\ffiASURES IN
l\ffiCHANICALLY AERATED ACTIVATED SLUDGE TREATMENT PROCESSES IN SOUTHEAST
FLORIDA
By
Eric Stanley
This thesis was prepared under the direction of the candidate's thesis advisor, Dr. Frederick Bloetscher,
Department of Civil, Environmental, and Geomatics Engineering" and.has been approved by the members
of his supervisory committee. It was submitted to the faculty of the College of Engineering and Computer
Science and was accepted in partial fulfillment of the requirements for the degree of Master of Science.
SUPERVISORY COMMITTEE:
eoerickBloetscher, Ph.D., P.E.
Thesis Advi r
,Ph.D.
. . _;:J-CPanagiotis D. Scaralatos, Ph.D ..
Chair, Departmentof Civil, Environmeniii ,
and Geomatics Engineering
Mohammad Ilyas, Ph.D.
Interim Dean, College of Engineering
and Computer Science
b·l/~/ 'UJ1'2.
Date
Barry T. R son, Ph.D.
Dean, Graduate College
ii
..
ABSTRACT
Author:
Eric Stanley
Title:
Identifying Cost Savings through Energy Conservation Measures in Mechanically
Aerated Activated Sludge Treatment Processes in Southeast Florida
Institution:
Florida Atlantic University
Thesis Advisor: Dr. Frederick Bloetscher
Degree:
Master of Science
Year:
2012
This thesis presents a model which estimates energy and cost savings that can be realized by
implementing Energy Conservation Measures (ECMs) at mechanically aerated wastewater treatment plants
(WWTPs) in southeast Florida. Historical plant monitoring data is used to estimate savings achieved by
implementing innovative aeration technologies which include; 1) Fine Bubble Diffusers; 2) Single-Stage
Turbo Blowers; 3) Automatic Dissolved Oxygen (DO) Control.
Key assumptions for modeling
performance of each technology are researched and discussed, such as trends in the future cost of
electricity, efficiency of blowers, and practical average DO levels for each scenario. Capital cost estimates
and operation and maintenance (O&M) costs are estimated to complete life-cycle cost and payback
analyses. The benefits are quantified on an individual and cumulative basis, to identify which technologies
are cost-beneficial. The results demonstrate that levels of payback of 20 years or less are available at the
three WWTPs studied.
iii
ACKNOWLEDGEMENTS
The author wishes to thank his wife, Tatyana, without whose love and support nothing would be
possible. The author also wishes to thank his employer, Hazen and Sawyer, P.C., including senior engineers
and coworkers, for providing a dynamic workplace environment supportive of furthering understanding of
complex engineering issues. The help of the utilities officials including Norm Wellings, Gabe Destio, and
Ed Catalano with the City of Boca Raton, and Chuck Flynn with the City of Plantation, was instrumental in
furthering the progress of this work. Lastly, the author would like to thank his thesis committee, including
Frederick Bloetscher, Ph.D., P.E., and Daniel Meerof, Ph.D, for their guidance in completing this thesis.
iv
IDENTIFYING COST SAVINGS THROUGH ENERGY CONSERVATION MEASURES IN
MECHANICALLY AERATED ACTIVATED SLUDGE TREATMENT PROCESSES IN SOUTHEAST
FLORIDA
LIST OF TABLES .........................................................................................................................................ix LIST OF FIGURES ..................................................................................................................................... xiii I. INTRODUCTION ....................................................................................................................................... 1 1.1 Overview of the Aeration Process ................................................................................................. 3 1.2 Less Efficient Mechanical Aeration Versus More Efficient Fine-Bubble Diffused Aeration........ 5 1.3 Less Efficient Multi-stage Centrifugal Blowers Versus More Efficient Single-stage Turbo
Blowers ....................................................................................................................................................... 6 1.4 Less Efficient Manual DO Control Versus More Efficient Automatic DO Control ...................... 7 1.5 Combining Technologies to Optimize Efficiency ........................................................................ 10 1.6 Summary of Facilities Studied ..................................................................................................... 11 II - LITERATURE REVIEW – DISCUSSION OF THE STATE OF THE ART IN ACTIVATED
SLUDGE PROCESS CONTROL AND KEY MODELING ASSUMPTIONS............................................ 13 2.1 Energy Conservation Measure Case Studies................................................................................ 13 2.2 Fine Bubble Diffusers .................................................................................................................. 17 2.3 Blower Technology...................................................................................................................... 18 2.4 DO Control Strategy ................................................................................................................... 23 2.4.1 Manual Control ........................................................................................................................ 23 2.4.2 Automatic DO Control............................................................................................................. 24 2.4.3 DO Probes ................................................................................................................................ 25 2.4.4 Modulating Valves ................................................................................................................... 25 2.4.5 Flow Meters ............................................................................................................................. 26 2.5 Piping ........................................................................................................................................... 27 v
2.6 Summary of Technologies ........................................................................................................... 27 2.7 Key Assumptions For Aeration Model ........................................................................................ 28 2.7.1 DO Levels ................................................................................................................................ 28 2.7.2 Blower Efficiency Assumptions .............................................................................................. 30 2.7.3 Flowrate Assumptions ............................................................................................................. 30 2.7.4 Aeration Modeling Global Assumptions ................................................................................. 31 III. LITERATURE REVIEW – COST ESTIMATING METHODS AND ASSUMPTIONS ...................... 33 3.1 Cost Estimate Level of Accuracy................................................................................................ 33 3.2 Life Cycle Cost Analysis Method And Assumptions .................................................................. 35 3.3 Capital Cost ................................................................................................................................. 41 3.3.1 Cost of Blower Technology ..................................................................................................... 42 3.3.2 Cost of Fine Bubble Diffused Aeration Technology ............................................................... 43 3.3.3 Foregone Capital Replacement Costs and Salvage Value........................................................ 43 3.4 Operation and Maintenance Costs ...............................................................................................44 IV. METHODOLOGY.................................................................................................................................. 46 4.1 Identifying Specific Energy Conservation Measures .................................................................. 46 4.2 Lifecycle Cost Analysis of ECMs ................................................................................................ 46 4.2.1 Historical Plant Data ................................................................................................................ 49 4.2.2 Estimating Yield ...................................................................................................................... 50 4.2.3 Project Future Flows and Loadings ......................................................................................... 52 4.2.4 Calculate Oxygen Requirement and Required Air Flowrates .................................................. 53 4.2.5 Size Process Air Piping ............................................................................................................ 66 4.2.6 Estimate Headloss Through Pipes and Create System Curve .................................................. 68 4.2.7 Size Blowers ............................................................................................................................ 73 4.2.8 Estimate Capital Cost............................................................................................................... 77 4.2.9 Estimate O&M and Foregone Capital Replacement Costs ...................................................... 78 4.2.10 Energy Baseline – Estimated Energy Consumption of Existing Mechanical Aerators ............ 79 vi
4.2.11 Complete Life Cycle Cost Analysis ......................................................................................... 81 4.2.12 Model Accuracy Verification................................................................................................... 86 V. PLANT ECM ASSESSMENT ................................................................................................................. 93 5.1 City of Boca Raton WWTP ......................................................................................................... 93 5.1.1 Boca Raton WWTP - Existing Secondary Treatment .............................................................. 93 5.1.2 Boca Raton WWTP –Influent and Effluent Water Quality ...................................................... 95 5.1.3 Boca Raton WWTP – Proposed ECM Design ......................................................................... 96 5.1.4 Boca Raton WWTP - Results and Discussion ......................................................................... 97 5.1.5 Boca Raton WWTP - Sensitivity Analysis ............................................................................ 101 5.2 Broward County North Regional WWTP .................................................................................. 102 5.2.1 Broward County North Regional WWTP - Existing Secondary Treatment .......................... 102 5.2.2 Broward County North Regional WWTP –Influent and Effluent Water Quality .................. 103 5.2.3 Broward County North Regional WWTP – Plant Specific Methodology
Considerations .................................................................................................................................... 104 5.2.4 Broward County North Regional WWTP – Proposed ECM Design ..................................... 106 5.2.5 Broward County North Regional WWTP – Results and Discussion ..................................... 107 5.2.6 Broward County North Regional WWTP - Sensitivity Analysis ........................................... 112 5.3 Plantation Regional WWTP ...................................................................................................... 113 5.3.1 Plantation Regional WWTP - Existing Secondary Treatment .............................................. 113 5.3.2 Plantation Regional WWTP – Influent and Effluent Water Quality ...................................... 113 5.3.3 Plantation Regional WWTP – Proposed ECM Design .......................................................... 115 5.3.4 Plantation Regional WWTP – Results and Discussion ......................................................... 115 5.3.5 Plantation Regional WWTP - Sensitivity Analysis............................................................... 119 VI. DISCUSSION AND COMPARISON OF RESULTS .......................................................................... 121 6.1 Improvement of Efficiency Comparison and Analysis .............................................................. 121 6.2 Capital Cost Comparison and Analysis .................................................................................... 125 6.3 Payback Comparison and Analysis ............................................................................................ 128 vii
6.4 Sensitivity Analysis Comparison ............................................................................................... 132 6.5 Total Savings And Regional Savings......................................................................................... 136 6.6 Current Energy Intensity Discrepancy and Potential Operational Modifications at
Plantation Regional WWTP .................................................................................................................... 136 6.7 Ocean Outfall Rule Compliance ................................................................................................ 142 6.8 Greenhouse Gas Emissions ........................................................................................................ 144 VII. CONCLUSIONS AND RECOMMENDATIONS .............................................................................. 146 7.1 Conclusions................................................................................................................................ 146 7.2 Recommendations...................................................................................................................... 151 APPENDICES............................................................................................... Error! Bookmark not defined. BIBILIOGRAPHY ...................................................................................................................................... 268 viii
LIST OF TABLES
Table 1.1 – Study Facility Summary ............................................................................................................. 12 Table 2.1 – General ECM Case Study Survey .............................................................................................. 14 Table 2.2 - Fine Bubble Diffuser Technologies with Highest SOTE’s ......................................................... 18 Table 2.3 – Blower Technology Comparison ................................................................................................ 23 Table 2.4 – Summary of Technologies.......................................................................................................... 28 Table 2.5 – Manual DO Control - Case Study DO Levels ............................................................................ 29 Table 2.6 – Automatic DO Control – Case Study DO Levels ....................................................................... 30 Table 3.1 - AACE Estimate Class Level Characteristics (Christensen, 2005) .............................................. 34 Table 3.2 – 2006 – 2011 AEO Report Average Predicted US Electricity Annual Real Inflation
Rates .............................................................................................................................................................. 39 Table 3.3 – 2011 AEO Report Base and Side Case Assumptions ................................................................. 39 Table 3.4 – Cost of Blower Technologies ..................................................................................................... 42 Table 3.5 – Cost of Fine Bubble Diffusers .................................................................................................... 43 Table 3.6 – Major Equipment Requiring Eventual Replacement .................................................................. 44 Table 3.7 – Major Equipment Requiring Eventual Replacement .................................................................. 45 Table 4.1 – Summary of Methodology.......................................................................................................... 48 Table 4.2 – Boca Raton WWTP– Incremental Life-Cycle Cost Analysis ..................................................... 52 Table 4.3 – Key Assumptions for ECMs ....................................................................................................... 57 Table 4.4 – Extreme Weather Design Conditions ......................................................................................... 74 Table 4.5 – Power Factor .............................................................................................................................. 80 Table 4.6 – Predicted SCFM vs. Standard Oxygen Requirement based on Loading .................................... 90 ix
Table 4.7 – Model Verification Sensitivity Analysis .................................................................................... 90 Table 4.8 – Mechanically Aerated Module A, B, vs. Fine Bubble Aerated Module C Measured
Energy Usage Comparison ............................................................................................................................ 91 Table 4.9 – Model Efficiency Gain Prediction Vs. Actual Efficiency Gain Prediction ................................ 92 Table 5.1 – Study Facility Summary ............................................................................................................. 93 Table 5.2 - Aeration Basin Characteristics .................................................................................................... 94 Table 5.3 - Mechanical Aeration Characteristics .......................................................................................... 94 Table 5.4 - Diffused Aeration Characteristics ............................................................................................... 94 Table 5.5 - Blower Characteristics ................................................................................................................ 95 Table 5.6 – Boca Raton WWTP – Design Influent/Effluent Based on 2007-2009 Flow/Loading
Data ............................................................................................................................................................... 95 Table 5.7 – Boca Raton WWTP – Design Influent/Effluent Adjusted to Est. 2011-2031 Avg
Flowrate......................................................................................................................................................... 96 Table 5.8 – Boca Raton WWTP – Design Influent/Effluent Adjusted to Design Flow ................................ 96 Table 5.9 – Life Cycle Cost Analyses Estimated Costs ................................................................................ 97 Table 5.10 – Life Cycle Cost Analyses Estimated Savings........................................................................... 97 Table 5.11 – Boca Raton WWTP– Incremental Life-Cycle Cost Analysis ................................................... 99 Table 5.12 – Boca Raton WWTP – Payback Sensitivity Analysis .............................................................. 101 Table 5.13 - Aeration Basin Characteristics – Modules A and B ................................................................ 103 Table 5.14 - Mechanical Aeration Characteristics – Modules A and B ...................................................... 103 Table 5.15 – Broward Co. N. Regional WWTP – Design Influent/Effluent Based on 2004-2006 ............. 104 Table 5.16 – Broward Co. N. Regional WWTP – Design Influent/Effluent Adjusted to Est. 20112031 Avg Flow ............................................................................................................................................ 104 Table 5.17 – Broward Co. N. Regional WWTP – Design Influent/Effluent Adjusted to Design
Flow ............................................................................................................................................................ 104 Table 5.18 – 2004-2006 # of Basins In Service vs. Flowrate ...................................................................... 105 Table 5.19 – Projected Module D Energy Reduction .................................................................................. 106 Table 5.20 – Life Cycle Cost Analyses Estimated Costs ............................................................................ 107 Table 5.21 – Life Cycle Cost Analyses Estimated Savings......................................................................... 108 x
Table 5.22 – Broward Co. N. Regional WWTP – Incremental Life-Cycle Cost Analysis .......................... 110 Table 5.23 – Broward Co. N. Regional WWTP – Payback Sensitivity Analysis ........................................ 112 Table 5.24 - Aeration Basin Characteristics ................................................................................................ 113 Table 5.25 - Mechanical Aeration Characteristics ...................................................................................... 113 Table 5.26 – Plantation Regional WWTP – Design Influent/Effluent Based on 2007-2009 Flow/
Loading Data ............................................................................................................................................... 114 Table 5.27 – Plantation Regional WWTP – Design Influent/Effluent Adjusted to Est. 2011-2031
Avg Flow ..................................................................................................................................................... 114 Table 5.28 – Plantation Regional WWTP – Design Influent/Effluent Adjusted to Design Flow................ 114 Table 5.29 – Life Cycle Cost Analyses Estimated Costs ............................................................................ 116 Table 5.30 – Life Cycle Cost Analyses Estimated Savings......................................................................... 116 Table 5.31 – Plantation Regional WWTP – Incremental Life-Cycle Cost Analysis ................................... 118 Table 5.32 – Plantation Regional WWTP – Payback Sensitivity Analysis ................................................. 119 Table 6.1 – Percent Efficiency Gain Per Plant and Scenario....................................................................... 121 Table 6.2 – Payback Per Plant and Scenario ............................................................................................... 121 Table 6.3 – Cumulative Capital Cost Per ECM........................................................................................... 126 Table 6.4 – Sensitivity Analysis Comparison ............................................................................................. 134 Table. 6.5 – Projected Energy Savings Related To Implementation of ECMs ............................................ 136 Table 6.6 – Current Aeration Energy Intensity Comparison ....................................................................... 136 Table 6.7 – Average Mechanical Aerator Energy Use Comparison ............................................................ 137 Table 6.8 – Average Power Supplied Per Zone........................................................................................... 138 Table 6.9 – Current Oxygen Supplied vs. Oxygen Required ...................................................................... 139 Table 6.10 – Plantation Operational Modification - Energy Intensity Comparison .................................... 140 Table 6.11 – Plantation Operational Modification - Current Oxygen Supplied vs. Oxygen Required ....... 141 Table 6.12 – Plantation Operational Modification –Energy Savings Resulting From ECM
Implementation Following Operational Modification ................................................................................. 141 Table 6.13 – Plantation Operational Modification – Payback Resulting From ECM Implementation
Following Operational Modification ........................................................................................................... 142 xi
Table 6.14 – Greenhouse Gas Prevention Equivalency For Three Facilities Studied ................................. 144 Table 7.1 – Life Cycle Cost Analysis Assumptions .................................................................................... 146 Table 7.2 – Life Cycle Cost Analyses Estimated Costs .............................................................................. 146 Table 7.3 – Life Cycle Cost Analyses Estimated Savings........................................................................... 147 Table 7.4 – Life Cycle Cost Analyses Estimated Median Paybacks ........................................................... 147 xii
LIST OF FIGURES
Figure 1.1 – Typical Electricity Requirements at Activated Sludge Treatment Processes in the US .............. 1 Figure 1.2 – Typical Activated Sludge Treatment Process With Aeration...................................................... 4 Figure 1.3 – Aerial Photograph - City of Boca Raton Activated Sludge Treatment Process (Photo by
Google Earth) .................................................................................................................................................. 4 Figure 1.4 – Surface Mechanical Aerator – Plantation Regional WWTP ....................................................... 5 Figure 1.5 – Fine Bubble Diffuser (Photo by ITT Water and Wastewater – Sanitaire) .................................. 6 Figure 1.6 – Multi-Stage Centrifugal Blower and Turbo Blower.................................................................... 7 Figure 1.7 – Manual vs. Automatic DO Control ............................................................................................. 8 Figure 1.8 – Automatic DO Controller (Photo by Hach Company) ................................................................ 9 Figure 1.9 – Automatic DO Control System ................................................................................................... 9 Figure 1.10 – Existing Aeration Basin and Proposed ECM Nos. 1 through 3............................................... 11 Figure 2.1 – Positive Displacement Blower Cross-Section (Photo by Aerzen USA Corporation) ............... 19 Figure 2.2 – Dual Guide Vane Control Blower Cross-Section (Graphic by Siemens, Inc.) .......................... 20 Figure 2.3 – Multi-Stage Centrifugal Blower Cross-Section (Graphic by Gardner Denver, Inc.) ................ 21 Figure 2.4 – Turbo Blower (Dual) Cross-Section (Graphic by APG Neuros)............................................... 22 Figure 2.5 – Typical Flow Meters for Measuring Air Flowrates................................................................... 26 Figure 2.6 – Temperature vs. Tau ................................................................................................................. 32 Figure 3.1 –2011 - 2035 AEO Report Predicted US Electricity Real Rates.................................................. 38 Figure 3.2 – 2006 – 2011 AEO Report Predicted US Electricity Annual Real Inflation Rates ..................... 39 Figure 4.1 – Spreadsheet 1. 1 – Influent-Effluent Specifier .......................................................................... 49 xiii
Figure 4.2 – Typical Yield for Primarily Treated Domestic Wastewater (Tchobanoglous et al., 2003) ....... 51 Figure 4.3 – Typical Yield for Raw Domestic Wastewater (Tchobanoglous et al., 2003) ............................ 51 Figure 4.4 – Spreadsheet 1. 2 – Flow Projection ........................................................................................... 53 Figure 4.5 – Sanitaire Silver Series II - SOTE Vs. SCFM per diffuser ........................................................58 Figure 4.6 – Spreadsheet 2.0 – Aeration Calculations – Global Parameters ................................................. 59 Figure 4.7 – Spreadsheet 2.1 – Aeration Calculations – Diffusers ................................................................ 63 Figure 4.8 – Spreadsheet 2.2 – Aeration Calculations – Turbo Blowers ....................................................... 64 Figure 4.9 – Spreadsheet 2.3 – Aeration Calculations – DO Control ............................................................ 65 Figure 4.10 – Spreadsheet 3.1 – System Design – Size Pipes ....................................................................... 68 Figure 4.11 – Spreadsheet 3.2 – System Design – Estimate Losses Through Pipes ..................................... 72 Figure 4.12 – Spreadsheet 3.3 – System Design – System Curve .................................................................73 Figure 4.13 – Spreadsheet 3.4 – System Design – Blower Design ............................................................... 77 Figure 4.14 – Spreadsheet 4.0 – Cost Estimate - Summary .......................................................................... 78 Figure 4.15 – Spreadsheet 5.0 – O&M Costs ................................................................................................ 79 Figure 4.16 – Spreadsheet 6.0 – Lifecycle Cost Analysis Inputs .................................................................. 81 Figure 4.17 – Spreadsheet 6.1.1 – Life Cycle Cost Analysis ........................................................................ 84 Figure 4.18 – Spreadsheet 6.2 – Incremental Life Cycle Cost Analysis Summary ....................................... 85 Figure 4.19 – Model Verification - Week of August 8, 2010 ........................................................................ 88 Figure 4.20 – Predicted SCFM vs. Measured SCFM .................................................................................... 89 Figure 5.1 – Present Value Comparison of Existing Process Versus Proposed ECMs ................................. 98 Figure 5.2 – Boca Raton WWTP – Incremental Increase in Efficiency Per ECM ...................................... 100 Figure 5.3 – Present Value Comparison of Existing Process Versus Proposed ECMs ............................... 109 Figure 5.4 – Present Value Comparison of Existing Process Versus Proposed ECMs – No
Consideration for Module D Effects ........................................................................................................... 109 Figure 5.5 – Broward Co. N. Regional WWTP – Incremental Increase in Efficiency Per ECM ................ 111 Figure 5.6 – Present Value Comparison of Existing Process Versus Proposed ECMs ............................... 117 Figure 5.7 – Plantation Regional WWTP – Incremental Increase in Efficiency Per ECM ......................... 118 xiv
Figure 6.1 – Improvement of Efficiency Per Scenario– kWh / lb BOD Treated ......................................... 122 Figure 6.2 – Improvement of Efficiency Per Scenario– kWh / SOR........................................................... 122 Figure 6.3 – Improvement of Efficiency Per Scenario– kWh / MGD Treated ............................................ 123 Figure 6.4 – Improvement of Efficiency Per Scenario– kWh / SOR - (not considering Broward
County North Regional WWTP Module D Assumptions) .......................................................................... 124 Figure 6.5 – Range of Capital Cost / MGD Treated .................................................................................... 126 Figure 6.6 – Range of Capital Cost / lb CBOD5 Treated ............................................................................ 127 Figure 6.7 – Range of Capital Cost / SOR .................................................................................................. 127 Figure 6.8 – ECM No. 1 - Fine Bubble Diffuser Payback Comparison ...................................................... 128 Figure 6.9 – ECM No. 2 - Turbo Blower Payback Comparison ................................................................. 129 Figure 6.10 – ECM No. 3 - DO Control Payback Comparison ................................................................... 130 Figure 6.11 – ECM No. 1 through 3 - Cumulative Payback Comparison ................................................... 131 Figure 6.12 – Sensitivity Analysis – Results of Variation in CPI Inflation or Bond Rate Assumptions
(Boca Raton WWTP Example) ................................................................................................................... 135 Figure 6.13 – Sensitivity Analysis – Results of Variation in Electricity Price (Boca Raton WWTP
Example) ..................................................................................................................................................... 135 Figure 7.1 – Average Contribution of Each ECM to Overall Total Energy Savings................................... 149 xv
I. INTRODUCTION
Electricity comprises a significant and rising portion of operating costs for municipal wastewater
utilities in the United States. Approximately 3 percent of energy consumed in the United States is by water
and wastewater treatment plants (WWTPs) (Krause et al., 2010). Seventy percent of WWTPs in the United
States exceeding 2.5 million gallons per day (MGD) utilize activated sludge secondary treatment, where 45
to 75 percent of electricity use is consumed in the aeration process (Rosso and Stenstrom, 2006). Because
the aeration treatment process consumes the majority of energy in WWTPs utilizing secondary treatment,
improving the efficiency of aeration can result in the largest cost and energy savings to utilities in southeast
Florida, nationwide and beyond. Figure 1.1 demonstrates the typical energy usage at wastewater treatment
facilities in the United States utilizing the activated sludge treatment process.
Anaerobic Digestion
Belt Press 14.2%
Gravity Thickening
0.1%
Return Sludge Pumping
0.5%
3.9%
Chlorination
0.3%
Aeration
54.1%
Lighting &
Buildings
8.1%
Pumping
14.3%
Screens
0.0%
Grit
1.4%
Clarifiers
3.2%
(SAIC, 2006)
Figure 1.1 – Typical Electricity Requirements at Activated Sludge Treatment Processes in the US
1
Within the southeast Florida region, the effects of the energy-consuming aeration process are also
apparent. For example, the Broward County North Regional WWTP utilizes secondary treatment and is the
largest single electricity user in Broward County consuming approximately 133,000 KW. The aeration
basins comprise approximately half of this power demand (Bloetscher, 2011).
The state-of-the-art for energy efficient wastewater treatment aeration technology continues to
advance. However, improved air diffusers, blowers, and automated control systems have not yet been
adopted by many WWTPs that could benefit from them. Treatment plants continue to delay modernizing
their aeration systems for various reasons. Joseph Cantwell with the Wisconsin Focus on Energy indicates
that this may be because plant operators typically focus on meeting effluent quality requirements and
keeping operating costs in accordance with expectations and not energy efficiency. Similarly, capital
expenditures are driven by the need to increase capacity and comply with permit requirements (Jones et al.,
2007).
.
This thesis presents a model developed to estimate the energy savings and resulting cost savings
that can be realized by implementing Energy Conservation Measures (ECMs) at conventional activated
sludge WWTPs, focusing on three facilities in southeast Florida; the City of Boca Raton WWTP (WWTP),
the Broward County North Regional WWTP, and the Plantation Regional WWTP. A model is developed
and presented which uses historical plant monitoring data to estimate the energy and cost savings achieved
by implementing innovative aeration technologies, which include; ECM No. 1 - fine bubble diffusers; ECM
No. 2 - single-stage turbo blowers; and ECM No. 3 - automatic dissolved oxygen (DO) control. Many key
assumptions for modeling the performance of each technology were researched, such as predicted trends in
the future cost of electricity, practical values to assume for efficiency of fine bubble diffuser or single-stage
turbo blower performance, and average DO level used for automatic DO control. The model was verified
to demonstrate reasonable accuracy using actual side by side efficiency data for mechanical aeration and
fine bubble diffused aeration.
A preliminary construction plan for implementing each ECM is designed and used for developing
a feasibility-level capital cost estimate. Operation and maintenance (O&M) costs for implementing each
technology are also estimated. The capital cost estimate is then compared with the net present value of
estimated energy savings and O&M costs to estimate the net present value life-cycle cost evaluation and
2
payback period. The net present value of implementing each technology is quantified on an individual and
cumulative basis, to identify the cost-effectiveness of each technology. The goal of the model is to provide
a tool to evaluate the cost-effectiveness of implementing ECMs within a reasonable level of effort.
1.1
Overview of the Aeration Process
The main purpose of aeration in conventional wastewater treatment processes is to stimulate
bacteria and protozoa to consume the organic material in wastewater. In the presence of oxygen, various
strains of bacteria incorporate organic matter into their biomass, replicate, and produce extracellular
polymers that result in the formation of biological flocs. Flocs are bodies made up of multiple bacterial
colonies that are heavier and have less surface area than the sum of their parts. Some of the organic
material is completely metabolized into simple end products such as carbon dioxide and water
(Tchobanoglous et al., 2003), but the majority remains solid material. Once exiting the aeration process, the
flocculated bacterial and organic matter enter the secondary clarification process which brings flow to a
relatively quiescent state, where most of the heavier flocs are able to settle out of the wastewater by gravity
and settle into a thickened sludge at the bottom of the tank, while the clarified effluent water overflows the
top of the tank and flows downstream where it is further treated.
A majority of the sludge containing
bacterial and protozoan biomass is then pumped back to the beginning of the aeration process to “seed” the
incoming flow as return activated sludge (RAS), and a smaller portion of the sludge is wasted as waste
activated sludge (WAS) to downstream solids treatment processes where it is ultimately disposed of.
Figure 1.2 provides an overview of a typical activated sludge treatment process with aeration. An aerial
photograph of the activated sludge treatment process at the City of Boca Raton WWTP is provided as
Figure 1.3 as an example.
3
Wastewater with
suspended organic
matter enters the
aeration basin
Bacteria and protozoa
incorporate organic matter
into their biomass and form
flocs in the presence of oxygen
A portion of biomass is returned
to the beginning of the aeration basin
to seed the incoming flow as RAS
Wastewater is brought
to standstill in clarifier
tank where flocs settle
out as sludge
Clarifier effluent spills
over the top of clarifier
tank for further treatment
downstream
A portion of the biomass wasted
to downstream solids treatment
processes as WAS
Figure 1.2 – Typical Activated Sludge Treatment Process with Aeration
Aeration Basin No. 1
Clarifier No. 1
Aeration Basin No. 2
Aeration Basin No. 3
Clarifier No. 2
Figure 1.3 – Aerial Photograph - City of Boca Raton Activated Sludge Treatment Process (Photo by
Google Earth)
4
1.2
Less Efficient Mechanical Aeration Versus More Efficient Fine-Bubble Diffused Aeration
The two most common methods of providing oxygen to wastewater in the aeration basin are
mechanical aeration or diffused aeration systems. Mechanical aeration is provided by large impellers that
are submerged in the wastewater and rotated using high capacity electric motors which consume a large
amount of electricity. For example, the Broward County North Regional WWTP utilizes twenty four 100
horsepower (hp) aerators in their module A and module B aeration basins, for a total nameplate power draw
of 2,400 hp. The mechanical aerator impellers agitate the wastewater so that it is splashed into the air at
the water surface, which increases the rate of transfer of oxygen from the atmosphere into the aqueous
phase. The three plants investigated in this study; the City of Boca Raton WWTP, Broward County North
Regional WWTP, and Plantation Regional WWTP, each utilize mechanical aeration. A view of one of the
mechanical aerators at the Plantation Regional WWTP is provided as Figure 1.4.
Figure 1.4 – Surface Mechanical Aerator – Plantation Regional WWTP
It has been well established that diffused air systems, specifically fine bubble diffused air systems,
are much more efficient at oxygen transfer than mechanical aeration (Shammas et al., 2007). The small
bubble size produced by fine bubble diffusers has a high surface area to volume ratio, which allows much
higher oxygen transfer efficiency compared to mechanical aeration. Thus, implementing fine bubble
5
diffused aeration at the treatment plants currently utilizing mechanical aeration will lead to cost and energy
savings.
Fine bubble diffusers are referred to throughout this paper as ECM No. 1. A view of a fine
bubble diffuser is provided as Figure 1.5 below.
Figure 1.5 – Fine Bubble Diffuser (Photo by ITT Water and Wastewater – Sanitaire)
1.3
Less Efficient Multi-stage Centrifugal Blowers versus More Efficient Single-stage Turbo
Blowers
For diffused air systems, it is necessary to provide a high volume of relatively high pressure air to
the diffusers. A blower is a compressor that is operated by a high-capacity electric motor which supplies
high-volume, high-pressure air to the activated sludge treatment process. In recent history the most
common blower technology for supplying air at WWTPs has been the multi-stage centrifugal blower,
which is a blower where multiple impellers are mounted on a common rotor shaft. More recently, a new
blower technology has come into use known as turbo blowers, which comprises a high-efficiency single
impeller direct-driven by a high-speed permanent magnet motor and variable frequency drive (VFD) to
achieve speed and airflow turndown. The first turbo blower units in North America were installed in 2004
(Rohrbacher et al., 2010). The combination of the high efficiency impeller and VFD capability combine to
provide efficiencies of approximately 10 to 15 percent greater than a comparable multi-stage centrifugal
blower (Rohrbacher et al., 2010). Thus, implementing turbo blowers instead of the typical multi-stage
centrifugal blowers at the treatment plants currently utilizing mechanical aeration could lead to cost and
6
energy savings.
Turbo blowers are referred to throughout this paper as ECM No. 2. Figure 1.6 provides
a view of a multi-stage centrifugal blower and a turbo blower.
Turbo Blower (Photo by Gray and Osborne, Inc.)
Multi-Stage Centrifugal Blower (Photo by HSI, Inc.)
Figure 1.6 – Multi-Stage Centrifugal Blower and Turbo Blower
1.4
Less Efficient Manual DO Control Versus More Efficient Automatic DO Control
Another way that WWTPs can save energy is by optimizing the amount of air that is supplied to
the aeration basins, by continuously varying the amount of air supplied based on the amount of oxygen
required by the treatment process. It is common for WWTPs to control the amount of air supplied based on
DO level, where most plants attempt to maintain a DO level of 1 to 3 mg/L in aeration basins. The most
common, yet inefficient method to control DO is the manual DO control strategy, where operators take one
or more manual readings of DO throughout the day. DO is typically measured with a handheld meter or insitu meter, and then a corresponding airflow rate to meet the required DO. The manual control method is
lacks accuracy and is most likely to result in excessive electricity costs, because operators must
conservatively set the airflow to a high setting that will meet the maximum oxygen demand during the time
of day where the peak wastewater loading occurs.
The alternative is the automatic DO control strategy, which utilizes DO sensors that are
permanently submerged in the wastewater of the aeration basins and continuously take readings and
“feedback” signals to a controller.
The controller then automatically adjusts airflow to maintain a
predetermined DO set point (typically 1 to 3 mg/L) by continuously adjusting the blowers and/or motor7
operated air distribution control valves to each basin. The automatic DO control feedback strategy greatly
reduces electricity costs when compared to manual DO control by preventing overaeration.
Recent
advances in DO probe technology within the past 10 years have increased the reliability of using automatic
DO control. Figure 1.7 shows a typical DO response curve plotted against the DO level of an aeration
basin with and without automatic DO control. The figure demonstrates how manual DO control results in
excessive aeration at most times during the day except for the time of peak oxygen demand, compared to
automatic DO control which maintains a constant low DO level which results in energy savings.
8.0
1,600
Manual DO control ‐ excessive DO is supplied throughout the day except for time of peak oxygen demand
1,400
Oxygen Demand (lb/hr)
DO supplied (manual control) (mg/L)
7.0
1,200
6.0
1,000
5.0
800
4.0
600
3.0
400
2.0
Automatic DO control ‐ DO is maintained at predetermined setpoint, preventing wasted
energy by supplying excessive air
200
DO Supplied (mg/L)
Oxygen Demand (lb/hr)
DO supplied (auto control) (mg/L)
1.0
0.0
0
0:00
4:00
8:00
12:00
Time of Day
16:00
20:00
0:00
Figure 1.7 – Manual vs. Automatic DO Control
A view of a typical DO controller and DO probe is shown in Figure 1.8. Automatic DO control
strategy is referred to throughout this paper as ECM No. 3. The automatic DO control system installed
alongside the aeration basins at the Jacksonville Electrical Authority (JEA) – Arlington East Water
Reclamation facility in Jacksonville, Florida is provided as Figure 1.9 for example.
8
DO controller – controller
processes signal from
probe, and sends signal to
motor operated valve to
open/close, or blower to
increase/decrease airflow
DO probe - probe is
permanently submerged in
wastewater, and provides
signal to DO controller
Figure 1.8 – Automatic DO Controller (Photo by Hach Company)
Figure 1.9 – Automatic DO Control System
9
1.5
Combining Technologies to Optimize Efficiency
In the previous sections, three ECMs were discussed that can be employed at WWTPs; ECM No.
1 - fine bubble diffusers; ECM No. 2 - single-stage turbo blowers; and ECM No. 3 - automatic DO control.
By combining the three ECMs, energy efficiency can be maximized. It will be shown in this paper that fine
bubble diffusers potentially account for an approximate 20 percent increase in efficiency in the aeration
process, single-stage turbo blowers potentially account for a 10 percent increase in efficiency, and
automatic DO control accounts for an approximate 20 percent increase in efficiency. The combination of
all three technologies can potentially result in a total potential increase in energy efficiency of
approximately 50 percent within the aeration process.
Case studies for making similar improvements to
aeration basins have shown increases in efficiency as high as 77% (Peters et al., 2008).
A model was developed and presented which uses historical plant monitoring data to estimate the
energy and cost savings achieved by implementing the innovative aeration technologies discussed above.
Capital costs, O&M costs, and energy savings are estimated and a life cycle cost analysis is completed for
the following options.
•
Base case – implement no ECMs, continue operating with mechanical aeration
•
ECM No. 1 – fine bubble diffusers
•
ECM No. 1 – fine bubble diffusers, and ECM No. 2 – single-stage turbo blowers
•
ECM No. 1 – fine bubble diffusers, ECM No. 2 – single stage turbo blowers, and ECM No. 3 –
automatic DO control
Figure 1.10 illustrates the proposed ECMs for each option:
10
Surface mechanical aerators
Aeration Basin
Aeration Basin
ECM No. 1 - fine bubble diffusers
Existing system
Aeration Basin
Aeration Basin
ECM No. 2 – turbo blowers
ECM No. 3 – automatic DO control system
Figure 1.10 – Existing Aeration Basin and Proposed ECM Nos. 1 through 3
1.6
Summary of Facilities Studied
The model developed to estimate the energy savings and resulting cost savings by implementing
ECMs was applied to the plants shown in Table 1.1. These facilities are the only three plants in the
Southeast Florida region that currently utilize mechanically aerated conventional activated sludge treatment
processes.
11
Table 1.1 – Study Facility Summary
PLANT NAME
CITY
AERATION SYSTEM SUMMARY
17.5 MGD capacity plant, (3) 2.1 MG aeration basins each with (3)
Boca Raton WWTP Boca Raton, FL 100-hp mechanical surface aerators. (3) multi-stage centrifugal
blowers provide peak season / high loading supplemental aeration.
Broward County
95 MGD capacity plant with both mechanical and fine bubble
Pompano
North Regional
diffused aeration. Study focuses on (8) 2.2 MG aeration basins
Beach, FL
WWTP
each with (3) 100-hp mechanical surface aerators.
Plantation Regional
18.9 MGD capacity plant with (3) 1.1 MG aeration basins each with
Plantation, FL
WWTP
(1) 125-hp and (2) 100-hp mechanical surface aerators.
12
II - LITERATURE REVIEW – DISCUSSION OF THE STATE OF THE ART IN ACTIVATED
SLUDGE PROCESS CONTROL AND KEY MODELING ASSUMPTIONS
2.1
Energy Conservation Measure Case Studies
ECMs implemented by various municipalities have been presented and documented at the Water
Environment Federation Technical Exhibition and Conferences (WEFTEC) and are presented to provide an
approximate range of energy savings actually achieved at plants implementing ECMs similar to those in
this study. The scope of information and methodology for each case varies too widely to make scientific
comparisons. For example, capital costs are given for some projects but not for others, capital costs that are
given for ECMs are not isolated from other non-ECM related improvements, and methodology for
measuring energy savings varies. However, a general survey of the ECM’s implemented and resulting
energy savings is provided for demonstrative purposes in Table 2.1.
13
Savings
DO
Control
Turbo
Blowers
Fine
Bubble
Diffusers
Plant
ADF
(MGD)
Table 2.1 – General ECM Case Study Survey
Description
Source
Add luminescent DO probes and master control panel,
replace (2) 300 hp multi-stage w/ (2) 250 hp single stage
City of Conroe
WWTP (TX)
6.4
9
9
9
77%
centrifugal dual-point control blowers (efficiency roughly
Peters et
equal to turbo), replace coarse bubble with fine bubble
al., 2008
diffusers, install modulating butterfly valves at each
aeration basin, maintaining DO at 2 mg/L
14
Green Bay
Mont-
Metropolitan
enegro
Sewer District DePere WWTF
8
9
37.5%
Replace (5) 450 hp multi-stage centrifugal with (6) 330
and
hp turbo blowers, add DO probes.
Shum-
(WI)
aker,
2007
Fort Myers
Central
Advanced
Demonstration project of replacing 250-hp multi-stage
11
9
36.6%
WWTP (FL)
centrifugal with turbo blower in aerobic digester w/
Bell et
coarse bubble diffuser, average DO of 1 mg/L as opposed
al., 2010
to 1.5 mg/L maintained
14
Savings
DO
Control
Turbo
Blowers
Fine
Bubble
Diffusers
Plant
ADF
(MGD)
Table 2.1 – General ECM Case Study Survey
Florence
WWTP
Demonstration
9
9
17%
(AL)
Description
Source
Add luminescent DO probes and master control panel to
Brog-
control (3) existing 350 hp multi-stage and (1) 150 hp
don et
multi-stage centrifugal blowers w/ fine bubble diffusers
al., 2008
by throttling intake valve, DO maintained at 2 mg/L DO
Unnamed
15
Poultry
Processing
1
9
22%
Add luminescent DO probes and VFD to existing
centrifugal blower w/ fine bubble diffusers
Facility (MS)
Brogdon et
al., 2008
Installed (2) influent TSS meter, updated DO probes to
luminescent probes, implemented model-predictive
Oxnard WWTP
(CA)
control strategy to continuously modify DO setpoint
22.4
9
20%
based on influent TSS and DO with existing single stage
centrifugal dual point control blowers and fine bubble
diffusers
Moise
and
Morris,
2005
Savings
DO
Control
Turbo
Blowers
Fine
Bubble
Diffusers
Plant
ADF
(MGD)
Table 2.1 – General ECM Case Study Survey
Description
Phoenix 23rd
Install feed-forward BIOS system (BioChem
Ave WWTP
Technology, Inc.) with DO, flow, TSS, temperature,
(AZ)
nutrient and flow measurement to control DO setpoints in
48
9
15.3%
different zones, with minimum DO setpoint of 2.0, 1.3,
and 0.7 mg/L in three zones of a modified Ludzack-
Source
Walz et
al., 2009
Ettinger process, compared to fixed DO setpoints of 2.5,
2.0, and 2.0 mg/L, respectively.
Install feed-forward/feedback model predictive control
16
system, with BOD, TSS, nutrient, flow, and DO
Abington
WWTP (PA)
2
9
5.5%
measurement in a preanoxic selector/aeration process for
Liu et
a reduction of DO from 2 mg/L setpoint to average
al., 2005
adjustable setpoint of 1.5 mg/L with minimum and
maximum setpoints of 1.0 and 2.0 mg/L, respectively
Install feed-forward BIOS system (BioChem
Technology, Inc.) with DO, flow, TSS, temperature,
Enfield WWTP
(CT)
5
9
13%
nutrient and flow measurement to control DO setpoints in
Liu et
different zones of a modified Ludzack-Ettinger process to
al., 2005
unreported values, compared to fixed DO setpoints of
2.75, 2.0, and 0.5 mg/L, respectively.
Local ECM Case Study
Locally, the City of Pembroke Pines WWTP is currently replacing their existing multi-stage
centrifugal blowers with new turbo blowers. Six existing 100 hp and seven existing 200 hp blowers are
being replaced with four 150 HP and four 250 HP blowers provided by Houston Services Industries (HSI).
The blowers currently provide the process air to the 9.5-MGD plant equipped with Sanitaire silver series
fine bubble diffusers, one one-million gallon and one 500,000 gallon surge tanks, and one 70,000 gallon
sludge holding tank. The plant has an average annual daily flowrate (ADF) of 6.75 MGD and an average
annual BOD concentration of 294 mg/L. The system is designed to maintain a minimum DO concentration
of 2.0 mg/L (Pembroke Pines, 2011).
The project is still under construction at the time of publication. However, yearly power savings
estimates range from $27,000 to $73,000 annually, or 5.0% to 15.6% of the existing cost. Capital cost for
the blowers portion of the project is approximately $1,222,000 (Pembroke Pines, 2011). Assuming the
same bond discount rate and inflation assumptions for the life cycle cost analysis discussed later in this
report, a life cycle cost payback of 21 years results assuming $73,000 of annual power savings, to no
payback assuming the $27,000 of annual power savings. However, when considering that the existing
blowers were at the end of their service life and would be required to be replaced, an approximate capital
cost replacement of $900,000 was avoided. This consideration results in a life cycle cost payback of 5
years assuming $73,000 of annual power savings, to a 15 year payback assuming the $27,000 of annual
power savings.
2.2
Fine Bubble Diffusers
The principal types of aeration are diffused aeration, mechanical aeration, and high-purity oxygen
systems. High purity oxygen systems are not within the scope of this study. It has been well established
that diffused air systems, specifically fine bubble diffused air systems are much more efficient at oxygen
transfer than mechanical aeration or coarse bubble diffused air technology (Shammas et al., 2007). The
smaller bubble size produced by fine bubble diffusers has a high surface area to volume ratio, which allows
much higher oxygen transfer with the same volume of air as other technologies. As such, only fine bubble
17
diffused air technologies are considered in this paper. Table 2.2 summarizes fine bubble technologies
possessing the highest standard oxygen transfer efficiencies (SOTEs):
Table 2.2 - Fine Bubble Diffuser Technologies with Highest SOTE’s
Airflow rate
SOTE at 15-ft
Diffuser type and placement
scfm/diffuser
submergence (%)
Ceramic discs
0.4–3.4
25–40
Ceramic domes
0.5–2.5
27–39
Perforated flexible membrane discs
0.5–20.5
16–381
Nonrigid porous plastic tubes
1–7
19–371
1
Wider Range of Transfer Efficiency generally attributed to wider airflow rate range, transfer efficiency generally goes
down as airflow rate increases
(Shammas et al., 2007)
The perforated flexible membrane diffusers can provide energy savings beyond improved transfer
efficiency. Most membranes are required to be constantly submerged when not in use to prevent diffuser
degradation, including perforated membrane and ceramic diffusers. However, ceramic membranes require
air to be continually fed through the membranes even when the aeration basin is not in use to prevent
permanent fouling of the diffuser pores. Air to perforated flexible membrane diffusers can be completely
turned off, which can result in substantial energy savings (Cantwell et al., 2007). Since the perforated
flexible membrane discs have a high relative SOTE and have operational flexibility to completely turn off
airflow, this technology will be considered as the state of the art for comparison purposes. Membrane
diffusers have a useful life of 5 to 10 years, depending on operating conditions (Schroedel et al., 2010).
2.3
Blower Technology
WWTPs typically use four types of blowers for aeration as listed below:
•
Rotary lobe positive displacement blower
•
Single-stage dual guide vane blower
•
Multi-stage centrifugal blower
•
Single-stage turbo blower
18
A brief description of the four technologies are provided below.
Rotary Lobe Positive Displacement Blower
Rotary lobe positive displacement blowers have a wire to air efficiency of 45 to 65 percent, which
is the least efficient of the blower technologies typically implemented in a wastewater aeration process
(Liptak, 2006; O’Connor et al., 2010). Although less efficient (especially at lower speeds), advantages of
the positive displacement blowers are that they have a greater ability to turndown with VFDs compared to
the other blower technologies, can operate at a wide spectrum of pressures, and generally have the lowest
capital cost of the blower alternatives. Another benefit is that the control systems are relatively simple. A
view of a positive displacement blower is provided in Figure 2. 1.
Inlet
Outlet
Rotating Lobes
Figure 2.1 – Positive Displacement Blower Cross-Section (Photo by Aerzen USA Corporation)
Single-stage dual guide vane blowers
Dual guide vane control blowers have the ability to turndown speed and flow while maintaining a
relatively constant efficiency compared to multi-stage centrifugal and positive displacement blowers.
Single-stage centrifugal blowers range from 70 percent to 80 percent wire to air efficiency for designs
utilizing advanced impeller and case aerodynamics (Liptak, 2006; O’Connor et al., 2010). Inlet guide
vanes convert pressure drop into rotational energy to increase the efficiency of single stage blowers, and
19
variable diffuser vanes on the blower outlet control the flowrate (Lewis et al., 2004). The vanes continually
adjust their position to optimize efficiency. The dual vane control technology allows for a flow capacity of
approximately 45 to 100 percent with relatively constant high efficiency, and can be operated with a VFD
to achieve additional flexibility. The single-stage dual guide vane blowers tend to have higher maintenance
than other blower alternatives due to more complex mechanics. On plant in South Florida reports annual
maintenance costs of approximately $15,000 per blower, related to accelerated corrosion and locking of
guide vanes due to the humid south Florida climate. A cross section of a dual guide vane control blower is
provided in Figure 2.2.
Outlet
Inlet
Inlet Guide Vanes
Variable Diffuser Vanes
Impeller
Figure 2.2 – Dual Guide Vane Control Blower Cross-Section (Graphic by Siemens, Inc.)
Multi-Stage Centrifugal Blowers
Multi-stage centrifugal blowers are the most common type of blower used in the activated sludge
process (Schmidt Jr. et al., 2008), due to relatively high efficiencies compared to positive displacement
blowers and mechanical simplicity compared to single- stage dual guide vane blowers.
Multi-stage
centrifugal blowers have a wire to air efficiency between 50 to 70 percent (Liptak, 2006; O’Connor et al.,
2010). Similar to positive displacement blowers, multi-stage centrifugal blowers efficiency decreases with
20
speed. Multi-stage centrifugal blowers are also limited in their ability to turndown flow to a minimum of
about 55 percent before the blowers begin malfunctioning, by demonstrating a condition known as surging.
A cross section of a dual guide vane control blower is provided in Figure 2.3.
Outlet
Inlet
Impeller (one of
multiple stages)
Figure 2.3 – Multi-Stage Centrifugal Blower Cross-Section (Graphic by Gardner Denver, Inc.)
Single-Stage Turbo Blowers
Turbo blowers are direct-driven by high-speed permanent magnet motors and utilize VFDs to
achieve speed and flow turndown. Turbo blowers have reported wire to air efficiencies of 70 to 80 percent
(Rohrbacher et al., 2010; O’Connor et al., 2010). Rohrbacher et al., 2010, documented three life cycle
analysis case studies where turbo blowers were found to result in 10 to 15 percent present worth cost
savings compared to multi-stage centrifugal blowers. Turbo blowers have 10 to 20 percent greater
efficiency than the most-commonly utilized multistage centrifugal blowers. However, unlike dual vane
single stage blowers, turbo blowers are not capable of maintaining constant efficiencies throughout the flow
21
range, so when turned down the reported high efficiencies of turbo blowers drops off. Turbo blowers use
magnetic or air bearings which reduce maintenance compared to other blowers.
Besides having a high efficiency, advantages of turbo blowers are smaller footprint and ease of
installation compared to other blower options. Disadvantages of turbo blowers are that they typically have
a higher capital cost than multi-stage centrifugal or positive displacement blowers, and the airflow
capacities are currently limited to approximately 7,000 standard cubic feet per minute (scfm) meaning
multiple units must be installed in larger systems, or dual units that consist of two blowers operated by a
common rotor and stator. Turbo blowers were recently introduced to the municipal market in 2007,
therefore the general long-term performance is unknown (O’Connor et al., 2010). A cross section of a dual
turbo blower is provided in Figure 2.4.
Outlet
Stator
Rotor
Impeller
Inlet
Air foil
bearings
Figure 2.4 – Turbo Blower (Dual) Cross-Section (Graphic by APG Neuros)
Selection of Blower Technology
Turbo blower and single-stage dual guide vane blowers have similar efficiencies. However, dual
guide vane blowers typically require more maintenance due to more mechanical complexity, which can be
exacerbated by the humid south Florida climate. For the purpose of predicting capital and O&M costs,
turbo blowers are considered to be the state of the art. Based on efficiency and capital cost, it will be
demonstrated that turbo blowers have equivalent or less present value cost compared to the conventional
22
blower alternative of multi-stage centrifugal blowers, while utilizing less energy (O’Connor et al., 2010).
Table 2.3 summarizes the comparison of key blower technology parameters.
Table 2.3 – Blower Technology Comparison
Parameter
Positive
Displacement1
Multi-Stage
Centrifugal1
Single-Stage Dual
Guide Vane1
Turbo2
Wire to Air Efficiency
45 - 65
50 - 70
70 - 80
70 - 80
Capital Cost Factor3
1
1.5
2.5
2.4
Limited
Yes but not
necessary to
achieve high
efficiencies
Required
VFD Capability
Yes
1. (Liptak, Keskar, 2006), (O’Connor, 2010)
2. (Rohrbacher, 2010), (O’Connor, 2010), (Hazen and Sawyer, 2011), (Atlas Copco, 2008)
3. Capital cost factor indicates ratio of capital cost from 1 technology to the other. For example, multistage centrifucgla
blowers are approximately 1.5 times more expensive than positive displacement blowers
2.4
DO Control Strategy
The ratio of minimum to maximum oxygen demand within a typical activated sludge process
varies from approximately 3:1 to 5:1 between the peak and off-peak hours. For smaller plants the ratio can
be as much as 16:1 (Tchobanoglous et al., 2003). As wastewater flow and strength fluctuate, there is a
corresponding fluctuation in the amount of oxygen required to provide treatment. It is common to maintain
a DO level of 1 to 3 mg/L in aeration basins to ensure adequate oxygen is supplied to sustain the
microorganisms in the wastewater. There are two main alternatives for controlling the DO level in aeration
basins; manual DO control, or automatic DO control.
2.4.1
Manual Control
The most simple DO control strategy is manual control, where operators take periodic manual
readings of DO, or less commonly parameters related to DO such as nitrate concentration, ammonia
concentration, or average influent flow and mixed liquor suspended solids (MLSS) concentration. The
operator then manually sets a corresponding airflow rate to meet the required DO by adjusting valves or
blowers settings. However, because operators must conservatively set the airflow to the maximum worstcase airflow demand incurred during peak flow and wastewater strength, the result is that during many
23
times of the day DO levels higher than 1 to 3 mg/L are supplied, resulting in wasted energy. If additional
readings are taken throughout the day to more closely match air supplied to DO required, then labor costs
are increased.
Supplying excessive DO beyond that required by the activated sludge process can inhibit nutrient
removal of phosphorous. Conversely, supplying too little DO can also cause problems with effluent quality
like TSS, BOD, and ammonia. Reduced settleability and breakthrough of nitrite into the effluent causing
disinfection problems are also a concern related to low DO (Ekster et al., 2007).
2.4.2
Automatic DO Control
The main alternative to manual DO control is the automatic DO control strategy, which utilizes
DO sensors to continuously take DO readings and “feedback” signals to a controller that automatically
adjusts airflow to maintain a predetermined DO setpoint, (typically 1 to 3 mg/L), by continuously adjusting
the blowers and/or air distribution control valves to each basin. As such, implementing automated DO
control can greatly reduce electricity costs, operator workload, and help to maintain consistent effluent
quality.
By consistently matching the amount of air supplied to the amount of oxygen required to maintain
a DO setpoint, automatic DO control can prevent overaeration and resulting wasted electricity when
compared to manual DO control. However, the method of feedback control has some inherent problems in
that it is constantly controlling airflow to affect a change in DO after the high or low DO condition has
already occurred (and energy wasted). The automatic DO control strategy can also be problematic due to
the delayed response in DO following change in airflow. Additionally, problems with the control logic can
cause wide valve oscillations and blower output oscillations. In the past, unreliable control loop elements
that were hard to control and prone to fail such as DO meters have been problematic when utilizing the DO
control strategy (Ekster et al., 2005). However, recent advances in DO probe technology have increased
the reliability of using automatic DO control.
A variety of components in an aeration system can be controlled with the automatic DO control
strategy to optimize and control air flowrate. Depending on the type of blower technology, these options
include changing the total system airflow by continuously throttling the blower intake valve, changing the
24
speed of the blower motor with a VFD, repositioning the inlet guide vanes and discharge control vanes, or
other methods. The airflow to individual aeration zones can be controlled by adjusting air distribution
control valves. There are various DO control strategies available which are discussed in the following
sections. Figures 1.7 though 1.10 in the introduction illustrate the automatic DO control concept and
associated equipment.
2.4.3
DO Probes
One limiting factor in implementing well functioning DO control systems in the past has been the
unreliability of DO probes. Older galvanic and polarographic membrane-type DO probe technology using
anodes, cathodes, membranes, membrane-cleaning devices, and electrolyte solutions are relatively
unreliable (Liptak, 2006). Membrane DO probes are fragile and utilize an electrochemical process which
fouls the sensor, requiring frequent cleaning, maintenance, and recalibration (Hope, 2005).
Optical DO sensors use a light quenching process, as opposed to membrane-type probes that
utilize an electrochemical process which consumes oxygen. Optical DO sensors do not require flow across
the probes and do not intrinsically foul with byproducts from the oxygen-consuming electrochemical
measurement process. The optical DO probes are more accurate than membrane-type probes in measuring
low DO concentrations typical in activated sludge processes. Optical sensor probes have been installed in
activated sludge processes throughout the United States between 2000 and 2010 and have a record of
successful operation proving their reliability (Brogdon et al., 2008). Limited monthly and annual
maintenance and calibration of the optical probes are suggested by the manufacturers. The maintenance is
relatively unintensive compared to membrane probes which require time-consuming weekly calibration and
bimonthly membrane replacement of membranes (Brogdon et al., 2008).
2.4.4
Modulating Valves
To control DO level in different parts of the aeration basins, an automatic DO control system will
send a signal to one or more motor-operated modulating valves to open or close to sustain DO level within
a desired range. Automatically actuated equal percentage butterfly valves are commonly used in aeration
systems.
Facilities with valve actuators that are linear, equal percentage, and quick opening have had
success in controlling airflows (Liptak, 2006). The linear, equal percentage operators increase valve flow
25
capacity by the same percentage for each equal increment of travel, which simplifies control of the valves
and reduces tuning and calibration by instrumentation engineers. Therefore, automatically actuated equal
percentage butterfly valves are considered as state of the art.
2.4.5
Flow Meters
Automatic DO control systems typically have flow meters associated with each major control
valve so that operators can ensure flowrates are being maintained within a desired range in each aeration
basin section. Pitot tube, venturi tube, or thermal dispersion meters are typically used for measuring air
flow in aeration. The pitot tube is less accurate than the venturi or thermal dispersion. The venturi is
accurate but requires long runs of straight pipe upstream and downstream of the meter. Thermal dispersion
meters also require some distance of straight pipe upstream and downstream of the meter (Liptak, 2006).
Thermal dispersion devices in air service require cleaning once every six months (Hill et al., 2007),
whereas venturi flow tubes are not required to be removed and maintained. For this reason, venturi flow
tubes are considered the state of the art for this analysis. Figure 2.4.5.1 demonstrates the three main types
of flow meters.
Transmitter
Transmitter
Differential pressure
connections, transmitter
not shown
One heated and
one unheated
temperature
sensor
Pitot tube
Pitot Tube
Venturi Flow Tube Insert
(photo by ABB group)
(photo by BIF Flow Measurement)
Thermal Dispersion
(photo byABB group)
Figure 2.5 – Typical Flow Meters for Measuring Air Flowrates
26
2.5
Piping
Pipe materials for aeration process piping are often stainless steel, fiberglass, or plastics suitable
for high temperatures.
Mild steel or cast iron with external and interior coatings can also be used
(Tchobanoglous, 2003). Type 304 and 316 stainless steel are most commonly used in WWTPs. Type 304L
or Type 316L should be used when field welding is required due to the low carbon content. Type 316
stainless steel is approximately 40 percent more expensive than 304 stainless steel (MEPS International
LTD, 2012). Schedule 10S is a common thickness of stainless steel piping in aeration applications. Type
304L stainless steel piping provides the anti-corrosion benefits and durability of stainless steel with fieldweldability. For this reason, Schedule 10S 304L stainless steel is assumed for this analysis.
2.6
Summary of Technologies
The objective of this thesis is to identify the state of the art technology for ECMs in the activated
sludge process and determine the feasibility of their implementation on a cost-benefit basis at WWTPs in
South Florida. The preceding section has discussed the various alternatives for ECMs in the activated
sludge process. It is emphasized that the technologies identified here are for the purposes of providing a
general framework to estimate the costs and benefits of implementing ECM’s at WWTPs on a regional
basis. Every WWTP is unique in what technologies are most appropriate and could vary significantly from
those identified here on an individual basis. The findings of the preceding sections are summarized in
Table 2.4:
27
Table 2.4 – Summary of Technologies
System Component
State of the Art
ECM No.
Fine Bubble Diffusers
Perforated flexible membrane disk in grid pattern
1
Piping
304 L Sch 10S stainless steel
2
Blowers
Single stage centrifugal turbo
2
DO control
Automatic DO Control
3
DO probes
Optical DO probes
3
Modulating valves
Modulating equal-percentage butterfly
3
Flow meters
Thermal dispersion or venturi
3
2.7
Key Assumptions For Aeration Model
2.7.1
DO Levels
To model the energy consumption of implementing the various DO control strategies identified in
Section 2.4, case studies and authoritative texts were researched to determine the appropriate values to be
used. WEF MOP 8 recommends a design value of 1 to 2 mg/L DO for aerobic selectors (Krause et al.,
2010). (Mueller et al., 2002 indicates that a design value of 2 mg/L is typical for designing activated sludge
processes at average loading. Stenstrom et al., 1991indicated that values to achieve adequate nitrification
range from 0.5 to 2.5 mg/L DO.
Manual DO Control – DO Level Assumptions
To ensure that the required DO concentration is maintained at all times during the day, operators
using a manual DO control strategy will typically set the airflow to a high setting that will meet the
maximum worst-case airflow demand during peak flow and loading. In turn, this strategy often results in
over aeration except when the air demand matches the worst-case flow and loading. Available case studies
using manual control were researched to determine an average design value to assume for modeling
aeration system energy consumption and detailed in Table 2.5. Table 2.5 demonstrates that manually
controlled DO levels throughout the day vary widely due to variable oxygen demand and constant air
supply. The mean value of available case studies indicates an average DO level of 3.2 mg/L is common for
28
manually controlled systems. Rounding to the nearest whole number, a conservative design value of 3.0
mg/L is assumed which may slightly understate the amount of energy typically consumed with manual DO
control based on the case studies reviewed. It will be shown this assumption should not greatly affect the
calculated payback.
Table 2.5 – Manual DO Control - Case Study DO Levels
Min
Max
Avg
(mg/L)
(mg/L)
(mg/L)
1
6
2.3
( Malcolm Pirnie, 2005)
1.5
6
3.1
(Brischke et al., 2005)
2
7
3.7
(Dimassimo, 2000)
2
7
3.6
(Schroedel et al., 2009)
Total Average
3.2
Model Value
3.0
Source
Automatic DO Control – DO Level Assumptions
Automatic DO control strategy relies on finding a suitable setpoint which will maintain adequate
DO levels at all design loadings. Some case studies using automatic DO control were researched to support
an average design value to assume for modeling aeration system energy consumption and detailed in Table
2.6. Table 2.6 demonstrates that automatically controlled DO level setpoints average approximately 1.4
mg/L for the case studies reviewed. Actual DO setpoint requirements will vary for specific WWTPs on a
case by case basis, depending on the wastewater constituents and strength, process design, effluent limits,
and other factors. Based on these results, a conservative design value of 1.5 mg/L is assumed.
29
Table 2.6 – Automatic DO Control – Case Study DO Levels
Min
Max
Avg
Source
2.7.2
(mg/L)
(mg/L)
(mg/L)
0.5
2.1
1.5
(Sunner, 2009)
0.5
2.75
1.75
(Liu, 2005)
0.75
3
1.4
(Brischke, 2005)
0.8
1.2
1
(Moise and Norris, 2005)
1.4
1.6
1.5
(Leber, 2009)
Total Average
1.4
Model Value
1.5
Blower Efficiency Assumptions
Rohrbacher et al., 2010, completed multiple life-cycle cost analyses comparing multi-stage
centrifugal blower to single-stage turbo blowers from 150 horsepower to 500 horsepower based on blower
curves provided by manufacturers. The study included over 17 single-stage turbo blowers and 5 multistage centrifugal blowers. The study indicated that the average wire-to-air efficiency of single-stage turbo
blowers over their operating curve was approximately 72 percent, whereas the average efficiency of multistage centrifugal blowers was 62 percent.
O’Connor et al., 2010, indicates the typical range the
efficiencies of single-stage turbo blowers to be 10% higher than multi-stage centrifugal blowers. The
values used in the Rohrabacher et al., 2010, case studies are at the lower end of this range and are used as
conservative assumptions.
2.7.3
Flowrate Assumptions
The typical planning period used for calculating life cycle cost analyses and also used in this study
is 20 years. Accordingly, the flowrate and loading used as the basis of comparison for each ECM and
scenario is the average flow over the 20 year planning period. Assuming a linear growth in loading and
flowrate over the 20 year design period, the average flowrate and loading is equal to the year 2021 average
daily flow and loading. The average flows over the 20 year planning periods are determined using various
methods depending on the data available for each plant and are discussed in Section 5.
30
2.7.4
Aeration Modeling Global Assumptions
The following assumptions are made for modeling the performance of the proposed aeration
systems.
Minimum Mixing Requirements
It is required to maintain a minimum level of aeration at all times to maintain minimum mixing
requirements. According to (Mueller et al., 2002) and (Krause et al., 2010), for a full-floor grid, 0.12
cfm/sf is a typical value for providing adequate mixing.
Minimum and Maximum Flow Per Diffuser
According to Sanitaire literature (Sanitaire, 2010), the Silver Series II diffuser has a range of 0.5 to
4.5 cfm per diffuser. Since the SOTE of the diffusers drops off at higher ranges, and to guard against
overshooting the diffuser range causing coarse bubble production, a conservative limit of 3.0 cfm per
diffuser is assumed at maximum day average flow and loading.
Beta
Beta is a factor which reduces the predicted oxygen transfer efficiency of the system based on total
dissolved solids concentration effects. A lower beta value results in reduced oxygen transfer per unit
volume of air supplied and higher energy consumption. According to (Mueller et al., 2002), for municipal
wastewater where TDS < 1,500 mg/L, an appropriate Beta value is 0.99. However, (Tchobanoglous et al.,
2003) report that values of 0.95 – 0.98 are typical. TDS concentrations greater than 1,500 mg/L is not
common in domestic wastewater, even at facilities blending nanofiltration or reverse osmosis concentrate
with effluent (Stanley et al., 2009). The high value of the (Tchobanoglous et al., 2003) recommended
range of 0.98 is assumed for the model.
Alpha
The alpha factor is the ratio of oxygen mass transfer coefficients in dirty water versus clean water.
It is generally accepted that alpha factors vary as a function of SRT in conventional activated sludge
treatment processes. A lower alpha value results in reduced oxygen transfer per unit volume of air supplied
and higher energy consumption. Alpha factors for fine bubble diffused aeration fall within 0.1 to 0.7, with
the average observed value of 0.4 (Krause et al., 2010). The alpha factors used in the models were
31
determined based on published SRT versus alpha data (Rosso et al., 2005). A conservative alpha value of
0.43 was assumed based on published SRT versus alpha data except in scenarios where full nitrification is
achieved, in which case an alpha value of 0.5 is assumed as would be expected with a higher SRT
associated with nitrification (Krause et al., 2010).
Temperature
A range of 23 to 27 degrees Celsius are typically recorded for wastewater temperatures during
sampling of WWTPs in South Florida. An average of 25 degrees is assumed for the model.
Standard Oxygen Transfer Efficiency
Tables that relate SOTE to flow per diffuser are provided by the diffuser manufacturer. Silver
Series II diffuser is assumed. A best fit fourth order curve is fit to the SOTE data available from Sanitaire
and is provided in Section 4.2.3 (Sanitaire, 2010).
Tau
The tau value (τ) is a termperature correction factor for the oxygen saturation value. Since
Henry’s law constant increases with increasing temperature, a termperature correction for the oxygen
saturation value must be applied. τ is interpolated using empirical oxygen saturation values from the
following Figure 2.6 (Mueller et al., 2002). A best fit exponential curve is fit to the data to obtain the
equation used in the model to estimate τ.
Tau (dimensionless)
1.6
y = 1.5394e-0.02x
R² = 0.9925
1.2
0.8
0.4
0
5
10
15
20
25
Temperature (°C)
Figure 2.6 – Temperature vs. Tau
32
30
35
40
III. LITERATURE REVIEW – COST ESTIMATING METHODS AND ASSUMPTIONS
3.1
Cost Estimate Level of Accuracy
The capital cost of construction for implementing the proposed ECM’s are estimated to compare
to the life-cycle cost evaluation of operating and maintaining the ECM’s. Cost estimates are by definition
not completely accurate, they are an estimate. A range of unknown and constantly changing conditions
affect the accuracy of an estimate, such as the economy, market conditions, and competiveness of bidding a
specific job, which in turn affect material, equipment, and labor rates (ASPE, 2008). The preliminarydesign level of project definition for ECM implementation at each wastewater treatment facility does not
imply a high level of accuracy. Rather, the goal of this analysis is to provide a reasonable level of
accuracy.
Multiple agencies, such as the Association for the Advancement of Cost Engineering (AACE),
American National Standards Institute (ANSI), and the American Society of Professional Estimators
(ASPE) recommend classifying cost estimates based on degree of project definition, end usage of the
estimate, estimating methodology, expected accuracy range, and the effort and time needed to prepare the
estimate. The Water Environment Federation – Manual of Practice 8 recommends using the AACE system
(Krause et al., 2010). ANSI recommends a three-tiered system of estimate classification. Both AACE and
ASPE define a five-tiered range of estimate classes, with AACE Class 1 being the highest level or project
definition and AACE Class 5 being the lowest level of project definition.
The AACE classes of estimate levels are reproduced in Table 3.1 below for reference and to help
demonstrate how the level of estimate used in this paper was determined by AACE International
Recommended Practice No. 18R-97 (Christensen et al., 2005).
33
Table 3.1 - AACE Estimate Class Level Characteristics (Christensen, 2005)
ESTIMATE
LEVEL OF
CLASS
DEFINITION
Class 5
0% to 2%
PURPOSE
METHODOLOGY
ACCURACY
EFFORT
RANGE
(As %
(Expected)
Of total cost)
0.005%
Concept
Capacity Factored,
Low: -20% to -50%
Screening
Parametric Models,
High: +30% to +100%
Judgment, or
Analogy
Class 4
1% to 15%
Study or
Equipment
Low: -15% to -30%
Feasibility
Factored or
High: +20% to +50%
0.01% to 0.02%
Parametric Models
Class 3
Class 2
Class 1
10% to 40%
30% to 70%
50% to 100%
Budget,
Semi-Detailed Unit
Low: -10% to -20%
0.015% to
Authorizati
Costs with
High: +10% to +30%
0.05%
on, or
Assembly Level
Control
Line Items
Control or
Detailed Unit Cost
Low: -5% to -15%
0.02% to 0.1%
High: +5% to +20%
Bid/
with Forced
Tender
Detailed Take-Off
Check
Detailed Unit Cost
Low: -3% to -10%
Estimate or
with Detailed
High: +3% to +15%
Bid/Tender
Take-
0.025% to 0.5%
Off
Study
Facilities
20% to 30%
Study or
Semi-Detailed Unit
Low: -20%
Feasibility
Costs with
High: +30%
0.1% to 0.3%
Assembly Level
Line Items
Table 3.1 and the Estimate Input Checklist and Maturity Matrix available in the AACE
International Recommended Practice No. 18R-97 were referenced to ascertain the recommended class of
estimate and associated accuracy range of the capital cost estimates. The level of project definition for the
case studies detailed in this paper demonstrate characteristics of both a Class 4 and Class 3 cost estimate.
The estimated level of project definition is 20 to 30 percent and the cost estimates do comprise semi34
detailed unit costs with assembly line items, consistent with Class 3 estimate characteristics. Additionally,
preliminary mechanical, electrical, instrumentation, and structural site drawings are completed, which are
characteristic of a Class 3 cost estimate and not a Class 4. However, when referencing the Estimate Input
Checklist and Maturity Matrix, many required deliverables are not developed to a preliminary or complete
level characteristic of a Class 3 estimate. As a conservative assumption, the cost estimates completed for
this project are considered to be AACE Level 4. Since the estimate does exhibit many characteristics of a
Class 3 level, the most conservative recommended Class 3 accuracy range (-20 to +30 percent) is assumed,
which falls within the confines of the Class 4 estimate accuracy (Low -15 to -30 percent, High +20 to 50
percent).
3.2
Life Cycle Cost Analysis Method And Assumptions
The electricity and maintenance costs will be incurred over the life of the operation of the plant.
Electricity costs are subject to a different rate of escalation than general inflation. For this reason, the
appropriate equations to use for calculating net present value considering the contrasting escalation rate of
energy costs over general inflation are the Present Worth of a Geometric Gradient Series equations.
⎡1−(1+ g)n(1+i)−n ⎤
P= A1⎢
⎥
i −g
⎣
⎦
if i ≠ g
(1)
⎡n⎤
P= A1⎢ ⎥ if i = g
⎣1+i⎦
Where P = present value
A = annuity value
n = number of periods
i = average annual bond rate (%)
g = average annual inflation rate (%)
The appropriate equation to use for calculating net present value of annual costs that rise with
inflation such as operation and maintenance costs over general inflation are the Present Worth of a Periodic
Series equation.
35
(2)
Where P = present value
A = annuity value
n = number of periods
i = average annual bond rate (%)
Payback
This paper compares the energy savings of implementing ECMs to the sum of capital costs, and
present value of change in operation and maintenance costs and foregone capital costs. The payback is
defined as the point in time at which the accruing energy savings realized by implementing the ECMs is
equal to the capital cost and change in O&M cost, and foregone capital cost. This can be expressed as
follows:
Penergy saving,n = Capital Cost + Pforegone caital + P∆O&M,n
(3)
Where Penergy savings = present value of energy savings at time = n
Capital Cost = capital cost for implementing ECMs
Pforegone capital = capital improvements avoided by implementing ECMs
P∆O&M,n = present value of change in O&M costs due to implementing ECMs
Payback = n = number of periods per equation (1) and (2) (years), solved for iteratively in
equation (3)
Inflation rate
The Consumer Price Index (CPI), reported by the U.S. Bureau of Labor Statistics, is the most
common indicator for price and wage inflation. It is the most common indicator used by businesses and
labor unions in making economic decisions and adjusting income payments. Over 80 million Americans
collecting Social Security, Federal Civil service pensions, and Federal food stamp recipients are affected by
the CPI (US BLS, 2010).
The Producer Price Index is another common indicator for inflation. The PPI measures the average
change in selling prices received by domestic producers of goods and services over time from the
36
perspective of the seller.
The PPI contrasts with the CPI, which measures price change from the
perspective of the purchaser. Sellers' and purchasers' prices differ because of distribution costs, sales and
excise taxes, and government subsidies (US BLS, 2010).
Since the planning period for the life-cycle cost analysis is over 20 years, the annual average CPI
is assumed. The US BLS has been reporting CPI statistics since 1919. The US BLS 1919 to 2010 annual
average CPI inflation rate is 3.0 percent. For comparison, the more recent US BLS 1991 to 2010 20-year
annual average CPI inflation rate is similar at 2.5 percent, whereas the 20-year PPI average is 2.3 percent
(US BLS, 2010). For the purposes of this analysis, the more conservative 2.5 percent inflation rate is
assumed, which will effect wages and electricity rate. The small difference between CPI and PPI will not
have a substantial effect on a lifecycle cost analysis.
Electricity costs and electricity escalation rate
Electricity rates used in the life cycle cost analysis are subject to escalation over the course of the
planning period and are taken into account. The Annual Energy Outlook (AEO) reports released by the
United States Energy Information Administration (US EIA) are used to predict trends in the national price
of electricity. According to the 2011 AEO, long term electricity trends will be relatively steady. Figure 3.1
demonstrates that the 2011 real average electricity price of 9.0 cents per kilowatt-hour (kWh) is predicted
to increase to 9.2 cents per kWh in 2035 (in 2011 dollars) for a predicted 0.09 percent annual rise in real
electricity rate over the rate of inflation (US EIA, 2011).
37
9.3
9.2
9.2
Cents / kWh
9.1
9.1
9.0
9.0
8.9
8.9
8.8
8.8
2010
2015
2020
2025
2030
2035
Year
Figure 3.1 –2011 - 2035 AEO Report Predicted US Electricity Real Rates
Variations in key assumptions in the AEO reports can result in different outlooks for electricity
prices, especially in the long term. Figure 3.2 below demonstrates the variation in predicted electricity
inflation rates from the AEO 2006 report to the current AEO 2011 report. The 2009 AEO Report predicted
a rise in energy inflation due to the 2008 spike in global oil prices. More recently, predicted energy
inflation has dropped and actually turned negative due to the 2010-2011 global recession. The AEO
predicts electricity prices for “side cases”, based on the sensitive variables of US annual gross domestic
product (GDP) and global oil prices, and the effects of the variations in those variables are also
demonstrated in Figure 3.2 and Table 3.2.
The assumptions for the AEO 2011 Report side case
assumptions are included in Table 3.3.
38
1.0%
Base Case
AEO Report Annual Inflation Prediction
0.8%
High Economic Growth
Low Economic Growth
0.6%
High Oil Price
Low Oil Price
0.4%
0.2%
0.0%
2005
2006
2007
2008
2009
2010
2011
2012
‐0.2%
‐0.4%
‐0.6%
Year
Figure 3.2 – 2006 – 2011 AEO Report Predicted US Electricity Annual Real Inflation Rates
Table 3.2 – 2006 – 2011 AEO Report Average Predicted US Electricity Annual Real Inflation Rates
AEO Report Year
Base
Case
High
Economic
Growth
Low
Economic
Growth
High Oil
Price
Low Oil
Price
2006 – 2011 Average
0.08%
0.25%
-0.13%
0.20%
0.08%
Table 3.3 – 2011 AEO Report Base and Side Case Assumptions
Low
GDP
Base
GDP
High
GDP
2.1%
2.7%
3.2%
Low Oil
Price
Base Oil
Price
High Oil
Price
$50
$78
$200
Due to the variability in AEO electricity inflation predictions, the average of the base case from
the 2006 through 2011 reports of 0.08 percent is assumed. While this rate will have a minimal effect on the
outcome of the model, adding the capability into the model for consideration of energy inflation provides
39
the capability of modeling the effects of unpredicted future fluctuations in energy price or theoretical
scenarios.
The electricity costs for the facilities in this report were obtained through the average cost per
kWh. According to interviews with plant staff and review of electric bills, the three facilities in this study
are currently paying an average price of $0.07 per kWh (FPL, 2011). As recently as the end of 2009,
electricity costs for WWTPs in south Florida were averaging $0.09 per kWh. A recent precipitous drop in
southeast Florida plant’s electrical bills from 2009 to 2010 of approximately 20 percent occurred, due to a
reduction in “pass through fuel charge” from FPL. If fuel charges increase again on a similar scale, life
cycle cost analysis results could be greatly affected.
Discount (Bond) Rate
The discount rate is the return on capital that could be earned had the capital been invested or used
to pay down debt, as opposed to utilized for the capital project. The interest that could have been earned or
saved is “discounted” from the life-cycle cost analysis as a deduction to the net present value of a project.
The regulations that govern the State Revolving Fund (SRF) Program (40 CFR 35.2130[b][3], U.S. EPA
[1978]) mandate that facilities using the program use the discount rate established by the United States
Environmental Protection Agency (US EPA) for the year that facilities planning commences (Krause et al.,
2010). The Florida Department of Environmental Protection (FDEP) calculates the SRF funding rate based
on the bond market rate for interest established using the “Bond Buyer” 20-Bond GO Index published by
the Thomson Publishing Corporation. For the April to June 2011 3-month period, the bond market rate is
4.70 percent. It should be noted that projects that qualify for funding through the SRF program typically
receive funding at 60 percent to 80 percent of the market rate, which would improve the results of the lifecycle analysis. As a conservative assumption, no SRF funding revenue is assumed for the ECM analyses.
The United States Department of Energy (US DOE) annually publishes required discount rates to
use for projects funded under the Federal Energy Management Program (FEMP) in the Energy Price and
Discount Factors for Life-Cycle Cost Analysis Supplement (OMB, 2010). The discount factors reported
are used with the FEMP procedures for life-cycle cost analysis established by the US DOE in Subpart A of
Part 436 of Title 10 of the Code of Federal Regulations (10 CFR 436A) and summarized in the National
40
Institute of Standards and Technology (NIST) Handbook 135 (Fuller et al., 1995).
The discount factors
are specifically for use with federal projects related to energy and water conservation investments. While
the study facilities are not federal facilities, the aforementioned documents provide standardized guidelines
to follow when conducting life cycle cost analyses at publicly owned facilities. The US DOE Supplement
requires that applicable facilities use a nominal discount rate based on long-term Treasury bond rates
averaged over the 12 months prior to the preparation of this report.
The US Treasury Bond rate
approximates the interest rate a municipality would have to pay for a municipal bond issue. The US DOE
Supplement indicates that a nominal discount rate of 3.9 percent, which includes inflation, be used as the
discount rate for life-cycle cost analyses completed in 2011 (OMB, 2010).
Based on the FDEP, SRF, and US DOE recommended discount rates for public project life-cycle
cost analyses and the prevailing market interest rate for municipal bonds, a conservative nominal discount
rate of 4.7 percent which includes inflation is assumed for this analysis. It should be noted that factors such
as funding aid through programs such as the SRF program could greatly increase the cost-benefit ratio of
the analysis.
Planning Period and Life Expectancies
The planning period used for calculating life cycle cost analyses is typically 20 years. Equipment
is typically expected to have a design life expectancy of 15 to 20 years (Krause et al., 2010). Equipment
that is expected to last longer than the planning period can be recognized by realizing a salvage value at the
final year. Equipment that lasts less than 20 years will have replacement or overhaul costs for the
corresponding year. Buildings, structures, and pipelines generally have a life expectancy of 50 years, with
metal structures having a lower life expectancy (Krause et al., 2010).
3.3
Capital Cost
Following design of the proposed ECMs, a capital cost estimate of construction is completed. A
majority of the direct capital costs of construction are estimated using 2011 - RS Means Construction Cost
Data literature (Waier et al., 2011). RS Means Construction Cost Data is an industry standard for cost
estimating data. Major direct capital costs for proprietary and niche industry equipment, such as fine bubble
diffusers, blowers, and instrumentation are not available in RS Means and are estimated based on budgetary
41
quotes from specialty contractors or manufacturers. Markup and contingency percentages for overhead,
profit, mobilization, bond and insurance, and contingency are interpreted based on prevailing local rates
and information from Water Environment Federation – Manual of Practice No. 8, which is a resource that
is specific to the utility industry (Krause et al., 2010).
3.3.1
Cost of Blower Technology
The cost of turbo blowers varies between manufacturers. The cost of blowers were collected from
two data sources for various manufacturers and models. The capital cost assumed for the cost analysis is
the average of the costs for each data source. Cost data for turbo blowers was obtained from the USEPA
2010 study (O’Connor et al., 2010) and from (Rohrbacher et al., 2010), and are presented in Table 3.4
below:
Table 3.4 – Cost of Blower Technologies
hp
Budget $
50
$56,0001
50
$102,0001
75
$75,0001
100
$115,0001
100
$93,0002
150
$120,0001
150
Average
hp
Budget $
250
$180,0001
250
$151,0002
250
$165,0002
250
$168,0002
250
$188,0002
300
$175,0001
$134,0002
300
$142,0001
200
$120,0001
300
$119,0002
200
$160,0001
300
$119,0002
300
$143,000
2
300
$156,0002
300
$208,0002
$79,000
$75,000
$104,000
$127,000
$86,000
2
200
$90,000
2
200
$93,0002
200
$124,0002
300
$209,0002
200
$128,0002
400
$275,0001
200
$176,0002
400
$132,0002
400
$198,000
2
500
$325,0001
200
$122,000
(1) (O’Connor et al., 2010)
(2) (Rohrbacher et al., 2010)
42
Average
$170,000
$159,000
$202,000
$325,000
3.3.2
Cost of Fine Bubble Diffused Aeration Technology
The costs for fine bubble diffused aeration headers and membranes depend on a variety of factors,
such as material, amount of diffusers, and amount of grids. As such they must be assessed on a case by
case basis. Quotes from two manufacturers that provide flexible porous membrane fine bubble diffusers
were obtained for each plant studied. Prices are based upon market pricing of these systems based on
typical materials of construction, factory testing, warranty and field services.
As a competitive bidding
scenario amongst the two manufacturers would be likely, the low cost estimate is assumed. Details on the
cost of aeration grids for each technology are provided in Table 3.5.
Table 3.5 – Cost of Fine Bubble Diffusers
Plant
Description
Manufacturer
Estimate
Boca Raton
WWTP
10,700 diffusers, 18 grids
ITT Water and Wastewater - Sanitaire
$430,000
Aquarius Technologies
$320,000
Broward County
North Regional
WWTP
20,160 diffusers, 48 grids
ITT Water and Wastewater - Sanitaire
$845,000
Aquarius Technologies
$600,000
Plantation WWTP
11,020 diffusers, 18 grids
ITT Water and Wastewater - Sanitaire
$450,000
Aquarius Technologies
$330,000
3.3.3
Foregone Capital Replacement Costs and Salvage Value
Foregone capital replacement costs are an important component of lifecycle cost analyses. If new
aeration equipment was not installed at the study facilities, eventual significant capital investments would
be required for replacement of existing mechanical aeration equipment. The existing mechanical aerators
at the plants in this study have surpassed their typical 20 year lifespan. Typically equipment beyond a 20
year lifespan would be considered deferred maintenance and have no present value worth. However, for
this analysis it is recognized that most facilities keep this equipment in operation for more than the 20 year
design life. For this reason a conservative assumption of 5 years of remaining life is assumed for existing
mechanical aeration equipment for the life cycle analysis. Table 3.6 below summarizes major equipment at
each plant that would require eventual replacement and their characteristics.
43
Table 3.6 – Major Equipment Requiring Eventual Replacement
Aerators
Blowers
Amt
Capacity
(hp)
App.
Date of
Install
Typical
Useful
Life
Current
Life
Assumed
Remaining
Life
200
1986 1
20
25
5
Plant
Amt
Capacity
(hp)
Boca Raton
9
100
3
N Broward
24
100
0
1982 2
20
29
5
Plantation
9
100, 125
0
1989 3
20
22
5
1. (Hazen and Sawyer (2), 2007)
2. (Hazen and Sawyer (1), 2007)
3. (Hazen and Sawyer, 2004)
Salvage value of equipment is not considered in this analysis at 20 years. Mechanical aerators
replaced at 5 years would have a salvage value at the end of the 20 year time period under the baseline
case. However, under the ECM No. 1, No. 2, and No. 3 case, significant salvage value would also remain
at the 20 year time period for the blower building and piping network although the blowers, diffusers, and
instrumentation would theoretically be at the end of their useful life with no salvage value. Due to the
multiple competing salvage values of assets under the baseline versus ECM No. 1 through 3 cases, salvage
value is not considered in this analysis.
3.4
Operation and Maintenance Costs
Maintenance costs are typically accounted for assuming 1 percent of equipment capital costs
annually (Krause et al., 2010). This does not include periodic overhauls or major parts replacements.
Maintenance costs are assumed to escalate at the same rate as general inflation.
O&M costs for
components of this study were obtained from various sources and are provided as Table 3.7 below:
44
Table 3.7 – Major Equipment Requiring Eventual Replacement
System Component
Description
O&M Costs
Source
Base Case -
Annual general
$1,000
1% rule of thumb and
Mechanical Aerators
maintenance
$100K manufacturer’s
quote for replacement
Base Case - Manual
Collect DO manually
DO Measurement
one or more times per
30 minutes per shift
Boca Raton WWTP staff
interview
day
ECM No. 1 - Fine
Replace Membranes in
Approximately $6 per
(Sanitaire, 2010); (Rosso
Bubble Diffusers
every 7 to 10 years
membrane, 5 minutes
and Stenstrom, 2006)
per membrane
ECM No. 1 - Fine
Clean membranes, hose
8 manhours per tank
(Rosso and Stenstrom,
Bubble Diffusers
from top of tank
based on 8,500 sf tank
2006)
with 2,400 diffusers
ECM No. 1 - Multi-
Annual general
1.5% of Equipment
(Rohrbacher, 2010)
Stage Centrifugal
maintenance
Capital Cost
ECM No. 2 – Turbo
Annual filter
$2,500 per year
(Rohrbacher, 2010)
Blowers
replacement, inspection,
$140 per cap
(Hach, 2010)
adjustment, parts
replacement
ECM No. 3 – DO
Annual Replacement
Probe Maintenance
Sensor Caps
General
Hourly Average Staff
$70,000 per year or
Boca Raton WWTP staff
Rate Including Benefits
$36.45 per hour
interview
45
IV. METHODOLOGY
4.1
Identifying Specific Energy Conservation Measures
This paper analyzes the benefit of implementing three specific ECMs at wastewater treatment
facilities in southeast Florida by conducting a life-cycle cost analysis on each ECM. The ECMs that are
listed below will be analyzed for energy savings gained versus the capital cost and present value for change
in O&M costs associated with installing the ECM.
ECM No. 1 - Fine Bubble Diffusers
Implementation of ECM No. 1 - fine bubble diffusers results in increased aeration efficiency
compared to mechanical surface aeration, based on the amount of pounds of oxygen transferred to
wastewater per kilowatt-hour of electricity consumed (lb O2 / kWh). The plants considered in this analysis
currently utilize mechanical surface aeration, and in one case also medium-bubble diffusers.
ECM No. 2 – Turbo Blowers
Implementation of turbo blower technology results in greater efficiency compared to other blower
technologies due to better mechanical efficiencies, resulting in reduced electrical costs. The ECM No. 2
life cycle cost analysis scenario assumes that a fine bubble diffuser system with blowers of comparable
horsepower is already installed.
ECM No. 3 – Automatic DO Control Strategy
Implementation of automatic DO control strategy reduces electrical costs by matching blower
output to oxygen required. The ECM No. 3 life cycle cost analysis scenario assumes that a fine bubble
diffuser system and turbo blowers are already installed, but includes installation of DO probes, modulating
valves, flow meters, and other associate electrical and instrumentation costs.
4.2
Lifecycle Cost Analysis of ECMs
To complete a lifecycle cost analysis of each ECM, it is necessary to complete a preliminary
design of the aeration system at each plant and estimate the net present value of annual energy savings and
46
compares to the net present value of change in O&M costs and capital costs of the proposed ECMs. The
flow-chart below in Table 4.1 summarizes a step by step method used for completing the life cycle cost
analysis:
47
Table 4.1 – Summary of Methodology
1. Obtain and input historical plant operating data, estimate sludge yield (Spreadsheet 1.1)
2. Project future and design flowrates and loadings (Spreadsheet 1.2)
3. Calculate O2 requirement air flowrates for design flows and loadings (Spreadsheet 2.0 - 2.3)
4. Size and layout process air piping (Spreadsheet 3.1.)
5. Estimate friction loss through air piping and create system curve (Spreadsheet 3.2 and 3.3)
6. Size blowers using available manufacturer’s blower performance data (Spreadsheet 3.4)
7. Insert equation for system curve into Spreadsheet 2.0 and calculate required power and energy
consumption of blowers for ECM Nos. 1 through 3 (return to Spreadsheets 2.0 - 2.3)
8. Complete capital cost estimate (Spreadsheets 4.0 - 4.7)
9. Complete O&M and foregone capital cost estimate (Spreadsheet 5.0 and 5.1)
10. Estimate existing energy use under current plant configuration for comparison with Energy use
under ECM Nos. 1 through 3 (Spreadsheet 6.0)
11. Complete a Life Cycle Cost Analysis for ECM Nos. 1 through 3 and calculate payback.
(Spreadsheets 6.1 and 6.2)
48
The sections that follow detail the methodology used in the model. Screenshots of the actual
model spreadsheets are provided from the City of Boca Raton WWTP analysis for example. In the
screenshots, fields highlighted in grey indicate user input fields. All other fields are output fields.
4.2.1
Historical Plant Data
Available historical plant data is required for the model. It is typical to use at minimum two years
of historical data for determining design flowrates and loadings to a plant (Tchobanoglous et al., 2003).
Three years of historical data were used for this analysis to account for erratic seasonal flow and storm data
characteristic of the south Florida region. Historical data for the study facilities are gleaned from available
monthly operating reports and annual operating reports. Historical plant data is input into Spreadsheet 1. 1
of the model. A screenshot of Spreadsheet 1.1 is provided as Figure 4.1.
Figure 4.1 – Spreadsheet 1. 1 – Influent-Effluent Specifier
49
The fields in grey receive direct user input based on the years of historical data used, and the fields
in white are calculated based on the data input. In the case of the City of Boca Raton shown in Figure 4.1,
the future flowrates and loadings are predicted based on design plant flowrate as established per the
existing permit, and 2011-2031 average flowrate which is predicted in Spreadsheet 1.2.
4.2.2
Estimating Yield
One of the most common problems with obtaining accurate historical plant data is encountered
with obtaining accurate sludge wastage rates, which is a model input in Spreadsheet 1.1 (effluent waste
activated sludge volatile suspended solids, or EFF WAS VSS). WAS flow is the most commonly
mismeasured and misreported variable due to the relatively small magnitude of WAS flow compared to
other flows, and inadequate measurement instrumentation. The result is that significant uncertainty is often
associated with WAS when using historical data for modeling purposes (Melcer et al., 2003).
Since the
wastage is a key variable in calculating oxygen requirement and hence effecting predicted energy
consumption, historical wastage data available from each of the plants was compared to typical values to
check their reasonableness. Typical sludge yield values are obtained using Figure 8-7a and 8-7b from
(Tchobanoglous et al., 2003) and are provided as Figure 4.2 and Figure 4.3, below:
50
Figure 4.2 – Typical Yield for Primarily Treated Domestic Wastewater (Tchobanoglous et al., 2003)
Figure 4.3 – Typical Yield for Raw Domestic Wastewater (Tchobanoglous et al., 2003)
In addition, (Dold, 2007) indicated in Figures 4.2 and 4.3 above, particularly the typical yield
curve for raw wastewater from Figure 4.3, may significantly underpredict sludge yield. Equation (4) is
used to predict typical sludge yield for each plant. The results of observed yields compared to estimated
yields using both the (Tchobanoglous et al., 2003) typical yield curves and Equation (4) adapted from
(Dold, 2007) are provided in Table 4.2.
lb VSS produced
lb BOD5 influent
= BOD5
COD
(4)
Where COD = typical value of 2.04 for raw influent, or 1.87 for settled influent
BOD5
fUS = unbiodgradable soluble fraction, typical value of 0.05 for raw influent, or 0.08 for settled
influent
fUP = unbiodegradable particulate fraction, typical value of 0.13 for raw influent, or 0.08 for settled
influent
Y = 0.47 mg VSS/mg COD
Θx = SRT
51
f = 0.2
fCV,P = 1.6 mg COD / mg VSS
b = 0.24 x 1.029 T – 20 d-1
(5)
Where T = temperature (°C)
Table 4.2 – Boca Raton WWTP– Incremental Life-Cycle Cost Analysis
Plant
Type
INF
BOD
(lb/day)
Boca Raton
N Broward
Plantation
Primary Eff
Raw Inf
Primary Eff
18,410
54,818
8,615
INF
TSS
(lb/day)
WAS
VSS
(lb/day)
Avg
SRT
(days)
9,592
71,891
6,737
10,659
27,444
2,849
3.9
3.7
30
Obs.
Yield
(Metcalf
& Eddy,
2003) Est.
Yield
(Dold,
2007)
Est.
Yield
0.58
0.50
0.33
0.58
0.91
0.35
0.53
0.63
0.30
Table 4.2 demonstrates that both Boca Raton WWTP and Plantation Regional WWTP yields are
both within 10% of (Tchobanoglous et al., 2003) and (Dold, 2007). However, the observed yield at
Broward County North Regional WWTP is significantly lower than typical values. For this reason, the
(Dold, 2007) predicted yield of 0.63 is used to determine EFF WAS VSS in place of historical values due
to an apparent reporting error in sludge values. The model user must determine the viability of existing
sludge wastage data and make these calculations outside of the spreadsheets.
4.2.3
Project Future Flows and Loadings
It is necessary to project future 20-year flowrates and loadings for designing capital improvements
and estimating future energy use over the 20-year design horizon. The flowrates and loadings projected at
the end of the 20-year period are used to design capital improvements, and the average flowrate and
loading over the 20-year period is used to estimate average annual energy use. Future loadings are
extrapolated on a linear basis from the three year data on a flow-proportional basis using the equation
below:
Future Predicted Loading Rate = Three Year Average Loading Rate x Future Predicted Flowrate
Three Year Average Flowrate
52
(6)
Future predicted loading rates are input into Spreadsheet 1.2 of the model. A screenshot of
Spreadsheet 1.2 is provided as Figure 4.4.
Figure 4.4 – Spreadsheet 1. 2 – Flow Projection
4.2.4
Calculate Oxygen Requirement and Required Air Flowrates
The amount of oxygen required to achieve current treatment standards was determined using the
following equations:
1) Oxygen required by the activated sludge process is determined by the following equation,
Ro = So – S – 1.42PX,Bio + 4.33x(NOx) = SOTR
Where Ro = total oxygen required, lb/d
53
(7)
So = influent substrate concentration, lb/d (of bCOD)
S = effluent substrate concentration lb/d (of bCOD)
SOTR = Standard Oxygen Transfer Required (lb 02/d)
NOx = ammonia oxidized, lb/d
bCOD = 1.6 x BOD5
BOD5 = 1.16 x CBOD5
(Adapted f/ eq. 8-17, Tchobanoglous et al., 2003)
PX,Bio = WAS VSS – WAS nbVSS
(8)
Where WAS VSS = biomass as VSS wasted ( lb/d)
WAS nbVSS = nonbiodegradeable VSS in influent
(Adapted f/ eq. 8-17, Tchobanoglous et al., 2003)
Typical WAS nbVSS = 0.13 for raw influent, 0.08 for primary clarified influent (Dold, 2007)
The Boca Raton WWTP and the Broward County North Regional WWTP do not currently fully
nitrify. As such, WAS VSS must be estimated (as opposed to using historical measured values) for
predicting oxygen consumption for the three facilities.
Conversely, the Plantation Regional WWTP
currently completely nitrifies. Therefore, WAS VSS for a non-nitrifying condition at that plant must be
estimated. In these cases, Equation (4) presented in Section 4.2.1 is used to predict yield.
2) The amount of ammonia oxidized, or NOx by the activated sludge process is determined by the
following equation:
NOx = TKN – Ne – 0.12(PX,Bio)
Where TKN = influent TKN, lb/d
Ne = effluent NH4-N, lb/d
(Adapted f/ eq. 8-18, Tchobanoglous et al., 2003)
54
(9)
An alternate and more conservative method for calculating oxygen required for the purpose of
determining maximum aeration system capacity is often employed in the design and operation of WWTPs
as opposed to the method of Equation (7). The method in equation (10) below assumes that all CBOD5 that
does not leave the liquid stream treatment process through the plant effluent is oxidized in the activated
sludge process. However, at all plants a significant portion of CBOD5 and nitrogen is not oxidized in the
activated sludge process and exits the liquids stream process in the form of volatile suspended solids (VSS)
in the waste activated sludge (WAS) stream, or PX,Bio as denoted in equation (8) (Schroedel et al., 2010).
The CBOD5 is then further broken down in digesters or other solids stream treatment processes. This
method is not used for this paper as it results in a very conservative and more expensive design of aeration
systems.
Ro = (So – S eff) + 4.57(TKNo – TKN eff) = SOTR
(10)
The oxygen required that is estimated by equation (7) must then be adjusted to reflect the effect of
multiple external factors on oxygen transfer in the system such as salinity-surface tension (beta factor),
temperature, elevation, diffuser depth, target oxygen level, and the effects of mixing intensity and tank
geometry. The actual oxygen transfer required, or AOTR, is determined by the following expression:
(11)
Where AOTR = actual oxygen transfer rate under field conditions, lb 02/hr
SOTR
= standard oxygen transfer rate in clean water at 20° C, zero DO, lb 02/hr
β
= salinity-surface tension correction factor, 0.99 (Mueller et al., 2002)
CŚ,T,H
= average dissolved oxygen saturation concentration in clean water in aeration tank at
temp. T and altitude H, mg/L:
(12)
CS,T,H
=oxygen saturation concentration in clean water at temp. T and altitude H, mg/L
55
Pd
= pressure at the depth of air release, psi
Patm,H
= atmospheric pressure at altitude H, psi
Pw, mid depth = water column pressure at mid depth, above point of air release, psi
CL
= operating oxygen concentration, mg/L
Cs,20
= dissolved oxygen saturation concentration in clean water at 20° C and 1 atm, mg/L
T=
operating temperature, ° C
α=
oxygen transfer correction factor (values taken from Rosso, 2005)
F=
fouling factor (values taken from Rosso, 2005)
τ=
Oxygen saturation temperature correction factor of water
τ = 4.08x10-4(T2) – 3.82x10-2(T) + 1.6
(from Figure 3.6.1)
(13)
(Adapted f/ eq. 5-55, Tchobanoglous et al., 2003; and eq. 2.53, Mueller et al., 2002)
To calculate the estimated power draw for diffused aeration, an air flowrate must be calculated
based on the SOTR determined in equation (11) that will provide the amount of oxygen transfer required at
design conditions. The series of equations presented below are used to calculate the power requirement for
diffused aeration:
Air Flowrate, SCFM =
SOTR
.
[(SOTE)(24 hr/d) (60 min/hr) (O2 ρ)]
(14)
Where SCFM = Standard Cubic Feet Per Minute
SOTE = Standard Oxygen Transfer Efficiency
O2 ρ = density of oxygen in volume of air, lb O2 / lb air
The SOTE is an observed value that varies with every diffuser. SOTE charts are typically
provided by the diffuser manufactuer. For this analysis, the Sanitaire – Silver Series II diffuser is assumed.
A best fit fourth order curve was applied to the SOTE data available from Sanitaire to obtain the equation
used in the model to estimate SOTE at each flowrate as demonstrated in Figure 4.5.
56
The energy use of each proposed ECM was calculated by assuming the air requirement for the
average annual flowrate and loading in the blower power equation for 365 days of continual operation.
Blower power is estimated using the power requirement for adiabatic compression equation.
(15)
Where Pw = power requirement of blower, hp
R = engineering gas constant for air, 53.3 ft.lb / lb air . °R
°R = °F + 459.67
T1 = Absolute inlet temperature, °R
P1 = absolute inlet pressure, psi
P2 = absolute outlet pressure, psi
n = 0.283 for air
550 = constant, 550 ft-lb / s-hp
e = efficiency
w = mass flowrate of air, lb/s = (SCFM) (ρair) / (60 seconds/minute)
(16)
Where ρair = 0.0750 lb/cf (density of air at Standard Conditions, 68°F, 36% relative
humidity)
(Adapted f/ eq. 5-56b, Tchobanoglous et al., 2003)
The key assumptions used for ECM scenario Nos. 1 through 3 are detailed in previous sections
and are reiterated below.
Table 4.3 – Key Assumptions for ECMs
ECM No.
Description
DO
Efficiency
ECM No. 1
Fine bubble diffusers
3
62%
ECM No. 2
Turbo blowers
3
72%
ECM No. 3
Automatic DO control
1.5
72%
57
Spreadsheet 2.0 - Aeration Calculations – Global Parameters, is the main user input spreadsheet
for the aeration and airflow calculations. A screenshot of Spreadsheet 2.0 is provided as Figure 4.6.
Figure 4.5 – Sanitaire Silver Series II - SOTE Vs. SCFM per diffuser
58
Figure 4.6 – Spreadsheet 2.0 – Aeration Calculations – Global Parameters
Description of inputs for Spreadsheet 2.0 – Global Parameters
The numerous assumptions input into Spreadsheet 2.0 were discussed in Section 2.7, and are also
briefly discussed following Figure 4.6.
•
Area Under Aeration Per Basin (ft2) – Existing area per aeration basins, used for calculating
volume and calculating minimum mixing requirement
•
# of Basins Online – Average number of basins online at a given time over the 20 year study
period, used for calculating total volume
•
Side Water Depth (ft) – depth from water surface elevation to basin bottom, used for calculating
total volume
•
Diffuser Submergence (ft) – depth from water surface elevation to top of diffuser, typically 1 foot,
used in oxygen transfer calculations
59
•
Equation for System Curve – the system curve is estimated in Spreadsheet 3.3, a second order
polynomial best fit curve is applied to the system curve and the first number of the equation is
insert here
•
Number of Diffusers Per Basin – the number of diffusers is adjusted by the user to insure that the
maximum recommended airflow per diffuser is not exceeded under most conditions
•
Site Elevation (feet above MSL) – elevation of site above mean sea level, used for oxygen transfer
calculations
•
Minimum Mixing Requirements (scfm/ft2) – minimum recommended airflow to maintain adequate
mixing, 0.12 sfm per (Mueller et al., 2002)
•
Minimum Flow Per Diffuser (scfm) – minimum recommended flow per diffusers (0.5 cfm /
diffuser for Sanitaire Silver Series II diffusers)
•
Maximum Flow Per Diffuser (scfm) – maximum recommended flow per diffuser (3 cfm / diffuser
for Sanitaire Silver Series II diffusers)
•
General Temperature (°C) – Average temperature of wastewater, used for oxygen transfer
calculations
•
Beta (unitless) - Beta is a factor which reduces the predicted oxygen transfer efficiency of the
system based on total dissolved solids concentration effects
•
Patm (psi) – Standard atmospheric pressure, 14.7 psi at sea level
•
Patm (mid depth, ft wc/2/2.31(psi)) – Pressure at mid depth of water column between water
surface and top of diffuser)
•
CstH (per App D for mech aer, mg/L) – Saturated DO concentration in water at 25°C, 14.7 psi
•
CstH* (mg/L) – Average saturated DO concentration, assumed to be saturated DO concentration
at mid depth of water column between water surface and top of diffuser per (Metcalf & Eddy,
2003)
60
•
Dens air (lb/cf) – density of air at standard conditions, (68°F, 14.7 psi, 36% relative humidity)
•
Mass fraction O2 in air – fraction of oxygen in air at standard conditions, (68°F, 14.7 psi, 36%
relative humidity)
•
Alpha – oxygen transfer correction factor for wastewater based on SRT per (Rosso et al., 2005)
•
Alpha for complete nitrification - oxygen transfer correction factor for wastewater at SRT of 5
days
•
Average or minimum SOTE – when “a” is input into this field, the oxygen transfer calculations
assume the average efficiency reported by the manufacturer, when “m” is input into this field, the
oxygen transfer calculations assume to minimum efficiency reported by the manufacturer
•
Manual DO Control O2 (mg/L) – the average DO practically obtainable by using manual DO
control, 3.0 mg/L as determined in earlier sections
•
Auto DO Control O2 (mg/L) – the average DO practically obtainable by using automatic DO
control, 1.5 mg/L as discussed in earlier sections
•
MSC Blower Efficiency – the average total efficiency practically obtainable by using multi-stage
centrifugal blowers, 62% as discussed in earlier sections
•
Turbo Blower Efficiency - the average total efficiency practically obtainable by using turbo
blowers, 72% as discussed in earlier sections
•
O2 Concentration at Max Day (mg/L) – Allowable DO concentration at maximum day loading
conditions, 0.5 mg/L
•
Pre-ECM Existing DO (mg/L) – Existing DO concentration prior to implementing proposed
ECMs at plants, varies by plant
•
Y, (per Dold, 2007) – Sludge yield as measured by VSS, calculated using equation (4)
•
Fup (Dold, 2007) – Unbiodegradable particulate fraction of influent wastewater, 0.08 for settled
influent and 0.13 for raw influent
61
•
VSS/TSS (Tchobanoglous et al., 2003) – typical VSS/TSS ratio of 0.85
Description of Aeration Calculation Spreadsheets 2.1 – 2.3 – Aeration Calculations
Inputs into Spreadsheet 1.0 and Spreadsheet 2.0 feed into Spreadsheets 2.1 – Aeration Calculations –
Diffusers, Spreadsheet 2.2 – Aeration Calculations – Turbo Blowers, and Spreadsheet 2.3 – Aeration
Calculations – 1.5 mg/L DO Control. The first three columns of each spreadsheet are used as the basis for
calculating total air and horsepower required to satisfy the average daily flow and loading conditions over
the 20 year design period, using the methodology discussed earlier in this section. The horsepower
calculated in the first three columns of each spreadsheet are used as the basis for predicting energy savings
in Spreadsheet 6.1, where it is compared to existing horsepower usage. The remaining columns are used to
predict airflow at multiple design conditions such as minimum day, maximum month, and maximum day to
appropriately size the aeration system such as pipes, blowers, and number of diffusers so that capital cost
can then be estimated. It is necessary for the user to click the “Calculate SOTE” button in each spreadsheet,
which initiates a macro that iteratively solves for the SOTE through the diffusers at a given flowrate based
on manufacturer supplied SOTE curves. Screenshots of Spreadsheets 2.1 through 2.3 are provided as
Figures 4.7 through Figure 4.9.
62
63
Figure 4.7 – Spreadsheet 2.1 – Aeration Calculations – Diffusers
64
Figure 4.8 – Spreadsheet 2.2 – Aeration Calculations – Turbo Blowers
65
Figure 4.9 – Spreadsheet 2.3 – Aeration Calculations – DO Control
4.2.5
Size Process Air Piping
Process air piping is sized using the maximum day design air flow. Process air pipes are designed
to prevent velocities from exceeding the typical velocity ranges of 2,700 to 4,000 feet per minute (fpm) in
12 inch to 24 inch diameter piping, and 3,800 to 6,500 fpm in 30 inch to 60 inch piping (Tchobanoglous et
al., 2003). Exceptions are made for slight exceedances of the recommended velocities at peak day flows.
Once process air piping diameters have been appropriately sized and the air piping is laid out in a
preliminary design, the headloss through the system is estimated. To estimate the headloss through the
system, the flowrate of air moving through the system must be calculated. Because gasses that are
propelled through a blower turbine are compressed and heated, the air volume moving through the aeration
system is less than the air entering the system. The air moving through the aeration system is often referred
to as Actual Cubic Feet per Minute (ACFM). ACFM is converted from SCFM using the following
equation:
(17)
Where ACFM = Actual Cubic Feet Per Minute
SCFM = Standard Cubic Feet Per Minute (at Standard Conditions of 14.7 psia, 68°F and 36% RH)
TA = Actual Temperature (°F)
TS = Standard Temperature (68°F)
PA = Actual Pressure (psia)
PS = Standard Pressure (14.7 psia)
RHA = Actual Relative Humidity (%)
RHS = Standard Relative Humidity (36%)
VPA = Actual Saturation Water Vapor Pressure (psia)
VPS = Standard SaturationVapor Pressure (at Standard Conditions of 14.7 psig, 68°F and 36%
RH)
(Stephenson and Nixon, 1986)
66
The saturation water vapor pressure is determined from observed values (Stephenson and Nixon,
1986). A fifth order polynomial curve is fit to the data to arrive at the equation used for determining
saturation water vapor pressure from 32°F to 308°F, and is given below:
VPT = 2.27x10-11 (T5) – 2.5x10-10 (T4) + 5.08x10-7 (T3) + 7.42x10-6 (T2) + 1.46x10-3 (T) + 0.016
(18)
Where VPT = Saturation Water Vapor Pressure at temperature T
T = Temperature (°F)
Description of Spreadsheet 3.1 – System Design – Size Pipes
Spreadsheet 3.1 is used to size the pipes throughout the basin in accordance with the methodlogy
discussed in this section. In the case of Boca Raton WWTP, Spreadsheet 3.1.1 and Spreadsheet 3.1.2 are
required to size multiple sections. The user adjusts the pipe diameter for each section of pipe to remain
within the allowable velocities for Table 5-28 of (Tchobanoglous et al., 2003). Headloss should also be
considered when sizing pipes, oftentimes the pipe diameter corresponds to the upper end of the suggested
velocity range. However, the middle to lower velocity range may be recommended for particular sections
to mimimize headloss through the system while taking into account capital cost and constructability
concerns. The pipe diameters from Spreadsheet 3.1 are fed into Spreadsheet 3.2, where the system head
loss is calcualted. A screenshot of Spreadsheet 3.1 is provided as Figure 4.10.
67
Figure 4.10 – Spreadsheet 3.1 – System Design – Size Pipes
4.2.6
Estimate Headloss Through Pipes and Create System Curve
Headloss through the proposed piping system is estimated at the design flow using the following
equations:
The Swamee-Jain Equation is used to estimate the Darcy Weisbach Friction factor;
(19)
68
Where f = Darcy-Wesibach friction factor (unitless)
ε = roughness height (ft) (0.00005 for stainless steel)
D = Pipe Diameter (ft)
Re = Reynold’s Number
(Lindeburg, 2003)
The Reynolds Number is calculated using the following equation:
Re
(20)
Where Re = Reynold’s Number (unitless)
V = air velocity (ft/s)
L = Length of pipe (ft)
ν = kinematic viscosity at discharge temperature (ft2/s)
(Lindeburg, 2003)
Next, major headloss is calculated using the following equation:
(21)
Where hL major = major headloss (inches of water column) or (in w.c.)
f = Darcy-Weisbach friction factor (unitless)
D = Pipe Diameter (ft)
hi = Velocity head of air (in w.c.)
(Metcalf & Eddy, 2003)
Minor headloss is calculated by summing up the friction loss K factors for each fitting or valve at
each different velocity head and adding to the major headloss.
(22)
69
Where hL minor = minor headloss (in. w.c.)
Ki = friction loss coefficient
hi = Velocity head of air (in w.c.)
(Lindeburg, 2003)
Static headloss is the headloss due to static water pressure, which is directly related to the depth of the
water in the aeration basins above the fine bubble diffusers:
(23)
Where hL static = static headloss (in w.c.)
ddiffusers = depth of diffusers below water surface (inches)
(Lindeburg, 2003)
The total system headloss is the sum of major, minor, and static headlosses:
(24)
The process air piping system curve for the system is created based on the headloss and maximum design
flow from the equation above. The maximum design flow required by the process is the maximum day
design flow. Various points are plotted to create the system curve based on the following equation.
hL d
(25)
Where hL I = headloss at velocity vi
vi = velocity vi (fps)
vd = design velocity(fps)
hL d = headloss at velocity vd
(adapted from Lindeburg, 2003)
Description of Spreadsheet 3.2 – System Design – Estimate Losses Through Pipes and Spreadsheet 3.3 –
System Design – System Curve
Spreadsheet 3.2 is used to calculate system head loss in accordance with the methodlogy discussed
in this section. Once the system pressures and air flowrates are determined, the corresponding energy
70
requirements for supplying process air to meet the flowrate and pressure requirements can be determined
for ECM No. 1 through 3. Spreadsheet 3.3 is used to determine the system curve and the best fit second
order polynomial equation for user input back into Spreadsheet 2.0. A screenshot of Spreadsheet 3.2 and
Spreadsheet 3.3 are provided as Figure 4.11 and Figure 4.12, respectively.
71
72
Figure 4.11 – Spreadsheet 3.2 – System Design – Estimate Losses Through Pipes
Figure 4.12 – Spreadsheet 3.3 – System Design – System Curve
Note: The curve in Figure 4.12 results in an exact fit because psi is predicted based on equation (25)
4.2.7
Sizing Blowers
Once the maximum day design flow and associated headloss are determined, the blowers are
sized. The maximum day design flow and associated headloss through the system define the design point
for the blowers. Extreme weather conditions effect oxygen transfer and must be considered when sizing
blowers. Because hotter air expands and has less oxygen per unit volume, the blower system must provide
provide a high enough flowrate to supply adequate oxygen for the hottest summer day. Also effecting
oxygen transfer is humidity, because moisture contained in a unit volume of air displaces oxygen. The
following historical weather data was researched for the study area of West Palm Beach, Florida and is
assumed for all models.
73
Table 4.4 – Extreme Weather Design Conditions
Data Source
ASHRAE Extreme (1%) Conditions
for WPB (Kuehn et al., 2005)
Parameter
Value
Design Temperature (Wet Bulb) (°F):
80
Maximum Temperature (°F):
101
Resulting Relative Humidity*:
41%
NOAA Records for West Palm
Beach from www.ncdc.noaa.gov
(NESDIS, 2010)
Resulting relative humidity derived
from ASHRAE Psychrometric Chart
No. 1, Normal Temperature (Kuehn
et al., 2005)
Once the extreme weather design conditions are determined, it is necessary to determine the
design blower flowrate and pressure based on the extreme hot weather event. The required air flowrate for
the design condition as determined by equation (14) is adjusted for extreme hot weather conditions using
the formula below:
(26)
Where ICFM = Inlet Cubic Feet Per Minute
SCFM = Standard Cubic Feet Per Minute (at Standard Conditions of 14.7 psia, 68°F and 36% RH)
TA = Design Temperature (101 °F)
TS = Standard Temperature (68°F)
PA = Design Pressure (psia) (varies depending on specific design)
PS = Standard Pressure (14.7 psia)
RHA = Design Relative Humidity (41 %)
RHS = Standard Relative Humidity (36%)
VPA = Actual Saturation Water Vapor Pressure (0.9781 psi at 101 °F)
VPS = Standard SaturationVapor Pressure (at Std Conditions of 14.7 psig, 68°F and 36% RH)
(Stephenson and Nixon, 1986)
74
Equation (26) is used to specify the total capacity required from the blower system. Each facility blower
system design is subject to the following criteria:
•
Turbo blowers currently available on the market are generally limited to a maximum of
approximately 7,000 SCFM capacity.
•
To comply with EPA Class I Reliability standards, it is necessary to have at least two blower units
available, so that if one or more are out of service the oxygen requirement can still be satisfied
with the remaining blowers (US EPA, 1974). Three or more units are typical.
•
The blower system must be capable of providing the entire range of required airflows with
minimal gaps in coverage, from maximum day to minimum day design flow. This is generally
accomplished by providing at least one blower that is 60% to 80% capacity of larger blowers.
•
Turbo blowers generally have the ability to turn down air flow to 50 percent or greater, which
reduces or eliminates gaps in air coverage. However, installing “small” and “large” blower units
to further reduce concern of providing entire range of required airflows should be provided if
feasible. For multi-stage centrifugal blowers, this is a necessity.
•
The blower system must be sized so that with the largest unit out of service, it can still satisfy the
oxygen requirement of the system. To reduce capital costs and the need for extraneous blower
capacity, it is typical to allow the system to satisfy maximum month average daily loading with
one unit out of service, and maximum day loading with all units in service (Mueller et al., 2002).
•
To reduce capital costs and the need for extraneous blower capacity, it is typical to allow the
system to provide 0.5 to 1.0 mg/L of oxygen concentration in the aeration basins during maximum
day loadings, as opposed to the typical 2 mg/L DO for lesser loadings (Mueller et al., 2002).
•
The blower system must also be able to provide the minimum amount of air required for mixing,
which can be greater than the minimum day design loading oxygen requirements (Mueller et al.,
2002) .
The blower nameplate design pressure also must be adjusted to account for extreme weather conditions
using the following equation:
75
(27)
Where EAP = Equivalent Air Pressure (psi)
TA = Design Temperature (101 °F)
TS = Standard Temperature (68°F)
PI = Inlet Pressure (psia) (varies depending on specific design)
PS = Standard Pressure (14.7 psia)
(Stephenson and Nixon, 1986)
Spreadsheet 3.4 is used to size the blower requirements for the system in accordance with the
methodlogy discussed in this section. A screenshot of Spreadsheet 3.4 is provided as Figure 4.13.
76
Figure 4.13 – Spreadsheet 3.4 – System Design – Blower Design
4.2.8
Estimate Capital Cost
Following design of the proposed ECMs, a capital cost estimate of construction is completed. The
methodology and assumptions used for estimating the capital cost of the project are discussed fully in
Section 3.
Spreadsheet 4.0 is used to summarize the results of capital cost estimating for the various
components of the project including demolition, blowers, diffusers, structural, mechanical, instrumentation,
and electrical. Spreadsheets 4.1 through 4.7 are provided for each facility investigated in the appendix. A
screenshot of the summary Spreadsheet 4.0 is provided as Figure 4.14.
77
Figure 4.14 – Spreadsheet 4.0 – Cost Estimate - Summary
4.2.9
Estimate O&M and Foregone Capital Replacement Costs
The methodology and assumptions used for estimating the O&M and foregone capital replacement
costs of the project are discussed fully in Section 3.
Spreadsheet 5.0 is used to summarize the results of
O&M and foregone capital replacement costs. Spreadsheet 5.1 is provided for each facility investigated in
the appendix. A screenshot of the summary Spreadsheet 5.0 is provided as Figure 4.15.
78
Figure 4.15 – Spreadsheet 5.0 – O&M Costs
4.2.10
Energy Baseline – Estimated Energy Consumption of Existing Mechanical Aerators
The energy usage baseline is defined herein as the current energy usage of the existing system.
For mechanical aeration, the energy usage baseline is determined for comparison to predicted diffused
aeration performance.
Electric motors are commonly oversized by approximately 10%, and are
approximately 90% efficient. For this reason, it is common to take nameplate horsepower at face value for
calculating power draw in energy calculations (Schroedel et al., 2010).
However, if more detailed
information is available regarding a motor’s operation such as amperage draw measured in the field, a more
79
accurate estimate of energy consumption can be obtained using the three phase electric power equation.
Three phase electric power is calculated via the following equation:
P=VxIx
Where P
3 x PF
(28)
= Power consumed (kWh)
V
= line voltage (kW)
I
= average line current of 3 legs
PF
= power factor
(Schreodel et al., 2010)
Voltage for the equipment at the plants investigated is 3-phase, 480 volts, which is typical of most
treatment plant equipment. Amperage was measured on each phase of the mechanical aerators of each plant
using portable or integral ammeters. The power factor is the ratio of actual power to apparent power, and
reflects the principle that electric motors draw more power than they use and return a portion of the power
to the source (Schroedel et al., 2010). In the absence of actual power factors, it was neccesary to determine
a practical power factor value to assume for the eqipment studied. The power factors for premium
efficiency, squirrel cage induction 1,200 rpm motors from four prominent manufacturer’s were researched
and are detailed in Table 4.5 below to derive an average power factor at full load and half load.
Table 4.5 – Power Factor
Manufacturer
PF At Full Load
PF at 1/2 Load
U.S. Motors
81.4
NA
ABB
82.5
73
Reliance
85.6
77.3
GE
87.5
NA
Average
84.2
75.1
To estimate existing energy usage at each plant, amp draws from each mechanical aerator were
obtained and energy usage was estimated based on equation (28). Spreadsheet 6.0 is used to estimate the
existing energy useage baseline in accordance with the methodology discussed in this section.
screenshot of Spreadsheet 6.0 is provided as Figure 4.16.
80
A
4.2.11
Complete Life Cycle Cost Analysis
The methodology and assumptions used for completing a life-cycle cost analysis are discussed in
Section 3. Spreadsheet 6.0 is used to input life cycle assumptions and the energy baseline data discussed in
Section 4.3.9. A screenshot of the life cycle cost analuysis input Spreadsheet 6.0 is provided as Figure
4.16.
Figure 4.16 – Spreadsheet 6.0 – Lifecycle Cost Analysis Inputs
The energy savings analyses are were conducted on all ECM Nos. 1 thorugh 3 for three level of
treatment scenarios, “Current Treatment”, “Partial Nitrification (NOx)” and “Complete NOx”.
scenario is described below:
81
Each
1.
Current Treatment – Two of the three mechanically aerated plants in this study do not currently
achieve full nitrification. Accordingly, the Current Treatment scenario demonstrates the potential
energy savings assuming that the activated sludge process continues to only partially nitrify, with
the existing DO levels for the City of Boca Raton WWTP and the Broward County North
Regional WWTP. It is unlikely that the current treatment low DO levels would be designed for
were the plant upgraded. Rather they would be designed to provide the capability for a higher DO
(Partial Nitrification scenario) or provide the capability to aerate to the point of full nitrfication
(Complete Nitrification scenario). However, the purpose of the Current Treatment scenario is to
demonstrate the baseline cost savings that are achieved by only varying the method of oxygen
delivery, without the additional benefits achieved by raising the oxygen concentration and/or
achieving full nitrification of ammonia.
2.
Partial Nitrification – Similar to the Current Treatment scenario, the Partial Nitrification
comparison demonstrates the potential energy savings assuming that the activated sludge process
continues to only partially nitrify. Unlike the Current Treatment scenario, DO concentration is
raised beyond the existing low level baseline to a value more typical of fine bubble diffused
aeration systems (1.5 to 3.0 mg/L). The Partial Nitrification scenario is the most likely treatment
standard that a plant renovation would be designed to achieve.
3.
Complete Nitrification – The Complete Nitrification comparison demonstrates the potential energy
savings assuming that hypothetical diffused aeration system is designed to achieve complete
nitrification. Although the plants are not currently required to provide nitrification, leading to
denitrification, it is likely that an upgrade to the plant’s aeration system would be designed with
the flexibility to provide complete nitrification in anticipation of medium to long term changes in
regulatory requirements.
Spreadsheets 6.1.1 through 6.1.3 are used to summarize the results of the life cycle cost analysis
for each ECM and level of treatment scenario combination. The only variable between Spreadsheets 6.1.1
through 6.1.3 are the capital costs. Spreadsheet 6.1.1 calculates the estimated payback based on the median
predicted capital cost from Spreadsheet 4.0, and Spreadsheet 6.1.2 and 6.1.3 calculate the estimated
82
payback based on the Class 4 AACE Cost Estimate low range of -20% and high range of + 30%,
respectively.
Payback is computed by calculating the time at which the net present value of annual
estimated energy savings for each ECM and scenario is equal to the net present value of O&M and capital
costs. The user must activate the iterative calculation macro by clicking on the “Calculate Payback”
button. A screenshot of the life cycle cost analysis input Spreadsheet 6.1.1 is provided as Figure 4.17. The
life cycle cost analysis summary for Spreadsheets 6.1.1 through 6.1.3 is provided in Spreadsheet 6.1.2. A
screenshot of the life cycle cost analysis summary Spreadsheet 6.2 is provided as Figure 4.18.
83
84
Figure 4.17 – Spreadsheet 6.1.1 – Life Cycle Cost Analysis
85
Figure 4.18 – Spreadsheet 6.2 – Incremental Life Cycle Cost Analysis Summary
4.2.12
Model Accuracy Verification
The model was checked against real world conditions to verify it’s accuracy. Actual case study
data from other plants measuring electricity usage of mechanical aeration before replacement, and data
measuring electricity usage following implementation of fine bubble was not available. However, data
available from the Broward County North Regional WWTP was used to measure side by side efficiency of
mechanical aeration versus fine bubble diffused aeration, and also data to measure the model’s accuracy at
predicting average airflow rates and energy use.
Daily average electricity use and air flowrates from August through October 2010 were available
for Module C which was converted from mechanical air to fine bubble diffused air with multistage
centrifugal blowers and limited automatic DO control in 2005. The Module C basins are nearly identical to
the Module A and Module B tanks. The available daily flowrate and loading data for Module C was input
into the model, and the predicted air flowrate and horsepower was compared with measured air flowrate
and horsepower for the three month period. The following assumptions and considerations were made to
calibrate the model to the conditions at Module C for verification:
•
Detailed data on daily average air flowrate, horsepower, influent flowrate, and CBOD5 loading
was available for August through October, 2010
•
Actual daily influent CBOD5 loading data for August through October 2010 was assumed
•
Daily CBOD5 effluent was assumed as 5 mg/L
•
Daily TKN data for August through October 2010 was not available, so the 2004-2006 TKN
influent average of 33.7 mg/L was assumed
•
An SRT of 3.7 days was assumed, similar to the 2004 – 2006 average of Modules A and B
•
Wastewater temperature is assumed to vary each month based on the average ambient monthly
temperature provided by NOAA for West Palm Beach, FL. Yield is calculated per (Dold, 2007)
and is effected by the varying temperature, which results in a slightly lower yield and PX,Bio than
average conditions.
•
Record drawings and design documents from the 2005 aeration system improvement project
(Hazen and Sawyer, 2005) were examined and are provided in the appendix. The module C basin
86
has the same approximate footprint as Module A and Module B. Sidewater depth is 15.33 feet and
diffuser submergence is 14.33 feet. Each basin has 3,330 Sanitaire – Silver Series II diffusers for
a total of 13,320 diffusers.
•
The Module C system was designed with a limited DO control system. Each basin has a single
membrane type DO probe at the midpoint of the basin that is used to throttle a single MOV valve
to each basin. The system has a DO setpoint of 2.0 mg/L. Because DO data is not available for
the August through October 2010 timeframe, a range of 1.5 to 2.5 mg/L DO are checked in the
model verification.
•
Three (3) 500 horsepower multistage centrifugal blowers provide air to Module C.
The
dimensions of the piping system were ascertained from the record drawings for the 2005 aeration
system improvement project and used to determine the system curve and headloss for input into
the model verification.
•
The airflow through the aeration system at Module C is partially comprised of foul air from the
headworks (approximately 8,000 cfm), which is conveyed to the aeration basins for odor control.
A low pressure centrifugal FRP fan blows the air from the headworks into the aeration system. A
detailed analysis of the FRP fan capacity was not completed. It is assumed that the foul air
arriving at the blower suction is similar to ambient pressure for blower power calculations.
As an example, a screenshot of a week of data from the North Broward Regional WWTP that was used
to verify model accuracy is provided as Figure 4.19.
87
Figure 4.19 – Model Verification - Week of August 8, 2010
88
The bottom rows of the Figure 4.19 demonstrate how the model predicted air flowrate and
horsepower correlate to measured values for the week of August 8 through August 13, 2010. It is apparent
that the method used to estimate horsepower, based on SCFM and efficiency assumption of 62% for multistage centrifugal blowers, correlates well to the actual horsepower supplied at the Broward County
Northern Region WWTP – Module C. The values marked within the red box of Figure 4.19 show that the
model accurately predicts horsepower based on equation (19) and key efficiency assumptions, predicting a
daily average of 805 horsepower versus 803 horsepower measured.
It is also apparent from Figure 4.19 that the air flowrate and horsepower measured at Module C do
not correlate well with the model predicted values when considered on a day by day basis. It appears that
the Module C aeration system does not respond to fluctuations in influent loading as Equation (4) would
suggest. Figure 4.20 demonstrates the variability of predicted SCFM versus the much more confined
variation of measured SCFM.
35,000
Measured SCFM
30,000
Predicted SCFM
Linear (Measured SCFM)
25,000
Linear (Predicted SCFM)
SCFM
20,000
15,000
10,000
5,000
0
1‐Aug
31‐Aug
30‐Sep
Date
Figure 4.20 – Predicted SCFM vs. Measured SCFM
89
30‐Oct
Although predicted air flowrate and horsepower do not correlate well on a daily basis, Figure 4.20
and Table 4.6, below, demonstrate that when averaged over the three month timeframe from August
through October, 2010, a good correlation is apparent, with a SCFM predicted to SCFM measured value
ratio of 98%, and a horsepower predicted to horsepower measured value ratio of 100%.
Table 4.6 – Predicted SCFM vs. Standard Oxygen Requirement based on Loading
Comparison of Model’s Predicted Values to
Actual Measured Values
Key Assumptions
DO
(mg/L)
Yield
(lb VSS/ lb BOD)
Efficiency
(%)
Alpha
SCFM Predicted/Measured
(%)
hp Predicted/Measured
(%)
2.5
0.62
62%
0.43
98%
100%
Under the key assumptions listed in Table 4.6, a good correlation is apparent. However, the key
variables that were developed for this paper are based on typical expected values of DO, yield, efficiency,
and alpha. The actual values at the Broward County North Regional WWTP – Module C were not able to
be verified. To determine the effects of variability of these key assumptions on the models accuracy, a
sensitivity analysis of the key assumptions was completed. Table 4.7 demonstrates that the model results
are most sensitive to variation of DO and alpha.
Table 4.7 – Model Verification Sensitivity Analysis
Parameter
Value
1.5
SCFM Predict /
Measured
81%
hp Predicted /Measured
79%
DO (mg/L)
2
88%
89%
2.5
98%
100%
0.57
102%
106%
0.62
98%
100%
0.67
93%
94%
57%
-
108%
62%
-
100%
67%
-
92%
Yield (lb VSS / lb
BOD)
Efficiency (%)
(Table 4.7 continued on next page)
90
Parameter
(Table 4.7 continued)
Alpha
Value
SCFM Predict /
Measured
hp Predicted /Measured
0.38
113%
120%
0.43
98%
100%
0.48
85%
84%
Daily average electricity usage was available for August through October, 2010 for mechanically
aerated Module A and Module B and compared to energy usage of Module C, presented in Table 4.8.
Table 4.8 demonstrates that all three modules are approximately equivalent in energy use over the three
month period on a hp/MGD basis. While this finding may seem contrary to this thesis’ assertion that
installation of fine bubble diffusers will improve the energy efficiency of treatment, it is important to note
that the treatment being supplied in Modules A and B are not equivalent to the level of treatment being
supplied in Module C. DO levels of 2.0 mg/L or higher are being supplied in Module C, and air is being
supplied beyond that required to satisfy carbonaceous oxygen demand to achieve complete nitrification.
Although Module C has fine bubble diffusers, it does not have the additional ECMs of turbo blowers and
automatic DO control with probes and valves in each zone with the capability to tightly control DO within
1.5 mg/L. Table 4.9 shows that using the assumptions in Table 4.6, a gain in efficiency of 4% is predicted,
matching relatively close to the measured gain in efficiency of 1% for the August to October 2010
timeframe (based on the key assumptions listed in Table 4.6).
Table 4.8 – Mechanically Aerated Module A, B, vs. Fine Bubble Aerated Module C Measured Energy
Usage Comparison
Module
hp/MGD
Mechanically Aerated Module A
47.3
Mechanically Aerated Module B
45.7
Fine Bubble Aerated Module C
46.1
Actual % Efficiency Gain of Module
1%
C vs. Module A/B for Aug – Oct 2010
91
Table 4.9 – Model Efficiency Gain Prediction Vs. Actual Efficiency Gain Prediction
Technology
Level of
Treatment
1. Fine Bubble
Diffusers
Complete
Nitrification
Current hp
(Mechanical
Aeration) 1
Proposed
hp (Fine
Bubble
Diffused
Air)
Predicted
%
Efficiency
Gain
Actual % Efficiency
Gain of Module C vs.
Module A/B for Aug –
Oct 2010
823
786
4%
1%
1. Projected hp assuming all aerators are on for each module
In summary, the model predictions appear to correlate reasonably well to the limited data available
from the Broward County North Regional WWTP for fine bubble diffused aeration energy, indicating that
the model is reasonably accurate at predicting average airflow rates and energy use. Broward County North
Regional WWTP provides a remarkably unique opportunity to measure the model’s accuracy due to the
side by side arrangement of mechanical aeration versus fine bubble diffused aeration in identical basins and
influent wastewater characteristics. Unfortunately similar information is not available at the Boca Raton
WWTP nor the Plantation Regional WWTP. The side by side measured efficiency of mechanical aeration
at Module A and Module B versus fine bubble diffused aeration at Module C was also compared, and
correlates reasonably well with the model. Variations in key assumptions can affect the model results as
demonstrated in Table 4.7. However, reasonable assumptions based on key assumption values in Table 4.6
demonstrate good correlation in this case and provide preliminary verification of the model’s relative
accuracy and precision. It is recommended that additional data sets and verification of key assumptions be
completed and used to verify the model.
92
V. PLANT ECM ASSESSMENT
The facilities shown in Table 5.1 are analyzed using the methodology discussed in previous
sections for ECM upgrades to the activated sludge process. The plants were chosen based on the common
factor that they all use a mechanically aerated conventional activated sludge treatment process.
Table 5.1 – Study Facility Summary
PLANT NAME
CITY
AERATION SYSTEM SUMMARY
17.5 MGD capacity plant, (3) 2.1 MG aeration basins each
with (3) 100-hp mechanical surface aerators. (3) multi-stage
Boca Raton WWTP
Boca Raton, FL
centrifugal blowers provide peak season / high loading
supplemental aeration.
95 MGD capacity plant with both mechanical and fine bubble
Broward Co North
Pompano Beach, FL diffused aeration. Study focuses on (8) 2.2 MG aeration
Regional WWTP
basins each with (3) 100-hp mechanical surface aerators.
18.9 MGD capacity plant with (3) 1.1 MG aeration basins
Plantation Regional
Plantation, FL
each with (1) 125-hp and (2) 100-hp mechanical surface
WWTP
aerators.
5.1
City of Boca Raton WWTP
5.1.1
Boca Raton WWTP - Existing Secondary Treatment
The Boca Raton WWTP utilizes the following liquid stream treatment processes; influent
screening and grit removal, primary clarification, a conventional activated sludge system with mechanical
aeration and limited medium-bubble diffused aeration, secondary clarification, chlorination, and high rate
filtration for producing reclaimed water. The secondary treatment process comprises three (3) 85-feet wide
93
by 255-feet long aeration basins with sidewater depth of 13 feet. Three (3) 100 hp mechanical surface
aerators normally provide air to each basin on a constant basis, with two of three basins in operation at any
given time. Additionally, supplemental aeration is typically provided by a medium-bubble diffuser system
in the first third of each basin during peak season / peak loading hours, approximately four hours per day.
Air is provided to the diffusers via one of three multi-stage centrifugal blowers. The details of the aeration
system at the Boca Raton WWTP are summarized in Table 5.2 through 5. 5.
Table 5.2 - Aeration Basin Characteristics
Description
Unit
Value
Conventional Activated Sludge
3
Type of Unit
No. of Basins
Basin Dimensions:
Width
Length
Side Water Depth
Volume (each)
Total Volume
85
255
13
281,775
6.32
ft
ft
ft
cf
MG
Table 5.3 - Mechanical Aeration Characteristics
Description
No. of Aerators
Per Basin
Total
Mechanical Aerator Rating, each
Total Mechanical Aeration Capacity
Unit
Value
lbs-O2/hr
lbs-O2/day
3
9
300
64,800
Table 5.4 - Diffused Aeration Characteristics
Description
Manufacturer
No. of Diffusers
Per Basin
Total
Diffuser Rating
Oxygen Transfer Capacity
Total Oxygen Transfer Capacity
Unit
lbs-O2/hour
lbs-O2/day
lbs-O2/day
94
Value
Parkson Flex-a-Tube
860
2,580
0.674
13,911
41,730
Table 5.5 - Blower Characteristics
Description
Manufacturer
No. of Units
Type
Air Flow (each)
Horsepower
Unit
Value
scfm
hp
Gardner Denver / Hoffman
3
Multi-Stage Centrifugal
4,000
200
(Hazen and Sawyer (2), 2007)
5.1.2
Boca Raton WWTP –Influent and Effluent Water Quality
Water quality data for the Boca Raton WWTP was gleaned from the 2007-2009 monthly operating
reports and is presented in Table 5.6 througuh 5.8, below. The data was adjusted to the average study
period flow (2011 to 2031) based on predicted population increase in the plant service boundaries which
were gleaned and interpolated from a 2001 South Florida Water Management District (SFWMD)
Consumptive Use Permit for the Boca Raton WWTP, and are used for the purposes of predicting average
energy consumption of the 20-year design horizon. Also, the data was adjusted to the plant design flow of
17.5 MGD which was used for designing the capital improvements. The CBOD5 loading data for the Boca
Raton WWTP following the primary clarifier process was not available. Primary clarifier removal rates are
typically 25 to 40 percent of BOD and 50 to 70 percent of TSS (Tchobanoglous et al., 2003).
A
conservative value of 25 percent CBOD5 removal and 50 percent TSS removal was assumed and applied to
the City of Boca Raton raw influent loading rates. The data that was used for analysis of the Boca Raton
WWTP’s activated sludge treatment process and is presented in Tables 5.6 through 5.8 below.
Table 5.6 – Boca Raton WWTP – Design Influent/Effluent Based on 2007-2009 Flow/Loading Data
Loading
Condition
Min Day
ADF
MMADF
Max Day
Inf
Flow
(MGD)
Pri. Eff
CBOD5
(lbs)
9.72
13.98
15.73
21.02
6,433
15,870
20,223
28,204
Pri.
Eff
TSS
(lbs)
Eff
CBOD5
(lbs)
4,180
9,592
12,267
35,070
84
333
496
968
95
Eff
WAS
VSS
(lbs)
Inf
TKN
(lbs)
Eff
NH3
(lbs)
1,370
10,659
14,054
17,200
2,277
4,153
4,956
6,596
419
1,104
1,554
1,972
Avg
DO
(lbs)
0.50
Avg
SRT
(days)
3.91
Table 5.7 – Boca Raton WWTP – Design Influent/Effluent Adjusted to Est. 2011-2031 Avg Flowrate
Loading
Condition
Min Day
ADF
MMADF
Max Day
Inf Flow
(MGD)
10.12
14.55
16.37
21.87
Pri. Eff
CBOD5
(lbs)
6,695
16,516
21,046
29,351
Pri. Eff
TSS
(lbs)
4,350
9,983
12,766
36,497
Eff
CBOD5
(lbs)
87
347
516
1,008
Eff
WAS
VSS
(lbs)
1,426
11,093
14,626
17,900
Inf
TKN
(lbs)
Eff
NH3
(lbs)
2,369
4,322
5,158
6,865
436
1,149
1,618
2,053
Table 5.8 – Boca Raton WWTP – Design Influent/Effluent Adjusted to Design Flow
Loading
Condition
Min Day
ADF
MMADF
Max Day
5.1.3
Inf Flow
(MGD)
12.16
17.50
19.69
26.30
Pri. Eff
CBOD5
(lbs)
8,051
19,861
25,308
35,295
Pri. Eff
TSS
(lbs)
5,231
12,004
15,351
43,888
Eff
CBOD5
(lbs)
105
417
621
1,212
Eff
WAS
VSS
(lbs)
1,715
13,339
17,587
21,525
Inf
TKN
(lbs)
2,849
5,197
6,202
8,255
Eff
NH3
(lbs)
524
1,382
1,945
2,468
Boca Raton WWTP – Proposed ECM Design
Each ECM is cumulative and cannot be installed without the installation of the prior ECM. For
example, ECM No. 2 – Turbo Blowers cannot be installed without prior installation of ECM No. 1 – Fine
Bubble Diffusers (refer to Figure 1.10).
ECM No. 1 - Fine Bubble Diffusers –To install membrane fine bubble diffusers, it is necessary to
demolish the existing diffusers and mechanical aerators. Each basin is divided into three zones, and each
zone will be fitted with a grid of 1,167 diffusers, for a total of 9 grids and 10,500 diffusers. ECM No. 1
also requires the demolition of the existing concrete blower canopy structure and blowers, and the
construction of a new blower building with (1) 200-hp and (3) 300 hp multi-stage centrifugal blowers. It is
assumed that the nearby existing motor control center (MCC) room has adequate capacity to support the
three blowers since three 300-hp blowers and three 100-hp mechanical surface aerator starters that are
being removed from the nearby MCC exceed the horsepower of the proposed improvements. Although the
existing blowers are housed under an open air blower shelter, it is common to store blowers indoors for
protection from heat and extreme weather. Therefore, the existing blower shelter will be demolished and
replaced with a dedicated blower building.
96
ECM No. 2 – Turbo Blowers – ECM No. 2 entails installing (1) 200-hp and (3) 300-hp more
efficient turbo blowers in place of the multi-stage centrifugal blowers proposed under ECM No. 1.
ECM No. 3 – Automatic DO Control Strategy – Dissolved oxygen probes and transmitters will be
installed at each zone for a total of nine probes and six transmitters. Motor-operated modulating valves
(MOVs) and venturi flow meters will be installed on the aeration piping of each grid, to control flow to
each basin based on the DO level signal from the probe, for a total of nine MOVs and nine venturi flow
meters. A programmable logic control (PLC) unit will be installed in the blower building to control the
modulating valves and blowers based on DO and air flowrate measurement.
The preliminary design drawings for the proposed ECMs at the Boca Raton WWTP are provided
in Appendix A.
5.1.4
Boca Raton WWTP - Results and Discussion
The Boca Raton WWTP does not currently achieve full nitrification, as the average ammonia
concentration in the secondary effluent for the 2007-2009 was 9.8 mg/L and the historical average DO level
in the aeration basins was 0.5 mg/L. Accordingly, the Current Treatment scenario demonstrates the
potential energy savings assuming that the activated sludge process continues to only partially nitrify, with
an average DO of 0.5 mg/L. The estimated life cycle costs and savings are presented in Table 5.9 and 5.10,
below. The detailed spreadsheet calculations for the analysis are attached in Appendix A.
Table 5.9 – Life Cycle Cost Analyses Estimated Costs
Plant
Boca Raton WWTP
Level of
Treatment
Partial
Nitrification
NPV of
Change in
O&M Costs
- $161,857
NPV of
Foregone
Capital
Replacement
-$1,558,926
Capital
Cost
$3,261,794
NPV of
Capital,
O&M,
Foregone
Capital
$1,541,011
Table 5.10 – Life Cycle Cost Analyses Estimated Savings
Plant
Boca Raton WWTP
Level of
Treatment
Partial
Nitrification
Power
Reduction
(hp)
209
% Eff.
Gain
Ann.
Energy
Cost
Savings
Energy
Savings Net
Present
Value
37%
$95,403
-$1,541,492
1. Range for AACE Class 4 cost estimate of -20% to + 30% of median estimate shown in brackets
97
Payback
(years)
[range]
20
[11 to 37]
Figure 5.1 demonstrates the payback of implementing ECM Nos. 1 through 3 at the Boca Raton
WWTP. The point where the lines cross is the payback point, or the point at which the sum of O&M,
energy, and capital costs for ECM No. 1 through 3 become cost beneficial compared maintaining operation
of the existing mechanical aeration system.
Figure 5.1 also demonstrates the range of error for payback
based on the AACE Class 4 cost estimate range of -20% to +30%, with a minimum range of 11 years and a
maximum of beyond 20 years (37 years).
$8,000,000
$7,000,000
Present Value Worth
$6,000,000
$5,000,000
$4,000,000
Exist.
$3,000,000
Partial Nitrification
$2,000,000
‐20% Capital Cost
$1,000,000
+30% Capital Cost
$0
0
5
10
15
20
25
Years
Figure 5.1 – Present Value Comparison of Existing Process Versus Proposed ECMs
Table 5.11 and Figure 5.2 indicate that the cumulative effects of the ECMs result in a median
estimated payback of 16 years under the Current Treatment Scenario, 20 years under the Partial
Nitrification scenario, and 31 years for the Complete Nitrification scenario. The paybacks for the Current
Treatment and Partial Nitrification scenarios are at or beneath the payback threshold of 20 years that most
plant managers consider to be an actionable threshold. The Complete Nitrification scenario is not below
the threshold, however still presents a considerable payback.
98
In an anaysis of the paybacks of each individual ECM, Table 5.11 reveals that the only ECM that
does not have a payback under 20 years is ECM No. 1 - Fine Bubble Diffusers. These results indicate that
once the Boca Raton WWTP clears the hurdle of the implementation of ECM No. 1, that implementation of
ECM Nos. 2 through 4 are very cost benefical even under the high capital cost estimate assumption for the
partial nitrification and complete nitrification scenarios.
Table 5.11 – Boca Raton WWTP– Incremental Life-Cycle Cost Analysis
Technology
1. Fine
Bubble
Diffusers
2. Turbo
Blowers
3. Auto DO
Control 1.5 mg/L
Total
Cumulative
Level of Treatment
% Eff.
Gain
Avg.
Daily
Energy
Savings
(kWh)
Ann.
Energy
Cost
Savings
($)
Payback
(Low
Est)
(Years)
Payback
(Median
Est)
(Years)
Payback
(High
Est)
(Years)
Cur. Treatment - 1.5 mg/L DO
38%
3,819
$97,588
5
12
24
Part. Nitrification - 3.0 mg/L DO
3%
261
$6,668
-
-
-
Complete Nitrification
-17%
-1,672
($42,714)
-
-
-
Cur. Treatment - 1.5 mg/L DO
9%
858
$21,929
13
17
24
Part. Nitrification - 3.0 mg/L DO
14%
1,353
$34,557
8
10
14
Complete Nitrification
16%
1,621
$41,416
7
8
11
Cur. Treatment - 1.5 mg/L DO
0%
0
$0
-
-
-
Part. Nitrification - 1.5 mg/L DO
21%
2,120
$54,179
5
7
9
Complete Nitrification
26%
2,604
$66,534
4
6
8
Cur. Treatment - 1.5 mg/L DO
47%
4,678
$119,517
9
16
28
Part. Nitrification - 1.5 mg/L DO
37%
3,734
$95,404
11
20
37
Complete Nitrification
26%
2,553
$65,235
17
31
67
(1) The Current Treatment scenario for ECM No. 3 is not applicable because there is no difference in any of the variables
or assumptions for that scenario between the ECM No. 2 and ECM No. 3
99
100%
90%
Current Treatment ‐ 0.5 mg/L
80%
Partial Nitrification ‐ 1.5 mg/L
70%
Complete NOx
Efficency (%)
60%
50%
40%
30%
20%
10%
0%
‐10%
1. Fine Bubble Diffusers
2. Turbo Blowers
‐20%
3. Auto DO Control ‐
1.5 mg/L
Total ECM
Figure 5.2 – Boca Raton WWTP – Incremental Increase in Efficiency Per ECM
The results demonstrate that each successive ECM accumulates for a cumulative total
improvement in efficiency, resulting in predicted energy and cost savings. Figure 5.2 demonstrates the
contribution of each ECM to the total improvement of efficiency over the existing aeration system. For the
Boca Raton WWTP, it is apparent that implementation of ECM No. 1 actually results in a loss of efficiency
for the Partial and Complete Nitrification scenarios. It is important to reemphasize that this loss in
efficiency is due to the additional treatment benefits of providing higher dissolved oxygen and complete
nitrification and is not a like for like comparison of the efficiency of the proposed system to the existing.
A theoretical like for like comparison is provided under the Current Treatment scenario, where DO is
maintained at 0.5 mg/L and partial nitrification continues at the previous rate. Under the theoretical
Current Treatment scenario, great improvement efficiency is realized with the implementation of ECM No.
1 and for the total efficiency
100
5.1.5
Boca Raton WWTP - Sensitivity Analysis
Variables were isolated and manipulated in the model to determine their effects on the payback
results, which are demonstrated in Table 5.12 below.
Table 5.12 – Boca Raton WWTP – Payback Sensitivity Analysis
Payback
Current
Treatment
18
Partial
Nitrification
20
Complete
Nitrification
36
10% Capital Reduction
16
17
29
20% Capital Reduction
13
14
24
AEO High Electricity Growth of +0.25%
16
20
32
AEO Low Electricity Growth of -0.18%
15
20
30
$0.08 per kWh
13
17
27
$0.09 per kWh
12
15
23
CPI Inflation + 1% or Bond Rate - 1%
14
18
26
CPI Inflation - 1% or Bond Rate + 1%
17
23
40
+5% Turbo Blower Efficiency
14
18
25
-5% Turbo Blower Efficiency
17
23
43
2.0 mg/L DO
16
24
47
1.0 mg/L DO
16
17
24
Case
Base
The effects of capital cost reduction are explored to determine how the payback improves with the
effects of grants or error in the capital cost estimate. The Current Treatment and Partial Nitrification
scenarios reduce considerably with capital cost reduction. The Complete Nitrification scenario payback
also improves considerably but not close to the 20 year threshold.
The effects of variations in the rate of electricity inflation used in the model were investigated by
testing how the model responds to the AEO 2006 – 2011 Report Low Economic Growth and High
101
Economic Growth “side case” average electricity inflation rates detailed in Table 3.2. The effects of the
Low Oil Price and High Oil Price side cases were not tested because their effects on the upward and
downward rate of electricity inflation are less pronounced than the economic cases as demonstrated in
Figure 3.2 .
The effects of variations in the CPI inflation rate or bond rate are similar because they are both
used to determine the real interest rate used in equation (1) and equation (2) for the life cycle cost analyses.
An equivalent rise in the CPI Rate will have an identical effect to an equivalent drop in the bond rate, and
vice-versa.
The effects of an increase or decrease in turbo blower efficiency are tested because the average
turbo blower efficiency of 72 percent determined from (Rohrbacher et al., 2010) would likely vary on a
case by case basis.
The effects of a variation in DO levels is tested to determine the model’s sensitivity to variations
in plant DO level, which may not be able to be held an an average target level of 1.5 mg/L due to operator
or insrument error, or other practical limitations such as peak loadings or toxic slugs.
The ramifications of the sensitivity analysis and comparison to the other plants are further
discussed in Section 6.5.
5.2
Broward County North Regional WWTP
5.2.1
Broward County North Regional WWTP - Existing Secondary Treatment
The Broward County North Regional WWTP utilizes the following liquid stream treatment
processes; influent screening and grit removal, a conventional activated sludge system with mechanical
aerators or fine-bubble diffusers, secondary clarification, and then discharge via deep well injection or
ocean outfall discharge, or high rate filtration and chlorination for reclaimed water distribution. The plant
exerts a demand of approximately 133,000 kW, making it the largest single electricity user in Broward
County. The aeration basins comprise approximately half of this power demand (Bloetscher, 2011).
The secondary treatment process comprises five modules of aeration basins.
Each module
contains four 75-feet wide by 255-feet long aeration basins with sidewater depth of 15.5 feet. Modules A,
B, and D are equipped with mechanical aerators, and fine bubble diffused aeration is equipped in modules
102
C and E. The focus of this study is on improvements to modules A and B, where three (3) 100 hp
mechanical surface aerators provide air to each mechanically aerated basin on a constant basis. The details
of the aeration system at the Broward County North Regional WWTP are summarized in Table 5.13 and
Table 5. 14.
Table 5.13 - Aeration Basin Characteristics – Modules A and B
Description
Unit
Type of Unit
No. of Basins
Basin Dimensions:
Width
Length
Side Water Depth
Volume (each)
Total Volume
Value
Conventional Activated Sludge
8
ft
ft
ft
cf
MG
75
255
15.5
296,000
17.74
Table 5.14 - Mechanical Aeration Characteristics – Modules A and B
Description
No. of Aerators
Per Basin
Total
Mechanical Aerator Rating, each
Total Mechanical Aeration Capacity
Unit
Value
lbs-O2/hr
lbs-O2/day
3
24
300
172,800
(Hazen and Sawyer (1), 2007)
5.2.2
Broward County North Regional WWTP –Influent and Effluent Water Quality
Water quality data for the Broward County North Regional WWTP was gleaned from the 2004-
2006 monthly operating reports and is presented in Table 5.15 through 5.17, below.
More recent data was
not able to be obtained. The data was adjusted to the average study period flow (2011 to 2031) based on
predicted population increase in the service boundaries gleaned and interpolated from a 2011 Capacity
Analysis Report (CAR) completed by Hazen and Sawyer, P.C. for the plant, which is used for the purposes
of predicting average energy consumption of the 20-year design horizon. Also, the data was adjusted to the
current plant design flow of 95 MGD which was used for designing the capital improvements.
103
Table 5.15 – Broward Co. N. Regional WWTP – Design Influent/Effluent Based on 2004-2006
Inf
CBOD5
(lbs)
1,994
Inf
TSS
(lbs)
10,522
Eff
CBOD5
(lbs)
510
Eff
WAS
VSS(1)
( )
1,457
Inf
TKN
(lbs)
4,707
Eff
NH3
(lbs)
1,011
Avg
DO
(lbs)
Avg
SRT
(days)
Min Day
Inf
Flow
(MGD)
14.21
ADF
37.20
47,257
71,891
1,599
34,536
10,458
3,268
1.0
3.7
MMADF
44.15
71,927
126,168
2,643
52,564
13,935
5,459
Yield
Max Day
56.72
180,246
733,683
6,810
131,724
15,516
8,453
0.63
Loading
Condition
(1) Calculated based on Yield, estimated per (Dold, 2007) method
Table 5.16 – Broward Co. N. Regional WWTP – Design Influent/Effluent Adjusted to Est. 2011-2031
Avg Flow
Eff
Inf
Inf
Inf
Eff
WAS
Inf
Eff
Loading
Flow
CBOD5
TSS
CBOD5
VSS(1)
TKN
NH3
Condition
(MGD)
(lbs)
(lbs)
(lbs)
(lbs)
(lbs)
(lbs)
Min Day
15.94
2,236
11,800
572
1,634
5,279
1,134
ADF
41.72
52,998
80,624
1,793
38,731
11,729
3,665
MMADF
49.52
80,665
141,495
2,964
58,950
15,628
6,122
Max Day
63.61
202,143
822,813
7,638
147,726
17,401
9,480
Table 5.17 – Broward Co. N. Regional WWTP – Design Influent/Effluent Adjusted to Design Flow
5.2.3
Loading
Condition
Min Day
Inf
Flow
(MGD)
18.14
Inf
CBOD5
(lbs)
2,546
Inf
TSS
(lbs)
13,434
Eff
CBOD5
(lbs)
652
Eff
WAS
VSS(1)
(lbs)
1,861
Inf
TKN
(lbs)
6,010
Eff
NH3
(lbs)
1,291
ADF
47.50
60,338
91,790
2,042
44,095
13,353
4,173
MMADF
56.37
91,836
161,090
3,375
67,114
17,792
6,970
Max Day
72.41
230,137
936,761
8,695
168,184
19,810
10,793
Broward County North Regional WWTP – Plant Specific Methodology Considerations
Number of Basins Normally In Service
The calculation for the amount of horsepower used and the number of basins in service for the
Broward County North Regional WWTP model is nuanced. Unlike the Boca Raton WWTP or the
Plantation Regional WWTP, which both typically have a fixed number of basins in service at all times,
monthly operating reports reveal that Broward County North Regional WWTP brings basins at Modules A
and B in and out of service as flow and loading change, with as little as 5 and as many as 8 basins in service
104
during the 2004-2006 data study period. It is important to consider that over the 2011 – 2031 model period,
basins will be taken on and offline as neccesary depending on flowrates and loadings through the plant, and
also for scheduled maintenance. To estimate the amount of basins and horsepower used in the model, the
number of basins online compared with the amount of flow through each basin were analyzed for the years
2004 through 2006, and extrapolated to the 2011-2031 study period to predict the average amount of basins
in service . The results of this analysis are presented in Table 5.18.
Table 5.18 – 2004-2006 # of Basins In Service vs. Flowrate
Condition
Avg # of Basins
in Service
Module A and B
Flow (MGD)
MGD Per Basin
Avg Day
6.3
36.3
5.8
2011-2031 Avg
7.2
41.7
5.8
Module D Energy Reduction
Module D is similar to Module A and B, except that the aerator in the first zone of each basin at
Module D is 150 hp capacity. Currently the Broward County North Regional WWTP typically operates
two of the four basins at Module D. Once Module A and Module B are brought online with fine bubble
diffused air, it will be practical for the Broward County North Regional WWTP to divert flow away from
the mechanically aerated Module D to Module A and B, or to the existing fine-bubble aerated Module C
and E to achieve improved treatment efficiency. The mechanical aerators that are no longer required to be
operated at Module D are a key source of energy savings for this analysis.
According to the most recent O&M Performance Report (Hazen and Sawyer (1), 2007), the
average flow to each basin is 5.6 MGD, with a design capacity of 7 MGD per basin. Conservatively
assuming 5.6 MGD through each basin, the fine-bubble aerated Modules A, B, C, and E should have
adequate capacity to treat 89.6 MGD of flow, or 84 MGD with one basin out of service. Given that the
projected average flow over the 2011-2031 design period is 83.4 MGD, Module D should be able to be
kept out of service for the majority of the time, providing spare aeration capacity as needed for peak
seasonal flows and loadings, and for growth in flows and loadings towards the end of the design period.
For this analysis, it is conservatively assumed that on avearge one of the four basins at Module D will
remain in service over the 2011-2031 timeframe, and the energy saved by bringing one basin out of service
105
is deducted from the projected energy use for implementing ECM Nos. 1 through 3. Since Module D is
assumed to be offline, for modeling puporses it is assumed that half of all flow and loading entering the
plant will be routed through Module A and B, with the other half routed to Module C and E. Table 5.19
below summarizes the calculation of the Module D Energy Reduction.
Table 5.19 – Projected Module D Energy Reduction
Parameter
Value
Typical flow through each basin per 2007 O&M Report
Unit
5.6
MGD
Number of basins per module
4
Basins
Number of basins per module A, B, C, and E
16
Basins
89.6
MGD
84
MGD
83.4
MGD
Number of basins at Module D typically online
2
Basins
Number of basins at Module D assumed to be brought offline due to flow
routed to fine-bubble aerated modules
1
Basin
Total capacity Module A, B, C, and E
Total capacity of Module A, B, C, and E with one basin out of service
Projected average flow over 2011-2031 time period
Typical energy usage per basin at Module D according to Aug through
Oct 2010 average daily data (to be deducted from projected energy use
for ECM No. 1 through 3)
5.2.4
309
hp
Broward County North Regional WWTP – Proposed ECM Design
ECM No. 1 - Fine Bubble Diffusers –To install membrane fine bubble diffusers, the existing
mechanical aerators will need to be demolished. Each basin is divided into three zones, and each zone will
be fitted with a grid of 830 diffusers, for a total of 24 grids and 20,000 diffusers. ECM No. 1 also entails
the construction of a new blower building with (2) 200-hp and (6) 300 hp multi-stage centrifugal blowers.
It is assumed that the nearby existing motor control center (MCC) room has adequate capacity to support
the eight blowers since the twenty four (24) 100-hp mechanical surface aerators that are being removed
exceed the horsepower of the proposed improvements. Although the existing blowers are housed under an
open air blower shelter, it is common to store blowers indoors for protection from heat and extreme
weather. The existing blower shelter will be demolished and replaced with a blower building.
106
ECM No. 2 – Turbo Blowers – ECM No. 2 entails installing (2) 200-hp and (6) 300-hp more
efficient turbo blowers in place of the multi-stage centrifugal blowers proposed under ECM No. 1.
ECM No. 3 – Automatic DO Control Strategy – Dissolved oxygen probes and transmitters will be
installed at each zone for a total of twenty four probes and twelve transmitters. Motor-operated modulating
valves (MOVs) and venturi flow meters will be installed on the aeration piping of each grid, to control flow
to each basin based on the DO level signal from the probe, for a total of twenty four MOVs and twenty four
venturi flow meters. A programmable logic control (PLC) unit will be installed in the blower building to
control the modulating valves and blowers based on DO and air flowrate.
The preliminary design drawings for the proposed ECMs at the Broward County North Regional
WWTP are provided in Appendix B.
5.2.5
Broward County North Regional WWTP – Results and Discussion
The Broward County North Regional WWTP does not achieve full nitrification, as the average
ammonia concentration in the secondary effluent (from the entire plant, not just Modules A and B) for the
2004-2006 year was 10.8 mg/L and the historical average DO level is 1.0 mg/L. Accordingly, the Current
Treatment scenario demonstrates the potential energy savings assuming that the activated sludge process
continues to only partially nitrify, with an average DO of 1.0 mg/L. The estimated life cycle costs and
savings are presented in Table 5.20 and 5.21, below. The detailed spreadsheet calculations for the analysis
are attached in Appendix B.
Table 5.20 – Life Cycle Cost Analyses Estimated Costs
Conditions
Broward Co N Regional
Broward WWTP
Level of
Treatment
Partial
Nitrification
NPV of
Change in
O&M
Costs
-$194,519
107
NPV of
Foregone
Capital
Replacement
- $3,035,109
Capital
Cost
$7,954,846
NPV of
Capital,
O&M,
Foregone
Capital
$4,725,218
Table 5.21 – Life Cycle Cost Analyses Estimated Savings
Power
Reduction
(hp)
%
Eff.
Gain
Ann.
Energy
Cost
Savings
Energy
Savings Net
Present
Value
Payback
(years)
[range]
33
[19 to 63]
Condition
Level of
Treatment
Not Considering
Module D
Partial
Nitrification
434
29%
$198,730
($3,211,003)
Considering One Basin at
Module D Out of Service
Partial
Nitrification
743
50%
$340,081
($5,494,902)
17
[11 to 28]
Considering Module D
Completely Out of Service
Partial
Nitrification
1052
71%
$481,432
($7,778,801)
11
[7 to 18]
1. Range for AACE Class 4 cost estimate of -20% to + 30% of median estimate shown in brackets
Figure 5.3 and Figure 5.4 demonstrate the payback of implementing ECM Nos. 1 through 3 at the
Broward County North Regional WWTP considering one basin at Module D out of service, and not
considering Module D effects, respectively. The point where the lines cross is the payback point, or the
point at which the sum of O&M, energy, and capital costs for ECM No. 1 through 3 becomes cost
beneficial compared to the current operation.
Figure 5.3 and 5.4 demonstrate the range of error for
payback based on the AACE Class 4 cost estimate range of -20% to +30%, with a minimum range of 11
and maximum range of beyond 20 years (28 years) for the consideration of one basin at Module D out of
service, and a minimum range or 19 years and a maxmum beyond 20 years (63 years) for no consideration
of Module D effects.
108
$20,000,000
$18,000,000
$16,000,000
Present Value Worth
$14,000,000
$12,000,000
$10,000,000
$8,000,000
Exist.
$6,000,000
Partial Nitrification
$4,000,000
‐20% Capital Cost
$2,000,000
+30% Capital Cost
$0
0
5
10
15
20
25
Years
Figure 5.3 – Present Value Comparison of Existing Process Versus Proposed ECMs
$25,000,000
Present Value Worth
$20,000,000
$15,000,000
$10,000,000
Exist.
Partial Nitrification
$5,000,000
‐20% Capital Cost
+30% Capital Cost
$0
0
5
10
15
20
Years
Figure 5.4 – Present Value Comparison of Existing Process Versus Proposed ECMs – No
Consideration for Module D Effects
109
25
Table 5.22 and Figure 5.5 indicate that the cumulative effects of the ECMs result in a median
estimated payback of 15 years under the Current Treatment Scenario, 17 years under the Partial
Nitrification scenario, and 21 years for the Complete Nitrification scenario. In an anaysis of the paybacks
of each individual ECM, Table 5.20 reveals that the each individual ECM achieves a considerable payback
at or beneath the 20 year threshold, except for the ECM No. 1 Partial Nitrification and Complete
Nitrification Scenarios.
Table 5.22 – Broward Co. N. Regional WWTP – Incremental Life-Cycle Cost Analysis
Technology
1. Fine
Bubble
Diffusers
2. Turbo
Blowers
3. Auto DO
Control - 1.5
mg/L
Total
Cumulative
Level of Treatment
%
Eff.
Gain
Ann.
Energy
Cost
Savings
($)
$306,702
Payback
(Low
Est)
(Years)
Payback
(Median
Est)
(Years)
Payback
(High
Est)
(Years)
45%
Avg.
Daily
Energy
Savings
(kWh)
6472
Cur. Treatment - 1.5 mg/L DO
7
13
22
Part. Nitrification - 3.0 mg/L DO
12%
-2310
$82,343
47
-
-
Complete Nitrification
-1%
-5847
($8,051)
-
-
-
Cur. Treatment - 1.5 mg/L DO
10%
2784
$71,123
9
12
16
Part. Nitrification - 3.0 mg/L DO
15%
4003
$102,284
6
7
10
Complete Nitrification
17%
4495
$114,839
5
7
9
Cur. Treatment - 1.5 mg/L DO
0%
0
$0
-
-
-
Part. Nitrification - 1.5 mg/L DO
23%
6084
$155,455
5
6
8
Complete Nitrification
26%
6871
$175,551
4
5
7
Cur. Treatment - 1.5 mg/L DO
56%
9255
$377,824
10
15
24
Part. Nitrification - 1.5 mg/L DO
50%
7778
$340,081
11
17
28
Complete Nitrification
42%
5518
$282,338
13
21
36
(1) The Current Treatment scenario for ECM No. 3 is not applicable because there is no difference in any of the
variables or assumptions for that scenario between the ECM No. 2 and ECM No. 3
110
60%
Current Treatment ‐ 1.0 mg/L
Current Treatment ‐ 1.5 mg/L
50%
Complete NOx
Incease in Efficency (%)
40%
30%
20%
10%
0%
1. Fine Bubble Diffusers
2. Turbo Blowers
‐10%
3. Auto DO Control ‐
1.5 mg/L
Total ECM
Figure 5.5 – Broward Co. N. Regional WWTP – Incremental Increase in Efficiency Per ECM
The results demonstrate that each successive ECM accumulates for a cumulative total
improvement in efficiency, resulting in predicted energy and cost savings. Figure 5.5 demonstrates the
contribution of each ECM to the total improvement of efficiency over the existing aeration system. For the
Broward County North Regional WWTP, it is apparent that implementation of ECM No. 1 actually results
in a loss of efficiency for the Partial and Complete Nitrification scenarios similar to the Boca Raton
WWTP. It is important to reemphasize that this loss in efficiency is due to the additional treatment benefits
of providing higher dissolved oxygen and complete nitrification and is not a like for like comparison of the
efficiency of the proposed system to the existing. A theoretical like for like comparison is provided under
the Current Treatment scenario, where DO is maintained at 1.0 mg/L and partial nitrification continues at
the previous rate. Under the theoretical Current Treatment scenario, a great improvement efficiency is
realized with the implementation of ECM No. 1 and for the total efficiency
111
5.2.6
Broward County North Regional WWTP - Sensitivity Analysis
Variables were isolated and manipulated in the model to determine their effects on the payback
results, which are demonstrated in Table 5.23 below.
Table 5.23 – Broward Co. N. Regional WWTP – Payback Sensitivity Analysis
Payback
Current
Treatment
15
Partial
Nitrification
17
Complete
Nitrification
21
10% Capital Reduction
12
14
17
20% Capital Reduction
10
11
13
AEO High Electricity Growth of +0.25%
15
17
20
AEO Low Electricity Growth of -0.18%
15
17
21
$0.08 per kWh
13
14
18
$0.09 per kWh
11
13
16
CPI Inflation + 1% or Bond Rate - 1%
14
15
19
CPI Inflation - 1% or Bond Rate + 1%
16
19
24
+5% Turbo Blower Efficiency
14
15
18
-5% Turbo Blower Efficiency
16
19
25
2.0 mg/L DO
15
20
26
1.0 mg/L DO
15
15
17
Case
Base
All scenarios show reasonable paybacks, with most cases for the Current Treatment and Partial
Nitrification base cases at or beneath the typical 20 year threshold that plant managers consider the
actionable threshold. The results in Table 5.23 generally do not deviate greatly from the Base Case. This
indicates that the Life Cycle Cost Analysis and Payback Analysis for the Broward County North Regional
WWTP are less sensitive to certain variable input parameters than the Boca Raton WWTP. This is due to
the the smaller relative effect of each change on the analysis at lower paybacks. Refer to Section 5.1.5 for a
discussion of the other parameters tested for sensitivity analysis which are similar between facilities
112
studied. The ramifications of the sensitivity analysis and comparison to the other plants are further
discussed in Section 6.5.
5.3
Plantation Regional WWTP
5.3.1
Plantation Regional WWTP - Existing Secondary Treatment
The Plantation Regional WWTP utilizes the following liquid stream treatment processes; influent
screening and grit removal, primary clarifiers, a conventional activated sludge system with mechanical
aerators, secondary clarification, and then deep well injection. The secondary treatment process comprises
three 65-feet wide by 195-feet long aeration basins with sidewater depth of 12 feet. One (1) 125-hp and
two (2) 100 hp mechanical surface aerators normally provide air to each basin on a constant basis, with all
basins normally in operation. One of the two 100-hp mechanical aerators is typically operating at a low
speed during the winter season when DO is able to be maintained with less power. The details of the
aeration system at the Broward County North Regional WWTP are summarized in Table 5.24 and Table
5.25.
Table 5.24 - Aeration Basin Characteristics
Description
Type of Unit
No. of Basins
Basin Dimensions:
Width
Length
Side Water Depth
Volume (each)
Total Volume
Unit
Value
Conventional Activated Sludge
3
65
195
12
152,100
3.41
ft
ft
ft
cf
MG
Table 5.25 - Mechanical Aeration Characteristics
Description
No. of Aerators
Per Basin
Total
Unit
Value
(1) 125 hp and (2) 100-hp
(3) 125 hp and (6) 100-hp
(Hazen and Sawyer, 2004)
5.3.2
Plantation Regional WWTP – Influent and Effluent Water Quality
Water quality data for the Plantation Regional WWTP was gleaned from the 2007-2009 monthly
operating reports and is presented in Table 5.26 through 5.28, below. The data was adjusted to the average
113
study period flow (2011 to 2031) based on predicted population increase in the service boundaries gleaned
and interpolated from a 2011 Capacity Analysis Report (CAR) for the plant, which is used for the purposes
of predicting average energy consumption of the 20-year design horizon (Hazen and Sawyer, 2011). Also,
the data was adjusted to the plant design flow of 18.9 MGD which was used for designing the capital
improvements.
Table 5.26 – Plantation Regional WWTP – Design Influent/Effluent Based on 2007-2009
Flow/Loading Data
Loading
Condition
Min Day
Inf
Flow
(MGD)
9.52
Pri. Eff
CBOD5
(lbs)
3,359
Pri.
Eff
TSS
(lbs)
3,974
Eff
CBOD5
(lbs)
74
Eff
WAS
VSS
(lbs)
2,278
Inf
TKN
(lbs)
1,370
Eff
NH3
(lbs)
0
Avg
DO
(lbs)
Avg
SRT
(days)
ADF
14.21
7,427
6,737
173
2,849
1,861
0
1.5
30.0
MMADF
16.06
11,614
10,131
256
3,263
2,237
0
Max Day
21.88
22,580
61,358
500
4,159
2,992
0
Table 5.27 – Plantation Regional WWTP – Design Influent/Effluent Adjusted to Est. 2011-2031 Avg
Flow
Eff
Pri. Eff
Pri. Eff
Eff
WAS
Inf
Eff
Loading
Inf Flow
CBOD5
TSS
CBOD5
VSS
TKN
NH3
Condition
(MGD)
(lbs)
(lbs)
(lbs)
(lbs)
(lbs)
(lbs)
10.44
3,682
4,356
81
2,498
1,502
0
Min Day
15.58
8,142
7,385
190
3,123
2,040
0
ADF
MMADF
17.60
12,732
11,106
281
3,577
2,453
0
Max Day
23.99
24,754
67,264
548
4,559
3,280
0
Table 5.28 – Plantation Regional WWTP – Design Influent/Effluent Adjusted to Design Flow
Eff
Pri. Eff
Pri. Eff
Eff
WAS
Inf
Eff
Loading
Inf Flow
CBOD5
TSS
CBOD5
VSS
TKN
NH3
Condition
(MGD)
(lbs)
(lbs)
(lbs)
(lbs)
(lbs)
(lbs)
12.66
4,467
5,285
99
3,030
1,823
0
Min Day
18.90
9,879
8,961
230
3,789
2,475
0
ADF
MMADF
21.36
15,448
13,474
341
4,340
2,976
0
Max Day
29.11
30,033
81,609
665
5,531
3,979
0
114
5.3.3
Plantation Regional WWTP – Proposed ECM Design
ECM No. 1 - Fine Bubble Diffusers –To install membrane fine bubble diffusers, the existing
diffusers and mechanical aerators will need to be demolished. Each basin is divided into three zones, and
each zone will be fitted with a grid of 667 diffusers, for a total of 9 grids and 2,000 diffusers. ECM No. 1
also entails the construction of a new blower building with (1) 200-hp and (3) 300 hp multi-stage
centrifugal blowers. It is assumed that the nearby existing motor control center (MCC) room has adequate
capacity to support the four blowers since the six 100-hp and three 125-hp mechanical surface aerator
starters that are being removed from the nearby Motor Control Center are of approximate equivalent power
capacity to the proposed improvements.
ECM No. 2 – Turbo Blowers – ECM No. 2 entails installing (1) 200-hp and (3) 300-hp more
efficient turbo blowers in place of the multi-stage centrifugal blowers proposed under ECM No. 1.
ECM No. 3 – Automatic DO Control Strategy – Dissolved oxygen probes and transmitters will be
installed at each zone for a total of nine probes and six transmitters. Motor-operated modulating valves
(MOVs) and venturi flow meters will be installed on the aeration piping of each grid, to control flow to
each basin based on the DO level signal from the probe, for a total of nine MOVs and nine venturi flow
meters. A programmable logic control (PLC) unit will be installed in the blower building to control the
modulating valves and blowers based on DO and air flowrate measurement.
The preliminary design drawings for the proposed ECMs at the Plantation Regional WWTP are
provided in Appendix C.
5.3.4
Plantation Regional WWTP – Results and Discussion
The Plantation Regional WWTP currently achieves full nitrification, as the average ammonia
concentration in the secondary effluent is less than 0.5 mg/L and DO is typically mainatined at 1.5 mg/L.
Accordingly, the Current Treatment scenario for the Plantation Regional WWTP case demonstrates the
potential energy savings assuming that the activated sludge process continues to completely nitrify, with an
average DO of 1.5 mg/L. The estimated life cycle costs and savings are presented in Table 5.29 and 5.30,
below. The detailed spreadsheet calculations for the analysis are attached in Appendix C.
115
Table 5.29 – Life Cycle Cost Analyses Estimated Costs
Plant
Plantation Regional
WWTP
Level of
Treatment
Complete
Nitrification
NPV of
Change in
O&M
Costs
-$146,489
NPV of
Foregone
Capital
Replacement
-$1,034,902
Capital
Cost
$3,099,083
NPV of
Capital,
O&M,
Foregone
Capital
$1,917,692
Table 5.30 – Life Cycle Cost Analyses Estimated Savings
Plant
Plantation Regional
WWTP
Level of
Treatment
Complete
Nitrification
Power
Reduction
(hp)
580
% Eff.
Gain
Ann.
Energy
Cost
Savings
Energy
Savings Net
Present
Value
70%
$265,401
($4,288,241)
Payback
(years)
[range]
8
[6 to 13]
1. Range for AACE Class 4 cost estimate of -20% to + 30% of median estimate shown in brackets
Figure 5.6 demonstrates the payback of implementing ECM Nos. 1 through 3 at the Plantation
Regional WWTP. The point where the lines cross is the payback point, or the point at which the sum of
O&M, energy, and capital costs for ECM No. 1 through 3 become cost beneficial compared to maintaining
operation of the existing mechanical aeration system.
Figure 5.6 demonstrates the range of error for
payback based on the AACE Class 4 cost estimate range of -20% to +30%, with a minimum range of 6
years and a maximum of 13 years.
116
$12,000,000
Existing Treatment.
Proposed Upgrade
$10,000,000
‐20% Capital Cost
Present Value Worth
+30% Capital Cost
$8,000,000
$6,000,000
$4,000,000
$2,000,000
$0
0
5
10
15
Years
20
25
30
Figure 5.6 – Present Value Comparison of Existing Process Versus Proposed ECMs
Table 5.31 and Figure 5.7 indicate that the cumulative effects of the ECMs result in a median
estimated payback of 8 years under the Current Treatment Scenario and 13 years under the Complete
Nitrification Scenario (essentially the same scenarios from a cumulative perspective). A payback of 7
years results under the Partial Nitrification scenario which assumes that 8 mg/L of ammonia remains in the
effluent. In an analysis of the paybacks of each individual ECM, Table 5.31 reveals that the each
individual ECM achieves a considerable payback near or below the 20 year threshold, except for the ECM
No. 2.
117
Table 5.31 – Plantation Regional WWTP – Incremental Life-Cycle Cost Analysis
Technology
1. Fine
Bubble
Diffusers
2. Turbo
Blowers
3. Auto DO
Control 1.5 mg/L
Total
Cumulative
Level of Treatment
%
Eff.
Gain
Avg.
Daily
Energy
Savings
(kWh)
Ann.
Energy
Cost
Savings
($)
Payback
(Low
Est)
(Years)
Payback
(Median
Est)
(Years)
Payback
(High
Est)
(Years)
Cur. Treatment - 1.5 mg/L DO
65%
9663
$246,886
4
6
10
Part. Nitrification - 3.0 mg/L DO
72%
10658
$272,309
4
6
9
Complete Nitrification
53%
7910
$202,091
5
8
12
Cur. Treatment - 1.5 mg/L DO
5%
725
$18,515
18
24
34
Part. Nitrification - 3.0 mg/L DO
-1%
-79
-$2,020
-
-
-
Complete Nitrification
7%
968
$24,736
12
16
21
Cur. Treatment - 1.5 mg/L DO
0%
0
$0
-
-
-
Part. Nitrification - 1.5 mg/L DO
8%
1152
$29,422
7
9
12
Complete Nitrification
10%
1510
$38,573
6
8
10
Cur. Treatment - 1.5 mg/L DO
70%
10387
$265,401
6
8
13
Part. Nitrification - 1.5 mg/L DO
79%
11730
$299,711
5
7
11
Complete Nitrification
70%
10387
$265,401
6
8
13
1) The Current Treatment scenario for ECM No. 3 is not applicable because there is no difference in any of the
variables or assumptions for that scenario between the ECM No. 2 and ECM No. 3
100%
Current Treatment ‐ 0.5 mg/L
90%
Partial Nitrification ‐ 1.5 mg/L
80%
Complete NOx
Increase in Efficency (%)
70%
60%
50%
40%
30%
20%
10%
0%
1. Fine Bubble Diffusers
2. Turbo Blowers
‐10%
3. Auto DO Control ‐ 1.5 mg /L
Total ECM
Figure 5.7 – Plantation Regional WWTP – Incremental Increase in Efficiency Per ECM
118
The results demonstrate that each successive ECM accumulates for a cumulative total
improvement in efficiency, resulting in predicted energy and cost savings. Figure 5.7 demonstrates the
contribution of each ECM to the total improvement of efficiency over the existing aeration system.
5.3.5
Plantation Regional WWTP - Sensitivity Analysis
Variables were isolated and manipulated in the model to determine their effects on the payback
results, which are demonstrated in Table 5.32 below.
Table 5.32 – Plantation Regional WWTP – Payback Sensitivity Analysis
Payback (Years)
Current
Treatment
8
Partial
Nitrification
7
Complete
Nitrification
8
10% Capital Reduction
7
6
7
20% Capital Reduction
6
5
6
AEO High Electricity Growth of +0.25%
8
7
8
AEO Low Electricity Growth of -0.18%
8
7
8
$0.08 per kWh
7
6
7
$0.09 per kWh
6
6
6
CPI Inflation + 1% or Bond Rate - 1%
8
7
8
CPI Inflation - 1% or Bond Rate + 1%
9
8
9
+5% Turbo Blower Efficiency
8
7
8
-5% Turbo Blower Efficiency
9
7
9
2.0 mg/L DO
8
8
9
1.0 mg/L DO
8
7
8
Case
Base
The results in Table 5.32 generally do not deviate greatly from the Base Case. This indicates that
the Life Cycle Cost Analysis and Payback Analysis for the Plantation Regional WWTP are generally less
sensitive to certain variable input parameters compared to the Boca Raton WWTP due to lower paybacks
being less sensitive to these changes in variables. Refer to Section 5.1.5 for a discussion of the other
119
parameters tested for sensitivity analysis which are similar between facilities studied. The ramifications of
the sensitivity analysis and comparison to the other plants are further discussed in Section 6.5.
120
VI. DISCUSSION AND COMPARISON OF RESULTS
The results of the analysis for each plant are compared and contrasted in this section.
6.1
Improvement of Efficiency Comparison and Analysis
Table 6.1 summarizes the results of the percent efficiency gain for each plant and scenario. Table
6.2 demonstrates the payback for each plant and scenario. The tables demonstrate that the Plantation
Regional WWTP is predicted to receive the highest proportional increase in efficiency and demonstrates
the most advantageous payback for each of the three plants.
Table 6.1 – Percent Efficiency Gain Per Plant and Scenario
% Eff. Gain
Current Treatment
Boca Raton
47%
Broward
56%
Plantation
70%
Partial Nitrification - 1.5 mg/L DO
37%
50%
79%
Complete Nitrification
26%
42%
70%
Table 6.2 – Payback Per Plant and Scenario
Payback (Median Estimate) (Years)
Current Treatment
Boca Raton
16
Broward
15
Plantation
8
Partial Nitrification - 1.5 mg/L DO
20
17
7
Complete Nitrification
31
21
8
To meaningfully compare the results of the analyses, it is important that the results are reflective
of the varying plant sizes and average flow through each plant, and the varying average loading through
each plant. Figure 6.1, Figure 6.2, and Figure 6.3 provide a comparison of the results and presents them on
a kWh / lb CBOD5, kWh / lb SOR, and also kWh / MGD basis, respectively.
121
2.00
Boca Raton
1.80
North Broward
1.60
Plantation
kWh / lb BOD Treated
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
Base Case
Current Treatment
Partial Nitrification
Complete Nitrification
Scenario
Figure 6.1 – Improvement of Efficiency Per Scenario– kWh / lb BOD Treated
0.35
0.30
Boca Raton
North Broward
0.25
kWh / SOR Plantation
0.20
0.15
0.10
0.05
0.00
Base Case
Current Treatment
Partial Nitrification
Complete Nitrification
Scenario
Figure 6.2 – Improvement of Efficiency Per Scenario– kWh / SOR
122
1,200
Boca Raton
1,000
North Broward
Plantation
kWh / MGD
800
600
400
200
0
Base Case
Current Treatment
Partial Nitrification
Complete Nitrification
Scenario
Figure 6.3 – Improvement of Efficiency Per Scenario– kWh / MGD Treated
The results demonstrate that prior to implementing ECMs, the Boca Raton WWTP and Broward
County North Regional WWTP demonstrate similar scales of efficiency. However, Plantation Regional
WWTP shows a scale of efficiency significantly greater that the other two plants on all three metrics for
Figure 6.1 through Figure 6.3. The main reason Plantation Regional WWTP is the least efficient prior to
ECM implementation is that the plant fully nitrifies, meaning that the plant fully oxidizes ammonia to
nitrate by aerating mixed liquor to a greater degree than the other plants, and also maintains higher solids
retention time (SRT) above 30 days. Although Plantation Regional WWTP is not required to fully nitrify
per the FDEP operation permit, they reportedly operate with increased DO and SRT levels to minimize
sludge yield and to reduce their solids loading to their digesters.
The results demonstrate that following implementation of the ECMs, each plants efficiency
improves greatly. However, a variable scale of efficiency following implementation of ECMs is apparent
between the plants on a kWh / lb of CBOD5 treated basis. Comparing the results on a SOR basis as shown
in Figure 6.2, as opposed to comparing the results on a kWh / lb CBOD5 or kWh / MGD basis as shown in
Figure 6.1 and Figure 6.3, results in the closest comparison of the three metrics. This is because the SOR
123
metric accounts for the varying degrees of nitrogen loading in addition to carbonaceous loading at each
plant, and also accounts for varying depths of diffuser submergence, temperature, DO, and alpha factors.
However, since the plants are not required to nitrify per their permit, the kWh / lb CBOD5 metric is still
meaningful as an efficiency measure.
Because the efficiency for the Broward County North Regional Plant was calculated with the side
assumption that a basin at Module D could be taken offline resulting in additional energy savings, the
metrics in Figure 6.1 through Figure 6.3 cannot be used as a baseline to measure plants outside of the study.
Removing the module D offline assumption from consideration results in an approximately equivalent
comparison in predicted energy use between each plant following implementation of the ECMs using the
kWh / lb SOR metric, as shown in Figure 6.4.
0.35
0.30
Boca Raton
North Broward
0.25
kWh / SOR Plantation
0.20
0.15
0.10
0.05
0.00
Base Case
Current Treatment
Partial Nitrification
Complete Nitrification
Scenario
Figure 6.4 – Improvement of Efficiency Per Scenario– kWh / SOR - (not considering Broward
County North Regional WWTP Module D Assumptions)
124
For this reason, the results of this study indicate that mechanically aerated plants implementing the
ECMs suggested in this study may roughly predict that they will achieve the average kWh / SOR treated
shown in Figure 6.4. The equation below formulates the estimated energy improvement.
Esaved = [kWhexisting - 0.10 ( SORavg)] x 8,760 hr/yr
Where Esaved
6.2
(29)
= predicted annual energy savings (kWh)
kWhexisting
= plants exsting energy usage specific to activated sludge treatment process
SORavg
= average predicted SOR folloing implementation of ECMs
Capital Cost Comparison and Analysis
The capital costs resulting from the analysis were also analyzed on a Capital Cost / MGD, Capital
Cost / lb CBOD5 treated, and Capital Cost / SOR basis. Table 6.3 demonstrates that all of the plants fall
within a similar capital cost range in proportion to plant capacity (in MGD). Figure 6.5 through 6.7 further
demonstrate that the Capital Cost / MGD appears to be the metric where the plants are most correlated.
125
Table 6.3 – Cumulative Capital Cost Per ECM
Boca
Raton
N
Broward
Plantation
Average
Range
ECM No. 1
$2,486,493
$6,247,399
$2,428,616
-
-
Capital Cost / ADF MGD Capacity
$170,857
$149,738
$155,903
$158,833
14.1%
Capital Cost / lb BOD Treated
$151
$118
$298
$189
153.0%
Capital Cost / SOR
$31
$27
$44
$34
64.7%
ECM No. 1 and 2
$2,807,759
$6,889,931
$2,702,913
-
-
Capital Cost / ADF MGD Capacity
$192,933
$165,139
$173,512
$177,194
16.8%
Capital Cost / lb BOD Treated
$170
$130
$332
$211
155.3%
Capital Cost / SOR
$35
$30
$49
$38
66.3%
ECM No. 1 Through 3
$3,261,794
$7,954,846
$3,099,083
-
-
Capital Cost / ADF MGD Capacity
$224,132
$190,663
$198,943
$204,579
17.6%
Capital Cost / lb BOD Treated
$197
$150
$381
$243
153.6%
Capital Cost / SOR
$52
$43
$72
$56
67.4%
$250,000
Capital Cost ($) / MGD
$200,000
$150,000
$100,000
High ‐ Boca Raton
$50,000
Avg
Low ‐ Broward
$0
ECM No. 1
ECM No. 1 and 2
Figure 6.5 – Range of Capital Cost / MGD Treated
126
ECM No. 1 Through 3
$400
$350
Capital Cost ($) / lb CBOD
$300
$250
$200
$150
$100
High ‐ Plantation
Avg
$50
Low ‐ Broward
$0
ECM No. 1
ECM No. 1 and 2
ECM No. 1 Through 3
Figure 6.6 – Range of Capital Cost / lb CBOD5 Treated
$80 $70 Capital Cost ($) / SOR
$60 $50 $40 $30 $20 High ‐ Plantation
Avg
$10 Low ‐ Broward
$0 ECM No. 1
ECM No. 1 and 2
Figure 6.7 – Range of Capital Cost / SOR
127
ECM No. 1 Through 3
From Table 6.4 and Figures 6.5 through 6.7, it is apparent that the plants are within a closer range
on a Capital Cost / Avg MGD capacity basis compared to the Capital Cost / lb BOD or Capital Cost / SOR
basis. For this reason, the results of this study indicate that mechanically aerated plants implementing the
ECMs suggested in this study may estimate their capital cost based on the equation below.
Ccapital = Cavg x Qavg
Where Ccapital
6.3
(30)
= predicted capital cost for implmenting ECMs
Cavg
= average Capital Cost / ADF MGD from Table 6.3
Qavg
= average predicted flowrate over the design period
Payback Comparison and Analysis
The incremental payback for each ECM is compared in Figure 6.8, Figure 6.9, Figure 6.10, and
Figure 6.11.
15
1. Fine Bubble Diffusers
Payback (years)
10
Over 100 Years
Over 100 Years
Boca
Boca
5
0
Boca
SCENARIO:
N Broward Plantation
Current Treatment
N Broward Plantation
Partial Nitrification
N Broward Plantation
Complete Nitrification
Figure 6.8 – ECM No. 1 - Fine Bubble Diffuser Payback Comparison
128
Comparing Figure 6.8 with Figure 6.9 and Figure 6.10, it is apparent that ECM No. 1 – Fine
Bubble Diffusers is the ECM resulting in the least advantageous incremental payback. This is related to the
fact that the capital cost involved with implementing ECM No. 1 is a major hurdle, comprising
approximately 75 to 85 percent of the total capital cost of each project. Another important trend to note in
Figure 6.8 is that for ECM No. 1, the payback decreases as the level of treatment increases from the current
treatment scenario Æ partial nitrification scenario Æ complete nitrification scenario. This is because the
amount of aeration and corresponding energy requirements increases as the level of treatment increases,
however the capital cost remains the same. The more cost advantageous incremental paybacks associated
with implementation of ECM No. 2 and ECM No. 3 cannot be realized without first implementing ECM
No. 1. Figure 6.9 and Figure 6.10 demonstrate that once ECM No. 1 is implemented, that ECM No. 2 and
ECM No. 3 are cost advantageous for most scenarios.
30
2. Turbo Blowers
25
Payback (years)
20
15
10
5
N/A
0
Boca
SCENARIO:
N Broward Plantation
Current Treatment
Boca
N Broward Plantation
Partial Nitrification
Boca
N Broward Plantation
Complete Nitrification
Figure 6.9 – ECM No. 2 - Turbo Blower Payback Comparison
129
50
45
3. Auto DO Control ‐ 1.5 mg/L
40
Payback (years)
35
30
25
20
15
10
5
N/A
0
Boca
SCENARIO:
N/A
N Broward Plantation
Current Treatment
Boca
N Broward Plantation
Partial Nitrification
Boca
N Broward Plantation
Complete Nitrification
Figure 6.10 – ECM No. 3 - DO Control Payback Comparison
The trend of payback going from the current treatment scenario Æ partial nitrification scenario Æ
complete nitrification scenario for ECM No. 2 and No. 3 is decreasing. This decreasing trend may appear
counterintuitive, because as additional energy is required to achieve a higher DO going from the current
treatment scenario Æ partial nitrification scenario, or as even more energy is required to provide additional
air for complete oxidation of ammonia going from the partial nitrification scenario Æ complete nitrification
scenario, the amount of energy used increases which would result in more dollars spent on electricity.
However, the decreasing trend is explained by the fact that as the electricity required to supply additional
aeration increases, it also provides more opportunity for energy savings when compared to the alternative
of operating a fine bubble diffuser system without installing ECM No. 2 or ECM No. 3.
130
35
Total (Cumulative)
30
Payback (years)
25
20
15
10
5
0
Boca
SCENARIO:
N Broward Plantation
Current Treatment
Boca
N Broward Plantation
Partial Nitrification
Boca
N Broward Plantation
Complete Nitrification
Figure 6.11 – ECM No. 1 through 3 - Cumulative Payback Comparison
The cumulative payback shown in Figure 6.11 demonstrates that excellent paybacks are obtained
for all three plants modeled for the current treatment and partial nitrification scenarios, with paybacks for
the complete nitrification scenarios below the 20 year range only for Plantation Regional WWTP.
Comparing Figures 6.8 through 6.11 clearly demonstrates that to achieve excellent paybacks at the three
plants studied, implementation of fine bubble diffusers is not enough. Installation of high efficiency
blowers and DO control systems are needed. This finding should be instructive for utilities considering
implementation of fine bubble diffusers but possibly not high efficiency blowers or DO control due to
capital constraints. Installation of ECM Nos. 2 and No. 3 leverages the benefit of the fine bubble diffusers
and will likely have a payback below 20 years at other facilities.
Finally, due the trends identified in the study related to predicted capital cost versus flowrate, and
predicted energy saved versus SOR, a general formula is presented to predict the payback of the ECM Nos.
1 through 3 at mechanically aerated activated sludge treatment processes.
131
NPV [Esaved * (Celectricity)] = NPV (∆O&M) + NPV Cforegone + Ccapital
Where Ccapital
(31)
= predicted capital cost for implmenting ECMs from Eq. (30)
Esaved
= predicted annual energy savings (kWh) from Eq. (29)
Celectricity
= current cost of electricity specific to each plant ($ / kWh)
∆O&M
= change in O&M due to implementing ECMs specific to each plant
Cforegone
= foregone capital replacement due to implementing ECMs specific to each
plant
NPV
Æ indicates to find Net Present Value over the 20 year time period using Eq. (1)
The above equation can then be iteratively solved for n (number of time periods in Present Worth
of a Geometric Gradient Series) to determine payback.
6.4
Sensitivity Analysis Comparison
The sensitivity analyses of the three plants were compared to identify parameters that are more or
less likely to affect the results. It should be noted that the greater the base case payback, the more
exaggerated are the effects of changing sensitive parameters such as in the case of Boca Raton WWTP.
The comparison in Table 6.4 indicates that one of the sensitive parameters affecting the payback is the
current price of electricity. A $.01 change in the price of electricity will alter the payback significantly.
Another sensitive parameter effecting payback is the capital cost. Capital cost may be offset by 10 percent
or more by public or private grants. Additionally, capital cost estimating methods are -20 / +30 percent
level of accuracy with a 10 percent contingency (Krause, 2010). Blower efficiencies are known to vary
from project to project. A 5 percent increase or decrease in efficiency appears to significantly affect the
payback.
Reductions in capital costs through public or private grants are obtainable. Locally, the Palm
Beach County – Southern Regional Water Reclamation Facility (SRWRF) recently received a $1.2 million
grant in 2009 from the US Department of Energy’s Efficiency and Conservation Block Grant toward the
construction of a biogas generator, which uses methane produced from the anaerobic digestion process to
power a generator to produce electricity as opposed to sending the methane to a waste gas flare. The grant
132
reduced the capital cost of total project delivery by 33%, which included the costs for a feasibility study,
engineering design, and construction. The grant was justified as a way to reduce dependence on fossil fuels
by reducing the facility’s energy draw by 14%, provide local job opportunities, and reduce greenhouse gas
emissions by approximately 1,250 metric tons annually (Palm Beach County, 2012).
Less sensitive parameters include inflation/bond rate. A 1 percent rise in inflation or drop in bond
rate can result in a marked improvement in payback. Conversely, a 1 percent drop in inflation or rise in
bond rate can result in a marked degradation of payback. However since inflation and bond rates generally
rise and fall in unison, the net effect can be expected to be minimial. Figure 6.12 illustrates the effects of
variation in the CPI inflation rate or bond rate on payback at the Boca Raton WWTP for example. Although
electricity prices are a sensitive parameter if changed, the AEO 2011 high and low economic growth
electricty predictions do no predict great variation in electricity prices which indicates a lower likelihood
that they would vary greatly from this analysis. However, a recent precipitous drop in southeast Florida
plant’s electrical bills from 2009 to 2010 of approximately 20 percent recently occurred, due to a reduction
in “pass through fuel charge” from FPL. Were fuel charges to rise again on a similar scale, paybacks
would be reduced for each plant from 2 to 5 years. Figure 6.13 illustrates the effects of a rise in electricity
price on payback at the Boca Raton WWTP for example.
133
Table 6.4 – Sensitivity Analysis Comparison
Change in Payback (years)
Boca1
N. Broward1
Plantation2
Base
20
17
8
10% Capital Reduction
-3
-3
-1
20% Capital Reduction
-6
-6
-2
AEO Report High Growth
0
0
0
AEO Report Low Growth
0
0
0
$0.08 per kWh
-3
-3
-1
$0.09 per kWh
-5
-5
-2
CPI Inflation + 1% or Bond Rate - 1%
-2
-2
0
CPI Inflation - 1% or Bond Rate + 1%
+3
+2
+1
+5% Turbo Blower Efficiency
-2
-2
0
-5% Turbo Blower Efficiency
+3
+2
+1
2.0 mg/L DO
+4
+3
+1
1.0 mg/L DO
-3
-2
0
(1) Considers partial nitrification case for the Boca Raton WWTP and the Broward County North Regional WWTP
(2) Considers complete nitrification case for the Plantation Regional WWTP
134
$9,000,000
$8,000,000
Present Value Worth
$7,000,000
$6,000,000
$5,000,000
$4,000,000
$3,000,000
Exist.
$2,000,000
Partial Nitrification
CPI Inflation + 1% or Bond Rate ‐ 1%
$1,000,000
CPI Inflation ‐1% or Bond Rate + 1%
$0
0
5
10
15
20
25
Years
Figure 6.12 – Sensitivity Analysis – Results of Variation in CPI Inflation or Bond Rate Assumptions
(Boca Raton WWTP Example)
$10,000,000
$9,000,000
$8,000,000
Present Value Worth
$7,000,000
$6,000,000
$5,000,000
$4,000,000
$3,000,000
Exist ($0.07 per kwh).
$2,000,000
Partial Nitrification
$1,000,000
$0.09 per kwh
$0
0
5
10
15
20
25
Years
Figure 6.13 – Sensitivity Analysis – Results of Variation in Electricity Price (Boca Raton WWTP
Example)
135
6.5
Total Savings And Regional Savings
The available energy saving for each plant, and total available energy savings, are tabulated in
Table 6.5. Table 6.5 demonstrates that on a regional basis, approximately 1.14 megawatts can be saved, or
approximately 10,000 megawatt-hours (MWh) can be saved per year if the ECMs were implemented at all
three plants. At the current price of $0.07 per kWh, 10,000 MWhs translates to $701K per year.
Table. 6.5 – Projected Energy Savings Related To Implementation of ECMs
Boca
Raton
North
Broward
Plantation
6.6
Level of Treatment
kWh
kWh /
Day
kWh /
Year
% Eff.
Gain
Base Case
417
9,999
3,649,689
-
Part. Nitrification - 1.5 mg/L DO
261
6,265
2,286,780
37%
Base Case
1,105
26,514
9,677,648
-
Part. Nitrification - 1.5 mg/L DO
550
13,204
4,819,453
50%
Base Case
620
14,880
5,431,323
-
Part. Nitrification - 1.5 mg/L DO
187
4,493
1,639,919
70%
Total Savings
1,143
27,432
10,012,507
Current Energy Intensity Discrepancy and Potential Operational Modifications at
Plantation Regional WWTP
Table 6.6 below demonstrates the difference in energy intensity between the plants prior to
implementing ECMs, (considering energy usage of aeration equipment only).
Table 6.6 – Current Aeration Energy Intensity Comparison
Power per carbonaceous load treated (kWh / lb CBOD5)
Boca
Raton
0.61
N
Broward
0.50
Factor
1.21
1.00
3.65
Power per total load treated (kWh / lb SOR)
0.19
0.17
0.33
Factor
1.14
1.00
2.00
Power per volume treated (kWh / MG)
687
635
955
Factor
1.08
1.00
1.50
Aeration Energy Intensity (Current Usage)
136
Plantation
1.83
From Table 6.6, it is apparent that the Broward County North Regional WWTP is currently the
most efficient of the three plants. On a power per carbonaceous load treated basis, it is apparent that
Plantation utilizes 265% additional energy than the most efficient plant, Broward County North Regional
WWTP. However, because each plant is treating varying degrees of nitrogen loading in addition to
carbonaceous loading, and has varying depths of diffuser submergence and alpha factors, a more
appropriate efficiency comparison is provided as power per total load treated as measured by the standard
oxygen requirement (SOR). On this basis, the Broward County North Regional WWTP and Boca Raton
WWTP are closer in efficiency, whereas the Plantation Regional WWTP utilizes 100% more energy than
the most efficient plant. The following section explores the reasons that the Plantation Regional WWTP,
and to a much lesser extent, the Boca Raton WWTP, are less efficient than the Broward County North
Regional WWTP.
The average energy use of the mechanical aerators at each facility are provided in Table 6.7. It is
apparent from Table 6.7 that the Broward County North Regional WWTP aerators indeed use less power
than the Boca Raton WWTP or Plantation Regional WWTP.
Table 6.7 – Average Mechanical Aerator Energy Use Comparison
(Nameplate hp)
Boca
Raton
(hp used)
N
Broward
(hp used)
Plantation
(hp used)
56
-
-
59
100
92
69
100
125
-
-
123
Avg Operating hp / Nameplate hp
92%
69%
98%
Factor
1.34
1.00
1.43
The mechanical aerator average power usage is broken down on a zone by zone basis in Table 6.8.
Table 6.8 demonstrates that Broward County North Regional WWTP and Plantation Regional WWTP both
taper their power usage down from Zone 1 to Zones 2 and 3, whereas Boca Raton WWTP does not.
Tapering aeration, from more aeration in the first zone to less in the later zones, is a common practice that
is used to provide more aeration where it is required in the first zone where most of the oxygen demand is
137
incurred.
Table 6.8 also demonstrates that on a power per tank volume basis, the Boca Raton WWTP
provides 26% more power and the Plantation Regional WWTP provides 82% more power than the most
efficient plant. The relative energy efficiency of the Broward County North Regional WWTP on the power
per aeration tank volume measure is related to their tapering down of power supplied in Zones 2 and 3.
However, it is important to note that Broward County North Regional WWTP is operating below the
recommended power input range for providing complete mixing of 0.75 – 1.5 hp per 1,000 cf
(Tchobanoglous et al., 2003) in zones 2 and 3. It is not known whether or not Broward County North
Regional WWTP currently experiences settling issues in their basins related to this factor.
Table 6.8 – Average Power Supplied Per Zone
Boca Raton
N Broward
Plantation
Zone 1 Avg Power (hp)
96.3
84.2
123.0
Zone 2 Avg Power (hp)
87.3
59.9
85.6
Zone 3 Avg Power (hp)
91.8
61.5
68.4
Zone 1 power / volume (hp / 1,000 cf)
1.03
0.97
2.43
Zone 2 power / volume (hp / 1,000 cf)
0.93
0.69
1.69
Zone 3 power / volume (hp / 1,000 cf)
0.98
0.71
1.35
Total power / volume (hp / 1,000 cf)
0.99
0.79
1.82
Factor
1.26
1.00
1.82
Typical power / volume requirement for adequate mixing (hp / 1,000 cf)
0.75 - 1.5
To further compare efficiencies, the current oxygen supplied by the mechanical aerators is
estimated based on horsepower, and the estimated oxygen required based on the methodology presented
earlier in this paper are compared in Table 6.9. From Table 6.9, it is apparent that Plantation Regional
WWTP is providing more than double the amount of oxygen required to meet their current treatment,
whereas Boca Raton WWTP and Broward County North Regional WWTP are currently supplying much
less excess oxygen.
138
Table 6.9 – Current Oxygen Supplied vs. Oxygen Required
Boca
Raton
2.3
Broward
2.1
Plantation
2.0
Current average power supplied (hp)
558
1,481
831
Current estimated avg oxygen supplied (lb 02 / day)
30,600
75,700
39,500
Current estimated avg oxygen required (lb 02 / day)
22,600
64,300
16,900
% lb supplied vs required
135%
118%
234%
Factor
1.15
1.00
1.99
Adjusted oxygen transfer capacity (lb 02 / hr) (based on 3.0 lb
/ hp.hr and per Metcalf & Eddy, 2003 eq. 5-62)
Potential Operational Modifications Based on Existing Energy Usage Comparison
The Plantation Regional WWTP aeration process energy intensity is significantly greater than the
City of Boca Raton WWTP and Broward County North Regional WWTP. The comparison in the previous
section indicates that the Plantation Regional WWTP is supplying power in excess of that required to meet
their oxygen demand.
It is apparent that the difference in energy intensity is due to a combination of three main factors:
1) Complete Nitrification / Extended SRT - Unlike the other two plants, the Plantation Regional
WWTP completely nitrifies, meaning that they typically supply more oxygen to the activated
sludge process compared to the other plants to completely oxidize ammonia to nitrite or nitrate.
The additional air supplied results in additional energy use. Although Plantation Regional WWTP
is not required to fully nitrify per the FDEP operation permit, the complete nitrification that occurs
is a byproduct of their extended SRT operating condition of over 30 days which they maintain to
reduce their solids loading to their digesters.
2) Higher DO Level - Plantation Regional maintains a DO of 1.5 mg/L compared to 1.0 mg/L at
Broward County North Regional WWTP and 0.5 mg/L at the City of Boca Raton WWTP. The
increased DO that the Plantation Regional WWTP is able to maintain is likely due to the reduced
oxygen demand in the system related to a high SRT and resulting low food to mass (F/M) ratio.
139
3) Inefficient Equipment - Thirdly, cursory measurements obtained of the amp draws from Plantation
Regional WWTP’s mechanical aerators indicate that their energy consumption per aerators is
greater than the City of Boca Raton and Broward County North Regional WWTPs. It is not clear
whether the additional measured amp draws are due to greater submergence of the aerators (which
helps maintain the apparent higher DO levels), or motor or mechanical inefficiency due to aged or
obsolete motors or mechanical components.
The payback for the Plantation Regional WWTP is calculated based on the existing base condition
of inefficient operation related to the three factors discussed above. For the purposes of comparison, a
hypothetical side case is calculated by assuming that the Plantation Regional WWTP could operate with
one basin normally out of service. SRT could be maintained at greater than 20 days with the same mixed
liquor concentration by reducing the aerated volume by one-third, which would sustain complete
nitrification and result in a relatively small percent increase in sludge production. Therefore, the costs
related to processing and hauling the additional sludge downstream would also be expected to be minimal.
Operating with one basin out of service and assuming the same proportional power usage (two
thirds) results in the following scenario. Table 6.10 demonstrates that with one basin out of service, the
power per total load treated is still greater than the most efficient Broward County North Regional WWTP
and the power per volume is equivalent to the Broward County North Regional WWTP. Table 6.11
demonstrates that the oxygen supplied under the operational modification still exceeds the amount required
by 56%.
Table 6.10 – Plantation Operational Modification - Energy Intensity Comparison
Parameter
Value
Power per carbonaceous load treated (kWh / lb CBOD5)
1.22
Factor (compared to N. Broward)
2.44
Power per total load treated (kWh / lb SOR)
0.22
Factor (compared to N. Broward)
1.33
Power per volume treated (kWh / MG)
637
Factor (Compared to N. Broward)
1.00
140
Table 6.11 – Plantation Operational Modification - Current Oxygen Supplied vs. Oxygen Required
Parameter
Value
Adjusted oxygen transfer capacity (lb 02 / hr) (per eq. 5-62)
2.0
Projected average power supplied (hp)
554.1
Projected avg oxygen supplied (lb 02 / day)
26,330
Projected avg oxygen required (lb 02 / day)
16,886
% lb supplied vs required
156%
Table 6.12 and Table 6.13 present the results of implementing the ECMs following making the
operational modification of taking one basin out of service at the Plantation Regional WWTP. It is
apparent from the results that even if Plantation were to make the suggested operational modification or
taking one basin out of service, the payback for implementing the ECMs is still excellent at a median
estimate of 17 years were they to maintain a fully nitrifying plant. If the Plantation Regional WWTP were
to only partially nitrify, even greater energy savings and payback would result. It is important to note that
the decision to reduce SRT and partially nitrify would need to be balanced with the consideration of the
additional sludge that would be produced and how much could be reliably digested in the anaerobic
digesters to prevent a great increase in final sludge requiring disposal. Because taking one basin offline
would still maintain an SRT of greater than 20 days, a significant increase in sludge production should not
be anticipated.
Table 6.12 – Plantation Operational Modification –Energy Savings Resulting From ECM
Implementation Following Operational Modification
Technology
Level of Treatment
Avg.
Operating
hp
kWh /
Day
Base Case
Complete Nitrification
554
9,920
-
-
ECM No. 1 - 3
Complete Nitrification
251
4,493
55%
$138,667
ECM No. 1 - 3
Partial Nitrification
176
3,150
68%
$172,980
141
% Eff.
Ann. Energy
Gain
Cost Savings ($)
Table 6.13 – Plantation Operational Modification – Payback Resulting From ECM Implementation
Following Operational Modification
Technology
Level of
Treatment
%
Eff.
Gain
Avg.
Daily
Energy
Savings
(kWh)
Ann.
Energy
Cost
Savings
($)
Payback
(Low
Est)
(Years)
Payback
(Median
Est)
(Years)
Payback
(High
Est)
(Years)
ECM No. 1 - 3
Complete
Nitrification
55%
5427
$138,667
11
17
27
ECM No. 1 - 3
Partial Nitrification
68%
6770
$172,980
9
13
20
6.7
Ocean Outfall Rule Compliance
In addition to providing energy savings and increased treatment capacity, installation of the
proposed ECMs at the Boca Raton WWTP and the Broward County North Regional WWTP provide
additional capacity to comply with the ‘Ocean Outfall’ rule, (the Plantation Regional WWTP does not
discharge to an ocean outfall thus the Ocean Outfall rule is not applicable). The use of ocean outfalls for
wastewater effluent disposal were mandated in consolidated bill Chapter 2008-232 and was signed into law
on July 1, 2008, known as the ‘Outfall Rule’, which mandates that the discharge of domestic wastewater
through ocean outfalls meet advanced wastewater treatment (AWT) and management requirements by
December 31, 2018 and that outfall use cease except for emergency usage by December 31, 2025. The rule
also requires that utilities distribute at least 60% of the effluent waste stream that was previously being
discharged to the ocean as reclaimed water. AWT standards as defined by Florida Statute 403.086(4) are
limited to the following concentrations (Hazen and Sawyer, 2010):
•
Biochemical Oxygen Demand (CBOD5) = 5 mg/L
•
Total Suspended Solids (TSS) = 5 mg/L
•
Total Nitrogen (TN) = 3 mg/L
•
Total Phosphorus (TP) = 1 mg/L
•
High level disinfection (HLD) of the effluent per Florida Administrative Code 62-600.440(5)
142
To meet these requirements, plants in southeast Florida utilizing ocean outfalls are generally faced
with the following options:
•
Option 1: Continue the current treatment process and construct facilities to meet AWT standards
by 2018
•
Option 2: Reduce cumulative outfall loadings of TN and TP occurring between December 31,
2008 and December 31, 2025, as equivalent to that which would be achieved if the AWT
requirements were fully implemented beginning December 31, 2018, and continued through
December 31, 2025; or
•
Option 3: Continue the current treatment process and construct a 100% reuse system by 2018.
Option 1 has been investigated at southeast Florida WWTPs, and it has generally been concluded
that it is not cost feasible. As such, utilities are exploring Option 2 and Option 3 as more cost beneficial
options. To delay the conversion to 100% reuse, Broward County North Regional WWTP concluded that
they could operate their aeration basins in partial nutrient removal mode, in which they fully nitrify their
wastestream from ammonia to nitrate, and partially denitrify to nitrogen gas utilizing an anoxic zone in the
first zone of their aeration basins. The anoxic zone could be outfitted with fine bubble diffusers that could
normally remain off to maintain anoxic conditions, but could periodically be “bumped” To maintain mixing
and prevent solids form depositing. Operation in partial nutrient removal mode would allow Broward
County North Regional WWTP to reduce their cumulative loading to the outfall from current to 2025 as
equivalent to that which would be achieved if the AWT requirements were fully implemented by 2018
(Hazen and Sawyer, 2010).
At the City of Boca Raton, the Outfall Rule could not be satisfied solely by switching to partial
nutrient removal. Loading would also have to be reduced by increasing reclaimed water distribution
capacity. The City of Boca Raton’s strategy for meeting the Ocean Outfall rule is shifting to 100% reuse
by 2018. However, reducing their current loading TN and TP loading to the ocean outfall would provide
additional time and flexibility for the City of Boca Raton WWTP to comply with the Outfall Rule. The
143
current mechanical aeration processes at Boca Raton WWTP and North Broward WWTP cannot provide
adequate oxygen to operate in partial nutrient removal mode.
6.8
Greenhouse Gas Emissions
Table 6.14 presents the amount of total annual electricity saved for the three facilities studied. The
table also shows various greenhouse gas reduction measures that municipalities may employ, and shows the
equivalent units for each method that result in an equal amount of annual greenhouse gas emissions
reduction.
Table 6.14 – Greenhouse Gas Prevention Equivalency For Three Facilities Studied
Total
Total Electricity saved (MWh/Year)
10,013
Saving this amount of electricity annually is equivalent to preventing or sequestering CO2
gas by the following methods:
Total
Release of Metric Tons of CO2 (per year)
6,904
Converting From Full-Size Pick Up Trucks to Toyota Prius Hybrids (# of vehicles) a, c
1,548
Sequestering Carbon By Planting Tree Seedlings Grown For 10 Years (# of seedlings) d
177,030
Amount of pine forest acreage that sequesters an equivalent amount of CO2 (# of acres) d
1,472
Converting traffic signals from incandescent to LED bulbs (# of signals) b
13,716
a Assumes average mileage per gallon being increased from 16 mpg to 46 mpg at 15,000 miles per driven annually.
(Peters 2008)
b Assumes signals are reduced from an average of 100W to 20W, for a savings of 730 kWh/year
(Peters 2008)
c Calculations based on 8.92*10-3 metric tons CO2/gallon of gasoline and 6.8956 x 10-4 metric tons CO2 / kWh (US
EPA 2011)
d Calculated using EPA’s Greenhouse Gas Equivalency calculator (US EPA 2011)
Reduction of greenhouse gases is a tangible benefit that will help the utilities in the study meet
regional goals for greenhouse gas reduction and energy efficiency. For example, the Broward County
Climate Change Action Plan states as a specific goal to reduce their utility carbon footprint (Broward
County, 2010), which could help be achieved with the implementation of ECMs at the Broward County
144
North Regional WWTP and Plantation Regional WWTP. The Palm Beach County – Green Task Force On
Environmental Sustainability and Conservation recommended that a comprehensive county wide energy
conservation and greenhouse gas reduction strategy be implemented (Palm Beach County, 2009), which
could help be achieved through implementation of ECMs at the City of Boca Raton WWTP.
On a
statewide level, the Governor’s Climate Action Plan, Executive Order # 07-128, mandates reduction of
statewide Greenhouse Gas Emissions by the year 2017 to the year 2000 levels (Palm Beach County, 2009).
145
VII. CONCLUSIONS AND RECOMMENDATIONS
7.1
Conclusions
A model was developed to estimate the energy savings and resulting cost savings that can be
realized by implementing ECMs at three conventional activated sludge WWTPs in southeast Florida. The
ECMs investigated are 1) Fine Bubble Diffusers; 2) Single-Stage Turbo Blowers; and 3) Automatic
Dissolved Oxygen (DO) Control. The results of the analysis are provided as Tables 7.1 through 7.4:
Table 7.1 – Life Cycle Cost Analysis Assumptions
$/ kWh
Bond Rate
CPI
Inflation
0.07
4.7%
2.5%
Real
Rate
(interest)
Energy
Inflation
Planning
Period
(years)
2.2%
0.08%
20
Table 7.2 – Life Cycle Cost Analyses Estimated Costs
Plant
Level of
Treatment
Annual
Delta
O&M
Foregone
Capital
Replacement
Net Present
Value
Capital
Cost
NPV of
Capital,
O&M,
Foregone
Capital
Boca Raton
Partial
Nitrification
-$10,091
-$1,558,926
$3,261,794
$1,541,011
N Broward
Partial
Nitrification
-$12,127
-$3,035,109
$7,954,846
$4,725,218
Plantation
Complete
Nitrification
-$9,133
-$1,034,902
$3,099,083
$1,917,692
146
Table 7.3 – Life Cycle Cost Analyses Estimated Savings
Plant
Boca Raton
Level of
Treatment
Partial
Nitrification
hp
Reduction
% Eff.
Gain
Ann.
Energy
Cost
Savings
Energy
Savings Net
Present
Value
209
37%
$95,404
($1,541,495)
N Broward
Partial
Nitrification
743
50%
$340,074
($5,494,781)
Plantation
Complete
Nitrification
580
70%
$265,398
($4,288,205)
Table 7.4 – Life Cycle Cost Analyses Estimated Median Paybacks
Boca Raton
N Broward
Plantation
Level of Treatment
Partial Nitrification
Partial Nitrification
Complete
Nitrification
Payback (years)
20
17
8
AACE Class 4 Cost
Estimate Range
(years)
11 - 37
11 - 28
6 - 13
Paybacks – A median payback estimate of 20 years or under is predicted at all three plants studied,
which meets the 20 year threshold typically considered by most plant managers to be a compelling level of
payback. The predicted levels of payback of 20 years or less for all plants are compelling arguments for
plants to implement ECM Nos. 1 through 3. When accounting for the cost estimating accuracy range for
AACE Class 4 estimates of -20 to + 30 percent, the paybacks for the three plants can rise to 13 to 37 years.
Regional Electricity Savings - Approximately 1.14 MWs can be saved, or approximately 10,000
MWh can be saved per year if the ECMs were implemented at all three plants. At the current price of
$0.07 per kWh, 10,000 MWh translates to $701K per year.
Greenhouse Gas Prevention - Saving this amount of energy is equivalent to preventing 6,900
metric tons per year of greenhouse gas release by converting approximately 13,700 traffic signals from
incandescent to LED bulbs, a commonly employed tactic by municipalities. The amount of greenhouse gas
emissions is also equivalent to converting 1,548 fleet vehicles from full-size pick up trucks to Toyota
147
Priuses, or by planting 177,000 tree seedlings every year (assuming amount of carbon sequestered in 10
years of growth).
Model Accuracy Verification – The model’s accuracy was verified by comparing actual side-byside data available from the Broward County North Regional WWTP for fine bubble diffused aeration and
mechanical aeration energy usage. Broward County North Regional WWTP provides a remarkably unique
opportunity to measure the model’s accuracy due to the side by side arrangement of mechanical aeration
versus fine bubble diffused aeration in identical basins with identical influent wastewater characteristics.
The verification results indicated that the model is reasonably accurate at predicting average airflow rates
and energy use.
The Greatest Cumulative Benefit Is Achieved When All 3 ECMs are Implemented - The benefit of
implementing each technology is quantified on an individual and cumulative basis, to identify which
technologies are cost-beneficial and which are not. It is apparent that the ECM No. 1 – Fine Bubble
Diffusers has the greatest (least beneficial) incremental payback in general, generally over 20 years when
not considering addition of ECM No. 2 and No. 3. What these results clearly demonstrate is that to achieve
excellent paybacks at the three plants studied, implementation of fine bubble diffusers is not enough.
Installation of high efficiency blowers and DO control systems are needed. This finding should be
instructive for utilities considering implementation of fine bubble diffusers but possibly not high efficiency
blowers or DO control due to capital constraints. Installation of high efficiency blowers (ECM No. 2) and
automatic DO control (ECM No. 3) leverages the benefit of fine bubble diffusers (ECM No. 1) and will
likely result in a payback below 20 years. The results demonstrate that each successive ECM accumulates
for a cumulative total improvement in efficiency, resulting in an average predicted energy savings of 52
percent at the three plants studied. Figure 7.1 demonstrates the average contribution of each ECM to the
total overall efficiency improvement.
148
Fine Bubble Diffusers,
23%
Remaining Energy Use,
48%
Turbo Blowers, 12%
DO Control, 18%
Figure 7.1 – Average Contribution of Each ECM to Overall Total Energy Savings
Sensitivity Analysis - Paybacks can be degraded or improved by varying sensitive model
parameters. Payback predictions are improved by considering the effects of public or private grants on
capital cost such as the $1.2 million grant recently received by the Palm Beach County SRWRF for
installation of a biogas generator, resulting in a project capital cost reduction of 33%. Payback can also be
improved from a rise in the cost of electricity, increase in assumed predicted blower efficiency, or other
factors. Conversely, payback predictions are degraded by considering a lower assumed cost of electricity,
blower efficiency, or other factors. However, the paybacks predicted by the model are relatively resilient to
variations in the key variable inputs discussed above. Changes in capital cost due to third-party grants or
cost estimating errors, or sudden changes in electricity costs are the most sensitive parameters effecting
payback. A recent precipitous drop in southeast Florida plant’s electrical bills from 2009 to 2010 of
approximately 20 percent recently occurred, due to a reduction in “pass through fuel charge” from FPL.
Were fuel charges to rise again on a similar scale, paybacks would be improved for each plant from 2 to 5
years.
Variable Treatment Efficiencies Prior to ECM Implementation - The results demonstrate that prior
to implementing ECM’s, the Boca Raton WWTP and Broward County North Regional WWTP
149
demonstrate similar scales of efficiency on a kWh / lb of CBOD5 and kWh / SOR basis with Broward
County North Regional WWTP being the most efficient. However, Plantation Regional WWTP shows a
scale of efficiency almost three times less efficient than the other two plants. The main reason Plantation
Regional WWTP is the least efficient prior to ECM implementation is that it operates as an extended
aeration facility by maintaining a long SRT above 30 days, to minimize sludge yield and reduce their
digester solids loading.
The apparent discrepancy in current energy intensity between Plantation WWTP and the other two
facilities is the main reason for the excellent payback of 8 years predicted relative to the other plants due to
the increased opportunity for realizing energy savings. Therefore, the effects of making zero-capital cost
operational improvements first to improve the efficiency before implementing ECMs was explored. It is
apparent that even if Plantation were to improve their efficiency by reducing SRT through taking one of the
three aeration basins offline, the payback for implementing the ECMs is still excellent at a median estimate
of 17 years.
Conversely, the Broward County North Regional WWTP current operation is currently the most
efficient. As a consequence, the payback would be the least beneficial at a median value of 32 years if not
considering the effects of removing Module D from service. However, the mechanical aerators that are no
longer required to be operated at Module D are a key source of energy savings for this analysis, resulting in
an excellent payback for implementing EMC Nos. 1 through 3 of 17 years.
Correlated Unit Efficiencies and Capital Costs Following ECM Implementation - Following
theoretical implementation of the ECM’s, each activated sludge treatment process demonstrates relatively
correlated scales of predicted efficiency on a kWh / SOR basis with average value of 0.10 kWh / SOR
treated for the Current Treatment, Partial Nitrification, and Complete Nitrification scenarios. The predicted
capital costs for implementing the proposed ECMs are well correlated on a Capital Cost / MGD ADF
Capacity treated basis with an average value of $205K / MGD ADF Capacity treated over the design
period. Although the dataset of three plants is too limited to predict universal correlation, it appears that
other mechanically aerated plants implementing the ECMs suggested in this study may roughly predict
their achievable energy savings based on the 0.10 kWh / SOR benchmark and their rough capital cost based
on the $205K / MGD ADF Capacity benchmark. The kWh / SOR treated and capital cost / MGD ADF
150
benchmark values can be supplemented with plant specific O&M and foregone repair and replacement
costs to estimate a given plant’s payback in accordance with the methodology of this study. An equation
was developed and is provided herein, which is a formula for completing a rough payback analysis for
other mechanically aerated plants implementing ECM Nos. 1 through 3.
Critical Assumptions Were Researched - An average value of 72 percent efficiency was
determined to estimate average turbo blower performance and 62 percent to estimate multi-stage
centrifugal blower performance based on available surveys (Rohrbacher et al., 2010). An average value of
3.0 mg/L was determined to estimate average fine-bubble aeration DO levels without DO control, and 1.5
mg/L was determined to estimate practical fine-bubble aeration DO levels following implementation of DO
control based on numerous studies surveyed.
It was determined that a feasibility study-level AACE Class
4 capital cost estimate was practical for this level of study, which implies a -20 / +30 percent accuracy
range in capital cost.
Operation and maintenance (O&M) costs associated with implementing each
technology were researched based on similar studies and interviews with plant personnel. The critical
assumptions researched in this paper should inform other researchers conducting similar analyses
elsewhere.
7.2
Recommendations
Further Model Accuracy Verification
Although the model predictions appear to correlate reasonably well to the limited data available
from the Broward County North Regional WWTP for fine bubble diffused aeration energy usage and side
by side measured efficiency of mechanical aeration versus fine bubble diffused aeration, it is recommended
that additional data sets and verification of key assumptions be completed and used to verify the model.
The Broward County North Regional WWTP is currently under preliminary study by a third party for
potentially implementing ECMs similar to those proposed in this study at aeration basin Module A and
Module B. If implemented, the results of the implementation can be used to further gauge the accuracy of
the model predictions developed in this thesis.
Specific Wastewater Characterization
More accurate model results could be achieved through completing wastewater characterization
sampling events at each facility. Typical values were assumed for important variables for modeling
151
purposes, such as the nonbiodegradable volatile suspended solids or readily biodegradable chemical oxygen
demand (Dold, 2007; Melcer et al., 2003). More accurate characterization of these wastewater fractions at
each facility through conducting sampling events would allow for more accurate predictions of oxygen
demand and energy use through the methodology outlined in this thesis. In addition, removal of TSS and
BOD by primary clarifiers at the City of Boca Raton were conservatively estimated based on typical values
due to lack of historical primary clarifier effluent data. Specific characterization of the settleability of the
influent wastewater and removal capacity of the clarifiers at the City of Boca Raton through sampling
events would allow for more accurate prediction of influent wastewater, which could effect oxygen demand
and energy use predictions.
Biogas Optimization and Cogeneration
Another ECM at WWTPs that is an excellent candidate for completing regional life cycle cost
analyses is biogas optimization and cogeneration.
Innovative power generation technologies, primary
sludge capture, and waste activated sludge pretreatment are technologies and methods that should be
included in a biogas optimization study. Locally, a biogas generator at the Palm Beach County –SRWRF
facility is currently under construction, which uses methane produced from the anaerobic digestion process
to power a generator to produce electricity, as opposed to wasting the methane to a waste gas flare. The
biogas generator is anticipated to reduce the facility’s energy draw by 14%. Many other plants could also
realize a benefit from biogas generation, including the Boca Raton WWTP, Broward County North
Regional WWTP, and the Plantation Regional WWTP.
Grants, Incentives, and Funding Sources
Payback can be improved through obtaining grants, incentives, or reduced interest loans.
Available public and private funding at the local, state, and federal level should be investigated for each
facility as a potential way to improve the payback for ECMs. As a local example of success, the Palm
Beach County – SRWRF recently received a $1.2 million grant in 2009 from the US Department of Energy
toward the construction of a biogas generator, which reduced the capital cost of total project delivery by
33%. Alternative project delivery from Energy Services Performance Contractors (ESCOs) can also be
explored to finance projects, in which the ESCO finances the project with no or little capital upfront from
the owner and guarantees the energy savings, and the debt is paid back by the owner with money generated
152
by the energy savings over a certain time frame (Dobyns and Lequio, 2008).
At the time of this
publication, the Broward County North Regional WWTP is currently under discussions with Chevron
Energy Solutions, an ESCO, to install a biogas generator, as well as ECMs similar to those discussed in this
study.
153
APPENDIX A-1 –BOCA RATON WWTP PRELIMINARY DESIGN DRAWINGS
154
155
156
157
158
159
APPENDIX A-2 –BOCA RATON WWTP DATA SPREADSHEETS
160
CITY OF BOCA RATON - ENERGY EFFICIENCY ANALYSIS SPREADSHEETS
SPREADSHEET TABLE OF CONTENTS
1.1 INFLUENT EFFLUENT SPECIFIER
1.2 FLOW PROJECTION
2.0 AERATION CALCULATIONS - GLOBAL PARAMETERS
2.1 AERATION CALCULATIONS - DIFFUSERS
2.2 AERATION CALCULATIONS - TURBO BLOWERS
2.3 AERATION CALCULATIONS - 1.5 MG/L DO CONTROL
3.1.1 SYSTEM DESIGN - SIZE PIPES - TRAIN 1
3.1.2 SYSTEM DESIGN - SIZE PIPES - TRAINS 2 AND 3
3.2 SYSTEM DESIGN - ESTIMATE LOSSES THROUGH PIPES
3.3 SYSTEM DESIGN - SYSTEM CURVE
3.4 SYSTEM DESIGN - BLOWER DESIGN
4.0 - COST ESTIMATE - SUMMARY
4.1 - COST ESTIMATE - DEMOLITION
4.2 - COST ESTIMATE - BLOWERS
4.3 - COST ESTIMATE - DIFFUSERS
4.4 - COST ESTIMATE - STRUCTURAL
4.5 - COST ESTIMATE - MECHANICAL PIPING
4.6 - COST ESTIMATE - INSTRUMENTATION
4.7 - COST ESTIMATE - ELECTRICAL
5.0 - O&M COSTS
5.1 - O&M COSTS - REPLACE AERATORS
6.0LIFECYCLECOSTANALYSISINPUTS
6.1.1 LIFE-CYCLE COST ANALYSIS
6.1.2 LIFE-CYCLE COST ANALYSIS (LOW RANGE)
6.1.3 LIFE-CYCLE COST ANALYSIS (HIGH RANGE)
6.2 LIFE-CYCLE COST ANALYSIS SUMMARY
161
162
1.1 INFLUENT EFFLUENT SPECIFIER
INF TKN
EFF NH3
LBS
LBS.
2369
436
4322
1149
5158
1618
6865
2053
INF TKN
EFF NH3
LBS
LBS.
2849
524
5197
1382
6202
1945
8255
2468
2007 - 2009 3 Year Average - Adjusted to 2011-2031 ADF
PRIMARY
INF FLOW EFF CBOD
INF TSS
EFF CBOD EFF WAS VS
MGD
LBS
LBS
LBS.
LBS
10.12
6695
4350
87
1426
14.55
16516
9983
347
11093
16.37
21046
12766
516
14626
21.87
29351
36497
1008
17900
2007 - 2009 - Adjusted to Design Flow of 17.5 MGD
PRIMARY
INF FLOW EFF CBOD
INF TSS
EFF CBOD EFF WAS VS
MGD
LBS
LBS
LBS.
LBS
12.16
8051
5231
105
1715
17.50
19861
12004
417
13339
19.69
25308
15351
621
17587
26.30
35295
43888
1212
21525
Min Day
ADF
MMADF
Max Day
Min Day
ADF
MMADF
Max Day
Min Day
ADF
MMADF
Max Day
EFF CBOD
LBS.
84
333
496
968
INF TKN
EFF NH3
LBS
LBS
2277
419
4153
1104
4956
1554
6596
1972
PRIMARY
EFF TSS
LBS
4180
9592
12267
35070
AVG
DO
MG/L
0.5
AVG
SRT
DAYS
3.9
Note: For Boca assume low range 25% CBOD, 50% TSS clarifier removal (Metcalf & Eddy, 2003)
EFF WAS
VSS
LBS
1370
10659
14054
17200
PRIMARY
EFF CBOD
LBS
6433
15870
20223
28204
INF FLOW
MGD
9.72
13.98
15.73
21.02
2007 - 2009
This spreadsheet summarizes the values gleaned from available historical monitoring data at the WWTP
Values from this spreadsheet are inserted directly into Spreadsheets 2.1 - 2.3.
1.2 FLOW PROJECTION
This spreadsheet summarizes the Flow Projection through the 20 year design horizo
Flow Projection
15.20
15.00
14.80
Flow (MGD)
Projected Projected
Year
Population
Flow
2008
128107
14.28
2009
128517
13.88
2010
129472
13.79
2011
130082
14.13
2012
130520
14.18
2013
131017
14.24
2014
131378
14.27
2015
131892
14.33
2016
132425
14.39
2017
133017
14.45
2018
133435
14.50
2019
133854
14.54
2020
134483
14.61
2021
134902
14.66
2022
135320
14.70
2023
135739
14.75
2024
136157
14.79
2025
136609
14.84
2026
137034
14.89
2027
137461
14.94
2028
137889
14.98
2029
138319
15.03
2030
138751
15.08
2031
139179
15.12
14.60
14.40
14.20
14.00
2010
2015
2020
2025
2030
Year
2007-2009 ADF 13.98 MGD
2031 ADF 15.12 MGD
2011-2031 Avg Flow 14.55 MGD
Projected Population to 2025 per SFWMD 2001 Consumptive Use Perm
Extrapolated 2026 population =2025 population + average 2021-2025 population grow
Extrapolated 2027 population = extrapolated 2026 population + average 2022-2026 project
Projected Flow Year Y = (Projected Population Year Y / Projected Population Year X) * Projected Flow Year
163
2035
2.0 AERATION CALCULATIONS - GLOBAL PARAMETERS
Spreadsheet 2.1 - 2.3 calculates the amount of air and horsepower needed to treat various flowrates and loading rates throughout the plant.
2.0 Aeration Calculations - Global Paramters spreadsheet specifies the glbaal variables input to spreadsheets 2.1 - 2.3.
AreaunderAerationperBasin(ft2)=
#ofbasinsonline=
SidewaterDepth(ft)=
DiffuserSubmergence(ft)=
EquationForSystemCurve
NumberofDiffusersperBasin=
SiteElevation(ftaboveMSL)=
MinimumMixRequirements(scfm/ft2)
MinimumFlowperDiffuser(scfm)
MaximumFlowperDiffuser(scfm)
GeneralTemperature
Beta(unitless)=
Patm(psi)=
Patm(middepth,ftwc/2/2.31psi,psi)=
Csth(perAppDformechaer,mg/L)=
Cs20([email protected],1atm,mg/L)=
CstH*(mg/L)=
DensAir(lb/cf)=
MassFractionO2inair=
Alpha=
Alphaforcompletenitrification=
AverageofminimumSOTE
21675
2
13
12
2.74E09 *x^2
3500
10
0.12
0.5
3.0
25
0.98
14.7
2.60
8.24
9.08
9.70
0.0750
0.2315
0.43
0.5
a
Figure 2.10 & Sanitaire
Tau
1.6
1.4
1.24
1.12
1
0.91
0.83
0.77
0.71
Air
Average
Flow
SOTE
(SCFM/Unit
(%)
0.59
0.88
1.00
1.18
1.47
1.75
2.06
2.35
2.50
2.65
2.94
3.00
46.83
42.50
41.26
39.89
38.48
38.33
37.52
37.21
37.07
36.87
36.69
36.66
40.58
36.83
35.75
34.56
33.34
33.21
32.51
32.24
32.12
31.95
31.79
31.77
0.49
Fup(Dold,2007)
VSS/TSS(Metcalf&Eddy,2003)
0.08
0.85
1.2
y = 4.08E-04x2 - 3.82E-02x + 1.60E+00
R² = 9.98E-01
0.8
0.4
0
5
10
15
20
25
30
35
40
Temperature (C)
Submergence = 20.00-ft
Minimum Average
Minimum
SOTE
SOTE
SOTE
(%)
(%/ft)
(%/ft)
41.25
37.98
37.37
36.95
35.92
35.90
35.39
35.35
35.20
35.18
35.01
35.00
2.34
2.13
2.06
1.99
1.92
1.92
1.88
1.86
1.85
1.84
1.83
1.83
35.74
32.91
32.38
32.02
31.12
31.11
30.67
30.63
30.57
30.48
30.34
30.33
2.34
2.13
2.06
1.99
1.92
1.92
1.88
1.86
1.85
1.84
1.83
1.83
Results from trendline in chart
Constantsforthefollowingformula:ax4+bx3+cx2+dx+e
2.06
1.90
1.87
1.85
1.80
1.80
1.77
1.77
1.76
1.76
1.75
1.75
Submergence = 17.33-ft
Air
Average Minimum Average
Minimum
Flow
SOTE
SOTE
SOTE
SOTE
(SCFM/Unit
(%)
(%)
(%/ft)
(%/ft)
0.59
0.88
1.00
1.18
1.47
1.75
2.06
2.35
2.50
2.65
2.94
3.00
Y(perDold,2007)
(fornitrifyingassume5daySRT)
1.6
2.06
1.90
1.87
1.85
1.80
1.80
1.77
1.77
1.76
1.76
1.75
1.75
Avg SOTE
Avg SOTE
Avg SOTE
Avg SOTE
Avg SOTE
Min SOTE
Min SOTE
Min SOTE
Min SOTE
Min SOTE
0.0514
0.4603
1.5405
2.3473
3.2779
0.0467
0.4015
1.2724
1.7984
2.7526
SOTEvs.SCFM/diffuser
Sanitaire SilverSeriesII9"MembraneDiscDiffuser
SOTE%/footofdiffusersubmergence
0
5
10
15
20
25
30
35
40
3
1.5
0.62
0.72
0.5
0.5
Tau vs. Temperature
Tau (dimensionless)
Temp.
ManualDOControlO2(mg/L)
AutoDOControlO2(mg/L)
MSCBlowerEfficiency
TurboBlowerEfficiency
ConcentrationatMaxDay(mg/L)
PreECMExistingDO(mg/L)
2.50
AverageSOTE
2.40
Min.SOTE
2.30
Poly.(AverageSOTE)
2.20
Poly.(Min.SOTE)
2.10
y=0.0514x4 0.4603x3 +1.5405x2 2.3473x+3.2779
R²=0.9987
2.00
1.90
1.80
y=0.0467x4 0.4015x3 +1.2724x2 1.7984x+2.7526
R²=0.9944
1.70
1.60
1.50
0.00
0.50
1.00
1.50
2.00
SCFM/Diffuser
164
2.50
3.00
3.50
165
2.1 AERATION CALCULATIONS - DIFFUSERS
Cur Treat
1,923
23,551
0.90
0.43
54,857
2,194
7 000
7,000
1.33
1.33
0.00
23.50%
9,338
4.SORCalculations
Tau=
AOR/SOR={[(Beta*CstH*CL)/Cs20][1.024^(T20)](Alpha)(F)}
SOR=
5.AerationDemandCalculations
Airrequiredat100%Efficiency=
Total Number of Diffusers =
TotalNumberofDiffusers=
DiffuserFlow,scfm/diffuser(macroinput)=
DiffuserFlow,scfm/diffuser=
Difference=
SOTEatDesSubmandDiffFlow=
SCFM=SOTR/(SOTE*60min/hr*24hr/day*DensAir*%02inair)
ADF
3,182
7 000
7,000
2.01
2.01
0.00
22.62%
14,070
0.90
0.30
79,559
1,923
23,551
3,668
7,000
7
000
2.34
2.34
0.00
22.36%
16,405
0.90
0.34
91,717
3,216
31,570
MinimumMixingAirflowRequirement(scfm)
MinimumMixingRequirementMet?
IsDiffuserFlowWithinRange?
AllEquationsreferenced,(Metcalf&Eddy,2003)
7. Checks
5202
TRUE
TRUE
5202
TRUE
TRUE
5202
TRUE
TRUE
6.PowerDemandCalculations
Pw=[(W*R*T1)/(550*n*Eff)]*[(P2/P1)^.2831]
Pw(blowerhorsepowerrequired)=
345
544
652
DynamicLosses
0.24
0.54
0.74
WiretoAirEff=
0.62
0.62
0.62
e=100%*((P1+14.7)/14.7)0.2831)/1(P2+14.7)/14.7)0.2831)/2)/((P1+14.7)/14.7)0.2831)/2
Eq555
ADF
Min Day Min Day
ADF
ADF
0.90
0.30
74,916
2,162
22,177
0.90
0.30
95,670
2,313
28,320
5202
TRUE
TRUE
385
0.29
0.62
5202
TRUE
TRUE
505
0.48
0.62
5202
TRUE
TRUE
689
0.81
0.62
2,394
2,996
3,826
7,000
7
000
7 000
7,000
7 000
7,000
1.47
1.88
2.45
1.47
1.88
2.45
0.00
0.00
0.00
23.20% 22.72% 22.28%
10,320 13,191 17,178
0.90
0.30
59,864
1,727
17,721
2,271
32,163
4,519
46,441
Des Des+Nit
19.69
19.69
2
2
25,308 25,308
621
621
16,544 13,341
6,202
6,202
1,945
82
3
3
25
25
0.43
0.5
a
a
MMADF MMADF
5202
TRUE
TRUE
835
1.10
0.62
5202
TRUE
TRUE
819
1.06
0.62
4,411
4,346
7,000
7
000
7 000
7,000
2.86
2.82
2.86
2.82
0.00
0.00
22.03% 22.05%
20,020 19,710
5202
TRUE
TRUE
1055
1.56
0.62
5,396
7,000
7
000
3.41
3.41
0.00
22.62%
23,862
0.90
0.90
0.90
0.34
0.30
0.34
110,290 108,650 134,922
3,868
37,963
1131ADF 1131ADF 1131ADF Current Design Design Des+Nit
14.55
14.55
14.55
9.72
12.16
17.50
17.50
2
2
2
2
2
2
2
16,516
16,516
16,516
6,433
8,051 19,861
19,861
347
347
347
84
105
417
417
10,414
10,414
8,709
1,086
1,359 12,523
10,473
4,322
4,322
4,322
2,277
2,849
5,197
5,197
1,149
1,149
61
419
524
1,382
73
0.5
3
3
3
3
3
3
25
25
25
25
25
25
25
0.43
0.43
0.5
0.43
0.43
0.43
0.5
a
a
a
a
a
a
a
3.AORCalculations
Eq.818 TKNinfNH3eff0.12(PxBio)=NOx=
Eq.817 1.6*1.16*(SoS)1.42(PxBio)+4.33(NOx)=AOR=
MGD
NumberofBasinsOnline
So=CBODinf
S=CBODeff
Eq.815(wherehilighted),PxBio=
TKN=
NH3eff=
CL(operat.oxygenconcentration,mg/L)=
T(degC)
Alpha=
AverageofminimumSOTE
2.Inputs
Assumes multi-stage centrifugal blowers at 62% efficiency.
Spreadsheet 2.1 - 2.3 calculates the amount of air and horsepower need to treat various flowrates and loading rates throughout the plant.
2.1 Aeration Calculations - Diffusers spreadsheet predicts the efficiency improvement by upgrading to fine bubble diffusers with no other ECIs.
MDF
5202
TRUE
TRUE
948
1.33
0.62
4,877
7,000
7
000
3.15
3.15
0.00
22.12%
22,053
0.90
0.43
121,945
3,562
52,353
5202
TRUE
TRUE
1025 hp
1.50 psi
0.62 Unitless
5,240
7,000
7
000
3.34
3.34
0.00
22.42%
23,368
0.90
0.50
131,015 (lb/day)
6,096 (lb/day)
65,403 (lb/day)
Des
Des+Nit
26.30
26.30
2
2
35,295
35,295 (lb/day)
1,212
1,212 (lb/day)
18,540
17,077 (lb/day)
8,255
8,255 (lb/day)
2,468
110 (lb/day)
0.5
0.5 mg/L
25
25 degC
0.43
0.5 unitless
a
a
MDF
Cur Treat
5202
TRUE
TRUE
331
0.22
0.62
2,108
7,000
7
000
1.33
1.28
0.05
23.50%
8,973
0.90
0.43
52,712
1,848
22,630
20072009
13.98
2
15,870
333
10,007
4,153
1,104
0.5
25
0.43
a
166
2.2 AERATION CALCULATIONS - TURBO BLOWERS
2,194
7 000
7,000
1.33
1.33
0.00
23.50%
9,338
5.AerationDemandCalculations
Airrequiredat100%Efficiency=
Total Number of Diffusers =
TotalNumberofDiffusers=
DiffuserFlow,scfm/diffuser(macroinput)=
DiffuserFlow,scfm/diffuser=
Difference=
SOTEatDesSubmandDiffFlow=
SCFM=SOTR/(SOTE*60min/hr*24hr/day*DensAir*%02inair)
MinimumMixingAirflowRequirement(scfm)
MinimumMixingRequirementMet?
IsDiffuserFlowWithinRange?
AllEquationsreferenced,(Metcalf&Eddy,2003)
7. Checks
6.PowerDemandCalculations
Pw=[(W*R*T1)/(550*n*Eff)]*[(P2/P1)^.2831]
Pw(blowerhorsepowerrequired)=
DynamicLosses
WiretoAirEff=
5202
TRUE
TRUE
297
0.24
0.72
0.90
0.43
54,857
4.SORCalculations
Tau=
AOR/SOR={[(Beta*CstH*CL)/Cs20][1.024^(T20)](Alpha)(F)}
SOR=
Eq555
1,923
23,551
3.AORCalculations
Eq.818 TKNinfNH3eff0.12(PxBio)=NOx=
Eq.817 1.6*1.16*(SoS)1.42(PxBio)+4.33(NOx)=AOR=
MGD
NumberofBasinsOnline
So=CBODinf
S=CBODeff
Eq.815(wherehilighted),PxBio=
TKN=
NH3eff=
CL(operat.oxygenconcentration,mg/L)=
T(degC)
Alpha=
AverageofminimumSOTE
2.Inputs
ADF
ADF
Min Day Min Day
ADF
ADF
5202
TRUE
TRUE
468
0.54
0.72
3,182
7 000
7,000
2.01
2.01
0.00
22.62%
14,070
0.90
0.30
79,559
1,923
23,551
5202
TRUE
TRUE
561
0.74
0.72
3,668
7,000
7
000
2.34
2.34
0.00
22.36%
16,405
0.90
0.34
91,717
3,216
31,570
0.90
0.30
74,916
2,162
22,177
0.90
0.30
95,670
2,313
28,320
5202
TRUE
TRUE
331
0.29
0.72
5202
TRUE
TRUE
435
0.48
0.72
5202
TRUE
TRUE
594
0.81
0.72
2,394
2,996
3,826
7,000
7
000
7 000
7,000
7 000
7,000
1.47
1.88
2.45
1.47
1.88
2.45
0.00
0.00
0.00
23.20% 22.72% 22.28%
10,320 13,191 17,178
0.90
0.30
59,864
1,727
17,721
2,271
32,163
4,519
46,441
Des Des+Nit
19.69
19.69
2
2
25,308 25,308
621
621
16,544 13,341
6,202
6,202
1,945
82
3
3
25
25
0.43
0.5
a
a
MMADF MMADF
5202
TRUE
TRUE
719
1.10
0.72
5202
TRUE
TRUE
705
1.06
0.72
4,411
4,346
7,000
7
000
7 000
7,000
2.86
2.82
2.86
2.82
0.00
0.00
22.03% 22.05%
20,020 19,710
5202
TRUE
TRUE
908
1.56
0.72
5,396
7,000
7
000
3.41
3.41
0.00
22.62%
23,862
0.90
0.90
0.90
0.34
0.30
0.34
110,290 108,650 134,922
3,868
37,963
1131ADF 1131ADF 1131ADF Current Design Design Des+Nit
14.55
14.55
14.55
9.72
12.16
17.50
17.50
2
2
2
2
2
2
2
16,516
16,516
16,516
6,433
8,051 19,861
19,861
347
347
347
84
105
417
417
10,414
10,414
8,709
1,086
1,359 12,523
10,473
4,322
4,322
4,322
2,277
2,849
5,197
5,197
1,149
1,149
61
419
524
1,382
73
0.5
3
3
3
3
3
3
25
25
25
25
25
25
25
0.43
0.43
0.5
0.43
0.43
0.43
0.5
a
a
a
a
a
a
a
Cur Treat
Spreadsheet 2.1 - 2.3 calculates the amount of air and horsepower need to treat various flowrates and loading rates throughout the plant.
2.2 Aeration Calculations -Turbo Blowers spreadsheet predicts efficiency improvement of fine bubble diffusers with turbo blowers assuming 72% effiency.
MDF
5202
TRUE
TRUE
816
1.33
0.72
4,877
7,000
7
000
3.15
3.15
0.00
22.12%
22,053
0.90
0.43
121,945
3,562
52,353
5202
TRUE
TRUE
883 hp
1.50 psi
0.72 Unitless
5,240
7,000
7
000
3.34
3.34
0.00
22.42%
23,368
0.90
0.50
131,015 (lb/day)
6,096 (lb/day)
65,403 (lb/day)
Des
Des+Nit
26.30
26.30
2
2
35,295
35,295 (lb/day)
1,212
1,212 (lb/day)
18,540
17,077 (lb/day)
8,255
8,255 (lb/day)
2,468
110 (lb/day)
0.5
0.5 mg/L
25
25 degC
0.43
0.5 unitless
a
a
MDF
167
2.3 AERATION CALCULATIONS - 1.5 MG/L DO CONTROL
2,194
7 000
7,000
1.33
1.33
0.00
23.50%
9,338
5.AerationDemandCalculations
Airrequiredat100%Efficiency=
Total Number of Diffusers =
TotalNumberofDiffusers=
DiffuserFlow,scfm/diffuser(macroinput)=
DiffuserFlow,scfm/diffuser=
Difference=
SOTEatDesSubmandDiffFlow=
SCFM=SOTR/(SOTE*60min/hr*24hr/day*DensAir*%02inair)
MinimumMixingAirflowRequirement(scfm)
MinimumMixingRequirementMet?
IsDiffuserFlowWithinRange?
AllEquationsreferenced,(Metcalf&Eddy,2003)
7. Checks
6.PowerDemandCalculations
Pw=[(W*R*T1)/(550*n*Eff)]*[(P2/P1)^.2831]
Pw(blowerhorsepowerrequired)=
DynamicLosses
WiretoAirEff=
5202
TRUE
TRUE
297
0.24
0.72
0.90
0.43
54,857
4.SORCalculations
Tau=
AOR/SOR={[(Beta*CstH*CL)/Cs20][1.024^(T20)](Alpha)(F)}
SOR=
Eq555
1,923
23,551
3.AORCalculations
Eq.818 TKNinfNH3eff0.12(PxBio)=NOx=
Eq.817 1.6*1.16*(SoS)1.42(PxBio)+4.33(NOx)=AOR=
MGD
NumberofBasinsOnline
So=CBODinf
S=CBODeff
Eq.815(wherehilighted),PxBio=
TKN=
NH3eff=
CL(operat.oxygenconcentration,mg/L)=
T(degC)
Alpha=
AverageofminimumSOTE
2.Inputs
ADF
ADF + Nit Min Day Min Day
ADF
ADF
5202
TRUE
TRUE
350
0.32
0.72
2,505
7 000
7,000
1.55
1.55
0.00
23.08%
10,856
0.90
0.38
62,636
1,923
23,551
5202
TRUE
TRUE
416
0.44
0.72
2,888
7,000
7
000
1.81
1.81
0.00
22.78%
12,679
0.90
0.44
72,208
3,216
31,570
0.90
0.38
58,981
2,162
22,177
0.90
0.38
75,320
2,313
28,320
5202
TRUE
TRUE
245
0.17
0.72
5202
TRUE
TRUE
325
0.28
0.72
5202
TRUE
TRUE
438
0.48
0.72
1,885
2,359
3,013
7,000
7
000
7 000
7,000
7 000
7,000
1.11
1.45
1.90
1.11
1.45
1.90
0.00
0.00
0.00
24.22% 23.25% 22.71%
7,783 10,148 13,268
0.90
0.38
47,131
1,727
17,721
5202
TRUE
TRUE
523
0.65
0.72
4,519
46,441
5202
TRUE
TRUE
513
0.63
0.72
5202
TRUE
TRUE
684
1.01
0.72
4,249
7,000
7
000
2.75
2.75
0.00
22.08%
19,245
0.90
0.90
0.38
0.44
85,539 106,223
2,271
32,163
Des Des+Nit
19.69
19.69
2
2
25,308 25,308
621
621
16,544 13,341
6,202
6,202
1,945
82
1.5
1.5
25
25
0.43
0.5
a
a
MMADF MMADF
3,473
3,421
7,000
7
000
7 000
7,000
2.21
2.17
2.21
2.17
0.00
0.00
22.47% 22.49%
15,459 15,211
0.90
0.44
86,830
3,868
37,963
1131ADF 1131ADF 1131ADF Current Design Design Des+Nit
14.55
14.55
14.55
9.72
12.16
17.50
17.50
2
2
2
2
2
2
2
16,516
16,516
16,516
6,433
8,051 19,861
19,861
347
347
347
84
105
417
417
10,414
10,414
8,709
1,086
1,359 12,523
10,473
4,322
4,322
4,322
2,277
2,849
5,197
5,197
1,149
1,149
61
419
524
1,382
73
0.5
1.5
1.5
1.5
1.5
1.5
1.5
25
25
25
25
25
25
25
0.43
0.43
0.5
0.43
0.43
0.43
0.5
a
a
a
a
a
a
a
Cur Treat
Spreadsheet 2.1 - 2.3 calculates the amount of air and horsepower required to treat various flowrates and loading rates throughout the plant.
2.3 Aeration Calculations -1.5 MG/L Do Control spreadsheet predicts efficiency improvement of fine bubble diffusers, turbo blowers, and DO Control.
MDF
5202
TRUE
TRUE
816
1.33
0.72
4,877
7,000
7
000
3.15
3.15
0.00
22.12%
22,053
0.90
0.43
121,945
3,562
52,353
5202
TRUE
TRUE
883 hp
1.50 psi
0.72 Unitless
5,240
7,000
7
000
3.34
3.34
0.00
22.42%
23,368
0.90
0.50
131,015 (lb/day)
6,096 (lb/day)
65,403 (lb/day)
Des
Des+Nit
26.30
26.30
2
2
35,295
35,295 (lb/day)
1,212
1,212 (lb/day)
18,540
17,077 (lb/day)
8,255
8,255 (lb/day)
2,468
110 (lb/day)
0.5
0.5 mg/L
25
25 degC
0.43
0.5 unitless
a
a
MDF
168
3.1.1 SYSTEM DESIGN - SIZE PIPES - TRAIN 1
VP = a*T5 +b*T4 +c*T3 +d*T2 +e*T+f
Where:
a = 2.268E-11
b = -2.49E-10
c = 5.083E-07
d = 7.416E-06
e = 0.0014849
f = 0.0162738
3 ea
#VALUE!
scfm
24 in
#VALUE!
fpm
#VALUE!
scfm
16 in
#VALUE!
fpm
#VALUE!
Number of Zones per train:
Air Flow To Train 2 and 3:
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
Air Flow To Train 3:
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
Air Flow Split:
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
scfm
12 in
fpm
2 ea
#VALUE!
scfm
30 in
#VALUE!
fpm
Number of Parallel Aeration Trains:
Air Flow Per Treatment Train:
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
#VALUE!
Max. Month
#VALUE!
scfm
36 in
#VALUE!
fpm
Total Air Flow:
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
#VALUE! fpm
#VALUE! scfm
#VALUE! fpm
#VALUE! scfm
#VALUE! fpm
3 ea
#VALUE! scfm
#VALUE! fpm
2 ea
#VALUE! scfm
#VALUE! fpm
Peak Day
#VALUE! scfm
#VALUE! acfm
#VALUE! acfm
#VALUE! acfm
§ T 460 · ª PS RH S * VPS º
SCFM * ¨¨ A
»
¸¸ «
© TS 460 ¹ ¬ PI RH A * VPA ¼
Airflows
20,020 scfm
23,862 scfm
23,368 scfm
Per Table 5-28 - Metcalf & Eddy
Typical air velocities in aeration
header pipes
Velocity
fpm
1200 - 1800
1800 - 3000
ICFM
2700 - 4000
3800 - 6500
6.716900698
0.33902046
Average Annual Air Flow, Fully Nitrify:
Maximum Month Air Flow, Fully Nitrify:
Maximum Day Air Flow, Fully Nitrify:
Pipe Dia
In
1-3
4 - 10
12 - 24
30 - 60
Vp act
VP std
This spreadsheet demonstrates the sizing of the proposed aeration process air pipes at Train 1.
From 5th Order Curve Fit of Stephenson/Nixon,
RH Inlet =
0.41
Figure 4-1 - Saturation Water Vapor Pressure,
Tdischarge=
175 F
Water vapor pressure (psi) vs temperature (°F) can
Pdischarge =
#VALUE!
psig
be calculated with the following formula:
169
3.1.2 SYSTEM DESIGN - SIZE PIPES - TRAINS 2 AND 3
Pipe Dia
In
1-3
4 - 10
12 - 24
30 - 60
ICFM
Max. Month
21,918 scfm
36 in
3,101 fpm
14,612 scfm
30 in
2,977 fpm
7,306 scfm
24 in
Air Flow To Zones 2 and 3 for Trains 1 and 2:
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
Air Flow To Zones 3 for Trains 1 and 2:
Minimum Pipe Size to Meet Velocity Criteria:
7,155 scfm
2,915 fpm
14,309 scfm
3,036 fpm
Peak Day
21,464 scfm
18,389 acfm
21,918 acfm
21,464
acfm
,
§ T 460 · ª PS RH S * VPS º
¸¸ «
SCFM * ¨¨ A
»
© TS 460 ¹ ¬ PI RH A * VPA ¼
From 5th Order Curve Fit of Stephenson/Nixon,
Figure 4-1 - Saturation Water Vapor Pressure,
Water vapor pressure (psi) vs temperature (°F) can
be calculated with the following formula:
VP = a*T5 +b*T4+c*T3+d*T2 +e*T+f
Where:
a = 2.268E-11
b = -2.49E-10
c = 5.083E-07
d = 7.416E-06
e = 0.0014849
f = 0.0162738
Air Flow To Zones 1,2, and 3 for Trains 1 and 2:
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
Airflows
20,020 scfm
23,862 scfm
23,368
scfm
,
Per Table 5-28 - Metcalf & Eddy
Typical air velocities in aeration
header pipes
Velocity
fpm
1200 - 1800
1800 - 3000
2700 - 4000
3800 - 6500
Average Annual Air Flow, Fully Nitrify:
Maximum Month Air Flow, Fully Nitrify:
Maximum Dayy Air Flow,, Fullyy Nitrify:
y
0.41
175 °F
7.14 psig
6.716900698
0.33902046
RH Inlet =
Tdischarge=
Pdischarge =
Vp act
VP std
This spreadsheet demonstrates the sizing of the proposed aeration process air pipes at Train 2-3.
170
Pdischarge =
=
H=
J act=
Vp act
VP std
Vp inlet
for st. steel
Based on 13/64" orifice Silver Series II Diffusers
Recommended per Sanitaire
1 Check Valve, 1 BFV, 14' x 16" Exp.
1 90 Bend, 4 thru tees
30" x 24" contraction, 2 90 bends, 1 thru tee
24" x 20" contraction, 1 thru tee
1 thru tee, 1 90 bend, venturi meter, modulating valve 10 deg closed
2 tees, 2 90 deg bends
16" Blower Outlet
30" Air Piping
24" Air Piping
20" Air Piping
14" Air Piping
12" Air Piping/Diff. Head
6" Air Piping
Loss Through Diffuser
Diffuser Loss w/ Age
7.14 psi
3851.41
3043.089
2191.024
2501.371
2567.607
2282.317
760.7723
Blower Discharge Pressure Required =
16
36
30
24
16
12
6
1.51 psi
5377.58
21510.3
10755.2
7858.29
3585.06
1792.53
149.377
5.63 psi
6402.628
25610.51
12805.26
8536.837
4268.418
2134.209
177.8508
Aeration System Losses
13
77
129
84
125
52
52
4.95E+06
5.21E+07
5.23E+07
3.11E+07
3.17E+07
8.79E+06
1.47E+06
Q (acfm) Diam (in) Vel (fpm) Length (ft) Re
Static Pressure =
5841.93
23367.7
11683.9
8536.84
3894.62
1947.31
162.276
Q (scfm) Q (icfm)
0.16 psi
Blower Piping Inlet Losses
Cell M
Cell N
Cell O
0.000003
0.000001
0.000002
0.000002
0.000003
0.000004
0.000008
H/D
2.27E-11
1.141064
0.71236
0.369288
0.481312
0.507139
0.400703
0.044523
0.102743
0.127462
0.134155
0.150422
0.362048
0.181259
0.051656
15
14
hL (inH2O)
b = -2.5E-10
c = 5.08E-07
d = 7.42E-06
e = 0.001485
f = 0.016274
a=
hi (inH2O)
Where:
5.2
3.3
2.65
0.85
2.27
4.8
4.8
5.93353
2.350789
0.978612
0.409115
1.151206
1.923373
0.213708
15
14
Minor Losses (est.)
6K
hL (inH2O)
0.214052
0.084805
0.035303
0.014759
0.04153
0.069386
0.00771
0.541126
0 541126
0.505051
hL (psi)
From 5th Order Curve Fit of Stephenson/Nixon,
Figure 4-1 - Saturation Water Vapor Pressure,
Water vapor pressure (psi) vs temperature (°F) can
be calculated with the following formula:
VP = a*T5 +b*T4 +c*T3 +d*T2 +e*T+f
fcalc based on Swamee Jain equation
hi (inH2O) Pressure V
Darcy Weisbach
0.009
0.007
0.007
0.007
0.008
0.009
0.011
fcalc
§ T 460 · ª PS RH S * VPS º
¸¸ «
SCFM * ¨¨ A
»
© TS 460 ¹ ¬ PI RH A * VPA ¼
Total Blower Piping Discharge Losses =
16
36
30
24
16
12
6
Diam (in)
Cummulative Loss
hL (psi)
hL (inH2O)
3
0.10823
1.5
0.05411
12
0.4329
Total Blower Piping Inlet Losses =
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
ICFM
21510.33 acfm
Qprocess
175 °F
psig
ft2/s
inches
lb/scf
23368 scfm
25610.51 icfm
Qprocess
Qprocess
0.41
14.53 psia
101 °F
7.1
0.000225
0.00005
0.0924042
6.7169007
0.3390205
0.9780971
16" Blower Outlet
30" Air Piping
24" Air Piping
20" Air Piping
14" Air Piping
12" Air Piping/Diff. Head
6" Air Piping
Loss
L
Through
Th
h Diffuser/Orifice
Diff
/O ifi
Diffuser Fouling Loss
Description
Inlet Filter Loss
Inlet Silencer Loss
Loss across diffuser
Description
P inlet =
T inlet =
#VALUE!
Tdischarge=
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(1)
(2)
(3)
3.2 SYSTEM DESIGN - ESTIMATE LOSSES THROUGH PIPES
This spreadsheet demonstrates the calculation of worst-case headloss through the proposed aeration piping system.
5.93353
8.28432
9.262932
9.672047
10.82325
12.74663
12.96033
27.96033
27 96033
41.96033
0.214052
0.298857
0.334161
0.348919
0.390449
0.459835
0.467545
1.00867
1 00867
1.513721
Cummulative Loss
hL (inH2O)
hL (psi)
3.3 SYSTEM DESIGN - SYSTEM CURVE
This spreadsheet displays the system curve of the aeration blower piping system. The data is poltted on graphs on the following spreadsh
SCFM
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
12000
13000
14000
15000
16000
17000
18000
19000
20000
21000
22000
23000
24000
25000
PSI
5.63
5.63
5.64
5.65
5.67
5.70
5.73
5.76
5.81
5.85
5.90
5.96
6.03
6.10
6.17
6.25
6.34
6.43
6.53
6.63
6.74
6.85
6.97
7.09
7.22
7.36
8.00
y=2.77E09x2 +1.73E18x+5.63E+00
R²=1.00E+00
7.00
6.00
5.00
4.00
Series1
3.00
Poly.(Series1)
2.00
1.00
0.00
0
5000
10000
171
15000
20000
25000
30000
3.4 SYSTEM DESIGN - BLOWER DESIGN
This spreadsheet details the multiple temperature, pressure, and flow related conditions that are taken into account to correctly size the blowers.
Historical Weather Data for West Palm Beach
Data Source
Parameter
ASHRAE
Extreme (1%)
#VALUE!
Conditions for
WPB
NOAA
Records for
West Palm
Beach
Value
80
Maximum Temperature (°F):
101
Resulting Relative Humidity*:
41%
Blower Inlet and Discharge Pressures
Ambient Barometric Pressure (psia)
Blower Inlet Pressure (psia )
System Design Pressure Loss (psig):
Estimated Discharge Pressure (psia ):
From 5th Order Curve Fit of Stephenson/Nixon,
Figure 4-1 - Saturation Water Vapor Pressure,
Water vapor pressure (psi) vs temperature (°F) can
be calculated with the following formula:
VP = a*T5 +b*T4 +c*T3+d*T2+e*T+f
Where:
a = 2.27E-11 32°F T 140°F
b = -2.5E-10
c = 5.08E-07
d = 7.42E-06
e = 0.001485
f = 0.016274
-------------->
14.696
14.53
7.14
21.84
Correct Blower Florate Design Point for Extreme Hot Weather Condition
Parameter
Std. Cond.
Design
Inlet Temperature (°F):
68.0
101.0
Absolute Inlet Temperature (°R):
528
561
Relative Humidity:
36%
41%
Vapor Pressure (psi):
0.3390
0.9781
Barometric Pressure (psi):
14.70
14.53
Density Correction Factor (ICFM/SCFM):
1.00
1.10 -------------->
ICFM
Maximum Day Air Flow (CFM):
23,368
25,604
Correct Blower Pressure Design Point for Extreme Hot Weather Condition
k-1/k
0.283
0.283
Approximate Site Discharge Pressure (psig):
7.14
Equivalent Air Pressure (EAP) (psig):
7.92 -------------->
Size Blowers
Minimum Mixing Air Flow (SCFM):
Average Annual Air Flow (SCFM), not nitrifying:
Maximum Month Air Flow (SCFM), not nitrifying:
Maximum Day Air Flow (SCFM), not nitrifying:
Conversion Factor (ICFM/SCFM):
Number of Blowers:
Ratio of Large To Small
Small Blower Capacity (ICFM): (1 x)
Large Blower Capacity (ICFM): (3 x)
Firm Blower Capacity (ICFM):
Is Max. Month Requirement met w/ Firm Capacity?
Required Blower Turn Down to Meet Minimum Flow:
Site Barometric Pressure (psia):
Small Blower Rating Point (SCFM)
Large Blower Rating Point (SCFM)
Additional Information
5,202
13,268
14,538 icfm
15,211
16,667 icfm
22,053
24,163 icfm
1.10
4
1.5
5,000
4,563 SCFM
7,000
6,389 SCFM
12,000
No
25.7%
14.70
5,000 @ 7.92 psig
200 HP
7,000 @ 7.92 psig
300 HP
EAP
§ T 460 · ª PS RH S * VPS º
SCFM * ¨¨ A
»
¸¸ «
© TS 460 ¹ ¬ PI RH A * VPA ¼
PS ­
°§ Ti
®¨¨
°© TS
¯
23728.7277
=IF(C38=2,ROUND(D36/2.5,-2),IF(C38=3,ROUND(D36/3.5,-2),IF(C38=4,ROUND(D36/5.5,-2),IF(C38=5,ROUND(D36/7,-2),0))))
172
k
k 1
º ½ k 1
ª
· «§ PDS · k
» °
¸¸ «¨¨ P ¸¸ 1» 1¾ 1
¹ «© BI ¹
°
¼» ¿
¬
4.0 - COST ESTIMATE - SUMMARY
This spreadsheet summarizes the results of the capital cost estimate in spreadsheets 4.1 - 4.7
Item
Demolition
Blowers
Diffusers
StructuralBlowerBuilding
MechanicalPiping
Instrumentation
Electrical
ECMNo.1
ECMNo.2
ECMNo.3
$52,271
$52,271
$52,271
#VALUE!
$748,750
$748,750
$432,000
$432,000
$432,000
$76,481
$76,481
$76,481
$334,214
$334,214
$334,214
$69,000
$69,000
$319,125
$155,387
$207,348
$155,387
Comments/Source
Spreadsheet8.1
Spreadsheet8.2
Spreadsheet8.3
Spreadsheet8.4
Spreadsheet8.5
Spreadsheet8.6
Spreadsheet8.7
SubTotal1
#VALUE!
$1,868,103
$2,170,189
ContractorOH&P
Mobilization/Demobilization
#VALUE!
#VALUE!
$280,215
$93,405
Subtotal2
#VALUE!
$2,241,724
PerformanceBond
Insurance
Permits
#VALUE!
#VALUE!
#VALUE!
$22,417
$11,209
$22,417
Subtotal3
#VALUE!
$2,297,767
Contingency
EngineeringFee(designand
constructionadministration
basedonsubtotal1)
#VALUE!
$229,777
$266,933 10%012116.50PreliminaryWorkingDrawingStage
#VALUE!
$280,215
$325,528 15%Basedonprevailingrates
GrandTotal
AACEClass4LowRange(20%)
AACEClass4HiRange(+30%)
#VALUE!
#VALUE!
#VALUE!
$2,807,759
$2,250,000
$3,650,000
$325,528 15%Basedonprevailingrates
$108,509 5%Basedonprevailingrates
$2,604,226
$26,042 1%
$13,021 0.5%Higherendof013113.30
$26,042 1%Midrange"ruleofthumb",014126.50
$2,669,332
$3,261,794
$2,610,000
$4,240,000
173
174
300 lf
300 lf
BlowerconduitandcablefMCCto
Blower
Demolish500MCMcable
Demolish1#1/0cable
260505.101990
160505.101910
LF
LF
LF
LF
LF
59.5 TON
3 EA
$0.49
$0.24
$1.62
$1.96
$0.65
$0.69
$0.12
$585.00
$4.25
$2.13
$0.14
470 CF
59.5 CY
59.5 CY
$7.45
$0.75
$8.75
$0.88
LF
LF
SF
SF
120
120
672
672
$218.00
$500.00
9 EA
4.5 TONS
9 EA
$1.87
Labor
2300 LF
6.4 TONS
$95.00
Material
$19.20
$15.10
MO
UNIT
200 LF
250 LF
1000
1000
2000
2000
2000
2
QUANTITY
DemolishRGSConduit,1/2"1"
DemolishRGSConduit,11/4"2"
Demolisharmoredcable,2#12
Demolisharmoredcable,3#14
Demolishcable,#6GND
Aerationbasinconduitonbasinsand
cablefMCCs
BLOWERSHELTER
Footings,Concrete,1'6"thick,2'wide
AverageReinforcing,add10%
Concrete,plainconcrete,8"thick
AverageReinforcing,add10%
Smallbldgs,concrete,incl20mihaul,no
foundationordumpfees
SelectiveDemolition,DisposalOnly,
loadingand5mihaultodump
Add50%for20mihaul
SelectiveDemolition,DumpCharges,
tippingfeesonly,(assumCY=TON)
Demolish200HPMotorandelectrical
Demolish100HPMotorandelectrical
DEMOLITION
#VALUE!
PIPING
Piping,metal24"26"dia.
Piping,metal16"20"dia.
Plasticpipew/fittings,2"3"dia.
(diffusers)
DIPpipeweight
MECHANICALAERATOR
RemoveMechAerator
MechanicalAeratorWeightX9
DESCRIPTION
260505.100100
260505.100120
260505.100300
260505.100290
260505.101870
024119.190100
260505.251090
024119.180300
024116.130600
024116.171080
024116.171200
024116.172420
024116.172600
260505.251070
220505.102162
220505.102155
220505.102153
KellyTractorQuote
SOURCE
4.1 - COST ESTIMATE - DEMOLITION
$5.20
$2.60
$0.17
$4.34
$0.43
$1.37
$0.14
$1.02
$0.80
Equip
ECMNo.1
ECMNo.2
ECMNo.3
$0.34
$0.17
$1.13
$1.37
$0.45
$0.48
$0.08
$91.58
$408.92
$8.17
$4.09
$0.27
$9.55
$0.95
$7.49
$0.75
$152.38
$349.50
$1.31
$0.00
$14.44
$11.35
$10,000.00
TotalUnit
Sum
$52,271
$52,271
$52,271
$103
$50
$1,132
$1,370
$909
$965
$168
$5,448
$1,227
$486
$243
$126
$1,146
$115
$5,031
$503
$1,371
$3,146
$0
$3,006
$2,888
$2,839
$20,000
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
WPBCity
MatIndex
0.964
WPBCity
1 Labor Index
0.699
1
1
TOTAL ECMNo.
175
Source
Source
EPA
EPA
EPA
EPA
Rohrbacher,et.al
EPA
Rohrbacher,et.al
EPA
EPA
Rohrbacher,et.al
Rohrbacher,et.al
Rohrbacher,et.al
Rohrbacher,et.al
Rohrbacher,et.al
Rohrbacher,et.al
MULTI_STAGECENTRIFUGALCOSTS
HP
Budget$
200
$98,000 H&S
250
$90,000 H&S
300
$153,000 H&S
300
$72,000 H&S
300
$104,000 H&S
350
$110,000 H&S
400
$135,000 H&S
400
$88,000 H&S
500
$245,000 H&S
500
$170,000 H&S
500
$190,000 H&S
Budget$
$56,000
$102,000
$75,000
$115,000
$93,000
$120,000
$134,000
$120,000
$160,000
$86,000
$90,000
$93,000
$124,000
$128,000
$176,000
$202,000
$112,000
$110,000
$110,000
Average
$98,000
$90,000
$122,000
$127,000
$104,000
$75,000
$79,000
Average
HP
250
250
250
250
250
300
300
300
300
300
300
300
300
400
400
400
500
$110,000
$98,000
Material
COMPARABLEMULTISTAGECENTRIFUGALCOST
(3)300HPBlowers
3 EA
(1)200HPBlowers
1 EA
UNIT
$159,000
$122,000
QUANTITY
3 EA
1 EA
DESCRIPTION
BLOWERS
(3)300HPBowers
(1)200HPBlower
BlowerCostData
HP
50
50
75
100
100
150
150
200
200
200
200
200
200
200
200
DIVISIONNO
4.2 - COST ESTIMATE - BLOWERS
Budget$
$180,000
$151,000
$165,000
$168,000
$188,000
$175,000
$142,000
$119,000
$119,000
$143,000
$156,000
$208,000
$209,000
$275,000
$132,000
$198,000
$325,000
$27,500
$24,500
$39,750
$30,500
Labor
Source
EPA
Rohrbache
Rohrbache
Rohrbache
Rohrbache
EPA
EPA
Rohrbache
Rohrbache
Rohrbache
Rohrbache
Rohrbache
Rohrbache
EPA
Rohrbache
Rohrbache
EPA
Equip
$748,750
$325,000
$202,000
$159,000
$170,000
Average
$535,000
Sum
ECMNo.1 $535,000
ECMNo.2 $748,750
ECMNo.3 $748,750
Total
$137,500 $412,500
$122,500 $122,500
Total
Ratio
TOTAL ECINo.
$198,750 $596,250
$152,500 $152,500
TotalUnit
1
1
2
2
200
250
300
400
500
1.24
1.89
1.45
1.80
1.61
1.60
176
DIVISIONNO
DESCRIPTION QUANTITY UNIT
DIFFUSERS
Equipment
1 LS
4.3 - COST ESTIMATE - DIFFUSERS
320000
Material
1.35
Factor
TOTAL
432000 $432,000
Sum
ECMNo.1 $432,000
ECMNo.2 $432,000
ECMNo.3 $432,000
TotalUnit
ECINo.
Aquariusquote
177
099113.601600
099123.722880
312316.166070
312323.131900
312323.132200
081163.23
083323.100100
233723.101100
092423.401000
034133.602200
033053.400820
033053.403940
033052.404050
042210.280300
033053.403570
033053.403550
072610.100700
DIVISIONNO
PaintStucco,rough,oilbase,paint2coats,spray
PaintCMUInterior,paint2coats,spray
2260 SF
2260 SF
DESCRIPTION
QUANTITY UNIT
BLOWERBUILDINGCONSTRUCT
PrecastTees,DoubleTees,RoofMembers,Std.
Weight,12"x8'wide,30'span
9 EA
16"x16",Avg.Reinforcing
9.4 CY
Footings,strip,24"x12",reinforced
9.3 CY
Foundationmat,over20C.Y.
42.2 CY
ConcreteBlock,HighStength,3500psi,8"thick
2260 SF
EquipmentPads,6'x6'x8"Thick
5 EA
EquipmentPads,4'x4'x8"Thick
5 EA
PoyethyleneVaporBarrier,Standard,.004"Thick
21.2 100SF
StructuralExcavationforMinorStructures,Sand,3/4
CYBucket
200 CY
DozerBackfill,bulk
100 CY
CompactBackfill,12"lifts
200 CY
StormDoor,ClearAnodicCoating,7'0"x3'wide
2 EA
RollingServiceDoor,10'x10'high
1 EA
HVACLouvers,Standard8"x5"
336 EA
ExteriorStucco,w/bondingagent
83.7 SY
4.4 - COST ESTIMATE - STRUCTURAL
$0
$0
$266
$1,675
$31
$4
$1,575
$455
$133
$197
$3
$157
$67
$3
Material
$0
$0
$6
$0
$1
$48
$490
$15
$7
$138
$610
$86
$106
$4
$129
$61
$8
Labor
$1
$6
$1
$2
$2
$1
$86
$60
$1
$1
$606
$708
Sum
$76,481
ECMNo.1
$1,990
$157
$510
$597
$2,026
$14,181
$776
$15,645
$9,238
$1,839
$11,676
$14,479
$1,283
$569
$200
TOTAL
$0
$0
$10
$2
$3
$299
$2,026
$42
$9
$1,738
$983
$198
$277
$6
$257
$114
$9
Equip otalUnitCo
ECINo.
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
WPBCity WPBCity
MatIndex Labor Index
98.10%
78.10%
178
300 lf
300 lf
BlowerconduitandcablefMCCto
Blower
Demolish500MCMcable
Demolish1#1/0cable
260505.101990
160505.101910
LF
LF
LF
LF
LF
59.5 TON
3 EA
$0.49
$0.24
$1.62
$1.96
$0.65
$0.69
$0.12
$585.00
$4.25
$2.13
$0.14
470 CF
59.5 CY
59.5 CY
$7.45
$0.75
$8.75
$0.88
LF
LF
SF
SF
120
120
672
672
$218.00
$500.00
9 EA
4.5 TONS
9 EA
$1.87
Labor
2300 LF
6.4 TONS
$95.00
Material
$19.20
$15.10
MO
UNIT
200 LF
250 LF
1000
1000
2000
2000
2000
2
QUANTITY
DemolishRGSConduit,1/2"1"
DemolishRGSConduit,11/4"2"
Demolisharmoredcable,2#12
Demolisharmoredcable,3#14
Demolishcable,#6GND
Aerationbasinconduitonbasinsand
cablefMCCs
BLOWERSHELTER
Footings,Concrete,1'6"thick,2'wide
AverageReinforcing,add10%
Concrete,plainconcrete,8"thick
AverageReinforcing,add10%
Smallbldgs,concrete,incl20mihaul,no
foundationordumpfees
SelectiveDemolition,DisposalOnly,
loadingand5mihaultodump
Add50%for20mihaul
SelectiveDemolition,DumpCharges,
tippingfeesonly,(assumCY=TON)
Demolish200HPMotorandelectrical
Demolish100HPMotorandelectrical
DEMOLITION
#VALUE!
PIPING
Piping,metal24"26"dia.
Piping,metal16"20"dia.
Plasticpipew/fittings,2"3"dia.
(diffusers)
DIPpipeweight
MECHANICALAERATOR
RemoveMechAerator
MechanicalAeratorWeightX9
DESCRIPTION
260505.100100
260505.100120
260505.100300
260505.100290
260505.101870
024119.190100
260505.251090
024119.180300
024116.130600
024116.171080
024116.171200
024116.172420
024116.172600
260505.251070
220505.102162
220505.102155
220505.102153
KellyTractorQuote
SOURCE
4.1 - COST ESTIMATE - DEMOLITION
$5.20
$2.60
$0.17
$4.34
$0.43
$1.37
$0.14
$1.02
$0.80
Equip
ECMNo.1
ECMNo.2
ECMNo.3
$0.34
$0.17
$1.13
$1.37
$0.45
$0.48
$0.08
$91.58
$408.92
$8.17
$4.09
$0.27
$9.55
$0.95
$7.49
$0.75
$152.38
$349.50
$1.31
$0.00
$14.44
$11.35
$10,000.00
TotalUnit
Sum
$52,271
$52,271
$52,271
$103
$50
$1,132
$1,370
$909
$965
$168
$5,448
$1,227
$486
$243
$126
$1,146
$115
$5,031
$503
$1,371
$3,146
$0
$3,006
$2,888
$2,839
$20,000
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
WPBCity
MatIndex
0.964
WPBCity
1 Labor Index
0.699
1
1
TOTAL ECMNo.
179
Source
Source
EPA
EPA
EPA
EPA
Rohrbacher,et.al
EPA
Rohrbacher,et.al
EPA
EPA
Rohrbacher,et.al
Rohrbacher,et.al
Rohrbacher,et.al
Rohrbacher,et.al
Rohrbacher,et.al
Rohrbacher,et.al
MULTI_STAGECENTRIFUGALCOSTS
HP
Budget$
200
$98,000 H&S
250
$90,000 H&S
300
$153,000 H&S
300
$72,000 H&S
300
$104,000 H&S
350
$110,000 H&S
400
$135,000 H&S
400
$88,000 H&S
500
$245,000 H&S
500
$170,000 H&S
500
$190,000 H&S
Budget$
$56,000
$102,000
$75,000
$115,000
$93,000
$120,000
$134,000
$120,000
$160,000
$86,000
$90,000
$93,000
$124,000
$128,000
$176,000
$202,000
$112,000
$110,000
$110,000
Average
$98,000
$90,000
$122,000
$127,000
$104,000
$75,000
$79,000
Average
HP
250
250
250
250
250
300
300
300
300
300
300
300
300
400
400
400
500
$110,000
$98,000
Material
COMPARABLEMULTISTAGECENTRIFUGALCOST
(3)300HPBlowers
3 EA
(1)200HPBlowers
1 EA
UNIT
$159,000
$122,000
QUANTITY
3 EA
1 EA
DESCRIPTION
BLOWERS
(3)300HPBowers
(1)200HPBlower
BlowerCostData
HP
50
50
75
100
100
150
150
200
200
200
200
200
200
200
200
DIVISIONNO
4.2 - COST ESTIMATE - BLOWERS
Budget$
$180,000
$151,000
$165,000
$168,000
$188,000
$175,000
$142,000
$119,000
$119,000
$143,000
$156,000
$208,000
$209,000
$275,000
$132,000
$198,000
$325,000
$27,500
$24,500
$39,750
$30,500
Labor
Source
EPA
Rohrbache
Rohrbache
Rohrbache
Rohrbache
EPA
EPA
Rohrbache
Rohrbache
Rohrbache
Rohrbache
Rohrbache
Rohrbache
EPA
Rohrbache
Rohrbache
EPA
Equip
$748,750
$325,000
$202,000
$159,000
$170,000
Average
$535,000
Sum
ECMNo.1 $535,000
ECMNo.2 $748,750
ECMNo.3 $748,750
Total
$137,500 $412,500
$122,500 $122,500
Total
Ratio
TOTAL ECINo.
$198,750 $596,250
$152,500 $152,500
TotalUnit
1
1
2
2
200
250
300
400
500
1.24
1.89
1.45
1.80
1.61
1.60
180
DIVISIONNO
DESCRIPTION QUANTITY UNIT
DIFFUSERS
Equipment
1 LS
4.3 - COST ESTIMATE - DIFFUSERS
320000
Material
1.35
Factor
TOTAL
432000 $432,000
Sum
ECMNo.1 $432,000
ECMNo.2 $432,000
ECMNo.3 $432,000
TotalUnit
ECINo.
Aquariusquote
181
099113.601600
099123.722880
312316.166070
312323.131900
312323.132200
081163.23
083323.100100
233723.101100
092423.401000
034133.602200
033053.400820
033053.403940
033052.404050
042210.280300
033053.403570
033053.403550
072610.100700
DIVISIONNO
PaintStucco,rough,oilbase,paint2coats,spray
PaintCMUInterior,paint2coats,spray
2260 SF
2260 SF
DESCRIPTION
QUANTITY UNIT
BLOWERBUILDINGCONSTRUCT
PrecastTees,DoubleTees,RoofMembers,Std.
Weight,12"x8'wide,30'span
9 EA
16"x16",Avg.Reinforcing
9.4 CY
Footings,strip,24"x12",reinforced
9.3 CY
Foundationmat,over20C.Y.
42.2 CY
ConcreteBlock,HighStength,3500psi,8"thick
2260 SF
EquipmentPads,6'x6'x8"Thick
5 EA
EquipmentPads,4'x4'x8"Thick
5 EA
PoyethyleneVaporBarrier,Standard,.004"Thick
21.2 100SF
StructuralExcavationforMinorStructures,Sand,3/4
CYBucket
200 CY
DozerBackfill,bulk
100 CY
CompactBackfill,12"lifts
200 CY
StormDoor,ClearAnodicCoating,7'0"x3'wide
2 EA
RollingServiceDoor,10'x10'high
1 EA
HVACLouvers,Standard8"x5"
336 EA
ExteriorStucco,w/bondingagent
83.7 SY
4.4 - COST ESTIMATE - STRUCTURAL
$0
$0
$266
$1,675
$31
$4
$1,575
$455
$133
$197
$3
$157
$67
$3
Material
$0
$0
$6
$0
$1
$48
$490
$15
$7
$138
$610
$86
$106
$4
$129
$61
$8
Labor
$1
$6
$1
$2
$2
$1
$86
$60
$1
$1
$606
$708
Sum
$76,481
ECMNo.1
$1,990
$157
$510
$597
$2,026
$14,181
$776
$15,645
$9,238
$1,839
$11,676
$14,479
$1,283
$569
$200
TOTAL
$0
$0
$10
$2
$3
$299
$2,026
$42
$9
$1,738
$983
$198
$277
$6
$257
$114
$9
Equip otalUnitCo
ECINo.
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
WPBCity WPBCity
MatIndex Labor Index
98.10%
78.10%
182
DESCRIPTION
36 EA
500
Adjustedmaterialcostforcarbonover304SSsteelprice,~5:1.
(f/MEPS.comtables).Assumingsupportis50lb,May2010$828per
tonsteel*50/2000=$20.7formaterialx1.5factor=$31formaterial
$174$31+$31*5=$298for304SSsupport
Quantityassumessupportsevery10',18+22*2+7*6=104
Added30%tolaborforconcreteinstallation
8'Tall304SSElevat
298
104 EA
Quotef/Vict
220529.10017HeavyDutyWallSS
2800
3000
900
3246
1000
3000
1500
3232
808
1500
900
400
2500
300
63
80
113
178
222
Material
1500
1000
950
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
FT
FT
FT
FT
FT
UNIT
1 EA
1 EA
9 EA
5
1
1
1
1
2
1
2
1
3
1
1
9
18
180
510
170
130
215
QUANTITY
30"x30"Exp.Coup
24"x24"Exp.Coup
14"DependoLok
2/08FelkerBro 30"x14"Tee
2/08FelkerBro 30"x30"Tee
2/08FelkerBro 30"x24"Red
2/08FelkerBro 30"x30"Elbow
2/08FelkerBro 30"x30"BlindFl
2/08FelkerBro 20"x14"Cross
2/08FelkerBro 30"x20"Red
2/08FelkerBro 24"x24"Elbow
2/08FelkerBro 24"x20"Red
2/08FelkerBro 20"x14"Tee
2/08FelkerBro 20"x14'Red
2/08FelkerBro 14"x14"Elbow
2/08FelkerBro 14'x12"Tee
2/08FelkerBro 12"x12"Elbow
2/08FelkerBro 12"304LSS
2/08FelkerBro 14"304LSS
2/08FelkerBro 20"304LSS
2/08FelkerBro 24"304LSS
2/08FelkerBro 30"304LSS
DIVISIONNO
4.5 - COST ESTIMATE - MECHANICAL PIPING
125
14.3
237.5
700
750
225
811.5
250
750
375
808
202
375
225
100
625
75
15.75
20
28.25
44.5
55.5
Labor
Equip
$32,479
$1,500
$1,000
$10,688
$17,500
$3,750
$1,125
$4,058
$1,250
$7,500
$1,875
$8,080
$1,010
$5,625
$1,125
$500
$28,125
$6,750
$14,175
$51,000
$24,013
$28,925
$59,663
TOTAL
$22,500
Sum
ECMNo.1 $334,214
ECMNo.2 $334,214
ECMNo.3 $334,214
625
312.3
1500
1000
1187.5
3500
3750
1125
4057.5
1250
3750
1875
4040
1010
1875
1125
500
3125
375
78.75
100
141.25
222.5
277.5
Total
ECINo.
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
183
DESCRIPTION
36 EA
500
Adjustedmaterialcostforcarbonover304SSsteelprice,~5:1.
(f/MEPS.comtables).Assumingsupportis50lb,May2010$828per
tonsteel*50/2000=$20.7formaterialx1.5factor=$31formaterial
$174$31+$31*5=$298for304SSsupport
Quantityassumessupportsevery10',18+22*2+7*6=104
Added30%tolaborforconcreteinstallation
8'Tall304SSElevat
298
104 EA
Quotef/Vict
220529.10017HeavyDutyWallSS
2800
3000
900
3246
1000
3000
1500
3232
808
1500
900
400
2500
300
63
80
113
178
222
Material
1500
1000
950
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
FT
FT
FT
FT
FT
UNIT
1 EA
1 EA
9 EA
5
1
1
1
1
2
1
2
1
3
1
1
9
18
180
510
170
130
215
QUANTITY
30"x30"Exp.Coup
24"x24"Exp.Coup
14"DependoLok
2/08FelkerBro 30"x14"Tee
2/08FelkerBro 30"x30"Tee
2/08FelkerBro 30"x24"Red
2/08FelkerBro 30"x30"Elbow
2/08FelkerBro 30"x30"BlindFl
2/08FelkerBro 20"x14"Cross
2/08FelkerBro 30"x20"Red
2/08FelkerBro 24"x24"Elbow
2/08FelkerBro 24"x20"Red
2/08FelkerBro 20"x14"Tee
2/08FelkerBro 20"x14'Red
2/08FelkerBro 14"x14"Elbow
2/08FelkerBro 14'x12"Tee
2/08FelkerBro 12"x12"Elbow
2/08FelkerBro 12"304LSS
2/08FelkerBro 14"304LSS
2/08FelkerBro 20"304LSS
2/08FelkerBro 24"304LSS
2/08FelkerBro 30"304LSS
DIVISIONNO
4.5 - COST ESTIMATE - MECHANICAL PIPING
125
14.3
237.5
700
750
225
811.5
250
750
375
808
202
375
225
100
625
75
15.75
20
28.25
44.5
55.5
Labor
Equip
$32,479
$1,500
$1,000
$10,688
$17,500
$3,750
$1,125
$4,058
$1,250
$7,500
$1,875
$8,080
$1,010
$5,625
$1,125
$500
$28,125
$6,750
$14,175
$51,000
$24,013
$28,925
$59,663
TOTAL
$22,500
Sum
ECMNo.1 $334,214
ECMNo.2 $334,214
ECMNo.3 $334,214
625
312.3
1500
1000
1187.5
3500
3750
1125
4057.5
1250
3750
1875
4040
1010
1875
1125
500
3125
375
78.75
100
141.25
222.5
277.5
Total
ECINo.
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
184
PLCandProgramming
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
ProgrammableLogicController
Software
Training/Calibration/Documents
ProgrammingandTroubleshooting
SpareParts
HMIProgrammingandReports
1
1
1
1
1
1
LS
LS
LS
LS
LS
LS
650
105
9
18
2200
50
6800
1350
1510
800
380
2750
Material
3300
1800
UNIT
9
18
9
9
9
6
9
9
9
HachSC100Controller,((3(2probe
controllers,(3)1probecontrollers)
LDOProbe
115VAirBlastCleaningSystem
PoleMountKit
14"ModulatingBFV
NEMA4Xbox,(1)24V+(1)120V
surgesuppressor,toggleswitch,
wiring
SSUnistrutMount
6
QUANTITY
AlumPipeStandMountw/
sunshield,NEMA4Xbox,(1)24V+
(1)120Vsurgesuppressor,toggle
switch,wiring
DESCRIPTION
DifferentialPressureIndicators(FlowMeter)
14"VenturiFlowElement
5/09PFSQuote
10/08PFSQuote`
PressureIndicatingTransmitter
CCControlsQuoteL.Garcia
9/16/10
AlumPipeStandMountw/sunshield
Amerisponse.com,9/19/10
420maSurgeSuppressor
CCControlsQuoteL.Garcia
9/16/10
ModulatingBFV
6/09DezurikQuote
HachListPrice
HachListPrice
HachListPrice
HachListPrice
CCControlsQuoteL.Garcia
9/16/10
DIVISIONNO
DOProbeandTransmitter
4.6 - COST ESTIMATE - INSTRUMENTATION
50000
3000
10000
15000
10000
50000
162.5
26.25
825
450
550
12.5
1700
337.5
377.5
200
95
687.5
Labor
Equip
$7,312.50
$2,362.50
$37,125.00
$40,500.00
$24,750.00
$562.50
$76,500.00
$10,125.00
$16,987.50
$9,000.00
$4,275.00
$20,625.00
TOTAL
$25,000.00
$1,500.00
$5,000.00
$7,500.00
$5,000.00
$25,000.00
Sum
ECMNo.1
$69,000.00
ECMNo.2
$69,000.00
ECMNo.3 $319,125.00
50000
3000
10000
15000
10000
50000
812.5
131.25
4125
2250
2750
62.5
8500
1687.5
1887.5
1000
475
3437.5
Total
3
3
3
3
3
3
3
3
3
3
3
3
1/3
1/3
1/3
1/3
1/3
1/3
ECINo.
185
4.7 - COST ESTIMATE - ELECTRICAL
DIVISIONNO
DESCRIPTION
QUANTITY UNIT
MotorRelated
D50201452520 MotorInstall,200HP
1 EA
interpolated
MotorInstall,300HP
3 EA
D50201450240 MotorInstall,1HP
1 EA
BuildingInternal
D50251201160 14Receptacles/2,000sf
2117 SF
D50251201280 LightSwitches/4switches
2117 SF
D50202080680 Lighting,FluroescentFixtures
2117 SF
262416.30
Panelboard
1 EA
Wiring
260519.903280 #350XHHW(6per300HP)
900 LF
260519.351400 Terminate#350
18 EA
260519.9033200 #500XHHW(3per200HP)
150 LF
260519.351500 Terminate#500
3 EA
260526.800700 #1GND
350 LF
260519.350750 Terminate#1
7 EA
260519.903140 #1
3540 LF
260519.350750 Terminate#1
18 EA
260519.903120 #2
200 LF
260519.350750 Terminate#2
4 EA
260519.903120 #2
1770 LF
260519.350750 Terminate#2
9 EA
260523.100020 2#12
1770 LF
260523.100030 3#12
1770 LF
260526.800330 #12GND
3540 LF
260519.351630 Terminate#12
63 EA
260523.100300 8#14
200 LF
260526.800320 #14GND
400 LF
260519.351620 Terminate#14
32 EA
260526.800320 #14GND
5310 LF
260519.351620 Terminate#14
27 EA
Conduit
260533.050700 1"Conduit,Alum
500 LF
260533.050700 1"Conduit,Alum
3540 LF
260533.051100 3"Conduit,Alum
450 LF
337719.170800 ConcreteHandholes
2 EA
331719.177000 DuctbankandConduit,[email protected]
50 LF
337119.177830 Concrete(15CY/100LF)
50 LF
337119.177860 Reinforcing(10Lb/LF)
50 LF
ExteriorGrounding/LightningProtection
260526.800130 GroundingRods,copper
8 EA
260526.801000 4/0Grounding
320 LF
264113.130500 AirTerminals
10 EA
264113.132500 AlumCable
270 LF
264113.133000 Arrestor
2 EA
Labor
$1.95
$0.35
$4.88
$605.00
$2.18
$85.00
$3.00
$98.00
$0.87
$35.50
$0.98
$35.50
$0.87
$32.50
$0.87
$32.50
$0.44
$0.49
$0.30
$7.85
$0.74
$0.28
$6.55
$0.28
$6.55
$4.90
$4.90
$8.70
$582.50
$39.25
$0.72
$3.40
$98.00
$1.38
$49.00
$1.40
$49.00
$0.56
$0.10
$2.33
$735.00
$8.45
$51.00
$14.00
$66.00
$1.66
$10.90
$2.74
$10.90
$2.14
$8.65
$2.14
$8.65
$0.18
$0.25
$0.11
$0.58
$0.67
$0.07
$0.43
$0.07
$0.43
$4.30
$4.30
$22.50
$510.00
$171.25
$1.61
$4.00
$92.00
$3.85
$24.50
$0.85
$78.50
$12,500.00 $4,075.00
$18,750.00 $6,112.00
$700.00 $890.00
Material
Equip
$166.79
$4.85
$62.30
$1.93
$115.28
$8.05
$8.05
$28.87
$955.24
$198.65
$2.14
$6.58
$9.99
$116.42
$16.08
$141.28
$2.31
$38.42
$3.45
$38.42
$2.78
$33.87
$2.78
$33.87
$0.52
$0.63
$0.34
$6.70
$1.24
$0.29
$5.54
$0.29
$5.54
$2.07
$0.37
$6.10
$1,193.54
$15,445.08
$23,167.22
$1,381.79
Total
ECMNo.1
ECMNo.2
ECMNo.3
INSTALLATION
$1,334.32
$1,553.48
$623.04
$520.36
$230.56
Sum
$155,387.37
$155,387.37
$207,348.06
$4,022.60
$28,480.01
$12,990.24
$1,910.49
$9,932.53
$107.09
$328.97
$8,992.83
$2,095.49
$2,411.55
$423.85
$807.78
$268.93
$12,224.75
$691.53
$555.76
$135.47
$4,918.49
$304.81
$920.79
$1,111.45
$1,211.42
$422.09
$247.04
$114.94
$177.20
$1,525.83
$149.51
$4,387.08
$786.36
$12,907.37
$1,193.54
1
1
1
1
1
1
3
1
1
1
1
1
1
1
1
1
1
1
3
3
1
1
3
3
3
3
3
3
1
1
1
3
3
1
1
1
1
WPBCity WPBCity
TOTAL ECINo. MatIndexLaborIndex
98.10%
78.10%
$15,445.08
1
$69,501.67
1
$1,381.79
1
15445.08
69501.67
1381.79
186
36.45
ECM
1,2,3
2,3
3
1,2,3
1
20
20
20
20
20
Source
CityofBocaRaton
CityofBocaRaton
1.5%Capitalcost,perRohrbacheret.al
CityofBocaRaton,replace25%ofdiffusersperbasineachyear
Source
Sanitaire,5/minperdiffuser,$6replacementcost,710yearinter
Rohrbacheret.al
Article:"DO"ingmorewithLess,ListPrice:Hach
Rosso,EconomicImplicationsofFinePoreDiffuserAging
1.5%CapitalCost,perRohrbacheret.al
Source
1,2,3
Quotefor200HP+25%installation
1,2,3
RSMeans262419.400600
1,2,3
RSMeans267113.105260+267113.202100
1,2,3
RSMeans262419.400500
1,2,3
6/17/11Quotef/TSCJacobs
Sum
NPV
ECMNo.1 $1,558,926
ECMNo.2 $1,558,926
ECMNo.3 $1,558,926
EquipmentReplacementCostsAvoided
RemainingReplaceme Amount Total
NPV
5 $122,500
3
$367,500 $329,612
5 $21,550
3
$64,650
$57,985
1000
$9,325
9
$83,925
$0
5
$6,425
9
$57,825
$51,863
5 $100,000
9
$1,248,146 $1,119,466
O&MNoLongerNeccesary
O&MItem
Cost
Amount
Annual
NPV
ECM
CollectDOManually
$55
365
$19,956 $320,104
3
ServiceMotors
$1,000
9
$9,000 $144,362
1,2,3
TypicalO&Mbasedon1 $1,500
3
$4,500 $72,181
2,3
ReplaceMembranes
$9
215
$1,943 $31,167
1,2,3
Sum
Sum
Annual
NPV
ECMNo.1
$9,106
$146,056
ECMNo.2
$8,606
$138,036
ECMNo.3
$10,091 $161,857
O&MCosts
Annual
NPV
$11,862 $190,264
$10,000 $160,402
$1,260 $20,211
$2,187 $35,080
$6,000 $96,241
Planning
Period
RealRate
(years)
0.025
0.022
20
CPI
O&MItem
Cost
Amount Unit
ReplaceMembranes
$9.04
10500 EA
ReplaceFilters,Inspectio $2,500
4 EA
ReplaceSensorCaps
$140
9 EA
CleanMembranes
$36
60 HR
TypicalO&Mbasedon1
$1,500
4
0.047
DiscountRate(interest)
Equipment
UsefulLife
200HPMultiStageCentrifu
200HPMotorStarters
100HPElectricMotors
100HPMotorStarters
ReplaceAerators
Equipment
ManualDO
MechDiffuserMotors
MultiStageBlowers
Diffusers
Equipment
Diffusers
Blowers
LDOProbes
Diffusers
MultiStageBlowers
PlantLaborRate
5.0 - O&M COSTS
187
KellyTractorQuote
SOURCE
CRANERENTAL40TONCAPACITY
RemoveMechAerator
MechanicalAeratorWeightX9
NewMechanicalAerators
DESCRIPTION
5.1 - O&M COSTS - REPLACE AERATORS
3
9
4.5
9
QUANTITY
MO
EA
TONS
EA
UNIT
100000
Material
35000
$500.00
Labor
Equip
TOTAL ECMNo. MatIndexLabor Index
0.964
0.699
$30,000
$3,146
$0
135000
$1,215,000
Sum
ECMNo.1
$1,248,145.50
$10,000.00
$349.50
TotalUnit
WPBCity WPBCity
6.0 LIFE-CYCLE COST ANALYSIS INPUTS
Current Bond Rate
Cost per
kwH
0.07
0.047
Power
Factor
0.84
Aerator # Nameplat
e HP
#1
#2
#3
#4
#5
#6
#7
#8
#9
CPI
Inflation
0.025
Real Rate
(interest)
0.022
Energy
Inflation
0.00083
Planning
Period
(years)
20
Total
Current
HP
558.5
If no Amp
Avg
draws,
Basins in
assumed Operation
% of
Nameplat
e
0.85
Avg Low
Speed
Amps
Avg High Months in Avg Amps
Speed low setting
Amps (1)
Avg KW
#1
#2
#3
0.00
0.00
0.00
92.66
100.2
84.66
77.47
76.85
93.71
Avg
Operating
HP
0
121.2
84.6
113.5
0
95.1
66.4
89.0
0
99.2
69.3
92.9
0
105.8
73.9
99.0
0
102.7
71.7
96.1
0
94.0
65.6
87.9
0
81.6
57.0
76.4
0
82.1
57.3
76.8
Avg
0
101.1
70.6
94.6
T t l
Total
883
616
616.4
4
826
826.3
3
(1)Databasedontypical3year24hraverageobtainedfromCityofBocaRatonfor20092011
Blower #
100
100
100
100
100
100
100
100
100
2
Nameplat Factor(2)
e HP
100
100
100
0.09
0
0
Adjusted
HP
7.65
(2)Factorbasedononebloweroperating4hoursperday,3monthsoutofyear
OperatingHP/NameplateHP
0.92
Zone1Avg Zone2Avg Zone3Avg
96.3
87.3
91.8
188
91.8
189
6.1.1 LIFE-CYCLE COST ANALYSIS
0%
21%
26%
47%
37%
26%
48
76
91
0
118
145
261
209
143
Current Treatment - 0.5 mg/L
Partial Nitrification - 3.0 mg/L
Complete NOx
2. Turbo Blowers
Current Treatment - 0.5 mg/L
3. Auto DO Control Partial Nitrification - 1.5 mg/L
1.5 mg/L
Complete NOx
Current Treatment - 0.5 mg/L
Total (Cumulative) Partial Nitrification - 1.5 mg/L
Complete NOx
$119,517
$95,404
$65,235
$0
$54,179
$66,534
$21,929
$34,557
$41,416
$97,588
$6,668
($42,714)
Ann. Energy
Cost Savings
1,541,011
1,541,011
1,541,011
11.98
#VALUE!
#VALUE!
#VALUE!
#VALUE!
#VALUE!
#VALUE!
$ 154,141
$ 154,141
$ 154,141
15.58
19.99
31.18
6.76
5.72
17.26
10.30
8.46
Payback
Capital and
O&M NPV
($1,931,113) $
($1,541,495) $
($1,054,043) $
$0
($875,399)
($1,075,026)
($354,324)
($558,359)
($669,178)
($1,576,789)
($107,737)
$690,161
Energy
Savings NPV
558
558
558
Current Treatment - 0.5 mg/L
3. Auto DO Control Partial Nitrification - 1.5 mg/L
1.5 mg/L
Complete NOx
297
350
416
47%
37%
26%
38%
3%
-17%
47%
16%
-1%
$119,517
$95,404
$65,235
$97,588
$6,668
($42,714)
$119,517
$41,225
($1,299)
Annual
Savings $
($1,931,113)
($1,541,495)
($1,054,043)
($1,576,789)
($107,737)
$690,161
($1,931,113)
($666,096)
$20,983
Estimate turbo blower efficiency gain by assuming 72% efficiency with turbo blowers at 3 mg/L average DO.
Estimate auto DO control efficiency gain by assuming 1.5 mg/L.
2. Turbo Blowers
3. Automatic DO
Control (2 mg/L)
4. Most Open Valve Estimate MOV efficiency by modeling diurnal hourly airflow requirements vs. pressure setpoint.
Blower Control vs/
Pressure Setpoint
Estimate fine bubble efficiency gain assuming plant operators will conservatively maintain DO at average of 3 mg/L
This option assumes conventional multi-stage centrifugal blowers at 62% avg. efficiency.
1. Fine Bubble
Diffusers
$ 9,106
$ 9,106
$ 9,106
$ 8,606
$ 8,606
$ 8,606
$ (10,091)
$ (10,091)
$ (10,091)
Energy Savings Annual Change
NPV
O&M
Description of Assumptions Technologies - All efficiency and DO values are supported by data compliled in the manuscript.
2. Turbo Blowers
1. Fine Bubble
Diffusers
345
544
652
297
468
561
Current HP Proposed Annual Savings
HP
%
558
558
558
558
558
558
Level of Treatment
Current Treatment - 0.5 mg/L
Partial Nitrification - 3.0 mg/L
Complete NOx
Current Treatment - 0.5 mg/L
Partial Nitrification - 3.0 mg/L
Complete NOx
Technology
TABLE 2 - CUMULATIVE GAIN (each proceeding improvement is accumulative of the previous listed)
$146,056
$146,056
$146,056
$138,036
$138,036
$138,036
$(161,857)
$(161,857)
$(161,857)
Change O&M
NPV
0.07
Current Cost per
kwH
* Current treatment indicates energy improvement realized by treating to partial nitrification at 0.5 mg/L, which is the plants current level of treatment
9%
14%
16%
38%
3%
-17%
213
15
-93
Current Treatment - 0.5 mg/L
Partial Nitrification - 3.0 mg/L
Complete NOx
1. Fine Bubble
Diffusers
% Eff.
Gain
HP
Reduction
Level of Treatment
Technology
TABLE 1 - INCREMENTAL GAIN
This spreadsheet summarizes the results of the life cycle cost analyses.
0.025
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
#VALUE!
#VALUE!
#VALUE!
$2,807,759
$2,807,759
$2,807,759
$3,261,794
$3,261,794
$3,261,794
#VALUE!
#VALUE!
#VALUE!
$ 1,386,870
$ 1,386,870
$ 1,386,870
$ 1,541,011
$ 1,541,011
$ 1,541,011
Capital and
O&M NPV
0.022
15.58
19.99
31.18
13.00
78.24
11.98
Payback
Planning
Period
(years)
0.00083
20
Global Cost Calculation Parameters
CPI Inflation Real Rate
Energy
(interest)
Inflation
Foregone Capital Capital Cost
Replacement
0.047
Bond Rate
190
6.1.2 LIFE-CYCLE COST ANALYSIS (LOW RANGE)
47%
37%
26%
0
118
145
261
209
143
Current Treatment - 0.5 mg/L
3. Auto DO Control Partial Nitrification - 1.5 mg/L
1.5 mg/L
Complete NOx
Total (Cumulative) Partial Nitrification - 1.5 mg/L
9%
14%
16%
$119,517
$95,404
$65,235
$0
$54,179
$66,534
$21,929
$34,557
$41,416
$97,588
$6,668
($42,714)
Ann. Energy
Cost Savings
889,217
889,217
889,217
5.20
#VALUE!
#VALUE!
#VALUE!
#VALUE!
#VALUE!
#VALUE!
$60,107
$60,107
$60,107
9.00
11.32
16.74
5.28
4.48
13.45
8.16
6.73
Payback
Capital and
O&M NPV
($1,931,113) $
($1,541,495) $
($1,054,043) $
$0
($875,399)
($1,075,026)
($354,324)
($558,359)
($669,178)
($1,576,789)
($107,737)
$690,161
Energy
Savings NPV
558
558
558
Current Treatment - 0.5 mg/L
3. Auto DO Control Partial Nitrification - 1.5 mg/L
1.5 mg/L
Complete NOx
297
350
416
47%
37%
26%
38%
3%
-17%
47%
16%
-1%
$119,517
$95,404
$65,235
$97,588
$6,668
($42,714)
$119,517
$41,225
($1 299)
($1,299)
($1,931,113)
($1,541,495)
($1,054,043)
($1,576,789)
($107,737)
$690,161
($1,931,113)
($666,096)
$20 983
$20,983
Estimate auto DO control efficiency gain by assuming 1.5 mg/L.
3. Automatic DO
Control (2 mg/L)
Estimate MOV efficiency by modeling diurnal hourly airflow requirements vs. pressure setpoint.
Estimate turbo blower efficiency gain by assuming 72% efficiency with turbo blowers at 3 mg/L average DO.
2. Turbo Blowers
4. Most Open Valve
Blower Control vs/
Pressure Setpoint
Estimate fine bubble efficiency gain assuming plant operators will conservatively maintain DO at average of 3 mg/L
This option assumes conventional multi-stage centrifugal blowers at 62% avg. efficiency.
1. Fine Bubble
Diffusers
$ 9,106
$ 9,106
$ 9,106
$ 8,606
$ 8,606
$
$
8 606
8,606
$(10,091)
$(10,091)
$(10,091)
Annual Savings Annual Savings Energy Savings Annual Change
$
NPV
O&M
%
Description of Assumptions Technologies - All efficiency and DO values are supported by data compliled in the manuscript.
2. Turbo Blowers
1. Fine Bubble
Diffusers
345
544
652
297
468
561
Current HP Proposed
HP
558
558
558
558
558
558
Level of Treatment
Current Treatment - 0.5 mg/L
Partial Nitrification - 3.0 mg/L
Complete NOx
Current Treatment - 0.5 mg/L
Partial Nitrification - 3.0 mg/L
Complete NOx
Technology
TABLE 2 - CUMULATIVE GAIN (each proceeding improvement is accumulative of the previous listed)
$146,056
$146,056
$146,056
$138,036
$138,036
$
$
138 036
138,036
$(161,857)
$(161,857)
$(161,857)
Change O&M
NPV
0.07
Current Cost per
kwH
* Current treatment indicates energy improvement realized by treating to partial nitrification at 0.5 mg/L, which is the plants current level of treatment
Complete NOx
Current Treatment - 0.5 mg/L
0%
21%
26%
48
76
91
Current Treatment - 0.5 mg/L
Partial Nitrification - 3.0 mg/L
Complete NOx
2. Turbo Blowers
38%
3%
-17%
213
15
-93
Current Treatment - 0.5 mg/L
Partial Nitrification - 3.0 mg/L
Complete NOx
1. Fine Bubble
Diffusers
% Eff.
Gain
HP
Reduction
Level of Treatment
Technology
TABLE 1 - INCREMENTAL GAIN
This spreadsheet summarizes the results of the life cycle cost analyses.
0.025
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
$
$
(1 558 926)
(1,558,926)
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
#VALUE!
#VALUE!
#VALUE!
$2,250,000
$2,250,000
$2 250 000
$2,250,000
$2,610,000
$2,610,000
$2,610,000
#VALUE!
#VALUE!
#VALUE!
$ 829,111
$ 829,111
$ 829,111
$
829 111
$ 889,217
$ 889,217
$ 889,217
Capital and
O&M NPV
0.022
11.32
16.74
6.76
28.33
5.20
Payback
Planning
Period
(years)
0.00083
20
Global Cost Calculation Parameters
CPI Inflation
Real Rate
Energy
(interest)
Inflation
Foregone Capital Capital Cost
Replacement
0.047
Bond Rate
191
6.1.3 LIFE-CYCLE COST ANALYSIS (HIGH RANGE)
47%
37%
26%
0
118
145
261
209
143
Current Treatment - 0.5 mg/L
3. Auto DO Control Partial Nitrification - 1.5 mg/L
1.5 mg/L
Complete NOx
Total (Cumulative) Partial Nitrification - 1.5 mg/L
9%
14%
16%
$119,517
$95,404
$65,235
$0
$54,179
$66,534
$21,929
$34,557
$41,416
$97,588
$6,668
($42,714)
Ann. Energy
Cost Savings
2,519,217
2,519,217
2,519,217
24.36
#VALUE!
#VALUE!
#VALUE!
#VALUE!
#VALUE!
#VALUE!
$ 290,107
$ 290,107
$ 290,107
27.55
36.96
67.30
8.99
7.57
24.13
13.98
11.39
Payback
Capital and
O&M NPV
($1,931,113) $
($1,541,495) $
($1,054,043) $
$0
($875,399)
($1,075,026)
($354,324)
($558,359)
($669,178)
($1,576,789)
($107,737)
$690,161
Energy
Savings NPV
558
558
558
Current Treatment - 0.5 mg/L
3. Auto DO Control Partial Nitrification - 1.5 mg/L
1.5 mg/L
Complete NOx
297
350
416
47%
37%
26%
38%
3%
-17%
47%
16%
-1%
$119,517
$95,404
$65,235
$97,588
$6,668
($42,714)
$119,517
$41,225
($1 299)
($1,299)
($1,931,113)
($1,541,495)
($1,054,043)
($1,576,789)
($107,737)
$690,161
($1,931,113)
($666,096)
$20 983
$20,983
Estimate auto DO control efficiency gain by assuming 1.5 mg/L.
3. Automatic DO
Control (2 mg/L)
Estimate MOV efficiency by modeling diurnal hourly airflow requirements vs. pressure setpoint.
Estimate turbo blower efficiency gain by assuming 72% efficiency with turbo blowers at 3 mg/L average DO.
2. Turbo Blowers
4. Most Open Valve
Blower Control vs/
Pressure Setpoint
Estimate fine bubble efficiency gain assuming plant operators will conservatively maintain DO at average of 3 mg/L
This option assumes conventional multi-stage centrifugal blowers at 62% avg. efficiency.
1. Fine Bubble
Diffusers
$ 9,106
$ 9,106
$ 9,106
$ 8,606
$ 8,606
$
$
8 606
8,606
$(10,091)
$(10,091)
$(10,091)
Annual Savings Annual Savings Energy Savings Annual Change
$
NPV
O&M
%
Description of Assumptions Technologies - All efficiency and DO values are supported by data compliled in the manuscript.
2. Turbo Blowers
1. Fine Bubble
Diffusers
345
544
652
297
468
561
Current HP Proposed
HP
558
558
558
558
558
558
Level of Treatment
Current Treatment - 0.5 mg/L
Partial Nitrification - 3.0 mg/L
Complete NOx
Current Treatment - 0.5 mg/L
Partial Nitrification - 3.0 mg/L
Complete NOx
Technology
TABLE 2 - CUMULATIVE GAIN (each proceeding improvement is accumulative of the previous listed)
$146,056
$146,056
$146,056
$138,036
$138,036
$
$
138 036
138,036
$(161,857)
$(161,857)
$(161,857)
Change O&M
NPV
0.07
Current Cost per
kwH
* Current treatment indicates energy improvement realized by treating to partial nitrification at 0.5 mg/L, which is the plants current level of treatment
Complete NOx
Current Treatment - 0.5 mg/L
0%
21%
26%
48
76
91
Current Treatment - 0.5 mg/L
Partial Nitrification - 3.0 mg/L
Complete NOx
2. Turbo Blowers
38%
3%
-17%
213
15
-93
Current Treatment - 0.5 mg/L
Partial Nitrification - 3.0 mg/L
Complete NOx
1. Fine Bubble
Diffusers
% Eff.
Gain
HP
Reduction
Level of Treatment
Technology
TABLE 1 - INCREMENTAL GAIN
This spreadsheet summarizes the results of the life cycle cost analyses.
0.025
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
$
$
(1 558 926)
(1,558,926)
$ (1,558,926)
$ (1,558,926)
$ (1,558,926)
#VALUE!
#VALUE!
#VALUE!
$3,650,000
$3,650,000
$3 650 000
$3,650,000
$4,240,000
$4,240,000
$4,240,000
#VALUE!
#VALUE!
#VALUE!
$ 2,229,111
$ 2,229,111
$ 2,229,111
$
2 229 111
$ 2,519,217
$ 2,519,217
$ 2,519,217
Capital and
O&M NPV
0.022
36.96
67.30
24.31
24.36
Payback
Planning
Period
(years)
0.00083
20
Global Cost Calculation Parameters
CPI Inflation
Real Rate
Energy
(interest)
Inflation
Foregone Capital Capital Cost
Replacement
0.047
Bond Rate
192
Total (Cumulative)
MWs
47%
37%
26%
Current Treatment - 0.5 mg/L DO
Par. Nitrification - 1.5 mg/L DO
Complete Nitrification
0%
Current Treatment - 0.5 mg/L DO
21%
26%
9%
14%
16%
Current Treatment - 0.5 mg/L DO
Part. Nitrification - 3.0 mg/L DO
Complete Nitrification
2. Turbo Blowers
Part. Nitrification - 1.5 mg/L DO
Complete Nitrification
38%
3%
-17%
Current Treatment - 0.5 mg/L DO
Part. Nitrification - 3.0 mg/L DO
Complete Nitrification
1. Fine Bubble Diffusers
3. Auto DO Control - 1.5 mg/L
% Eff. Gain
Level of Treatment
Technology
6.2 LIFE-CYCLE COST ANALYSIS SUMMARY
4,678
3,734
2,553
2,120
2,604
0
858
1,353
1,621
3,819
261
-1,672
0.16
Avg. Daily
Energy Savings
(kwH)
$119,517
$95,404
$65,235
$54,179
$66,534
$0
$21,929
$34,557
$41,416
$97,588
$6,668
($42,714)
Ann. Energy
Cost Savings
($)
9
11
17
5
4
-
13
8
7
5
-
Payback (Low
Estimate)
(Years)
16
20
31
7
6
-
17
10
8
28
37
67
9
8
-
24
14
11
Payback Payback (High
(Median
Estimate)
Estimate)
(Years)
(Years)
12
24
-
APPENDIX B-1 – BROWARD CO. N. REGIONAL WWTP PRELIMINARY DESIGN DRAWINGS
193
194
195
196
197
198
APPENDIX B-2 – BROWARD CO. N. REGIONAL WWTP DATA SPREADSHEETS
199
BROWARD COUNTY NORTH REGIONAL WWTP - ENERGY EFFICIENCY ANALYSIS SPREA
SPREADSHEET TABLE OF CONTENTS
1.1 INFLUENT EFFLUENT SPECIFIER
1.2FLOWPROJECTION
2.0 AERATION CALCULATIONS - GLOBAL PARAMETERS
2.1 AERATION CALCULATIONS - DIFFUSERS
2.2 AERATION CALCULATIONS - TURBO BLOWERS
2.3 AERATION CALCULATIONS - 1.5 MG/L DO CONTROL
3.1 SYSTEM DESIGN - SIZE PIPES - TRAIN 1
3.2 SYSTEM DESIGN - ESTIMATE LOSSES THROUGH PIPES
3.3 SYSTEM DESIGN - SYSTEM CURVE
3.4 SYSTEM DESIGN - BLOWER DESIGN
4.0 - COST ESTIMATE - SUMMARY
4.1 - COST ESTIMATE - DEMOLITION
4.2 - COST ESTIMATE - BLOWERS
4.3 - COST ESTIMATE - DIFFUSERS
4.4 - COST ESTIMATE - STRUCTURAL
4.5 - COST ESTIMATE - MECHANICAL PIPING
4.6 - COST ESTIMATE - INSTRUMENTATION
4.7 - COST ESTIMATE - ELECTRICAL
5.0 - O&M COSTS
5.1 - O&M COSTS - REPLACE AERATORS
6.0LIFECYCLECOSTANALYSISINPUTS
6.1.1 LIFE-CYCLE COST ANALYSIS
6.1.2 LIFE-CYCLE COST ANALYSIS (LOW RANGE)
6.1.3LIFECYCLECOSTANALYSIS(HIGHRANGE)
6.2 LIFE-CYCLE COST ANALYSIS SUMMARY
EricStanleyThesis2/19/2012Pg1of29
200
201
1.1 INFLUENT EFFLUENT SPECIFIER
Min Day
ADF
MMADF
Max Day
Min Day
ADF
MMADF
Max Day
Min Day
ADF
MMADF
Max Day
INF TSS
LBS
10522
71891
126168
733683
INF TSS
LBS
11800
80624
141495
822813
EFF CBOD EFF WAS VS
LBS.
LBS
572
1634
1793
38731
2964
58950
7638
147726
Calculated
EFF CBOD EFF WAS VS
LBS.
LBS
510
1457
1599
34536
2643
52564
6810
131724
INF TKN
EFF NH3
LBS
LBS.
5279
1134
11729
3665
15628
6122
17401
9480
INF TKN
EFF NH3
LBS
LBS.
4707
1011
10458
3268
13935
5459
15516
8453
Avg
DO
mg/L
1.0
INF FLOW INF CBOD
MGD
LBS
16.12
2262
42.20
53605
50.08
81589
64.33
204458
INF TSS
LBS
11935
81548
143116
832238
EFF CBOD EFF WAS VS
LBS.
LBS
579
1653
1814
39175
2998
59625
7725
149418
INF TKN
EFF NH3
LBS
LBS.
5339
1147
11863
3707
15807
6192
17600
9588
2004 - 2006 3 Year Average - Adjusted to Design Flow of 95 MGD (assumes 2 basins in Module D online)
INF FLOW INF CBOD
MGD
LBS
15.94
2236
41.72
52998
49.52
80665
63.61
202143
2004 - 2006 Adjusted to 2011 - 2031 ADF
INF FLOW INF CBOD
MGD
LBS
14.21
1994
37.20
47257
44.15
71927
56.72
180246
2004 - 2006
This spreadsheet summarizes the values gleaned from available historical monitoring data at the WWTP
Values from this spreadsheet are inserted directly into Spreadsheets 2.1 - 2.3.
Avg
Dold, 2007
SRT
Days
Yield
3.7
0.63
1.2 FLOW PROJECTION
Flow
2011(MGD) 2031 Avg
77.95 83.44419
78.4
78.85
90
79.3
79.75
88
80.626
81.502
86
82.378
83.254
84
84.13
84.376
82
84.622
80
84.868
85.114
78
85.36
85.8
76
86.3
2010
86.8
87.3
88
88
Flow Projection
Capita
Year
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2015
2020
2025
Year
Source: North Broward WWTP 2011 Capacity Analysis Report to FDEP
202
2030
2035
2.0 AERATION CALCULATIONS - GLOBAL PARAMETERS
Spreadsheet 2.1 - 2.3 calculates the amount of air and horsepower needed to treat various flowrates and loading rates throughout the plant.
2.0 Aeration Calculations - Global Paramters spreadsheet specifies the global variables input to spreadsheets 2.1 - 2.3
AreaunderAerationperBasin(ft2)=
#ofbasinsonline=
SidewaterDepth(ft)=
DiffuserSubmergence(ft)=
EquationForSystemCurve
NumberofDiffusersperBasin=
SiteElevation(ftaboveMSL)=
MinimumMixRequirements(scfm/ft2)
MinimumFlowperDiffuser(scfm)
MaximumFlowperDiffuser(scfm)
GeneralTemperature
Beta(unitless)=
Patm(psi)=
Patm(middepth,ftwc/2/2.31psi,psi)=
Csth(perAppDformechaer,mg/L)=
Cs20([email protected],1atm,mg/L)=
CstH*(mg/L)=
DensAir(lb/cf)=
MassFractionO2inair=
Alpha=
Alphaforcompletenitrification=
AverageofminimumSOTE
16875
ManualDOControlO2Concentration
7.2
AutoDOControlO2Concentration
15.5
MSCBlowerEfficiency
14.5
TurboBlowerEfficiency
ableO2ConcentrationatMaxDay
5.87E10 *x^2
2500
PreECMExistingDOConcentration
10
0.12
0.5
Doldyield,assume5days
3.0
25
0.98
Fup
14.7
VSS/TSS
3.14
8.24
9.08
10.00
0.0750
0.2315
0.43
0.5
a
3
1.5
0.62
0.72
0.5
1
0.59 Nitrifying
0.13 BiowindefaultforRaw
0.85
Tau vs. Temperature
Tau
0
5
10
15
20
25
30
35
40
Figure 2.10 & Sanitaire
1.6
Tau (dimensionless)
Temp.
1.6
1.4
1.24
1.12
1
0.91
0.83
0.77
0.71
1.2
y = 4.08E-04x2 - 3.82E-02x + 1.60E+00
R² = 9.98E-01
0.8
0.4
0
5
10
15
20
25
30
35
40
Temperature (C)
0.59
0.88
1.00
1.18
1.47
1.75
2.06
2.35
2.50
2.65
2.94
3.00
46.83
42.50
41.26
39.89
38.48
38.33
37.52
37.21
37.07
36.87
36.69
36.66
Air
Average
Flow
SOTE
(SCFM/Unit
(%)
0.59
0.88
1.00
1.18
1.47
1.75
2.06
2.35
2.50
2.65
2.94
3.00
40.58
36.83
35.75
34.56
33.34
33.21
32.51
32.24
32.12
31.95
31.79
31.77
Submergence = 20.00-ft
Minimum Average Minimum
SOTE
SOTE
SOTE
(%)
(%/ft)
(%/ft)
41.25
37.98
37.37
36.95
35.92
35.90
35.39
35.35
35.20
35.18
35.01
35.00
2.34
2.13
2.06
1.99
1.92
1.92
1.88
1.86
1.85
1.84
1.83
1.83
2.06
1.90
1.87
1.85
1.80
1.80
1.77
1.77
1.76
1.76
1.75
1.75
Submergence = 17.33-ft
Minimum Average Minimum
SOTE
SOTE
SOTE
(%)
(%/ft)
(%/ft)
35.74
32.91
32.38
32.02
31.12
31.11
30.67
30.63
30.57
30.48
30.34
30.33
2.34
2.13
2.06
1.99
1.92
1.92
1.88
1.86
1.85
1.84
1.83
1.83
2.06
1.90
1.87
1.85
1.80
1.80
1.77
1.77
1.76
1.76
1.75
1.75
Results from trendline in chart
Constantsforthefollowingformula:ax4+bx3+cx2+dx+e
Avg SOTE
Avg SOTE
Avg SOTE
Avg SOTE
Avg SOTE
Min SOTE
Min SOTE
Min SOTE
Min SOTE
Min SOTE
2.50
SOTE%/footofdiffusersubmergence
Air
Average
Flow
SOTE
(SCFM/Unit
(%)
2.40
2.30
2.20
2.10
0.0514
0.4603
SOTEvs.SCFM/diffuser
1.5405
Sanitaire SilverSeriesII9"MembraneDiscDiffuser
2.3473
3.2779
0.0467
0.4015
1.2724
1.7984
2.7526
AverageSOTE
Min.SOTE
Poly.(AverageSOTE)
Poly.(Min.SOTE)
y=0.0514x4 0.4603x3 +1.5405x2 2.3473x+3.2779
R²=0.9987
2.00
1.90
1.80
y=0.0467x4 0.4015x3 +1.2724x2 1.7984x+2.7526
R²=0.9944
1.70
1.60
1.50
0.00
0.50
1.00
1.50
2.00
SCFM/Diffuser
203
2.50
3.00
3.50
204
2.1 AERATION CALCULATIONS - DIFFUSERS
Cur Treat
ADF
ADF + Nit
0.90
0.42
172,953
6,918
18,000
18
000
1.36
1.36
0.00
28.33%
24421
4.SORCalculations
Tau=
Eq555
AOR/SOR={[(Beta*CstH*CL)/Cs20][1.024^(
SOR=
5.AerationDemandCalculations
Airrequiredat100%Efficiency=
Total Number of Diffusers =
TotalNumberofDiffusers=
DiffuserFlow,scfm/diffuser(macroinput)=
DiffuserFlow,scfm/diffuser=
Difference=
SOTEatDesSubmandDiffFlow=
SCFM=SOTR/(SOTE*60min/hr*24hr/day
9,295
18,000
18
000
1.88
1.88
0.00
27.45%
33860
0.90
0.31
232,394
4,485
72,108
10,198
18,000
18
000
2.08
2.08
0.00
27.27%
37404
0.90
0.36
254,979
8,271
91,995
2,344
18,000
18
000
0.34
0.34
0.00
38.28%
6124
0.90
0.31
58,611
3,661
18,186
Current
14.21
7.2
1,994
510
295
4,707
1,011
3
25
0.43
a
Min Day
MinimumMixingAirflowRequirement(scfm)
MinimumMixingRequirementMet?
IsDiffuserFlowWithinRange?
AllEquationsreferenced,(Metcalf&Eddy,2003)
7. Checks
14580
TRUE
TRUE
14580
TRUE
TRUE
14580
TRUE
TRUE
14580
FALSE
FALSE
6.PowerDemandCalculations
Pw=[(W*R*T1)/(550*n*Eff)]*[(P2/P1)^.2831]
Pw(blowerhorsepowerrequired)=
1119
1610
1808
270
DynamicLosses
0.35
0.67
0.82
0.02
WiretoAirEff=
0.62
0.62
0.62
0.62
e=100%*((P1+14.7)/14.7)0.2831)/1(P2+14.7)/14.7)0.2831)/2)/((P1+14.7)/14.7)0.2831)/2
4,485
72,108
1131ADF 1131ADF 1131ADF
41.72
41.72
41.72
7.2
7.2
7.2
52,998
52,998
52,998
1,793
1,793
1,793
29,822
29,822
27,363
11,729
11,729
11,729
3,665
3,665
174
1
3
3
25
25
25
0.43
0.43
0.5
a
a
a
3.AORCalculations
Eq.818 TKNinfNH3eff0.12(PxBio)=NOx=
Eq.817 1.6*1.16*(SoS)1.42(PxBio)+4.33(NOx)=AO
MGD
NumberofBasinsOnline
So=CBODinf
S=CBODeff
Eq.815(wherehilighted),PxBio=
TKN=
NH3eff=
CL(operat.oxygenconcentration,mg/L)=
T(degC)
Alpha=
AverageofminimumSOTE
2.Inputs
Assumes multi-stage centrifugal blowers at 62% efficiency.
14580
FALSE
FALSE
316
0.03
0.62
2,659
18,000
18
000
0.40
0.40
0.00
37.12%
7164
0.90
0.31
66,484
4,152
20,629
Design
16.12
7.2
2,262
579
334
5,339
1,147
3
25
0.43
a
Min Day
ADF
14580
TRUE
TRUE
1633
0.69
0.62
9,401
18,000
18
000
1.90
1.90
0.00
27.43%
34277
0.90
0.31
235,056
4,536
72,934
14580
TRUE
TRUE
1834
0.84
0.62
10,315
18,000
18
000
2.10
2.10
0.00
27.24%
37865
0.90
0.36
257,900
8,366
93,049
Design Des+Nit
42.20
42.20
7.2
7.2
53,605
53,605
1,814
1,814
30,164
27,676
11,863
11,863
3,707
176
3
3
25
25
0.43
0.5
a
a
ADF
Spreadsheet 2.1 - 2.3 calculates the amount of air and horsepower need to treat various flowrates and loading rates throughout the plant.
2.1 Aeration Calculations - Diffusers spreadsheet predicts the efficiency improvement by upgrading to fine bubble diffusers with no other ECIs.
MMADF
14580
TRUE
TRUE
2553
1.44
0.62
13,215
18,000
18
000
2.75
2.75
0.00
26.67%
49542
0.90
0.31
330,401
4,357
102,518
14580
TRUE
TRUE
3026
1.86
0.62
15,051
18,000
18
000
3.13
3.13
0.00
26.70%
56363
0.90
0.36
376,308
10,795
135,770
Des
Des+Nit
50.08
50.08
7.2
7.2
81,589
81,589
2,998
2,998
43,811
40,025
15,807
15,807
6,192
209
3
3
25
25
0.43
0.5
a
a
MMADF
MDF
16200
TRUE
TRUE
2754
1.62
0.62
14,055
20,000
20
000
2.63
2.63
0.00
26.77%
52511
0.90
0.44
351,395
7,093
155,872
16200
TRUE
TRUE
2426 hp
1.33 psi
0.62 Unitless
12,847
20,000
20
000
2.38
2.38
0.00
26.98%
47609
0.90
0.52
321,208 (lb/day)
13,326 (lb/day)
165,676 (lb/day)
Des
Des+Nit
64.33
64.33
8
8
104,806 104,806 (lb/day)
3,851
3,851 (lb/day)
43,811
55,915 (lb/day)
20,305
20,305 (lb/day)
7,955
268 (lb/day)
0.5
0.5 mg/L
25
25 degC
0.43
0.5 unitless
a
a
MDF
Cur Treat
16386.3
TRUE
TRUE
1269
2.02
0.62
6,387
22,050
22
050
1.33
1.23
0.10
23.50%
27,181
0.90
0.40
159,682
3,999
64,297
20042006
37.20
6.3
47,257
1,599
26,592
10,458
3,268
1
25
0.43
a
205
2.2 AERATION CALCULATIONS - TURBO BLOWERS
964
0.35
0.72
6.PowerDemandCalculations
Pw=[(W*R*T1)/(550*n*Eff)]*[(P2/P1)^.2831]
Pw(blowerhorsepowerrequired)=
DynamicLosses
WiretoAirEff=
AllEquationsreferenced,(Metcalf&Eddy,2003)
14580
TRUE
TRUE
6,918
18,000
18
000
1.36
1.36
0.00
28.33%
24421
5.AerationDemandCalculations
Airrequiredat100%Efficiency=
Total Number of Diffusers =
TotalNumberofDiffusers=
DiffuserFlow,scfm/diffuser(macroinput)=
DiffuserFlow,scfm/diffuser=
Difference=
SOTEatDesSubmandDiffFlow=
SCFM=SOTR/(SOTE*60min/hr*24hr/day
MinimumMixingAirflowRequirement(scfm)
MinimumMixingRequirementMet?
IsDiffuserFlowWithinRange?
0.90
0.42
172,953
4.SORCalculations
Tau=
Eq555
AOR/SOR={[(Beta*CstH*CL)/Cs20][1.024^(
SOR=
7. Checks
4,485
72,108
3.AORCalculations
Eq.818 TKNinfNH3eff0.12(PxBio)=NOx=
Eq.817 1.6*1.16*(SoS)1.42(PxBio)+4.33(NOx)=AO
MGD
NumberofBasinsOnline
So=CBODinf
S=CBODeff
Eq.815(wherehilighted),PxBio=
TKN=
NH3eff=
CL(operat.oxygenconcentration,mg/L)=
T(degC)
Alpha=
AverageofminimumSOTE
2.Inputs
ADF
ADF
14580
TRUE
TRUE
1386
0.67
0.72
9,295
18,000
18
000
1.88
1.88
0.00
27.45%
33860
0.90
0.31
232,394
4,485
72,108
14580
TRUE
TRUE
1556
0.82
0.72
10,198
18,000
18
000
2.08
2.08
0.00
27.27%
37404
0.90
0.36
254,979
8,271
91,995
1131ADF 1131ADF 1131ADF
41.72
41.72
41.72
7.2
7.2
7.2
52,998
52,998
52,998
1,793
1,793
1,793
29,822
29,822
27,363
11,729
11,729
11,729
3,665
3,665
174
1
3
3
25
25
25
0.43
0.43
0.5
a
a
a
Cur Treat
14580
FALSE
FALSE
232
0.02
0.72
2,344
18,000
18
000
0.34
0.34
0.00
38.28%
6124
0.90
0.31
58,611
3,661
18,186
Current
14.21
7.2
1,994
510
295
4,707
1,011
3
25
0.43
a
Min Day
14580
FALSE
FALSE
272
0.03
0.72
2,659
18,000
18
000
0.40
0.40
0.00
37.12%
7164
0.90
0.31
66,484
4,152
20,629
Design
16.12
7.2
2,262
579
334
5,339
1,147
3
25
0.43
a
Min Day
ADF
14580
TRUE
TRUE
1406
0.69
0.72
9,401
18,000
18
000
1.90
1.90
0.00
27.43%
34277
0.90
0.31
235,056
4,536
72,934
14580
TRUE
TRUE
1579
0.84
0.72
10,315
18,000
18
000
2.10
2.10
0.00
27.24%
37865
0.90
0.36
257,900
8,366
93,049
Design Des+Nit
42.20
42.20
7.2
7.2
53,605
53,605
1,814
1,814
30,164
27,676
11,863
11,863
3,707
176
3
3
25
25
0.43
0.5
a
a
ADF
MMADF
14580
TRUE
TRUE
2199
1.44
0.72
13,215
18,000
18
000
2.75
2.75
0.00
26.67%
49542
0.90
0.31
330,401
4,357
102,518
14580
TRUE
TRUE
2606
1.86
0.72
15,051
18,000
18
000
3.13
3.13
0.00
26.70%
56363
0.90
0.36
376,308
10,795
135,770
Des
Des+Nit
50.08
50.08
7.2
7.2
81,589
81,589
2,998
2,998
43,811
40,025
15,807
15,807
6,192
209
3
3
25
25
0.43
0.5
a
a
MMADF
Spreadsheet 2.1 - 2.3 calculates the amount of air and horsepower need to treat various flowrates and loading rates throughout the plant.
2.2 Aeration Calculations -Turbo Blowers spreadsheet predicts efficiency improvement of fine bubble diffusers with turbo blowers assuming 72% effiency.
MDF
16200
TRUE
TRUE
2371
1.62
0.72
14,055
20,000
20
000
2.63
2.63
0.00
26.77%
52511
0.90
0.44
351,395
7,093
155,872
16200
TRUE
TRUE
2089 hp
1.33 psi
0.72 Unitless
12,847
20,000
20
000
2.38
2.38
0.00
26.98%
47609
0.90
0.52
321,208 (lb/day)
13,326 (lb/day)
165,676 (lb/day)
Des
Des+Nit
64.33
64.33
8
8
104,806 104,806 (lb/day)
3,851
3,851 (lb/day)
43,811
55,915 (lb/day)
20,305
20,305 (lb/day)
7,955
268 (lb/day)
0.5
0.5 mg/L
25
25 degC
0.43
0.5 unitless
a
a
MDF
206
2.3 AERATION CALCULATIONS - 1.5 MG/L DO CONTROL
964
0.35
0.72
6.PowerDemandCalculations
Pw=[(W*R*T1)/(550*n*Eff)]*[(P2/P1)^.2831]
Pw(blowerhorsepowerrequired)=
DynamicLosses
WiretoAirEff=
AllEquationsreferenced,(Metcalf&Eddy,2003)
14580
TRUE
TRUE
6,918
18,000
18
000
1.36
1.36
0.00
28.33%
24421
5.AerationDemandCalculations
Airrequiredat100%Efficiency=
Total Number of Diffusers =
TotalNumberofDiffusers=
DiffuserFlow,scfm/diffuser(macroinput)=
DiffuserFlow,scfm/diffuser=
Difference=
SOTEatDesSubmandDiffFlow=
SCFM=SOTR/(SOTE*60min/hr*24hr/day
MinimumMixingAirflowRequirement(scfm)
MinimumMixingRequirementMet?
IsDiffuserFlowWithinRange?
0.90
0.42
172,953
4.SORCalculations
Tau=
Eq555
AOR/SOR={[(Beta*CstH*CL)/Cs20][1.024^(
SOR=
7. Checks
4,485
72,108
3.AORCalculations
Eq.818 TKNinfNH3eff0.12(PxBio)=NOx=
Eq.817 1.6*1.16*(SoS)1.42(PxBio)+4.33(NOx)=AO
MGD
NumberofBasinsOnline
So=CBODinf
S=CBODeff
Eq.815(wherehilighted),PxBio=
TKN=
NH3eff=
CL(operat.oxygenconcentration,mg/L)=
T(degC)
Alpha=
AverageofminimumSOTE
2.Inputs
ADF
ADF
14580
TRUE
TRUE
1046
0.41
0.72
7,390
18,000
18
000
1.46
1.46
0.00
28.06%
26338
0.90
0.39
184,768
4,485
72,108
14580
TRUE
TRUE
1173
0.50
0.72
8,108
18,000
18
000
1.62
1.62
0.00
27.77%
29201
0.90
0.45
202,725
8,271
91,995
1131ADF 1131ADF 1131ADF
41.72
41.72
41.72
7.2
7.2
7.2
52,998
52,998
52,998
1,793
1,793
1,793
29,822
29,822
27,363
11,729
11,729
11,729
3,665
3,665
174
1
1.5
1.5
25
25
25
0.43
0.43
0.5
a
a
a
Cur Treat
14580
FALSE
FALSE
176
0.01
0.72
1,864
18,000
18
000
0.26
0.26
0.00
40.12%
4645
0.90
0.39
46,599
3,661
18,186
Current
14.21
7.2
1,994
510
295
4,707
1,011
1.5
25
0.43
a
Min Day
14580
FALSE
FALSE
205
0.02
0.72
2,114
18,000
18
000
0.30
0.30
0.00
39.16%
5399
0.90
0.39
52,859
4,152
20,629
Design
16.12
7.2
2,262
579
334
5,339
1,147
1.5
25
0.43
a
Min Day
ADF
14580
TRUE
TRUE
1061
0.42
0.72
7,475
18,000
18
000
1.48
1.48
0.00
28.02%
26678
0.90
0.39
186,884
4,536
72,934
14580
TRUE
TRUE
1189
0.51
0.72
8,201
18,000
18
000
1.64
1.64
0.00
27.74%
29568
0.90
0.45
205,047
8,366
93,049
Design Des+Nit
42.20
42.20
7.2
7.2
53,605
53,605
1,814
1,814
30,164
27,676
11,863
11,863
3,707
176
1.5
1.5
25
25
0.43
0.5
a
a
ADF
MMADF
14580
TRUE
TRUE
1617
0.88
0.72
10,507
18,000
18
000
2.15
2.15
0.00
27.20%
38623
0.90
0.39
262,690
4,357
102,518
14580
TRUE
TRUE
1919
1.16
0.72
11,967
18,000
18
000
2.47
2.47
0.00
26.90%
44484
0.90
0.45
299,189
10,795
135,770
Des
Des+Nit
50.08
50.08
7.2
7.2
81,589
81,589
2,998
2,998
43,811
40,025
15,807
15,807
6,192
209
1.5
1.5
25
25
0.43
0.5
a
a
MMADF
Spreadsheet 2.1 -2.3 calculates the amount of air and horsepower required to treat various flowrates and loading rates throughout the plant.
2.3 Aeration Calculations -1.5 MG/L Do Control spreadsheet predicts efficiency improvement of fine bubble diffusers, turbo blowers, and DO Control.
MDF
16200
TRUE
TRUE
2371
1.62
0.72
14,055
20,000
20
000
2.63
2.63
0.00
26.77%
52511
0.90
0.44
351,395
7,093
155,872
16200
TRUE
TRUE
2089 hp
1.33 psi
0.72 Unitless
12,847
20,000
20
000
2.38
2.38
0.00
26.98%
47609
0.90
0.52
321,208 (lb/day)
13,326 (lb/day)
165,676 (lb/day)
Des
Des+Nit
64.33
64.33
8
8
104,806 104,806 (lb/day)
3,851
3,851 (lb/day)
43,811
55,915 (lb/day)
20,305
20,305 (lb/day)
7,955
268 (lb/day)
0.5
0.5 mg/L
25
25 degC
0.43
0.5 unitless
a
a
MDF
207
3.1 SYSTEM DESIGN - SIZE PIPES - TRAIN 1
8.71 psig
6.716900698
0.33902046
Airflows
26,678 scfm
44,484 scfm
47,609 scfm
0.41
175 F
0.67
6,292
24
2,003
0.33
3,146 scfm
20 in
1,442 fpm
Split 2
Air Flow to Zones 2, 3
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
Split 3
Air Flow To Train 3:
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
Split to half basin
2
9,437
30
1,923
Split 1
Air Flow To Zones 1, 2, 3:
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
ea
scfm
in
fpm
ea
scfm
in
fpm
2
18,875
36
2,670
ea
scfm
in
fpm
Max. Month
37,750 scfm
48 in
3,004 fpm
Number of Parallel Aeration Trains:
Air Flow Per Treatment Train:
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
Total Air Flow:
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
Average Annual Air Flow:
Maximum Month Air Flow:
Maximum Day Air Flow:
Pdischarge =
Vp act
VP std
RH Inlet =
Tdischarge=
This spreadsheet demonstrates the sizing of the proposed aeration process air pipes.
22639 acfm
37750 acfm
40402 acfm
1,543 fpm
0.33
3,367 scfm
2,143 fpm
0.67 ea
6,734 scfm
2,058 fpm
2 ea
10,100 scfm
2,858 fpm
2 ea
20,201 scfm
3,215 fpm
Peak Day
40,402 scfm
Pipe Dia
In
1-3
4 - 10
12 - 24
30 - 60
ICFM
From 5th Order Curve Fit
Figure 4-1 - Saturation W
Water vapor pressure (ps
be calculated with the foll
VP = a*T5 +b*T4 +c*T3 +
Where:
a = 2.27E-11
b = -2.5E-10
c = 5.08E-07
d = 7.42E-06
e = 0.001485
f = 0.016274
§ T 460 · ª PS RH S * VPS º
¸¸ «
SCFM * ¨¨ A
»
© TS 460 ¹ ¬ PI RH A * VPA ¼
Velocity
fpm
1200 - 1800
1800 - 3000
2700 - 4000
3800 - 6500
Per Table 5-28 - Metcalf & Eddy
Typical air velocities in aeration
header pipes
208
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(1)
(2)
(3)
3.2 SYSTEM DESIGN - ESTIMATE LOSSES THROUGH PIPES
F
psig
ft2/s
inches
lb/scf
psia
f
for st. steel
1 Check Valve, 1 BFV, 14' x 16" Exp.
16" Blower Outlet
36" Air Piping
1 tee, 4 thru tees
30" Air Piping
1 thru tee
24" Air Piping
1 thru tee, 1 90 bend, contraction
18" Air Piping
contraction, 1 thru tee
14" Air Piping
1 contraction, 2 tees, venturi meter, modulating butterfly valve
12" Air Piping/Diff. Head 2 90 bends
6" Air Piping
Loss Through Diffuser Recommended per Sanitaire
Diffuser Loss w/ Age
8.71 psi
4067.458
3163.579
2812.07
2024.69
2109.052
1518.518
2109.052
Blower Discharge Pressure Required =
16
48
36
30
24
20
12
1.57 psi
5679.24
39754.7
19877.4
9938.68
6625.78
3312.89
1656.45
7.14 psi
13044.65
52178.59
26089.29
17392.86
8696.431
8696.431
4348.215
13
77
192
195
68
68
100
5.22E+06
7.22E+07
1.20E+08
7.31E+07
2.12E+07
1.27E+07
1.56E+07
Cell M
Cell N
Cell O
0.000003
0.000001
0.000001
0.000002
0.000002
0.000003
0.000004
H/D
Aeration System Losses
Blower Piping Inlet Losses
Q (acfm) Diam (in)Vel (fpm) Length (ft) Re
Static Pressure =
6801.3
47609.1
23804.6
11902.3
7934.85
3967.43
1983.71
Q (scfm) Q (icfm)
47609 scfm
52178.59 icfm
39754.7 acfm
1.386512
0.838754
0.662719
0.343554
0.37278
0.193249
0.37278
hi (inH2O)
Where:
a=
b=
c=
d=
e=
f=
0.123965
0.107945
0.278922
0.184167
0.097732
0.064582
0.306356
15
14
hL (inH2O)
2.27E-11
-2.5E-10
5.08E-07
7.42E-06
0.001485
0.016274
5.2
3.9
1.4
0.8
0.8
6.1
0.6
7.209864
3.271142
0.927807
0.274843
0.298224
1.178819
0.223668
7.333829
3.379087
1.206729
0.45901
0.395956
1.2434
0.530024
15
14
0.264568
0.121901
0.043533
0.016559
0.014284
0.044856
0.019121
0.541126
0.505051
0 50505
Minor Losses (est.) Total Losses
6K
hL (inH2O) hL (inH2O) hL (psi)
From 5th Order Curve Fit of Stephenson/Nixon,
Figure 4-1 - Saturation Water Vapor Pressure,
Water vapor pressure (psi) vs temperature (°F) can
be calculated with the following formula
VP = a*T5 +b*T4 +c*T3 +d*T2 +e*T+f
Swamee Jain
Pressure V
Darcy Weisbach
0.009
0.007
0.007
0.007
0.008
0.008
0.008
fcalc
§ T 460 · ª PS RH S * VPS º
SCFM * ¨¨ A
»
¸¸ «
© TS 460 ¹ ¬ PI RH A * VPA ¼
0.16 psi
ICFM
Qprocess
Qprocess
Qprocess
Total Blower Piping Discharge Losses =
16
48
36
30
24
20
12
Diam (in)
Cummulative Loss
hL (inH2O)
hL (psi)
3
0.10823
1.5
0.05411
12
0.4329
Total Blower Piping Inlet Losses =
14.53
101
0.41
175
9.05
0.000225
0.00005
0.1006697
6.7169007
0.3390205
0.9780971
16" Blower Outlet
48" Air Piping
36" Air Piping
30" Air Piping
24" Air Piping
20" Air Piping
12" Air Piping/Diff. Head
Loss Through Diffuser/Orifice
Diffuser
use Fouling
ou g Loss
oss
Description
Inlet Filter Loss
Inlet Silencer Loss
Loss across diffuser
Description
P inlet =
T inlet =
RH Inlet =
Tdischarge=
Pdischarge =
=
H=
J act=
Vp act
VP std
Vp inlet
This spreadsheet demonstrates the calculation of worst-case headloss through the proposed aeration piping system
7.333829
10.71292
11.91964
12.37865
12.77461
14.01801
14.54803
29.54803
43.54803
3 5 803
0.264568
0.386469
0.430002
0.44656
0.460845
0.5057
0.524821
1.065946
1.570997
5 099
Cummulative Loss
hL (inH2O) hL (psi)
3.3 SYSTEM DESIGN - SYSTEM CURVE
This spreadsheet displays the system curve of the aeration blower piping system. The data is poltted on graphs on the following spreadsheets.
SCFM
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
12000
13000
14000
15000
16000
17000
18000
19000
20000
21000
22000
23000
24000
25000
26000
27000
28000
29000
30000
31000
32000
33000
34000
35000
36000
37000
38000
39000
40000
41000
42000
43000
44000
45000
46000
47000
48000
49000
50000
51000
52000
53000
54000
55000
56000
57000
58000
59000
60000
61000
62000
63000
64000
65000
66000
67000
PSI
7.14
7.14
7.15
7.15
7.15
7.16
7.17
7.18
7.19
7.20
7.21
7.23
7.24
7.26
7.28
7.30
7.32
7.34
7.37
7.39
7.42
7.45
7.48
7.51
7.54
7.58
7.61
7.65
7.69
7.73
7.77
7.81
7.85
7.90
7.94
7 99
7.99
8.04
8.09
8.14
8.20
8.25
8.31
8.37
8.42
8.48
8.55
8.61
8.67
8.74
8.81
8.88
8.95
9.02
9.09
9.16
9.24
9.32
9.39
9.47
9.56
9.64
9.72
9.81
9.89
9.98
10.07
10.16
10.25
12.00
y=6.93E10x2 +7.14E+00
R²=1.00E+00
10.00
8.00
Series1
6.00
Poly.(Series1)
4.00
2.00
0.00
0
20000
40000
60000
209
80000
3.4 SYSTEM DESIGN - BLOWER DESIGN
This spreadsheet details the multiple temperature, pressure, and flow related conditions that are taken into account to correctly size the blowers
Historical Weather Data for West Palm Beach
Data Source
Parameter
ASHRAE
Extreme (1%)
Design Temperature (Wet Bulb) (°F):
Conditions for
WPB
NOAA
Records for
Maximum Temperature (°F):
West Palm
Beach
Resulting Relative Humidity*:
Blower Inlet and Discharge Pressures
Ambient Barometric Pressure (psia)
Blower Inlet Pressure (psia)
System Design Pressure Loss (psig):
Estimated Discharge Pressure (psia):
Value
80
101
41%
From 5th Order Curve Fit of Stephenson/Nixon,
Figure 4-1 - Saturation Water Vapor Pressure,
Water vapor pressure (psi) vs temperature (°F) can
be calculated with the following formula:
5
4
3
2
VP = a*T +b*T +c*T +d*T +e*T+f
Where:
a = 2.27E-11 32°F T 140°F
b = -2.5E-10
c = 5.08E-07
d = 7.42E-06
e = 0.001485
f = 0.016274
-------------->
14.696
14.53
8.71
23.41
Correct Blower Florate Design Point for Extreme Hot Weather Condition
Std. Cond.
Design
Parameter
Inlet Temperature (°F):
68.0
101.0
Absolute Inlet Temperature (°R):
528
561
Relative Humidity:
36%
41%
Vapor Pressure (psi):
0.3390
0.9781
Barometric Pressure (psi):
14.70
14.53
1.00
1.10 -------------->
Density Correction Factor (ICFM/SCFM):
ICFM
Maximum Day Air Flow (CFM):
47,609
52,166
Correct Blower Pressure Design Point for Extreme Hot Weather Condition
k-1/k
0.283
0.283
8.71
Approximate Site Discharge Pressure (psig):
Equivalent Air Pressure (EAP) (psig):
9.64 --------------> EAP
Size Blowers
Minimum Mixing Air Flow (SCFM):
Average Annual Air Flow (SCFM):
Maximum Month Air Flow (SCFM):
Maximum Day Air Flow (SCFM): (no nitrification)
Conversion Factor (ICFM/SCFM):
Number of Blowers:
Ratio of Large To Small
Small Blower Capacity (ICFM): (2 x)
Large Blower Capacity (ICFM): (6 x)
Firm Blower Capacity (ICFM):
Is Max. Month Requirement met w/ Firm Capacity?
Required Blower Turn Down to Meet Minimum Flow:
Site Barometric Pressure (psia):
Small Blower Rating Point (SCFM)
Large Blower Rating Point (SCFM)
Additional Information
14,580
26,678
29,231 icfm
38,623
42,320 icfm
52,511
57,538 icfm
1.10
8
1.5
5,000
4,563 SCFM
7,000
6,389 SCFM
45,000
Yes
91.7%
14.70
5,000 @ 9.64 psig 200 HP
7,000 @ 9.64 psig 300 HP
§ T 460 · ª PS RH S * VPS º
¸¸ «
SCFM * ¨¨ A
»
© TS 460 ¹ ¬ PI RH A * VPA ¼
PS ­
°§ Ti
®¨¨
°© TS
¯
47457.4554
=IF(C38=2,ROUND(D36/2.5,-2),IF(C38=3,ROUND(D36/3.5,-2),IF(C38=4,ROUND(D36/5.5,-2),IF(C38=5,ROUND(D36/7,-2),0)))
210
k
k 1
ª
º ½ k 1
· «§ PDS · k
» °
¸¸ «¨¨ P ¸¸ 1» 1¾ 1
¹ «© BI ¹
»¼ °
¬
¿
4.0 - COST ESTIMATE - SUMMARY
This spreadsheet summarizes the results of the capital cost estimate in spreadsheets 8.1 - 8.7
Item
Demolition
Blowers
Diffusers
StructuralBlowerBuilding
MechanicalPiping
Instrumentation
Electrical
SubTotal1
ContractorOH&P
Mobilization/Demobilization
Subtotal2
PerformanceBond
Insurance
Permits
Subtotal3
Contingency
EngineeringFee(designand
constructionadministrationbased
onsubtotal1)
GrandTotal
AACEClass4LowRange(20%)
AACEClass4HiRange(+30%)
ECMNo.1
ECMNo.2
ECMNo.3
$41,132
$41,132
$41,132
$1,070,000 $1,497,500
$1,497,500
$810,000
$810,000
$810,000
$152,733
$152,733
$152,733
$1,367,733 $1,367,733
$1,367,733
$138,000
$138,000
$784,500
$577,021
$577,021
$639,047
Comments/Source
Spreadsheet8.1
Spreadsheet8.2
Spreadsheet8.3
Spreadsheet8.4
Spreadsheet8.5
Spreadsheet8.6
Spreadsheet8.7
$4,156,619
$4,584,119
$5,292,646
$623,493
$207,831
$687,618
$229,206
$4,987,943
$5,500,943
$49,879
$24,940
$49,879
$55,009
$27,505
$55,009
$5,112,642
$5,638,467
$511,264
$563,847
$650,995 10%012116.50PreliminaryWorkingDrawingStage
$623,493
$687,618
$793,897 15%Basedon???
$6,247,399
$5,000,000
$8,120,000
$6,889,931
$5,510,000
$8,960,000
$793,897 15%BasedonPrevailingRates
$264,632 5%Basedonprevailingrates
$6,351,175
$63,512 1%
$31,756 0.5%Higherendof013113.30
$63,512 1%Midrange"ruleofthumb",014126.50
$6,509,954
$7,954,846
$6,360,000
$10,340,000
211
212
260505.100100
260505.100120
260505.100300
260505.100290
260505.101870
260505.251070
KellyTractorQuote
SOURCE
DemolishRGSConduit,1/2"1"
DemolishRGSConduit,11/4"2"
Demolisharmoredcable,2#12
Demolisharmoredcable,3#14
Demolishcable,#6GND
2000
2000
4000
4000
4000
LF
LF
LF
LF
LF
24 EA
Demolish100HPMotorandelectrical
Aerationbasinconduitonbasinsand
cablefMCCs
24 EA
2
QUANTITY
MECHANICALAERATOR
RemoveMechAerator
CRANE RENTAL - 40 TON CAPACITY
DEMOLITION
DESCRIPTION
4.1 - COST ESTIMATE - DEMOLITION
MO
UNIT
Material
$1.62
$1.96
$0.65
$0.69
$0.12
$218.00
$500.00
Labor
Equip
ECMNo.1
ECMNo.2
ECMNo.3
$1.13
$1.37
$0.45
$0.48
$0.08
$152.38
$349.50
$10,000.00
Total Unit Cost
Sum
$41,132
$41,132
$41,132
$336
$1,929
$1,817
$2,740
$2,265
$3,657
$8,388
$20,000
TOTAL
ECI No.
1
1
1
1
1
1
1 Labor Index
0.699
1
0.964
WPBCity
Mat Index
WPBCity
213
Budget $
$56,000
$102,000
$75,000
$115,000
$93,000
$120,000
$134,000
$120,000
$160,000
$86,000
$90,000
$93,000
$124,000
$128,000
$176,000
HP
200
250
300
300
300
350
400
400
500
500
500
Source
Source
EPA
EPA
EPA
EPA
Rohrbacher, et. al
EPA
Rohrbacher, et. al
EPA
EPA
Rohrbacher, et. al
Rohrbacher, et. al
Rohrbacher, et. al
Rohrbacher, et. al
Rohrbacher, et. al
Rohrbacher, et. al
$98,000 H&S
$90,000 H&S
$153,000 H&S
$72,000 H&S
$104,000 H&S
$110,000 H&S
$135,000 H&S
$88,000 H&S
$245,000 H&S
$170,000 H&S
$190,000 H&S
Budget $
MULTI_STAGECENTRIFUGALCOSTS
HP
50
50
75
100
100
150
150
200
200
200
200
200
200
200
200
BlowerCostData
UNIT
$202,000
$112,000
$110,000
$110,000
$98,000
$90,000
Average
$122,000
$127,000
$104,000
$75,000
$79,000
Average
6 EA
2 EA
COMPARABLEMULTISTAGECENTRIFUGALCOST
(6)300HPBlowers
(2)200HPBlowers
QUANTITY
6 EA
2 EA
DESCRIPTION
BLOWERS
(6)300HPBowers
(2)200HPBlower
DIVISION NO
4.2 - COST ESTIMATE - BLOWERS
HP
250
250
250
250
250
300
300
300
300
300
300
300
300
400
400
400
500
$110,000
$98,000
$159,000
$122,000
Material
Labor
Budget $
$180,000
$151,000
$165,000
$168,000
$188,000
$175,000
$142,000
$119,000
$119,000
$143,000
$156,000
$208,000
$209,000
$275,000
$132,000
$198,000
$325,000
$27,500
$24,500
$39,750
$30,500
Source
EPA
Rohrbache
Rohrbache
Rohrbache
Rohrbache
EPA
EPA
Rohrbache
Rohrbache
Rohrbache
Rohrbache
Rohrbache
Rohrbache
EPA
Rohrbache
Rohrbache
EPA
Equip
Total
TOTAL
$245,000
$825,000
$1,497,500
$325,000
$202,000
$159,000
$170,000
Average
$1,070,000
Sum
ECMNo.1 $1,070,000
ECMNo.2 $1,497,500
ECMNo.3 $1,497,500
Total
$137,500
$122,500
Total
$198,750 $1,192,500
$152,500
$305,000
ECI No.
1
1
2
2
214
DIVISION NO
DIFFUSERS
Equipment
DESCRIPTION
1 LS
QUANTITY
4.3 - COST ESTIMATE - DIFFUSERS
UNIT
600000
Material
1.35
Factor
810000
ECMNo.1
ECMNo.2
ECMNo.3
Total Unit
810000 Aquariusquote
$810,000
$810,000
$810,000
Total
215
260505.100100
260505.100120
260505.100300
260505.100290
260505.101870
260505.251070
KellyTractorQuote
SOURCE
DemolishRGSConduit,1/2"1"
DemolishRGSConduit,11/4"2"
Demolisharmoredcable,2#12
Demolisharmoredcable,3#14
Demolishcable,#6GND
2000
2000
4000
4000
4000
LF
LF
LF
LF
LF
24 EA
Demolish100HPMotorandelectrical
Aerationbasinconduitonbasinsand
cablefMCCs
24 EA
2
QUANTITY
MECHANICALAERATOR
RemoveMechAerator
CRANE RENTAL - 40 TON CAPACITY
DEMOLITION
DESCRIPTION
4.1 - COST ESTIMATE - DEMOLITION
MO
UNIT
Material
$1.62
$1.96
$0.65
$0.69
$0.12
$218.00
$500.00
Labor
Equip
ECMNo.1
ECMNo.2
ECMNo.3
$1.13
$1.37
$0.45
$0.48
$0.08
$152.38
$349.50
$10,000.00
Total Unit Cost
Sum
$41,132
$41,132
$41,132
$336
$1,929
$1,817
$2,740
$2,265
$3,657
$8,388
$20,000
TOTAL
ECI No.
1
1
1
1
1
1
1 Labor Index
0.699
1
0.964
WPBCity
Mat Index
WPBCity
216
Budget $
$56,000
$102,000
$75,000
$115,000
$93,000
$120,000
$134,000
$120,000
$160,000
$86,000
$90,000
$93,000
$124,000
$128,000
$176,000
HP
200
250
300
300
300
350
400
400
500
500
500
Source
Source
EPA
EPA
EPA
EPA
Rohrbacher, et. al
EPA
Rohrbacher, et. al
EPA
EPA
Rohrbacher, et. al
Rohrbacher, et. al
Rohrbacher, et. al
Rohrbacher, et. al
Rohrbacher, et. al
Rohrbacher, et. al
$98,000 H&S
$90,000 H&S
$153,000 H&S
$72,000 H&S
$104,000 H&S
$110,000 H&S
$135,000 H&S
$88,000 H&S
$245,000 H&S
$170,000 H&S
$190,000 H&S
Budget $
MULTI_STAGECENTRIFUGALCOSTS
HP
50
50
75
100
100
150
150
200
200
200
200
200
200
200
200
BlowerCostData
UNIT
$202,000
$112,000
$110,000
$110,000
$98,000
$90,000
Average
$122,000
$127,000
$104,000
$75,000
$79,000
Average
6 EA
2 EA
COMPARABLEMULTISTAGECENTRIFUGALCOST
(6)300HPBlowers
(2)200HPBlowers
QUANTITY
6 EA
2 EA
DESCRIPTION
BLOWERS
(6)300HPBowers
(2)200HPBlower
DIVISION NO
4.2 - COST ESTIMATE - BLOWERS
HP
250
250
250
250
250
300
300
300
300
300
300
300
300
400
400
400
500
$110,000
$98,000
$159,000
$122,000
Material
Labor
Budget $
$180,000
$151,000
$165,000
$168,000
$188,000
$175,000
$142,000
$119,000
$119,000
$143,000
$156,000
$208,000
$209,000
$275,000
$132,000
$198,000
$325,000
$27,500
$24,500
$39,750
$30,500
Source
EPA
Rohrbache
Rohrbache
Rohrbache
Rohrbache
EPA
EPA
Rohrbache
Rohrbache
Rohrbache
Rohrbache
Rohrbache
Rohrbache
EPA
Rohrbache
Rohrbache
EPA
Equip
Total
TOTAL
$245,000
$825,000
$1,497,500
$325,000
$202,000
$159,000
$170,000
Average
$1,070,000
Sum
ECMNo.1 $1,070,000
ECMNo.2 $1,497,500
ECMNo.3 $1,497,500
Total
$137,500
$122,500
Total
$198,750 $1,192,500
$152,500
$305,000
ECI No.
1
1
2
2
217
DIVISION NO
DIFFUSERS
Equipment
DESCRIPTION
1 LS
QUANTITY
4.3 - COST ESTIMATE - DIFFUSERS
UNIT
600000
Material
1.35
Factor
810000
ECMNo.1
ECMNo.2
ECMNo.3
Total Unit
810000 Aquariusquote
$810,000
$810,000
$810,000
Total
218
099113.601600
099123.722880
312316.166070
312323.131900
312323.132200
081163.23
083323.100100
233723.101100
092423.401000
034133.602200
033053.400820
033053.403940
033052.404050
042210.280300
033053.403570
033053.403550
072610.100700
DIVISION NO
PaintStucco,rough,oilbase,paint2coats,spray
PaintCMUInterior,paint2coats,spray
BLOWERBUILDINGCONSTRUCT
PrecastTees,DoubleTees,RoofMembers,Std.
Weight,12"x8'wide,30'span
16"x16",Avg.Reinforcing
Footings,strip,24"x12",reinforced
Foundationmat,over20C.Y.
ConcreteBlock,HighStength,3500psi,8"thick
EquipmentPads,6'x6'x8"Thick
EquipmentPads,4'x4'x8"Thick
PoyethyleneVaporBarrier,Standard,.004"Thick
StructuralExcavationforMinorStructures,Sand,3/4
CYBucket
DozerBackfill,bulk
CompactBackfill,12"lifts
StormDoor,ClearAnodicCoating,7'0"x3'wide
RollingServiceDoor,10'x10'high
HVACLouvers,Standard8"x5"
ExteriorStucco,w/bondingagent
DESCRIPTION
4.4 - COST ESTIMATE - STRUCTURAL
UNIT
CY
CY
CY
EA
EA
EA
SY
EA
CY
CY
CY
SF
EA
EA
100SF
3540 SF
3540 SF
440
220
440
8
2
700
394.0
20
21
21
93
3540
10
10
46
QUANTITY
$0
$0
$266
$1,675
$31
$4
$1,575
$455
$133
$197
$3
$157
$67
$3
Material
$0
$0
$6
$0
$1
$48
$490
$15
$7
$138
$610
$86
$106
$4
$129
$61
$8
Labor
$1
$6
$1
$2
$2
$1
ECMNo.1
$0
$0
$9
$2
$3
$290
$1,957
$40
$9
$1,700
$925
$188
$265
$6
$243
$108
$9
Total Unit Cos
$86
$60
$1
$1
Equip
Sum
$152,733
$1,041
$889
$3,415
$28,307
$3,914
$2,321
$1,100
$337
$4,173
$401
$1,077
$2,433
$21,324
$24,612
$3,958
$19,425
$34,005
TOTAL
ECI No.
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0.964
0.699
Mat Index Labor Index
WPBCity WPBCity
219
099113.601600
099123.722880
312316.166070
312323.131900
312323.132200
081163.23
083323.100100
233723.101100
092423.401000
034133.602200
033053.400820
033053.403940
033052.404050
042210.280300
033053.403570
033053.403550
072610.100700
DIVISION NO
PaintStucco,rough,oilbase,paint2coats,spray
PaintCMUInterior,paint2coats,spray
BLOWERBUILDINGCONSTRUCT
PrecastTees,DoubleTees,RoofMembers,Std.
Weight,12"x8'wide,30'span
16"x16",Avg.Reinforcing
Footings,strip,24"x12",reinforced
Foundationmat,over20C.Y.
ConcreteBlock,HighStength,3500psi,8"thick
EquipmentPads,6'x6'x8"Thick
EquipmentPads,4'x4'x8"Thick
PoyethyleneVaporBarrier,Standard,.004"Thick
StructuralExcavationforMinorStructures,Sand,3/4
CYBucket
DozerBackfill,bulk
CompactBackfill,12"lifts
StormDoor,ClearAnodicCoating,7'0"x3'wide
RollingServiceDoor,10'x10'high
HVACLouvers,Standard8"x5"
ExteriorStucco,w/bondingagent
DESCRIPTION
4.4 - COST ESTIMATE - STRUCTURAL
UNIT
CY
CY
CY
EA
EA
EA
SY
EA
CY
CY
CY
SF
EA
EA
100SF
3540 SF
3540 SF
440
220
440
8
2
700
394.0
20
21
21
93
3540
10
10
46
QUANTITY
$0
$0
$266
$1,675
$31
$4
$1,575
$455
$133
$197
$3
$157
$67
$3
Material
$0
$0
$6
$0
$1
$48
$490
$15
$7
$138
$610
$86
$106
$4
$129
$61
$8
Labor
$1
$6
$1
$2
$2
$1
ECMNo.1
$0
$0
$9
$2
$3
$290
$1,957
$40
$9
$1,700
$925
$188
$265
$6
$243
$108
$9
Total Unit Cos
$86
$60
$1
$1
Equip
Sum
$152,733
$1,041
$889
$3,415
$28,307
$3,914
$2,321
$1,100
$337
$4,173
$401
$1,077
$2,433
$21,324
$24,612
$3,958
$19,425
$34,005
TOTAL
ECI No.
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0.964
0.699
Mat Index Labor Index
WPBCity WPBCity
220
DESCRIPTION
2500
500
7 EA
72 EA
12'TallGalvSteelSu
8'Tall304SSElevat
Adjustedmaterialcostforcarbonover304SSsteelprice,~5:1.
(f/MEPS.comtables).Assumingsupportis50lb,May2010$828per
tonsteel*50/2000=$20.7formaterialx1.5factor=$31formaterial
$174$31+$31*5=$298for304SSsupport
Quantityassumessupportsevery10',18+22*2+7*6=104
Added30%tolaborforconcreteinstallation
298
1500
1000
950
4500
5000
7500
7000
4000
5000
2500
400
500
100
200
310
400
500
600
Material
208 EA
UNIT
220529.10017HeavyDutyWallSup
2 EA
6 EA
24 EA
30"Exp.Coup
24"Exp.Coup
Quaotef/Vict 12"DependoLok
EA
EA
EA
EA
EA
EA
EA
EA
EA
2
11
1
2
4
4
4
24
48
FT
FT
FT
FT
FT
FT
30"Elbow
30"x20"Tee
36"x48"Tee
36"Tee
20"x12"Cross
2/08FelkerBro 24"x12"Cross
2/08FelkerBro 20"x12"Tee
12"Tee
12"90DegBend
1800
327
272
653
277
104
QUANTITY
NEEDRSMEANSQUOTES
2/08FelkerBro 12"304LSS
2/08FelkerBro 20"304LSS
2/08FelkerBro 24"304LSS
2/08FelkerBro 30"304LSS
2/08FelkerBro 36"304LSS
2/08FelkerBro 48"304LSS
DIVISION NO
4.5 - COST ESTIMATE - MECHANICAL PIPING
625
125
14.3
375
250
237.5
1125
1250
1875
1750
1000
1250
625
100
125
25
50
77.5
100
125
150
Labor
Equip
$64,958
$3,750
$7,500
$28,500
$11,250
$68,750
$9,375
$17,500
$20,000
$25,000
$12,500
$12,000
$30,000
$225,000
$81,750
$105,400
$326,500
$173,125
$78,000
TOTAL
$21,875
$45,000
Sum
ECMNo.1 #########
ECMNo.2 #########
ECMNo.3 #########
3125
625
312.3
1875
1250
1187.5
5625
6250
9375
8750
5000
6250
3125
500
625
125
250
387.5
500
625
750
Total
ECI No.
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
221
PLCandProgramming
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
ProgrammableLogicController
Software
Training/Calibration/Documents
ProgrammingandTroubleshooting
SpareParts
HMIProgrammingandReports
DifferentialPressureIndicators(FlowMeter)
5/09PFSQuote
14"VenturiFlowElement
10/08PFSQuote`
PressureIndicatingTransmitter
CCControlsQuoteL.Garcia
9/16/10
AlumPipeStandMountw/sunshield
Amerisponse.com,9/19/10
420maSurgeSuppressor
CCControlsQuoteL.Garcia
9/16/10
14"ModulatingBFV
NEMA4Xbox,(1)24V+(1)120V
surgesuppressor,toggleswitch,
wiring
SSUnistrutMount
1
1
1
1
1
1
LS
LS
LS
LS
LS
LS
650
105
24
48
2200
50
6800
1350
1510
800
380
2750
Material
3300
1800
UNIT
24
48
24
24
24
12
24
24
24
HachSC100Controller,((3(2probe
controllers,(3)1probecontrollers)
LDOProbe
115VAirBlastCleaningSystem
PoleMountKit
HachListPrice
HachListPrice
HachListPrice
HachListPrice
ModulatingBFV
6/09DezurikQuote
12
QUANTITY
CCControlsQuoteL.Garcia
9/16/10
DESCRIPTION
AlumPipeStandMountw/
sunshield,NEMA4Xbox,(1)24V+
(1)120Vsurgesuppressor,toggle
switch,wiring
DOProbeandTransmitter
DIVISION NO
4.6 - COST ESTIMATE - INSTRUMENTATION
50000
3000
10000
15000
10000
50000
162.5
26.25
825
450
550
12.5
1700
337.5
377.5
200
95
687.5
Labor
Equip
ECMNo.1
ECMNo.2
ECMNo.3
50000
3000
10000
15000
10000
50000
812.5
131.25
4125
2250
2750
62.5
8500
1687.5
1887.5
1000
475
3437.5
Total
Sum
$138,000.00
$138,000.00
$784,500.00
$50,000.00
$3,000.00
$10,000.00
$15,000.00
$10,000.00
$50,000.00
$19,500.00
$6,300.00
$99,000.00
$108,000.00
$66,000.00
$1,500.00
$204,000.00
$20,250.00
$45,300.00
$24,000.00
$11,400.00
$41,250.00
TOTAL
3
3
3
3
3
3
3
3
3
3
3
3
1/3
1/3
1/3
1/3
1/3
1/3
ECI No.
222
DESCRIPTION
D5020145252 MotorInstall,200HP
interpolated MotorInstall,300HP
D5020145024 MotorInstall,1HP
BuildingInternal
D5025120116 14Receptacles/2,000sf
D5025120128 LightSwitches/4switches
D5020208068 Lighting,FluroescentFixtures
262416.30
Panelboard
Wiring
260519.90328#350XHHW(6per300HP)
260519.35140Terminate#350
260519.90332#500XHHW(3per200HP)
260519.35150Terminate#500
260526.80070#1GND
260519.35075Terminate#1
260519.90314#1
260519.35075Terminate#1
260519.90312#2
260519.35075Terminate#2
260519.90312#2
260519.35075Terminate#2
260523.100022#12
260523.100033#12
260526.80033#12GND
260519.35163Terminate#12
260523.100308#14
260526.80032#14GND
260519.35162Terminate#14
260526.80032#14GND
260519.35162Terminate#14
Conduit
260533.050701"Conduit,Alum
260533.050701"Conduit,Alum
260533.051103"Conduit,Alum
337719.17080ConcreteHandholes
331719.17700DuctbankandConduit,[email protected]
337119.17783Concrete(15CY/100LF)
337119.17786Reinforcing(10Lb/LF)
ExteriorGrounding/LightningProtection
260526.80013GroundingRods,copper
260526.801004/0Grounding
264113.13050AirTerminals
264113.13250AlumCable
264113.13300Arrestor
Motor Related
DIVISION NO
SF
SF
SF
EA
LF
EA
LF
EA
LF
EA
LF
EA
LF
EA
LF
EA
LF
LF
LF
EA
LF
LF
EA
LF
EA
LF
LF
LF
EA
LF
LF
LF
EA
LF
EA
LF
EA
4584
4584
4584
1
5400
36
900
6
2080
14
4120
48
1650
13
2060
24
2060
2060
4120
48
1200
2400
16
6180
72
6000
4120
4500
2
150
150
150
8
380
15
320
2
3 EA
8 EA
2 EA
QUANTITY
4.7 - COST ESTIMATE - ELECTRICAL
UNIT
Labor
$92.00
$3.85
$24.50
$0.85
$78.50
$4.30
$4.30
$22.50
$510.00
$171.25
$1.61
$4.00
$8.45
$51.00
$14.00
$66.00
$1.66
$10.90
$2.74
$10.90
$2.14
$8.65
$2.14
$8.65
$0.18
$0.25
$0.11
$0.58
$0.67
$0.07
$0.43
$0.07
$0.43
$0.56
$0.10
$2.33
$735.00
$98.00
$1.38
$49.00
$1.40
$49.00
$4.90
$4.90
$8.70
$582.50
$39.25
$0.72
$3.40
$2.18
$85.00
$3.00
$98.00
$0.87
$35.50
$0.98
$35.50
$0.87
$32.50
$0.87
$32.50
$0.44
$0.49
$0.30
$7.85
$0.74
$0.28
$6.55
$0.28
$6.55
$1.95
$0.35
$4.88
$605.00
######## $4,075.00
######## $6,112.00
$700.00 $890.00
Material
Equip
$166.79
$4.85
$62.30
$1.93
$115.28
$8.05
$8.05
$28.87
$955.24
$198.65
$2.14
$6.58
$9.99
$116.42
$16.08
$141.28
$2.31
$38.42
$3.45
$38.42
$2.78
$33.87
$2.78
$33.87
$0.52
$0.63
$0.34
$6.70
$1.24
$0.29
$5.54
$0.29
$5.54
$2.07
$0.37
$6.10
$1,193.54
########
########
$1,381.79
Total
ECMNo.1
ECMNo.2
ECMNo.3
INSTALLATION
$1,334.32
$1,844.76
$934.55
$616.72
$230.56
Sum
$577,020.85
$577,020.85
$639,047.24
$48,271.20
$33,146.22
$129,902.40
$1,910.49
$29,797.58
$321.26
$986.91
$53,956.96
$4,190.98
$14,469.30
$847.70
$4,800.49
$537.86
$14,227.68
$1,844.08
$4,585.04
$440.29
$5,724.35
$812.84
$1,071.65
$1,293.56
$1,409.91
$321.59
$1,482.25
$689.64
$88.60
$1,775.82
$398.69
$9,499.47
$1,702.73
$27,948.69
$1,193.54
$46,335.23
$185,337.78
$2,763.58
TOTAL
ECI No.
1
1
1
1
1
1
3
1
1
1
1
1
1
1
1
1
1
1
3
3
1
1
3
3
3
3
3
3
1
1
1
3
3
1
1
1
1
1
1
1
98.10%
78.10%
Mat Index Labor Index
WPBCity WPBCity
223
36.45
Equipment
100HPElectricMotors
100HPMotorStarters
ReplaceAerators
Equipment
ManualDO
MechDiffuserMotors
Equipment
Diffusers
Blowers
LDOProbes
Diffusers
MultiStageBlowers
PlantLaborRate
5.0 - O&M COSTS
RealRate
0.025
0.022
CPI
UsefulLife
O&MItem
CollectDOManually
ServiceMotors
$22,594
$20,000
$3,360
$5,832
$12,000
NPV
$362,408
$320,804
$53,895
$93,546
$192,482
ECM
1,2,3
2,3
3
1,2,3
1
Source
SanitaireresponseforLesourdsville,5/minperdiffuser,$6replacementcost,710year
Rohrbacheret.al
Article:"DO"ingmorewithLess,ListPrice:Hach
Rosso,EconomicImplicationsofFinePoreDiffuserAging
1.5%CapitalCost,perRohrbacheret.al
ECMNo.1
ECMNo.2
ECMNo.3
EquipmentReplacementCostsAvoided
RemainingReplaceme Amount Total
NPV
20
1000
$6,025
24
$144,600
$0
20
5
$3,150
24
$75,600
$67,806
5
24
$3,308,388 $2,967,303
20
Cost
Sum
NPV
$3,035,109
$3,035,109
$3,035,109
ECM
1,2,3
1,2,3
1,2,3
Source
RSMeans267113.105260+267113.202100
RSMeans262419.400500
6/17/11Quotef/TSCJacobs
O&MNoLongerNeccesary
Amount
Annual
NPV
ECM
Source
$109
365
$39,913 $640,208
3
30MinsPerBasin,3timesperday
$1,000
24
$24,000 $384,964
1,2,3
1%ofaeratorreplacementcost
Sum
Sum
Annual
NPV
ECMNo.1
$16,426
$263,472
ECMNo.2
$24,426
$391,794
ECMNo.3
$12,127
$194,519
O&MCosts
Annual
Planning
Period
(years)
20
O&MItem
Cost
Amount Unit
ReplaceMembranes
$9.04
20000 EA
ReplaceFilters,Inspectio
$2,500
8 EA
ReplaceSensorCaps
$140
24 EA
CleanMembranes
$36
160 HR
TypicalO&Mbasedon1
$1,500
8
0.047
DiscountRate(interest)
224
KellyTractorQuote
SOURCE
CRANERENTAL40TONCAPACITY
RemoveMechAerator
MechanicalAeratorWeightX9
NewMechanicalAerators
DESCRIPTION
5.1 - O&M COSTS - REPLACE AERATORS
6
QUANTITY
MO
24 EA
4.5 TONS
24 EA
UNIT
100000
Material
35000
$500.00
Labor
Equip
WPBCity WPBCity
TOTAL ECMNo. MatIndexLabor Index
0.964
0.699
$60,000
$8,388
$0
135000
$3,240,000
Sum
ECMNo.1 $3,308,388.00
$10,000.00
$349.50
TotalUnit
6.0 LIFE-CYCLE COST ANALYSIS INPUTS
Current Bond Rate
Cost per
kwH
0.07
0.047
Power
Factor
0.84
Aerator # Nameplat
e HP
A1-1
A1-2
A1-3
A2-1
A2-2
A2-3
A3-1
A3-2
A3-3
A4-1
A4-2
A4-3
B1-11
B1
B1-2
B1-3
B2-1
B2-2
B2-3
B3-1
B3-2
B3-3
B4-1
B4-2
B4-3
CPI
Inflation
0.025
Real Rate
(interest)
0.022
Energy
Inflation
0.00083
Current
HP
Planning
Period
(years)
20
1480.9
If no Amp
Avg
draws,
Basins in
assumed Operation
% of
Nameplat
e
0.85
Avg Low
Speed
Amps
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
7.2
Avg High Months in Avg Amps
Speed low setting
Amps (1)
83.08
65.11
62.02
78.81
64.90
58.07
93.60
63.77
68.32
102.87
65.06
47.88
85.75
63.07
83.25
94.73
64.10
74.63
94.92
62.46
68.99
86.22
63.68
62.43
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Total
83
65
62
79
65
58
94
64
68
103
65
48
86
63
83
95
64
75
95
62
69
86
64
62
1758
Avg KW
Avg
Operating
HP
58.0
45.5
43.3
55.0
45.3
40.6
65.4
44.5
47.7
71.8
45.4
33.4
59.9
44.0
58.1
66.2
44.8
52.1
66.3
43.6
48.2
60.2
44.5
43.6
1227.5
77.8
61.0
58.1
73.8
60.8
54.4
87.6
59.7
64.0
96.3
60.9
44.8
80.3
59.0
77.9
88.7
60.0
69.9
88.9
58.5
64.6
80.7
59.6
58.4
1645.4
Avg
68.6
(1)DatabasedonAugSep2010dailyamperagerecordedbyBrowardCountyNorthRegionalWWTP
Blower #
Nameplat Factor(2)
e HP
Adjusted
HP
#1
#2
#3
OperatingHP/NameplateHP
0.69
Zone1Avg Zone2Avg Zone3Avg
84.2
59.9
61.5
225
kw
hp
230.5927 309.1054
226
6.1.1 LIFE-CYCLE COST ANALYSIS
$377,824
$340,074
$282,334
56%
50%
42%
0
340
384
826
743
617
Current Treatment - 1.0 mg/L
3. Auto DO Control Current Treatment - 1.5 mg/L
1.5 mg/L
Complete NOx
Total (Cumulative) Current Treatment - 1.5 mg/L
10%
15%
17%
$71,123
$102,284
$114,839
($6,104,744)
($5,494,781)
($4,561,846)
$0
($2,511,658)
($2,836,419)
($1,149,177)
($1,652,664)
($1,855,518)
($4,955,567)
($1,330,459)
$130,091
Energy Savings
NPV
$
$
$
4,725,218
4,725,218
4,725,218
12.75
$ 3,475,761
$ 3,475,761
$ 3,475,761
$ 770,854
$ 770,854
$ 770,854
$ 478,602
$ 478,602
$ 478,602
14.85
16.75
20.86
47.07
5.97
5.37
11.59
7.44
6.50
Payback
Capital and
O&M NPV
1481
1481
1481
Current Treatment - 1.0 mg/L
3. Auto DO Control Current Treatment - 1.5 mg/L
1.5 mg/L
Complete NOx
655
737
864
56%
50%
42%
45%
12%
-1%
56%
27%
16%
Annual Savings
%
$377,824
$340,074
$282,334
$306,702
$82,343
($8,051)
$377,824
$184,626
$106 787
$106,787
($6,104,744)
($5,494,781)
($4,561,846)
($4,955,567)
($1,330,459)
$130,091
($6,104,744)
($2,983,123)
($1 725 428)
($1,725,428)
Estimate auto DO control efficiency gain by assuming 1.5 mg/L.
3. Automatic DO
Control (2 mg/L)
Estimate MOV efficiency by modeling diurnal hourly airflow requirements vs. pressure setpoint.
Estimate turbo blower efficiency gain by assuming 72% efficiency with turbo blowers at 3 mg/L average DO.
2. Turbo Blowers
4. Most Open Valve
Blower Control vs/
Pressure Setpoint
Estimate fine bubble efficiency gain assuming plant operators will conservatively maintain DO at average of 3 mg/L
This option assumes conventional multi-stage centrifugal blowers at 62% avg. efficiency.
1. Fine Bubble
Diffusers
$ 16,426
$ 16,426
$ 16,426
$ 24,426
$ 24,426
$
$
24 426
24,426
$(12,127)
$(12,127)
$(12,127)
Annual Savings Energy Savings Annual Change
$
NPV
O&M
Description of Assumptions Technologies - All efficiency and DO values are supported by data compliled in the manuscript.
2. Turbo Blowers
1. Fine Bubble
Diffusers
810
1301
1499
655
1077
1247
Current HP Proposed
HP
1481
1481
1481
1481
1481
1481
Level of Treatment
Current Treatment - 1.0 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Current Treatment - 1.0 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Technology
TABLE 2 - CUMULATIVE GAIN (each proceeding improvement is accumulative of the previous listed)
$263,472
$263,472
$263,472
$391,794
$391,794
$
$
391 794
391,794
$(194,519)
$(194,519)
$(194,519)
Change O&M
NPV
0.07
Current Cost per
kwH
* Current treatment indicates energy improvement realized by treating to partial nitrification at 0.5 mg/L, which is the plants current level of treatment
Complete NOx
Current Treatment - 1.0 mg/L
$0
$155,447
$175,547
0%
23%
26%
155
224
251
Current Treatment - 1.0 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
$306,702
$82,343
($8,051)
2. Turbo Blowers
45%
12%
-1%
670
180
-18
Current Treatment - 1.0 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Ann. Energy
Cost Savings
1. Fine Bubble
Diffusers
% Eff.
Gain
HP
Reduction
Level of Treatment
Technology
TABLE 1 - INCREMENTAL GAIN
This spreadsheet summarizes the results of the life cycle cost analyses.
1
0.025
$ (3,035,109)
$ (3,035,109)
$ (3,035,109)
$ (3,035,109)
$ (3,035,109)
$
$
(3 035 109)
(3,035,109)
$ (3,035,109)
$ (3,035,109)
$ (3,035,109)
$ 6,247,399
$ 6,247,399
$ 6,247,399
$ 6,889,931
$ 6,889,931
$ 6,889,931
$
6 889 931
$ 7,954,846
$ 7,954,846
$ 7,954,846
$ 3,475,761
$ 3,475,761
$ 3,475,761
$ 4,246,615
$ 4,246,615
$ 4,246,615
$
4 246 615
$ 4,725,218
$ 4,725,218
$ 4,725,218
Capital and
O&M NPV
0.022
14.85
16.75
20.86
12.54
33.93
12.75
Payback
Planning
Period
(years)
0.00083
20
Global Cost Calculation Parameters
CPI Inflation
Real Rate
Energy
(interest)
Inflation
Foregone Capital Capital Cost
Replacement
Capital %
Module D savings
309
0.047
Bond Rate
227
6.1.1 LIFE-CYCLE COST ANALYSIS
$377,824
$340,074
$282,334
56%
50%
42%
0
340
384
826
743
617
Current Treatment - 1.0 mg/L
3. Auto DO Control Current Treatment - 1.5 mg/L
1.5 mg/L
Complete NOx
Total (Cumulative) Current Treatment - 1.5 mg/L
10%
15%
17%
$71,123
$102,284
$114,839
($6,104,744)
($5,494,781)
($4,561,846)
$0
($2,511,658)
($2,836,419)
($1,149,177)
($1,652,664)
($1,855,518)
($4,955,567)
($1,330,459)
$130,091
Energy Savings
NPV
$
$
$
3,134,248
3,134,248
3,134,248
7.38
47.23
$ 2,226,282
$ 2,226,282
$ 2,226,282
$ 642,347
$ 642,347
$ 642,347
$ 265,619
$ 265,619
$ 265,619
9.52
10.67
13.07
33.04
4.71
4.25
9.04
5.86
5.13
Payback
Capital and
O&M NPV
1481
1481
1481
Current Treatment - 1.0 mg/L
3. Auto DO Control Current Treatment - 1.5 mg/L
1.5 mg/L
Complete NOx
655
737
864
56%
50%
42%
45%
12%
-1%
56%
27%
16%
Annual Savings
%
$377,824
$340,074
$282,334
$306,702
$82,343
($8,051)
$377,824
$184,626
$106 787
$106,787
($6,104,744)
($5,494,781)
($4,561,846)
($4,955,567)
($1,330,459)
$130,091
($6,104,744)
($2,983,123)
($1 725 428)
($1,725,428)
Estimate auto DO control efficiency gain by assuming 1.5 mg/L.
3. Automatic DO
Control (2 mg/L)
Estimate MOV efficiency by modeling diurnal hourly airflow requirements vs. pressure setpoint.
Estimate turbo blower efficiency gain by assuming 72% efficiency with turbo blowers at 3 mg/L average DO.
2. Turbo Blowers
4. Most Open Valve
Blower Control vs/
Pressure Setpoint
Estimate fine bubble efficiency gain assuming plant operators will conservatively maintain DO at average of 3 mg/L
This option assumes conventional multi-stage centrifugal blowers at 62% avg. efficiency.
1. Fine Bubble
Diffusers
$ 16,426
$ 16,426
$ 16,426
$ 24,426
$ 24,426
$
$
24 426
24,426
$(12,127)
$(12,127)
$(12,127)
Annual Savings Energy Savings Annual Change
$
NPV
O&M
Description of Assumptions Technologies - All efficiency and DO values are supported by data compliled in the manuscript.
2. Turbo Blowers
1. Fine Bubble
Diffusers
810
1301
1499
655
1077
1247
Current HP Proposed
HP
1481
1481
1481
1481
1481
1481
Level of Treatment
Current Treatment - 1.0 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Current Treatment - 1.0 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Technology
TABLE 2 - CUMULATIVE GAIN (each proceeding improvement is accumulative of the previous listed)
$263,472
$263,472
$263,472
$391,794
$391,794
$
$
391 794
391,794
$(194,519)
$(194,519)
$(194,519)
Change O&M
NPV
0.07
Current Cost per
kwH
* Current treatment indicates energy improvement realized by treating to partial nitrification at 0.5 mg/L, which is the plants current level of treatment
Complete NOx
Current Treatment - 1.0 mg/L
$0
$155,447
$175,547
0%
23%
26%
155
224
251
Current Treatment - 1.0 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
$306,702
$82,343
($8,051)
2. Turbo Blowers
45%
12%
-1%
670
180
-18
Current Treatment - 1.0 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Ann. Energy
Cost Savings
1. Fine Bubble
Diffusers
% Eff.
Gain
HP
Reduction
Level of Treatment
Technology
TABLE 1 - INCREMENTAL GAIN
This spreadsheet summarizes the results of the life cycle cost analyses.
0.8
0.025
$ (3,035,109)
$ (3,035,109)
$ (3,035,109)
$ (3,035,109)
$ (3,035,109)
$
$
(3 035 109)
(3,035,109)
$ (3,035,109)
$ (3,035,109)
$ (3,035,109)
$ 4,997,919
$ 4,997,919
$ 4,997,919
$ 5,511,945
$ 5,511,945
$ 5,511,945
$
5 511 945
$ 6,363,877
$ 6,363,877
$ 6,363,877
$ 2,226,282
$ 2,226,282
$ 2,226,282
$ 2,868,629
$ 2,868,629
$ 2,868,629
$
2 868 629
$ 3,134,248
$ 3,134,248
$ 3,134,248
Capital and
O&M NPV
0.022
9.52
10.67
13.07
7.67
18.92
47 97
47.97
7.38
47.23
Payback
Planning
Period
(years)
0.00083
20
Global Cost Calculation Parameters
CPI Inflation
Real Rate
Energy
(interest)
Inflation
Foregone Capital Capital Cost
Replacement
Capital %
Module D savings
309
0.047
Bond Rate
228
6.1.1 LIFE-CYCLE COST ANALYSIS
$377,824
$340,074
$282,334
56%
50%
42%
0
340
384
826
743
617
Current Treatment - 1.0 mg/L
3. Auto DO Control Current Treatment - 1.5 mg/L
1.5 mg/L
Complete NOx
Total (Cumulative) Current Treatment - 1.5 mg/L
10%
15%
17%
$71,123
$102,284
$114,839
($6,104,744)
($5,494,781)
($4,561,846)
$0
($2,511,658)
($2,836,419)
($1,149,177)
($1,652,664)
($1,855,518)
($4,955,567)
($1,330,459)
$130,091
Energy Savings
NPV
$
$
$
7,111,672
7,111,672
7,111,672
22.13
$ 5,349,981
$ 5,349,981
$ 5,349,981
$ 963,614
$ 963,614
$ 963,614
$ 798,077
$ 798,077
$ 798,077
24.15
27.64
35.62
82.31
7.92
7.11
15.69
9.92
8.64
Payback
Capital and
O&M NPV
1481
1481
1481
Current Treatment - 1.0 mg/L
3. Auto DO Control Current Treatment - 1.5 mg/L
1.5 mg/L
Complete NOx
655
737
864
56%
50%
42%
45%
12%
-1%
56%
27%
16%
Annual Savings
%
$377,824
$340,074
$282,334
$306,702
$82,343
($8,051)
$377,824
$184,626
$106 787
$106,787
($6,104,744)
($5,494,781)
($4,561,846)
($4,955,567)
($1,330,459)
$130,091
($6,104,744)
($2,983,123)
($1 725 428)
($1,725,428)
Estimate auto DO control efficiency gain by assuming 1.5 mg/L.
3. Automatic DO
Control (2 mg/L)
Estimate MOV efficiency by modeling diurnal hourly airflow requirements vs. pressure setpoint.
Estimate turbo blower efficiency gain by assuming 72% efficiency with turbo blowers at 3 mg/L average DO.
2. Turbo Blowers
4. Most Open Valve
Blower Control vs/
Pressure Setpoint
Estimate fine bubble efficiency gain assuming plant operators will conservatively maintain DO at average of 3 mg/L
This option assumes conventional multi-stage centrifugal blowers at 62% avg. efficiency.
1. Fine Bubble
Diffusers
$ 16,426
$ 16,426
$ 16,426
$ 24,426
$ 24,426
$
$
24 426
24,426
$(12,127)
$(12,127)
$(12,127)
Annual Savings Energy Savings Annual Change
$
NPV
O&M
Description of Assumptions Technologies - All efficiency and DO values are supported by data compliled in the manuscript.
2. Turbo Blowers
1. Fine Bubble
Diffusers
810
1301
1499
655
1077
1247
Current HP Proposed
HP
1481
1481
1481
1481
1481
1481
Level of Treatment
Current Treatment - 1.0 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Current Treatment - 1.0 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Technology
TABLE 2 - CUMULATIVE GAIN (each proceeding improvement is accumulative of the previous listed)
$263,472
$263,472
$263,472
$391,794
$391,794
$
$
391 794
391,794
$(194,519)
$(194,519)
$(194,519)
Change O&M
NPV
0.07
Current Cost per
kwH
* Current treatment indicates energy improvement realized by treating to partial nitrification at 0.5 mg/L, which is the plants current level of treatment
Complete NOx
Current Treatment - 1.0 mg/L
$0
$155,447
$175,547
0%
23%
26%
155
224
251
Current Treatment - 1.0 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
$306,702
$82,343
($8,051)
2. Turbo Blowers
45%
12%
-1%
670
180
-18
Current Treatment - 1.0 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Ann. Energy
Cost Savings
1. Fine Bubble
Diffusers
% Eff.
Gain
HP
Reduction
Level of Treatment
Technology
TABLE 1 - INCREMENTAL GAIN
This spreadsheet summarizes the results of the life cycle cost analyses.
1.3
0.025
$ (3,035,109)
$ (3,035,109)
$ (3,035,109)
$ (3,035,109)
$ (3,035,109)
$
$
(3 035 109)
(3,035,109)
$ (3,035,109)
$ (3,035,109)
$ (3,035,109)
$ 8,121,618
$ 8,121,618
$ 8,121,618
$ 8,956,910
$ 8,956,910
$ 8,956,910
$
8 956 910
##########
##########
##########
$ 5,349,981
$ 5,349,981
$ 5,349,981
$ 6,313,595
$ 6,313,595
$ 6,313,595
$
6 313 595
$ 7,111,672
$ 7,111,672
$ 7,111,672
Capital and
O&M NPV
0.022
24.15
27.64
35.62
20.92
72.32
22.13
Payback
Planning
Period
(years)
0.00083
20
Global Cost Calculation Parameters
CPI Inflation
Real Rate
Energy
(interest)
Inflation
Foregone Capital Capital Cost
Replacement
Capital %
Module D savings
309
0.047
Bond Rate
APPENDIX B-3 – BROWARD CO. N. REGIONAL WWTP RECORD DRAWINGS
229
230
231
232
233
234
APPENDIX C-1 – PLANTATION REGIONAL WWTP PRELIMINARY DESIGN DRAWINGS
235
236
237
238
239
240
APPENDIX C-2 – PLANTATION REGIONAL WWTP DATA SPREADSHEETS
241
PLANTATION- ENERGY EFFICIENCY ANALYSIS SPREADSHEETS
SPREADSHEET TABLE OF CONTENTS
1.1 INFLUENT EFFLUENT SPECIFIER
1.2 FLOW PROJECTION
2.0 AERATION CALCULATIONS - GLOBAL PARAMETERS
2.1 AERATION CALCULATIONS - DIFFUSERS
2.2 AERATION CALCULATIONS - TURBO BLOWERS
2.3 AERATION CALCULATIONS - 1.5 MG/L DO CONTROL
3.1 SYSTEM DESIGN - SIZE PIPES
3.2 SYSTEM DESIGN - ESTIMATE LOSSES THROUGH PIPES
3.4 SYSTEM DESIGN - BLOWER DESIGN
3.3 SYSTEM DESIGN - SYSTEM CURVE
4.0 - COST ESTIMATE - SUMMARY
4.1 - COST ESTIMATE - DEMOLITION
4.2 - COST ESTIMATE - BLOWERS
4.3 - COST ESTIMATE - DIFFUSERS
4.4 - COST ESTIMATE - STRUCTURAL
4.5 - COST ESTIMATE - MECHANICAL PIPING
4.6 - COST ESTIMATE - INSTRUMENTATION
4.7 - COST ESTIMATE - ELECTRICAL
5.0 - O&M COSTS
5.1 - O&M COSTS - REPLACE AERATORS
6.0LIFECYCLECOSTANALYSISINPUTS
6.1.1LIFECYCLECOSTANALYSIS
6.1.2LIFECYCLECOSTANALYSIS(LOWRANGE)
6.1.3LIFECYCLECOSTANALYSIS(HIGHRANGE)
6.2LIFECYCLECOSTANALYSISSUMMARY
242
243
1.1 INFLUENT EFFLUENT SPECIFIER
2007 - 2009 3 Year Average - Adjusted to Design Flow of 16.9 MGD
PRIMARY
PRIMARY
INF FLOW
EFF CBOD
EFF TSS
EFF CBOD EFF WAS VSS INF TKN EFF NH3
MGD
LBS
LBS
LBS.
LBS
LBS
LBS.
12.66
4,467
5,285
99
3,030
1,823
0
18.90
9,879
8,961
230
3,789
2,475
0
21.36
15,448
13,474
341
4,340
2,976
0
29.11
30,033
81,609
665
5,531
3,979
0
Min Day
ADF
MMADF
Max Day
PRIMARY
EFF TSS
EFF CBOD EFF WAS VSS INF TKN EFF NH3
LBS
LBS.
LBS
LBS
LBS.
3,974
74
2,278
1,370
0
6,737
173
2,849
1,861
0
10,131
256
3,263
2,237
0
61,358
500
4,159
2,992
0
Min Day
ADF
MMADF
Max Day
PRIMARY
EFF CBOD
LBS
3,359
7,427
11,614
22,580
2007 - 2009 3 Year Average - Adjusted to 2011-2031 ADF
PRIMARY
PRIMARY
INF FLOW
EFF CBOD
EFF TSS
EFF CBOD EFF WAS VSS INF TKN EFF NH3
MGD
LBS
LBS
LBS.
LBS
LBS
LBS.
10.44
3,682
4,356
81
2,498
1,502
0
15.58
8,142
7,385
190
3,123
2,040
0
17.60
12,732
11,106
281
3,577
2,453
0
23.99
24,754
67,264
548
4,559
3,280
0
Min Day
ADF
MMADF
Max Day
INF FLOW
MGD
9.52
14.21
16.06
21.88
2007 - 2009 3 Year Average
This spreadsheet is a continuation of the previous Influent-Effluent Summary spreadsheet. All the values on
this spreadsheet are inserted directly into the 3.1 - 3.6 Aeration Calculation spreasheets that follow.
DO
mg/L
1.5
Avg
SRT
Days
30.0
1.2 FLOW PROJECTION
This spreadsheet summarizes the Flow Projection through the 20 year design horizon
Year
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
Plantation Wastewater
Population Generation
86208
161
87219.2
161
88230.4
161
89241.6
161
90252.8
161
91264
161
92275.2
161
93286.4
161
94297.6
161
95308.8
161
97191
161
98202.2
161
99213.4
161
100224.6
161
101235.8
161
102277
161
103288.2
161
104299.4
161
105310.6
161
106322
161
106727
161
Total
Annual
(MG)
AADF
(MGD)
5,066
5,125
5,185
5,244
5,304
5,363
5,423
5,482
5,541
5,601
5,711
5,771
5,830
5,890
5,949
6,010
6,070
6,129
6,189
6,248
6,272
13.88
14.04
14.21
14.37
14.53
14.69
14.86
15.02
15.18
15.34
15.65
15.81
15.97
16.14
16.30
16.47
16.63
16.79
16.96
17.12
17.18
15.58
Population Projection
110000
105000
Capita
100000
95000
90000
85000
80000
2005
2010
2015
2020
Year 2025
2030
244
2035
2.0 AERATION CALCULATIONS - GLOBAL PARAMETERS
Spreadsheet 3.1 - 3.5 calculates the amount of air and horsepower need to treat various flowrates and loading rates throughout the plant.
3.0 Aeration Calculations - Global Paramters spreadsheet specifies the golbale variables that are in put to each aeration calculation spreadsheet.
AreaunderAerationperBasin(ft2)=
#ofbasinsonline
SidewaterDepth(ft)=
DiffuserSubmergence(ft)=
EquationForSystemCurve
NumberofDiffusersperBasin=
SiteElevation(ftaboveMSL)=
MinimumMixingRequirements(scfm/ft2)
MinimumFlowperDiffuser(scfm)
MaximumFlowperDiffuser(scfm)
GeneralTemperature
Beta(unitless)=
Patm(psi)=
Patm(middepth,ftwc/2/2.31psi,psi)=
Csth(perAppDformechaer,mg/L)=
Cs20([email protected],1atm,mg/L)=
CstH*(mg/L)=
DensAir(lb/cf)=
MassFractionO2inair=
Alpha=
Alphaforcompletenitrification=
AverageofminimumSOTE
12675
3
12
11
2.51E09
2000
10
0.12
0.5
3.0
25
0.98
14.7
2.38
8.24
9.08
9.57
0.0750
0.2315
0.43
0.5
a
0.59
0.88
1.00
1.18
1.47
1.75
2.06
2.35
2.50
2.65
2.94
3.00
Air
Flow
(SCFM/Unit)
0.59
0.88
1.00
1.18
1.47
1.75
2.06
2.35
2.50
2.65
2.94
3.00
Tau (dimensionless)
1.6
1.4
1.24
1.12
1
0.91
0.83
0.77
0.71
3
1.5
0.62
0.72
0.5
1.5
Doldpredictedyield
nonfullynitrifyingassumeSRT4days
unitless
psi
psi
mg/L
mg/L
0.52
fup
VSS/TSS
0.08 Biowinsettleddefault
0.85
lb/cf
1.6
1.2
y = 4.08E-04x2 - 3.82E-02x + 1.60E+00
R² = 9.98E-01
0.8
0.4
0
5
10
15
20
25
30
35
40
Temperature (C)
Average
SOTE
(%)
46.83
42.50
41.26
39.89
38.48
38.33
37.52
37.21
37.07
36.87
36.69
36.66
Submergence = 20
20.00-ft
00 ft
Minimum Average
Minimum
SOTE
SOTE
SOTE
(%)
(%/ft)
(%/ft)
41.25
37.98
37.37
36.95
35.92
35.90
35.39
35.35
35.20
35.18
35.01
35.00
2.34
2.13
2.06
1.99
1.92
1.92
1.88
1.86
1.85
1.84
1.83
1.83
2.06
1.90
1.87
1.85
1.80
1.80
1.77
1.77
1.76
1.76
1.75
1.75
Submergence = 17.33-ft
Average Minimum Average
Minimum
SOTE
SOTE
SOTE
SOTE
(%)
(%)
(%/ft)
(%/ft)
40.58
36.83
35.75
34.56
33.34
33.21
32.51
32.24
32.12
31.95
31.79
31.77
35.74
32.91
32.38
32.02
31.12
31.11
30.67
30.63
30.57
30.48
30.34
30.33
2.34
2.13
2.06
1.99
1.92
1.92
1.88
1.86
1.85
1.84
1.83
1.83
2.06
1.90
1.87
1.85
1.80
1.80
1.77
1.77
1.76
1.76
1.75
1.75
Results from trendline in chart
Constantsforthefollowingformula:ax4+bx3+cx2+dx+e
Avg SOTE "a"
Avg SOTE
0.0514
Avg SOTE
0.4603
Avg SOTE
1.5405
Avg SOTE
2.3473
SOTEvs.SCFM/diffuser
Sanitaire SilverSeriesII9"MembraneDiscDiffuser
Min SOTE
3.2779
Min SOTE
0.0467
Min SOTE
0.4015
Min SOTE
1.2724
Min SOTE
1.7984
2.50
SOTE%/footofdiffusersubmergence
Air
Flow
(SCFM/Unit)
ManualDOControlO2(mg/L)
AutoDOControlO2(mg/L)
MSCBlowerEfficiency
TurboBlowerEfficiency
2ConcentrationatMaxDay(mg/L)
PreECMExistingDO(mg/L)
Tau vs. Temperature
Figure 2.10Tau
Temp.
0
5
10
15
20
25
30
35
40
ft
ft
*x^2
2.40
2.30
AverageSOTE
Min.SOTE
Poly.(AverageSOTE)
2.7526
2.20
Poly.(Min.SOTE)
2.10
y=0.0514x4 0.4603x3 +1.5405x2 2.3473x+3.2779
R²=0.9987
2.00
1.90
1.80
y=0.0467x4 0.4015x3 +1.2724x2 1.7984x+2.7526
R²=0.9944
1.70
1.60
1.50
0.00
0.50
1.00
1.50
2.00
SCFM/Diffuser
245
2.50
3.00
3.50
246
2.1 AERATION CALCULATIONS - DIFFUSERS
ADF + Nit
0.90
0.34
54,835
1,726
18,511
1,452
2,193
6 000
6,000
6 000
6,000
1.09
1.75
1.09
1.75
0.00
0.00
22.30%
20.94%
6512
10475
27.6106 26.90513
0.90
0.29
36,310
472
10,541
964
6,000
6
000
0.64
0.64
0.00
25.28%
3813
0.90
0.34
24,099
1,129
8,135
Current
9.52
3
3,359
74
2,008
1,370
0
3
25
0.5
a
Min Day
MinimumMixingAirflowRequirement(scfm)
MinimumMixingRequirementMet?
IsDiffuserFlowWithinRange?
AllEquationsreferenced,(Metcalf&Eddy,2003)
7. Checks
4563
TRUE
TRUE
4563
TRUE
TRUE
4563
TRUE
TRUE
4563
FALSE
TRUE
6.PowerDemandCalculations
Pw=[(W*R*T1)/(550*n*Eff)]*[(P2/P1)^.2831]
Pw(blowerhorsepowerrequired)=
291
236
389
137
DynamicLosses
0.16
0.11
0.28
0.04
WiretoAirEff=
0.62
0.62
0.62
0.62
e=100%*((P1+14.7)/14.7)0.2831)/1(P2+14.7)/14.7)0.2831)/2)/((P1+14.7)/14.7)0.2831)/2
5.AerationDemandCalculations
Airrequiredat100%Efficiency=
Total Number of Diffusers =
TotalNumberofDiffusers=
DiffuserFlow,scfm/diffuser(macroinput)=
DiffuserFlow,scfm/diffuser=
Difference=
SOTEatDesSubmandDiffFlow=
SCFM=SOTR/(SOTE*60min/hr*24hr/day
1,720
6 000
6,000
1.33
1.33
0.00
21.55%
7980
27.38324
0.90
0.43
42,992
4.SORCalculations
Tau=
AOR/SOR={[(Beta*CstH*CL)/Cs20][1.024^(
SOR=
Eq555
1,726
18,511
3.AORCalculations
Eq.818 TKNinfNH3eff0.12(PxBio)=NOx=
Eq.817 1.6*1.16*(SoS)1.42(PxBio)+4.33(NOx)=AO
MGD
NumberofBasinsOnline
So=CBODinf
S=CBODeff
Eq.815(wherehilighted),PxBio=
TKN=
NH3eff=
CL(operat.oxygenconcentration,mg/L)=
T(degC)
Alpha=
AverageofminimumSOTE
2.Inputs
ADF
1131ADF 1131ADF 1131ADF
15.58
15.58
15.58
3
3
3
8,142
8,142
8,142
190
190
190
2,620
4,409
2,620
2,040
2,040
2,040
0
1039
0
1.5
3
3
25
25
25
0.5
0.43
0.5
a
a
a
Cur Treat
4563
TRUE
TRUE
200
0.08
0.62
1,282
6,000
6
000
0.93
0.93
0.00
23.07%
5556
0.90
0.34
32,053
1,502
10,820
Design
12.66
3
4,467
99
2,671
1,823
0
3
25
0.5
a
Min Day
ADF
4563
TRUE
TRUE
490
0.42
0.62
2,661
6,000
6
000
2.15
2.15
0.00
20.63%
12896
0.90
0.34
66,530
2,094
22,459
4563
TRUE
TRUE
490
0.42
0.62
2,661
6,000
6
000
2.15
2.15
0.00
20.63%
12896
0.90
0.34
66,530
2,094
22,459
Design Des+Nit
18.90
18.90
3
3
9,879
9,879
230
230
3,179
3,179
2,475
2,475
0
0
3
3
25
25
0.5
0.5
a
a
ADF
MMADF
4563
TRUE
TRUE
815
0.99
0.62
4,062
6,000
6
000
3.30
3.30
0.00
20.49%
19827
0.90
0.34
101,558
2,565
34,283
4563
TRUE
TRUE
815
0.99
0.62
4,062
6,000
6
000
3.30
3.30
0.00
20.49%
19827
0.90
0.34
101,558
2,565
34,283
Des
Des+Nit
21.36
21.36
3
3
15,448
15,448
341
341
3,423
3,423
2,976
2,976
0
0
3
3
25
25
0.5
0.5
a
a
MMADF
Spreadsheet 3.1 - 3.5 calculates the amount of air and horsepower need to treat various flowrates and loading rates throughout the plant.
2.1 Aeration Calculations - Diffusers spreadsheet predicts the efficiency improvement by upgrading to fine bubble diffusers with no other ECMs.
MDF
4563
TRUE
TRUE
1056
1.46
0.62
6,016
6,000
6
000
4.03
4.03
0.00
24.90%
24157
0.90
0.49
150,402
4,124
74,084
4563
TRUE
TRUE
989 hp
1.33 psi
0.62 Unitless
5,286
6,000
6
000
3.83
3.84
0.00
22.97%
23010
0.90
0.49
132,158 (lb/day)
3,568 (lb/day)
65,097 (lb/day)
Des
Des+Nit
29.11
29.11
3
3
30,033
30,033 (lb/day)
665
665 (lb/day)
1,210
3,423 (lb/day)
3,979
3,979 (lb/day)
0
0 (lb/day)
0.5
0.5 mg/L
25
25 degC
0.5
0.5 unitless
a
a
MDF
Cur Treat
7803
FALSE
TRUE
279
0.16
0.62
1,796
10,500
10
500
1.33
0.73
0.61
23.50%
7,645
0.90
0.38
44,909
1,574
16,886
20072009
14.21
3
7,427
173
2,390
1,861
0
1.5
25
0.43
a
247
2.2 AERATION CALCULATIONS - TURBO BLOWERS
251
0.16
0.72
6.PowerDemandCalculations
Pw=[(W*R*T1)/(550*n*Eff)]*[(P2/P1)^.2831]
Pw(blowerhorsepowerrequired)=
DynamicLosses
WiretoAirEff=
AllEquationsreferenced,(Metcalf&Eddy,2003)
4563
TRUE
TRUE
1,720
6 000
6,000
1.33
1.33
0.00
21.55%
7980
5.AerationDemandCalculations
Airrequiredat100%Efficiency=
Total Number of Diffusers =
TotalNumberofDiffusers=
DiffuserFlow,scfm/diffuser(macroinput)=
DiffuserFlow,scfm/diffuser=
Difference=
SOTEatDesSubmandDiffFlow=
SCFM=SOTR/(SOTE*60min/hr*24hr/day
MinimumMixingAirflowRequirement(scfm)
MinimumMixingRequirementMet?
IsDiffuserFlowWithinRange?
0.90
0.43
42,992
4.SORCalculations
Tau=
Eq555
AOR/SOR={[(Beta*CstH*CL)/Cs20][1.024^(
SOR=
7. Checks
1,726
18,511
3.AORCalculations
Eq.818 TKNinfNH3eff0.12(PxBio)=NOx=
Eq.817 1.6*1.16*(SoS)1.42(PxBio)+4.33(NOx)=AO
MGD
NumberofBasinsOnline
So=CBODinf
S=CBODeff
Eq.815(wherehilighted),PxBio=
TKN=
NH3eff=
CL(operat.oxygenconcentration,mg/L)=
T(degC)
Alpha=
AverageofminimumSOTE
2.Inputs
ADF
ADF
0.90
0.34
54,835
1,726
18,511
4563
TRUE
TRUE
240
0.15
0.72
4563
TRUE
TRUE
335
0.28
0.72
1,660
2,193
6,000
6
000
6 000
6,000
1.28
1.75
1.28
1.75
0.00
0.00
21.68%
20.94%
7655
10475
31.86246 31.24467
0.90
0.29
41,495
565
12,047
1131ADF 1131ADF 1131ADF
15.58
15.58
15.58
3
3
3
8,142
8,142
8,142
190
190
190
2,620
3,633
2,620
2,040
2,040
2,040
0
1039
0
1.5
3
3
25
25
25
0.5
0.43
0.5
a
a
a
Cur Treat
4563
FALSE
TRUE
118
0.04
0.72
964
6,000
6
000
0.64
0.64
0.00
25.28%
3813
0.90
0.34
24,099
1,129
8,135
Current
9.52
3
3,359
74
2,008
1,370
0
3
25
0.5
a
Min Day
4563
TRUE
TRUE
173
0.08
0.72
1,282
6,000
6
000
0.93
0.93
0.00
23.07%
5556
0.90
0.34
32,053
1,502
10,820
Design
12.66
3
4,467
99
2,671
1,823
0
3
25
0.5
a
Min Day
ADF
4563
TRUE
TRUE
422
0.42
0.72
2,661
6,000
6
000
2.15
2.15
0.00
20.63%
12896
0.90
0.34
66,530
2,094
22,459
4563
TRUE
TRUE
422
0.42
0.72
2,661
6,000
6
000
2.15
2.15
0.00
20.63%
12896
0.90
0.34
66,530
2,094
22,459
Design Des+Nit
18.90
18.90
3
3
9,879
9,879
230
230
3,179
3,179
2,475
2,475
0
0
3
3
25
25
0.5
0.5
a
a
ADF
Spreadsheet 2.1 - 2.3 calculates the amount of air and horsepower need to treat various flowrates and loading rates throughout the plant.
2.2 Aeration Calculations -Turbo Blowers spreadsheet predicts efficiency improvement of fine bubble diffusers with turbo blowers.
MMADF
4563
TRUE
TRUE
702
0.99
0.72
4,062
6,000
6
000
3.30
3.30
0.00
20.49%
19827
0.90
0.34
101,558
2,565
34,283
4563
TRUE
TRUE
702
0.99
0.72
4,062
6,000
6
000
3.30
3.30
0.00
20.49%
19827
0.90
0.34
101,558
2,565
34,283
Des
Des+Nit
21.36
21.36
3
3
15,448
15,448
341
341
3,423
3,423
2,976
2,976
0
0
3
3
25
25
0.5
0.5
a
a
MMADF
MDF
4563
TRUE
TRUE
909
1.46
0.72
6,016
6,000
6
000
4.03
4.03
0.00
24.90%
24157
0.90
0.49
150,402
4,124
74,084
4563
TRUE
TRUE
851 hp
1.33 psi
0.72 Unitless
5,286
6,000
6
000
3.83
3.84
0.00
22.97%
23010
0.90
0.49
132,158 (lb/day)
3,568 (lb/day)
65,097 (lb/day)
Des
Des+Nit
29.11
29.11
3
3
30,033
30,033 (lb/day)
665
665 (lb/day)
1,210
3,423 (lb/day)
3,979
3,979 (lb/day)
0
0 (lb/day)
0.5
0.5 mg/L
25
25 degC
0.5
0.5 unitless
a
a
MDF
248
2.3 AERATION CALCULATIONS - 1.5 MG/L DO CONTROL
251
0.16
0.72
6.PowerDemandCalculations
Pw=[(W*R*T1)/(550*n*Eff)]*[(P2/P1)^.2831]
Pw(blowerhorsepowerrequired)=
DynamicLosses
WiretoAirEff=
AllEquationsreferenced,(Metcalf&Eddy,2003)
4563
TRUE
TRUE
1,720
6 000
6,000
1.33
1.33
0.00
21.55%
7980
5.AerationDemandCalculations
Airrequiredat100%Efficiency=
Total Number of Diffusers =
TotalNumberofDiffusers=
DiffuserFlow,scfm/diffuser(macroinput)=
DiffuserFlow,scfm/diffuser=
Difference=
SOTEatDesSubmandDiffFlow=
SCFM=SOTR/(SOTE*60min/hr*24hr/day
MinimumMixingAirflowRequirement(scfm)
MinimumMixingRequirementMet?
IsDiffuserFlowWithinRange?
0.90
0.43
42,992
4.SORCalculations
Tau=
Eq555
AOR/SOR={[(Beta*CstH*CL)/Cs20][1.024^(
SOR=
7. Checks
1,726
18,511
3.AORCalculations
Eq.818 TKNinfNH3eff0.12(PxBio)=NOx=
Eq.817 1.6*1.16*(SoS)1.42(PxBio)+4.33(NOx)=AO
MGD
NumberofBasinsOnline
So=CBODinf
S=CBODeff
Eq.815(wherehilighted),PxBio=
TKN=
NH3eff=
CL(operat.oxygenconcentration,mg/L)=
T(degC)
Alpha=
AverageofminimumSOTE
2.Inputs
ADF
ADF
0.90
0.43
42,992
1,726
18,511
4563
TRUE
TRUE
176
0.08
0.72
4563
TRUE
TRUE
251
0.16
0.72
1,301
1,720
6,000
6
000
6 000
6,000
0.94
1.33
0.94
1.33
0.00
0.00
22.97%
21.55%
5664
7980
32.19375 31.79986
0.90
0.37
32,533
565
12,047
1131ADF 1131ADF 1131ADF
15.58
15.58
15.58
3
3
3
8,142
8,142
8,142
190
190
190
2,620
3,633
2,620
2,040
2,040
2,040
0
1039
0
1.5
1.5
1.5
25
25
25
0.5
0.43
0.5
a
a
a
Cur Treat
4563
FALSE
FALSE
85
0.02
0.72
756
6,000
6
000
0.46
0.46
0.00
27.27%
2771
0.90
0.43
18,894
1,129
8,135
Current
9.52
3
3,359
74
2,008
1,370
0
1.5
25
0.5
a
Min Day
4563
FALSE
TRUE
124
0.04
0.72
1,005
6,000
6
000
0.67
0.67
0.00
24.93%
4031
0.90
0.43
25,130
1,502
10,820
Design
12.66
3
4,467
99
2,671
1,823
0
1.5
25
0.5
a
Min Day
ADF
4563
TRUE
TRUE
316
0.25
0.72
2,086
6,000
6
000
1.65
1.65
0.00
21.03%
9921
0.90
0.43
52,161
2,094
22,459
4563
TRUE
TRUE
316
0.25
0.72
2,086
6,000
6
000
1.65
1.65
0.00
21.03%
9921
0.90
0.43
52,161
2,094
22,459
Design Des+Nit
18.90
18.90
3
3
9,879
9,879
230
230
3,179
3,179
2,475
2,475
0
0
1.5
1.5
25
25
0.5
0.5
a
a
ADF
MMADF
4563
TRUE
TRUE
527
0.62
0.72
3,185
6,000
6
000
2.61
2.61
0.00
20.31%
15679
0.90
0.43
79,623
2,565
34,283
4563
TRUE
TRUE
527
0.62
0.72
3,185
6,000
6
000
2.61
2.61
0.00
20.31%
15679
0.90
0.43
79,623
2,565
34,283
Des
Des+Nit
21.36
21.36
3
3
15,448
15,448
341
341
3,423
3,423
2,976
2,976
0
0
1.5
1.5
25
25
0.5
0.5
a
a
MMADF
Spreadsheet 2.1 - 2.3 calculates the amount of air and horsepower need to treat various flowrates and loading rates throughout the plant.
2.3 Aeration Calculations -2 MG/L Do Control spreadsheet predicts efficiency improvement of fine bubble diffusers, turbo blowers, and DO Control.
MDF
4563
TRUE
TRUE
909
1.46
0.72
6,016
6,000
6
000
4.03
4.03
0.00
24.90%
24157
0.90
0.49
150,402
4,124
74,084
4563
TRUE
TRUE
851 hp
1.33 psi
0.72 Unitless
5,286
6,000
6
000
3.83
3.84
0.00
22.97%
23010
0.90
0.49
132,158 (lb/day)
3,568 (lb/day)
65,097 (lb/day)
Des
Des+Nit
29.11
29.11
3
3
30,033
30,033 (lb/day)
665
665 (lb/day)
1,210
3,423 (lb/day)
3,979
3,979 (lb/day)
0
0 (lb/day)
0.5
0.5 mg/L
25
25 degC
0.5
0.5 unitless
a
a
MDF
(0.5mg/L)
249
3.1 SYSTEM DESIGN - SIZE PIPES
6.5 psig
6.716900698
0.33902046
Airflows
10,528 scfm
11,734 scfm
20,074 scfm
0.41
175 F
0.33
0.67
4,957
20
2,272
Split 2
Air Flow to Zones 2, 3
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
Split 3
0.67
7,435
24
2,367
ea
scfm
in
fpm
ea
scfm
in
fpm
Max. Month
11,153 scfm
30 in
2,272 fpm
Flow to Aeration Trains 1 & 2:
Air Flow Per Treatment Train:
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
Total Air Flow:
Minimum Pipe Size to Meet Velocity Criteria:
Actual Velocity:
Average Annual Air Flow:
Maximum Month Air Flow:
Maximum Day Air Flow:
Pdischarge =
Vp act
VP std
RH Inlet =
Tdischarge=
10006 acfm
11153 acfm
19079 acfm
This spreadsheet demonstrates the sizing of the proposed aeration process air pipes at Train 1.
0.33
3,887 fpm
0.67 ea
8,480 scfm
4,049 fpm
0.67 ea
12,720 scfm
3,887 fpm
Peak Day
19,079 scfm
Pipe Dia
In
1-3
4 - 10
12 - 24
30 - 60
ICFM
From 5th Order Curve Fit
Figure 4-1 - Saturation W
Water vapor pressure (ps
be calculated with the foll
VP = a*T5 +b*T4 +c*T3 +
Where:
a = 2.27E-11
b = -2.5E-10
c = 5.08E-07
d = 7.42E-06
e = 0.001485
f = 0.016274
§ T 460 · ª PS RH S * VPS º
¸¸ «
SCFM * ¨¨ A
»
© TS 460 ¹ ¬ PI RH A * VPA ¼
Velocity
fpm
1200 - 1800
1800 - 3000
2700 - 4000
3800 - 6500
Per Table 5-28 - Metcalf & Eddy
Typical air velocities in aeration
header pipes
250
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(1)
(2)
(3)
(4)
(5)
(6)
(8)
(9)
(1)
(2)
(3)
3.2 SYSTEM DESIGN - ESTIMATE LOSSES THROUGH PIPES
F
psig
ft2/s
inches
lb/scf
psia
f
for st. steel
14" X 30" Bend
16" Blower Outlet
30" Bend, 30" x 18" Red
30" Air Piping
18" Air Piping
18" Bend, 18" x 14" Red
14" Air Piping
14" x 12" Red
12" Bend, 12" x 10" Tee
12" Air Piping
10" Air Piping/Diff. Head 10" Bend
Loss Through Diffuser Recommended per Sanitaire
Diffuser Loss w/ Age
7.09 psi
3611.749
4109.367
3804.97
4193.232
2853.727
2054.684
Blower Discharge Pressure Required =
16
30
18
14
12
10
1.47 psi
5042.95
20171.8
6723.94
4482.62
2241.31
1120.66
5.63 psi
6618.943
13237.89
8825.258
4412.629
4412.629
2206.314
13
150
105
66
95
20
4.64E+06
1.14E+08
4.44E+07
2.39E+07
2.01E+07
2.54E+06
Cell M
Cell N
Cell O
0.000003
0.000002
0.000003
0.000004
0.000004
0.000005
H/D
Aeration System Losses
Blower Piping Inlet Losses
Q (acfm) Diam (in)Vel (fpm) Length (ft) Re
Static Pressure =
6039.3
24157
8052.4
5368.27
2684.13
1342.07
Q (scfm) Q (icfm)
24157 scfm
26475.77 icfm
20171.81 acfm
1.093232
1.415231
1.213333
1.473585
0.6825
0.353808
hi (inH2O)
Where:
a=
b=
c=
d=
e=
f=
0.099267
0.56819
0.626206
0.654588
0.521569
0.086663
15
14
hL (inH2O)
2.27E-11
-2.5E-10
5.08E-07
7.42E-06
0.001485
0.016274
5.2
0.55
0.55
0.3
2.1
0.3
5.684809
0.778377
0.667333
0.442076
1.433249
0.106142
5.784075
1.346568
1.293538
1.096664
1.954818
0.192805
15
14
0.208661
0.048577
0.046664
0.039562
0.07052
0.006955
0.541126
0.505051
Minor Losses (est.) Total Losses
6K
hL (inH2O) hL (inH2O) hL (psi)
From 5th Order Curve Fit of Stephenson/Nixon,
Figure 4-1 - Saturation Water Vapor Pressure,
Water vapor pressure (psi) vs temperature (°F) can
be calculated with the following formula
VP = a*T5 +b*T4 +c*T3 +d*T2 +e*T+f
Swamee Jain
Pressure V
Darcy Weisbach
0.009
0.007
0.007
0.008
0.008
0.010
fcalc
§ T 460 · ª PS RH S * VPS º
SCFM * ¨¨ A
»
¸¸ «
© TS 460 ¹ ¬ PI RH A * VPA ¼
0.16 psi
ICFM
Qprocess
Qprocess
Qprocess
Total Blower Piping Discharge Losses =
16
30
18
14
12
10
Diam (in)
Cummulative Loss
hL (inH2O)
hL (psi)
3
0.10823
1.5
0.05411
12
0.4329
Total Blower Piping Inlet Losses =
14.53
101
0.41
175
9.05
0.000225
0.00005
0.1006697
6.7169007
0.3390205
0.9780971
16" Blower Outlet
30" Air Piping
18" Air Piping
14" Air Piping
12" Air Piping
10" Air Piping/Diff. Head
Loss Through Diffuser/Orifice
Diffuser Fouling Loss
Description
Inlet Filter Loss
Inlet Silencer Loss
Loss across diffuser
Description
P inlet =
T inlet =
RH Inlet =
Tdischarge=
Pdischarge =
=
H=
J act=
Vp act
VP std
Vp inlet
This spreadsheet demonstrates the calculation of worst-case headloss through the proposed aeration piping system
5.784075
7.130643
8.424181
9.520845
11.47566
11.66847
26.66847
40.66847
0.208661
0.257238
0.303903
0.343465
0.413985
0.42094
0.962066
1.467116
Cummulative Loss
hL (inH2O) hL (psi)
3.3 SYSTEM DESIGN - SYSTEM CURVE
This spreadsheet displays the system curve of the aeration blower piping system. The data is poltted on graphs on the following spreadsheets.
SCFM
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
12000
13000
14000
15000
16000
17000
18000
19000
20000
21000
PSI
5.63
5.63
5.64
5.65
5.67
5.69
5.72
5.75
5.79
5.83
5.88
5.93
5.99
6.05
6.12
6.19
6.27
6.35
6.44
6.54
6.63
6.74
6.80
y=2.51E09x2 +5.63E+00
R²=1.00E+00
6.60
6.40
6.20
Series1
6.00
Poly.(Series1)
5.80
5.60
5.40
0
5000
251
10000
15000
20000
25000
3.4 SYSTEM DESIGN - BLOWER DESIGN
This spreadsheet details the multiple temperature, pressure, and flow related conditions that are taken into account to correctly size the blowers
Historical Weather Data for West Palm Beach
Data Source
Parameter
ASHRAE
Extreme (1%)
Design Temperature (Wet Bulb) (°F):
Conditions for
WPB
NOAA
Records for
Maximum Temperature (°F):
West Palm
Beach
Resulting Relative Humidity*:
Blower Inlet and Discharge Pressures
Ambient Barometric Pressure (psia)
Blower Inlet Pressure (psia)
System Design Pressure Loss (psig):
Estimated Discharge Pressure (psia):
Value
80
101
41%
From 5th Order Curve Fit of Stephenson/Nixon,
Figure 4-1 - Saturation Water Vapor Pressure,
Water vapor pressure (psi) vs temperature (°F) can
be calculated with the following formula:
5
4
3
2
VP = a*T +b*T +c*T +d*T +e*T+f
Where:
a = 2.27E-11 32°F T 140°F
b = -2.5E-10
c = 5.08E-07
d = 7.42E-06
e = 0.001485
f = 0.016274
-------------->
14.696
14.53
7.09
21.79
Correct Blower Florate Design Point for Extreme Hot Weather Condition
Std. Cond.
Design
Parameter
Inlet Temperature (°F):
68.0
101.0
Absolute Inlet Temperature (°R):
528
561
Relative Humidity:
36%
41%
Vapor Pressure (psi):
0.3390
0.9781
Barometric Pressure (psi):
14.70
14.53
1.00
1.10 -------------->
Density Correction Factor (ICFM/SCFM):
ICFM
Maximum Day Air Flow (CFM):
24,157
26,469
Correct Blower Pressure Design Point for Extreme Hot Weather Condition
k-1/k
0.283
0.283
7.09
Approximate Site Discharge Pressure (psig):
Equivalent Air Pressure (EAP) (psig):
7.87 --------------> EAP
Size Blowers
Minimum Mixing Air Flow (SCFM):
Average Annual Air Flow (SCFM):
Maximum Month Air Flow (SCFM):
Maximum Day Air Flow (SCFM):
Conversion Factor (ICFM/SCFM):
Number of Blowers:
Ratio of Large To Small
Small Blower Capacity (ICFM): (1 x)
Large Blower Capacity (ICFM): (3 x)
Firm Blower Capacity (ICFM):
Is Max. Month Requirement met w/ Firm Capacity?
Required Blower Turn Down to Meet Minimum Flow:
Site Barometric Pressure (psia):
Small Blower Rating Point (SCFM)
Large Blower Rating Point (SCFM)
Additional Information
4,563
9,921
10,870 icfm
15,679
17,180 icfm
24,157
26,469 icfm
1.10
4
1.5
5,000
4,563 SCFM
7,000
6,389 SCFM
17,000
No
34.8%
14.70
5,000 @ 7.87 psig 200 HP
7,000 @ 7.87 psig 300 HP
§ T 460 · ª PS RH S * VPS º
¸¸ «
SCFM * ¨¨ A
»
© TS 460 ¹ ¬ PI RH A * VPA ¼
PS ­
°§ Ti
®¨¨
°© TS
¯
23728.7277
=IF(C38=2,ROUND(D36/2.5,-2),IF(C38=3,ROUND(D36/3.5,-2),IF(C38=4,ROUND(D36/5.5,-2),IF(C38=5,ROUND(D36/7,-2),0)))
252
k
k 1
ª
º ½ k 1
· «§ PDS · k
» °
¸¸ «¨¨ P ¸¸ 1» 1¾ 1
¹ «© BI ¹
»¼ °
¬
¿
253
4.0 - COST ESTIMATE - SUMMARY
GrandTotal
AACEClass4LowRange(20%)
AACEClass4HiRange(+30%)
Contingency
EngineeringFee(designand
constructionadministration
basedonsubtotal1)
Subtotal3
PerformanceBond
Insurance
Permits
Subtotal2
ContractorOH&P
SubTotal1
Item
Demolition
Blowers
Diffusers
StructuralBlowerBuilding
MechanicalPiping
Instrumentation
Electrical
$2,772,427
$2,220,000
$3,600,000
$3,168,597
$2,530,000
$4,120,000
$316,227 15%Basedontypical
$276,689
$244,627
$2,451,161
$1,960,000
$3,190,000
$259,306 10%012116.50PreliminaryWorkingDrawingStage
$2,593,063
$25,298 1%
$12,649 0.5%Higherendof013113.30
$25,298 1%Midrange"ruleofthumb",014126.50
$2,529,818
$421,636 20%Interpolatedfrom013113.80
$2,108,182
$226,885
$2,268,852
$22,135
$11,068
$22,135
$2,213,515
$368,919
$1,844,595
Comments/Source
Spreadsheet8.1
Spreadsheet8.2
Spreadsheet8.3
Spreadsheet8.4
Spreadsheet8.5
Spreadsheet8.6
Spreadsheet8.7
$200,594
$2,005,940
$19,570
$9,785
$19,570
$1,957,015
$326,169
$1,630,845
ECMNo.1
ECMNo.2
ECMNo.3
$30,242
$30,242
$30,242
$535,000
$748,750
$748,750
$445,500
$445,500
$445,500
$73,104
$73,104
$73,104
$290,786
$290,786
$290,786
$69,000
$69,000
$298,875
$187,213
$187,213
$220,924
This spreadsheet summarizes the results of the capital cost estimate in spreadsheets 8.1 - 8.7
254
260505.100100
260505.100120
260505.100300
260505.100290
260505.101870
260505.251070
KellyTractorQuote
SOURCE
DemolishRGSConduit,1/2"1"
DemolishRGSConduit,11/4"2"
Demolisharmoredcable,2#12
Demolisharmoredcable,3#14
Demolishcable,#6GND
Aerationbasinconduitonbasinsand
cablefMCCs
Demolish100HPMotorandelectrical
MECHANICALAERATOR
RemoveMechAerator
MechanicalAeratorWeightX9
CRANE RENTAL - 40 TON CAPACITY
DEMOLITION
DESCRIPTION
4.1 - COST ESTIMATE - DEMOLITION
2
QUANTITY
1400
1400
1400
2800
2800
LF
LF
LF
LF
LF
9 EA
9 EA
4.5 TONS
MO
UNIT
Material
$1.62
$1.96
$0.65
$0.69
$0.12
$218.00
$500.00
Labor
Equip
ECMNo.1
ECMNo.2
ECMNo.3
$1.13
$1.37
$0.45
$0.48
$0.08
$152.38
$349.50
$10,000.00
Total Unit Cost
Sum
WPBCity WPBCity
$30,242
$30,242
$30,242
$235
$1,350
$636
$1,918
$1,585
$1,371
$0
$3,146
$20,000
1
1
1
1
1
1
1
1
1
0.964
0.699
TOTAL Mat Index Labor Index
255
Budget $
$56,000
$102,000
$75,000
$115,000
$93,000
$120,000
$134,000
$120,000
$160,000
$86,000
$90,000
$93,000
$124,000
$128,000
$176,000
HP
200
250
300
300
300
350
400
400
500
500
500
Source
Source
EPA
EPA
EPA
EPA
Rohrbacher, et. al
EPA
Rohrbacher, et. al
EPA
EPA
Rohrbacher, et. al
Rohrbacher, et. al
Rohrbacher, et. al
Rohrbacher, et. al
Rohrbacher, et. al
Rohrbacher, et. al
$98,000 H&S
$90,000 H&S
$153,000 H&S
$72,000 H&S
$104,000 H&S
$110,000 H&S
$135,000 H&S
$88,000 H&S
$245,000 H&S
$170,000 H&S
$190,000 H&S
Budget $
MULTI_STAGECENTRIFUGALCOSTS
HP
50
50
75
100
100
150
150
200
200
200
200
200
200
200
200
UNIT
$202,000
$112,000
$110,000
$110,000
$98,000
$90,000
Average
$122,000
$127,000
$104,000
$75,000
$79,000
Average
3 EA
1 EA
COMPARABLEMULTISTAGECENTRIFUGALCOST
(2)300HPBlowers
(2)200HPBlowers
QUANTITY
3 EA
1 EA
DESCRIPTION
BLOWERS
(2)300HPBowers
(2)200HPBlower
DIVISION NO
4.2 - COST ESTIMATE - BLOWERS
HP
250
250
250
250
250
300
300
300
300
300
300
300
300
400
400
400
500
$110,000
$98,000
$159,000
$122,000
Material
Labor
Budget $
$180,000
$151,000
$165,000
$168,000
$188,000
$175,000
$142,000
$119,000
$119,000
$143,000
$156,000
$208,000
$209,000
$275,000
$132,000
$198,000
$325,000
$27,500
$24,500
$39,750
$30,500
Total
ECMNo.1
ECMNo.2
ECMNo.3
$137,500
$122,500
$198,750
$152,500
Source
Average
EPA
Rohrbache
Rohrbache $170,000
Rohrbache
Rohrbache
EPA
EPA
Rohrbache
Rohrbache
$159,000
Rohrbache
Rohrbache
Rohrbache
Rohrbache
EPA
Rohrbache $202,000
Rohrbache
EPA
$325,000
Equip
TOTAL
$535,000
$748,750
$748,750
$535,000
$122,500
$412,500
$748,750
$596,250
$152,500
1
1
2
2
256
DIVISION NO
DIFFUSERS
Sanitaire
DESCRIPTION
1 EA
QUANTITY
4.3 - COST ESTIMATE - DIFFUSERS
UNIT
330000
Material
1.35
Factor
ECMNo.1
ECMNo.2
ECMNo.3
445500
Total
$445,500
$445,500
$445,500
$445,500 AquariusQuote
TOTAL
257
099113.601600
099123.722880
312316.166070
312323.131900
312323.132200
081163.23
083323.100100
233723.101100
092423.401000
034133.602200
033053.400820
033053.403940
033052.404050
042210.280300
033053.403570
033053.403550
072610.100700
DIVISION NO
PaintStucco,rough,oilbase,paint2coats,spray
PaintCMUInterior,paint2coats,spray
BLOWERBUILDINGCONSTRUCT
PrecastTees,DoubleTees,RoofMembers,Std.
Weight,12"x8'wide,30'span
16"x16",Avg.Reinforcing
Footings,strip,24"x12",reinforced
Foundationmat,over20C.Y.
ConcreteBlock,HighStength,3500psi,8"thick
EquipmentPads,6'x6'x8"Thick
EquipmentPads,4'x4'x8"Thick
PoyethyleneVaporBarrier,Standard,.004"Thick
StructuralExcavationforMinorStructures,Sand,3/4
CYBucket
DozerBackfill,bulk
CompactBackfill,12"lifts
StormDoor,ClearAnodicCoating,7'0"x3'wide
RollingServiceDoor,10'x10'high
HVACLouvers,Standard8"x5"
ExteriorStucco,w/bondingagent
DESCRIPTION
4.4 - COST ESTIMATE - STRUCTURAL
UNIT
CY
CY
CY
EA
EA
EA
SY
EA
CY
CY
CY
SF
EA
EA
100SF
2260 SF
2260 SF
200
100
200
2
1
336
83.7
9
9.4
9.3
42.2
2260
5
5
21.2
QUANTITY
$0
$0
$266
$1,675
$31
$4
$1,575
$455
$133
$197
$3
$157
$67
$3
Material
$0
$0
$6
$0
$1
$48
$490
$15
$7
$138
$610
$86
$106
$4
$129
$61
$8
Labor
$1
$6
$1
$2
$2
$1
$86
$60
$1
$1
Equip
WPBCity WPBCity
$665
$73,104
ECMNo.1
$568
$725
$13,587
$1,957
$580
$500
$153
$1,897
$185
$539
$1,216
$13,614
$11,168
$1,753
$8,695
$15,302
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0.964
0.699
TOTAL Mat Index Labor Index
$0
$0
$9
$2
$3
$290
$1,957
$40
$9
$1,700
$925
$188
$265
$6
$243
$108
$9
otal Unit Cos
258
DESCRIPTION
298
500
19 EA
68 EA
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1500
1000
950
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
63
63
80
80
113
178
222
Material
1 EA
1 EA
9 EA
1
4
1
1
1
1
1
1
1
1
1
1
1
1
1
1
9
18
FT
FT
FT
FT
FT
FT
FT
UNIT
Adjustedmaterialcostforcarbonover304SSsteelprice,~5:1.
(f/MEPS.comtables).Assumingsupportis50lb,May2010$828per
tonsteel*50/2000=$20.7formaterialx1.5factor=$31formaterial
$174$31+$31*5=$298for304SSsupport
Quantityassumessupportsevery10',18+22*2+7*6=104
Added30%tolaborforconcreteinstallation
220529.10017HeavyDutyWallSS
8'Tall304SSElevat
30"Exp.Coup
24"Exp.Coup
Quaotef/Vict 12"DependoLok
14"x30"Elbow
14"x30"Tee
30"x18"Red
30"x30"Tee
30"x24"Red
24"x12"Cross
20"x12"Cross
14"x12"Tee
18"Elbow
18"x12"Tee
24"x20"Red
20"x14"Red
18"x14"Red
14"x12"Red
14"x12"Tee
12"x12"Elbow
12"x10"Tee
10"Elbow
340
316
155
102
66
37
150
QUANTITY
NEEDRSMEANSQUOTES
2/08FelkerBro 10"304LSS
2/08FelkerBro 12"304LSS
2/08FelkerBro 14"304LSS
2/08FelkerBro 18"304LSS
2/08FelkerBro 20"304LSS
2/08FelkerBro 24"304LSS
2/08FelkerBro 30"304LSS
DIVISION NO
4.5 - COST ESTIMATE - MECHANICAL PIPING
14.3
125
375
250
237.5
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
15.75
15.75
20
20
28.25
44.5
55.5
Labor
Equip
$5,934
$42,500
$1,875
$1,250
$10,688
$2,000
$8,000
$2,000
$2,000
$2,000
$2,000
$2,000
$2,000
$2,000
$2,000
$2,000
$2,000
$2,000
$2,000
$2,000
$2,000
$18,000
$36,000
$26,775
$24,885
$15,500
$10,200
$9,323
$8,233
$41,625
TOTAL
ECMNo.1 $290,786
ECMNo.2 $290,786
ECMNo.3 $290,786
312.3
625
1875
1250
1187.5
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
78.75
78.75
100
100
141.25
222.5
277.5
Total
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
259
ProgrammingCosts
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
Jobofsimilarscope/scale,1/11
ProgrammableLogicController
Software
Training/Calibration/Documents
ProgrammingandTroubleshooting
SpareParts
HMIProgrammingandReports
DifferentialPressureIndicators(FlowMeter)
5/09PFSQuote
14"VenturiFlowElement
10/08PFSQuote`
PressureIndicatingTransmitter
CCControlsQuoteL.Garcia
9/16/10
AlumPipeStandMountw/sunshield
Amerisponse.com,9/19/10
420maSurgeSuppressor
CCControlsQuoteL.Garcia
9/16/10
14"ModulatingBFV
NEMA4Xbox,(1)24V+(1)120V
surgesuppressor,toggleswitch,
wiring
SSUnistrutMount
1
1
1
1
1
1
LS
LS
LS
LS
LS
LS
650
105
9
18
2200
50
6800
1350
1510
800
380
2750
Material
3300
1800
UNIT
9
9
9
9
9
6
9
9
9
HachSC100Controller,((3(2probe
controllers,(3)1probecontrollers)
LDOProbe
115VAirBlastCleaningSystem
PoleMountKit
HachListPrice
HachListPrice
HachListPrice
HachListPrice
ModulatingBFV
6/09DezurikQuote
6
QUANTITY
CCControlsQuoteL.Garcia
9/16/10
DESCRIPTION
AlumPipeStandMountw/
sunshield,NEMA4Xbox,(1)24V+
(1)120Vsurgesuppressor,toggle
switch,wiring
DOProbeandTransmitter
DIVISION NO
4.6 - COST ESTIMATE - INSTRUMENTATION
50000
3000
10000
15000
10000
50000
162.5
26.25
825
450
550
12.5
1700
337.5
377.5
200
95
687.5
Labor
Equip
$25,000.00
$1,500.00
$5,000.00
$7,500.00
$5,000.00
$25,000.00
$69,000.00
$69,000.00
$298,875.00
ECMNo.1
ECMNo.2
ECMNo.3
$7,312.50
$2,362.50
$37,125.00
$20,250.00
$24,750.00
$562.50
$76,500.00
$10,125.00
$16,987.50
$9,000.00
$4,275.00
$20,625.00
TOTAL
50000
3000
10000
15000
10000
50000
812.5
131.25
4125
2250
2750
62.5
8500
1687.5
1887.5
1000
475
3437.5
Total
1/3
1/3
1/3
1/3
1/3
1/3
3
3
3
3
3
3
3
3
3
3
3
3
260
D50201452520MotorInstall,200HP
interpolated MotorInstall,300HP
D50201450240MotorInstall,1HP
BuildingInternal
D5025120116014Receptacles/2,000sf
D50251201280LightSwitches/4switches
D50202080680Lighting,FluroescentFixtures
262416.30
Panelboard
Wiring
260519.90328#350XHHW(6per300HP)
260519.35140Terminate#350
260519.90332#500XHHW(3per200HP)
260519.35150Terminate#500
260526.80070#1GND
260519.35075Terminate#1
260519.90314#1
260519.35075Terminate#1
260519.90312#2
260519.35075Terminate#2
260519.90312#2
260519.35075Terminate#2
260523.100022#12
260523.100033#12
260526.80033#12GND
260519.35163Terminate#12
260523.100308#14
260526.80032#14GND
260519.35162Terminate#14
260526.80032#14GND
260519.35162Terminate#14
Conduit
260533.050701"Conduit,Alum
260533.050701"Conduit,Alum
260533.051103"Conduit,Alum
337719.17080ConcreteHandholes
331719.17700DuctbankandConduit,[email protected]
337119.17783Concrete(15CY/100LF)
337119.17786Reinforcing(10Lb/LF)
ExteriorGrounding/LightningProtection
260526.80013GroundingRods,copper
260526.801004/0Grounding
264113.13050AirTerminals
264113.13250AlumCable
264113.13300Arrestor
Motor Related
DESCRIPTION
SF
SF
SF
EA
LF
EA
LF
EA
LF
EA
LF
EA
LF
EA
LF
EA
LF
LF
LF
EA
LF
LF
EA
LF
EA
LF
LF
LF
EA
LF
LF
LF
EA
LF
EA
LF
EA
2117
2117
2117
1
1200
12
1200
6
600
6
1050
18
200
4
525
9
1050
1050
1050
18
400
800
32
1575
27
800
3150
700
1
100
100
100
8
320
10
270
2
2 EA
2 EA
1 EA
QUANTITY
4.7 - COST ESTIMATE - ELECTRICAL
DIVISION NO
UNIT
Labor
$92.00
$3.85
$24.50
$0.85
$78.50
$4.30
$4.30
$22.50
$510.00
$171.25
$1.61
$4.00
$8.45
$51.00
$14.00
$66.00
$1.66
$10.90
$2.74
$10.90
$2.14
$8.65
$2.14
$8.65
$0.18
$0.25
$0.11
$0.58
$0.67
$0.07
$0.43
$0.07
$0.43
$0.56
$0.10
$2.33
$735.00
$98.00
$1.38
$49.00
$1.40
$49.00
$4.90
$4.90
$8.70
$582.50
$39.25
$0.72
$3.40
$2.18
$85.00
$3.00
$98.00
$0.87
$35.50
$0.98
$35.50
$0.87
$32.50
$0.87
$32.50
$0.44
$0.49
$0.30
$7.85
$0.74
$0.28
$6.55
$0.28
$6.55
$1.95
$0.35
$4.88
$605.00
######## $4,075.00
######## $6,112.00
$700.00 $890.00
Material
Equip
$166.79
$4.85
$62.30
$1.93
$115.28
$8.05
$8.05
$28.87
$955.24
$198.65
$2.14
$6.58
$9.99
$116.42
$16.08
$141.28
$2.31
$38.42
$3.45
$38.42
$2.78
$33.87
$2.78
$33.87
$0.52
$0.63
$0.34
$6.70
$1.24
$0.29
$5.54
$0.29
$5.54
$2.07
$0.37
$6.10
$1,193.54
########
########
$1,381.79
Total
ECMNo.1
ECMNo.2
ECMNo.3
INSTALLATION
$187,213.28
$187,213.28
$220,924.44
$1,334.32
$1,553.48
$623.04
$520.36
$230.56
$6,436.16
$25,342.38
$20,207.04
$955.24
$19,865.05
$214.17
$657.94
$11,990.44
$1,396.99
$19,292.40
$847.70
$1,384.76
$230.51
$3,625.99
$691.53
$555.76
$135.47
$1,458.88
$304.81
$546.23
$659.34
$359.32
$120.60
$494.08
$229.88
$177.20
$452.58
$149.51
$4,387.08
$786.36
$12,907.37
$1,193.54
$30,890.15
$46,334.44
$1,381.79
TOTAL
1
1
1
1
1
1
3
1
1
1
1
1
1
1
1
1
1
1
3
3
1
1
3
3
3
3
3
3
1
1
1
3
3
1
1
1
1
1
1
1
98.10%
78.10%
Mat Index Labor Index
WPBCity WPBCity
261
36.45
Equipment
100HPElectricMotors
100HPMotorStarters
ReplaceAerators
Equipment
ManualDO
MechDiffuserMotors
Equipment
Diffusers
TurboBlowers
LDOProbes
Diffusers
MultiStageBlowers
PlantLaborRate
5.0 - O&M COSTS
UsefulLife
O&MItem
CollectDOManually
ServiceMotors
ECM
3
1,2,3
O&MNoLongerNeccesary
Amount
Annual
NPV
$55
365
$19,956
$320,104
$292
9
$2,624
$42,096
SUMMARY
NPV
ECMNo.1 $1,034,902
ECMNo.2 $1,034,902
ECMNo.3 $1,034,902
SUMMARY
Annual
NPV
ECMNo.1O&M
$5,564
$89,243
ECMNo.2O&M
$9,564
$153,404
ECMNo.3O&M
$9,133
$146,489
EquipmentReplacementNoLongerNeccesary
RemainingReplaceme Amount Total
NPV
20
1000
6025
9
$54,225
$0
1,2,3
20
10
$3,150
9
$28,350
$22,806
1,2,3
20
10 $100,000
9
$1,258,146
$1,012,096 1,2,3
Cost
NPV
ECM
1,2,3
2,3
3
1,2,3
1
$1
$10,000
$1,260
$2,187
$6,000
$18
$160,402
$20,211
$35,080
$96,241
O&MCosts
Annual
Planning
Period
RealRate
(years)
0.025
0.022
20
CPI
O&MItem
Cost
Amount Unit
ReplaceMembranes
$9.04
1 EA
ReplaceFilters,Inspectio $2,500
4 EA
ReplaceSensorCaps
$140
9 EA
CleanMembranes
$36
60 HR
TypicalO&Mbasedon1
$1,500
4
0.047
DiscountRate(interest)
Source
RSMeans267113.105260+267113.202100
RSMeans262419.400500
6/17/11Quotef/TSCJacobs
Source
30MinsPerBasin,3timesperday
NeedtoaskBocaRaton
Source
Sanitaire/Lesourdsville,5/minperdiffuser,$6replacementcost,710yearinterv
Rohrbacheret.al
Article:"DO"ingmorewithLess,ListPrice:Hach
Rosso,EconomicImplicationsofFinePoreDiffuserAging
1.5%CapitalCost,perRohrbacheret.al
262
KellyTractorQuote
SOURCE
CRANERENTAL40TONCAPACITY
RemoveMechAerator
MechanicalAeratorWeightX9
NewMechanicalAerators
DESCRIPTION
5.1 - O&M COSTS - REPLACE AERATORS
4
QUANTITY
MO
9 EA
4.5 TONS
9 EA
UNIT
100000
Material
35000
$500.00
Labor
Equip
WPBCity WPBCity
TOTAL ECMNo. MatIndexLabor Index
0.964
0.699
$40,000
$3,146
$0
135000
$1,215,000
Sum
ECMNo.1 $1,258,145.50
$10,000.00
$349.50
TotalUnit
6.0 LIFE-CYCLE COST ANALYSIS INPUTS
Current Bond Rate
Cost per
kwH
0.07
0.047
Power
Factor
0.84
Aerator # Nameplat
e HP
#1
#2
#3
#4
#5
#6
#7
#8
#9
CPI
Inflation
0.025
Real Rate
(interest)
0.022
Energy
Inflation
0.00083
Planning
Period
(years)
20
Current
HP
831.1
Avg
If no Amp
draws,
Basins in
assumed Operation
% of
Nameplat
e
0.85
Avg Low
Speed
Amps
3
Avg High Months in Avg Amps
Speed low setting
Amps (1)
59
41.2
91
63.6
170
118.5
59
12
59
41.2
59.67
4
94
65.9
145
101.5
71.33
1
101
70.7
65.67
1
89
62.1
79
55.4
Total
888
620.0
(1)DatabasedonampdrawreadingsprovidedbyCityofPlantationfor11/29/11
Blower #
100
100
125
100
100
125
100
100
125
59
60.67
109.00
112.67
169.67
111
111.67
145.33
104
91
79.33
Nameplat
e HP
Factor(2)
Adjusted
HP
12
5
Avg KW
#1
#2
#3
125
123
100
100
56 OperatingHP/NameplateHP
59
0.98
Zone1Avg Zone2Avg Zone3Avg
123.0
85.6
68.4
263
Avg
Operating
HP
55.2
85.2
158.8
55.2
88.3
136.0
94.8
83.2
74.3
831.1
264
6.1.1 LIFE-CYCLE COST ANALYSIS
70%
79%
70%
0
64
84
580
655
580
Current Treatment - 1.5 mg/L
3. Auto DO Control Current Treatment - 1.5 mg/L
1.5 mg/L
Complete NOx
Total (Cumulative) Current Treatment - 1.5 mg/L
5%
-1%
7%
$265,401
$299,711
$265,398
$0
$29,422
$38,571
$18,515
($2,020)
$24,736
$246,886
$272,309
$202,091
Ann. Energy
Cost Savings
($4,288,241)
($4,842,614)
($4,288,205)
$0
($475,391)
($623,217)
($299,156)
$32,635
($399,681)
($3,989,085)
($4,399,859)
($3,265,307)
Energy
Savings NPV
$
$
$
1,987,205
1,987,205
1,987,205
6.34
5.70
7.91
$ 1,505,502
$ 1,505,502
$ 1,505,502
$ 385,427
$ 385,427
$ 385,427
$96,277
$96,277
$96,277
8.59
7.55
8.59
28.84
9.16
7.57
18.96
30.08
Payback
Capital and
O&M NPV
831
831
831
Current Treatment - 1.5 mg/L
3. Auto DO Control Current Treatment - 1.5 mg/L
1.5 mg/L
Complete NOx
251
176
251
70%
79%
70%
65%
72%
53%
70%
71%
60%
$265,401
$299,711
$265,398
$246,886
$272,309
$202,091
$265,401
$270,289
$226 827
$226,827
($4,288,241)
($4,842,614)
($4,288,205)
($3,989,085)
($4,399,859)
($3,265,307)
($4,288,241)
($4,367,224)
($3 664 988)
($3,664,988)
$ 5,564
$ 5,564
$ 5,564
$ 9,564
$ 9,564
$
$
9 564
9,564
$ (9,133)
$ (9,133)
$ (9,133)
Annual Savings Annual Savings Energy Savings Annual Change
$
NPV
O&M
%
Estimate auto DO control efficiency gain by assuming 1.5 mg/L.
Estimate turbo blower efficiency gain by assuming 62% efficiency w/ Multi-Stage centrifugal, then 72% with turbos.
at 3 mg/L average DO.
4. Most Open Valve Estimate MOV efficiency by using diurnal curve vs. pressure setpoint.
Blower Control vs/
Pressure Setpoint
3. Automatic DO
Control (1.5 mg/L)
2. Turbo Blowers
Description of Assumptions Technologies
Estimate fine bubble efficiency gain assuming plant operators will maintain
1. Fine Bubble
Diffusers
DO at average of 3 to 4 mg/L. The actual value used can be based on average DO measurements at other county plants.
2. Turbo Blowers
1. Fine Bubble
Diffusers
291
236
389
251
240
335
Current HP Proposed
HP
831
831
831
831
831
831
Level of Treatment
Current Treatment - 1.5 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Current Treatment - 1.5 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Technology
TABLE 2 - CUMULATIVE GAIN (each proceeding improvement is accumulative of the previous listed)
$89,243
$89,243
$89,243
$153,404
$153,404
$
$
153 404
153,404
$(146,489)
$(146,489)
$(146,489)
Change O&M
NPV
0.07
Current Cost per
kwH
* Current treatment indicates energy improvement realized by treating to partial nitrification at 0.5 mg/L, which is the plants current level of treatment
Complete NOx
Current Treatment - 1.5 mg/L
0%
8%
10%
40
-4
54
Current Treatment - 1.5 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
2. Turbo Blowers
65%
72%
53%
540
595
442
Current Treatment - 1.5 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
1. Fine Bubble
Diffusers
% Eff.
Gain
HP
Reduction
Level of Treatment
Technology
TABLE 1 - INCREMENTAL GAIN
This spreadsheet summarizes the results of the life cycle cost analyses.
0.025
CPI Inflation
$ (1,034,902)
$ (1,034,902)
$ (1,034,902)
$ (1,034,902)
$ (1,034,902)
$
$
(1 034 902)
(1,034,902)
$ (1,034,902)
$ (1,034,902)
$ (1,034,902)
$2,451,161
$2,451,161
$2,451,161
$2,772,427
$2,772,427
$2 772 427
$2,772,427
$3,168,597
$3,168,597
$3,168,597
Foregone Capital Capital Cost
Replacement
0.047
Bond Rate
$ 1,505,502
$ 1,505,502
$ 1,505,502
$ 1,890,929
$ 1,890,929
$ 1,890,929
$
1 890 929
$ 1,987,205
$ 1,987,205
$ 1,987,205
Capital and
O&M NPV
0.022
Real Rate
(interest)
8.59
7.55
8.59
6.34
5.70
7.91
7.41
7.26
8 86
8.86
Payback
Planning
Period
(years)
0.00083
20
Energy
Inflation
265
6.1.2 LIFE-CYCLE COST ANALYSIS (LOW RANGE)
70%
79%
70%
0
64
84
580
655
580
Current Treatment - 1.5 mg/L
3. Auto DO Control Current Treatment - 1.5 mg/L
1.5 mg/L
Complete NOx
Total (Cumulative) Current Treatment - 1.5 mg/L
5%
-1%
7%
$265,401
$299,711
$265,398
$0
$29,422
$38,571
$18,515
($2,020)
$24,736
$246,886
$272,309
$202,091
Ann. Energy
Cost Savings
($4,288,241)
($4,842,614)
($4,288,205)
$0
($475,391)
($623,217)
($299,156)
$32,635
($399,681)
($3,989,085)
($4,399,859)
($3,265,307)
Energy
Savings NPV
$
$
$
1,348,608
1,348,608
1,348,608
4.04
3.64
5.01
$ 1,014,341
$ 1,014,341
$ 1,014,341
$ 324,161
$ 324,161
$ 324,161
$10,107
$10,107
$10,107
5.85
5.17
5.85
20.85
7.01
5.82
14.72
22.71
Payback
Capital and
O&M NPV
831
831
831
Current Treatment - 1.5 mg/L
3. Auto DO Control Current Treatment - 1.5 mg/L
1.5 mg/L
Complete NOx
251
176
251
70%
79%
70%
65%
72%
53%
70%
71%
60%
$265,401
$299,711
$265,398
$246,886
$272,309
$202,091
$265,401
$270,289
$226 827
$226,827
($4,288,241)
($4,842,614)
($4,288,205)
($3,989,085)
($4,399,859)
($3,265,307)
($4,288,241)
($4,367,224)
($3 664 988)
($3,664,988)
$ 5,564
$ 5,564
$ 5,564
$ 9,564
$ 9,564
$
$
9 564
9,564
$ (9,133)
$ (9,133)
$ (9,133)
Annual Savings Annual Savings Energy Savings Annual Change
$
NPV
O&M
%
Estimate auto DO control efficiency gain by assuming 1.5 mg/L.
Estimate turbo blower efficiency gain by assuming 62% efficiency w/ Multi-Stage centrifugal, then 72% with turbos.
at 3 mg/L average DO.
4. Most Open Valve Estimate MOV efficiency by using diurnal curve vs. pressure setpoint.
Blower Control vs/
Pressure Setpoint
3. Automatic DO
Control (1.5 mg/L)
2. Turbo Blowers
Description of Assumptions Technologies
Estimate fine bubble efficiency gain assuming plant operators will maintain
1. Fine Bubble
Diffusers
DO at average of 3 to 4 mg/L. The actual value used can be based on average DO measurements at other county plants.
2. Turbo Blowers
1. Fine Bubble
Diffusers
291
236
389
251
240
335
Current HP Proposed
HP
831
831
831
831
831
831
Level of Treatment
Current Treatment - 1.5 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Current Treatment - 1.5 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Technology
TABLE 2 - CUMULATIVE GAIN (each proceeding improvement is accumulative of the previous listed)
$89,243
$89,243
$89,243
$153,404
$153,404
$
$
153 404
153,404
$(146,489)
$(146,489)
$(146,489)
Change O&M
NPV
0.07
Current Cost per
kwH
* Current treatment indicates energy improvement realized by treating to partial nitrification at 0.5 mg/L, which is the plants current level of treatment
Complete NOx
Current Treatment - 1.5 mg/L
0%
8%
10%
40
-4
54
Current Treatment - 1.5 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
2. Turbo Blowers
65%
72%
53%
540
595
442
Current Treatment - 1.5 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
1. Fine Bubble
Diffusers
% Eff.
Gain
HP
Reduction
Level of Treatment
Technology
TABLE 1 - INCREMENTAL GAIN
This spreadsheet summarizes the results of the life cycle cost analyses.
0.025
CPI Inflation
$ (1,034,902)
$ (1,034,902)
$ (1,034,902)
$ (1,034,902)
$ (1,034,902)
$
$
(1 034 902)
(1,034,902)
$ (1,034,902)
$ (1,034,902)
$ (1,034,902)
$1,960,000
$1,960,000
$1,960,000
$2,220,000
$2,220,000
$2 220 000
$2,220,000
$2,530,000
$2,530,000
$2,530,000
Foregone Capital Capital Cost
Replacement
0.047
Bond Rate
$ 1,014,341
$ 1,014,341
$ 1,014,341
$ 1,338,502
$ 1,338,502
$ 1,338,502
$
1 338 502
$ 1,348,608
$ 1,348,608
$ 1,348,608
Capital and
O&M NPV
0.022
Real Rate
(interest)
5.85
5.17
5.85
4.04
3.64
5.01
4.93
4.83
5 86
5.86
Payback
Planning
Period
(years)
0.00083
20
Energy
Inflation
266
6.1.3 LIFE-CYCLE COST ANALYSIS (HIGH RANGE)
70%
79%
70%
0
64
84
580
655
580
Current Treatment - 1.5 mg/L
3. Auto DO Control Current Treatment - 1.5 mg/L
1.5 mg/L
Complete NOx
Total (Cumulative) Current Treatment - 1.5 mg/L
5%
-1%
7%
$265,401
$299,711
$265,398
$0
$29,422
$38,571
$18,515
($2,020)
$24,736
$246,886
$272,309
$202,091
Ann. Energy
Cost Savings
($4,288,241)
($4,842,614)
($4,288,205)
$0
($475,391)
($623,217)
($299,156)
$32,635
($399,681)
($3,989,085)
($4,399,859)
($3,265,307)
Energy
Savings NPV
$
$
$
2,938,608
2,938,608
2,938,608
10.01
8.96
12.62
$ 2,244,341
$ 2,244,341
$ 2,244,341
$ 474,161
$ 474,161
$ 474,161
$ 220,107
$ 220,107
$ 220,107
12.98
11.35
12.98
43.49
12.44
10.21
25.85
43.25
Payback
Capital and
O&M NPV
831
831
831
Current Treatment - 1.5 mg/L
3. Auto DO Control Current Treatment - 1.5 mg/L
1.5 mg/L
Complete NOx
251
176
251
70%
79%
70%
65%
72%
53%
70%
71%
60%
$265,401
$299,711
$265,398
$246,886
$272,309
$202,091
$265,401
$270,289
$226 827
$226,827
($4,288,241)
($4,842,614)
($4,288,205)
($3,989,085)
($4,399,859)
($3,265,307)
($4,288,241)
($4,367,224)
($3 664 988)
($3,664,988)
$ 5,564
$ 5,564
$ 5,564
$ 9,564
$ 9,564
$
$
9 564
9,564
$ (9,133)
$ (9,133)
$ (9,133)
Annual Savings Annual Savings Energy Savings Annual Change
$
NPV
O&M
%
Estimate auto DO control efficiency gain by assuming 1.5 mg/L.
Estimate turbo blower efficiency gain by assuming 62% efficiency w/ Multi-Stage centrifugal, then 72% with turbos.
at 3 mg/L average DO.
4. Most Open Valve Estimate MOV efficiency by using diurnal curve vs. pressure setpoint.
Blower Control vs/
Pressure Setpoint
3. Automatic DO
Control (1.5 mg/L)
2. Turbo Blowers
Description of Assumptions Technologies
Estimate fine bubble efficiency gain assuming plant operators will maintain
1. Fine Bubble
Diffusers
DO at average of 3 to 4 mg/L. The actual value used can be based on average DO measurements at other county plants.
2. Turbo Blowers
1. Fine Bubble
Diffusers
291
236
389
251
240
335
Current HP Proposed
HP
831
831
831
831
831
831
Level of Treatment
Current Treatment - 1.5 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Current Treatment - 1.5 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
Technology
TABLE 2 - CUMULATIVE GAIN (each proceeding improvement is accumulative of the previous listed)
$89,243
$89,243
$89,243
$153,404
$153,404
$
$
153 404
153,404
$(146,489)
$(146,489)
$(146,489)
Change O&M
NPV
0.07
Current Cost per
kwH
* Current treatment indicates energy improvement realized by treating to partial nitrification at 0.5 mg/L, which is the plants current level of treatment
Complete NOx
Current Treatment - 1.5 mg/L
0%
8%
10%
40
-4
54
Current Treatment - 1.5 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
2. Turbo Blowers
65%
72%
53%
540
595
442
Current Treatment - 1.5 mg/L
Current Treatment - 3.0 mg/L
Complete NOx
1. Fine Bubble
Diffusers
% Eff.
Gain
HP
Reduction
Level of Treatment
Technology
TABLE 1 - INCREMENTAL GAIN
This spreadsheet summarizes the results of the life cycle cost analyses.
0.025
CPI Inflation
$ (1,034,902)
$ (1,034,902)
$ (1,034,902)
$ (1,034,902)
$ (1,034,902)
$
$
(1 034 902)
(1,034,902)
$ (1,034,902)
$ (1,034,902)
$ (1,034,902)
$3,190,000
$3,190,000
$3,190,000
$3,600,000
$3,600,000
$3 600 000
$3,600,000
$4,120,000
$4,120,000
$4,120,000
Foregone Capital Capital Cost
Replacement
0.047
Bond Rate
$ 2,244,341
$ 2,244,341
$ 2,244,341
$ 2,718,502
$ 2,718,502
$ 2,718,502
$
2 718 502
$ 2,938,608
$ 2,938,608
$ 2,938,608
Capital and
O&M NPV
0.022
Real Rate
(interest)
12.98
11.35
12.98
10.01
8.96
12.62
11.40
11.16
13 74
13.74
Payback
Planning
Period
(years)
0.00083
20
Energy
Inflation
267
Total (Cumulative)
70%
79%
70%
Current Treatment - 1.5 mg/L DO
Part. Nitrification - 1.5 mg/L DO
Complete Nitrification
0%
Current Treatment - 1.5 mg/L DO
8%
10%
5%
-1%
7%
Current Treatment - 1.5 mg/L DO
Part. Nitrification - 3.0 mg/L DO
Complete Nitrification
2. Turbo Blowers
Part. Nitrification - 1.5 mg/L DO
Complete Nitrification
65%
72%
53%
Current Treatment - 1.5 mg/L DO
Part. Nitrification - 3.0 mg/L DO
Complete Nitrification
1. Fine Bubble Diffusers
3. Auto DO Control - 1.5 mg/L
% Eff.
Gain
Level of Treatment
Technology
6.2 LIFE-CYCLE COST ANALYSIS SUMMARY
10387
11730
10387
1152
1510
0
725
-79
968
9663
10658
7910
0.43
$265,401
$299,711
$265,398
$29,422
$38,571
$0
$18,515
-$2,020
$24,736
$246,886
$272,309
$202,091
Avg. Daily
Ann. Energy
Energy Savings Cost Savings
(kwH)
($)
6
5
6
7
6
21
15
23
4
4
5
Payback
(Low Est)
(Years)
9
8
9
9
8
29
19
30
Payback
(Median
Est)
(Years)
6
6
8
13
11
13
12
10
43
26
43
10
9
13
Payback
(High Est)
(Years)
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