Jet Aeration
Aeration Systems Basics &
Sanitaire Liquid Diffuser Cleaning System
Serdar Umur
Sanitaire Aeration Product Manager
March 25, 2014
Discussion Topics
1.
Aeration Technologies
2.
FBDA Types and Components
3.
Diffuser Maintenance & fouling types
4.
How to determine?
5.
Effects of Fouling
6.
Cleaning Techniques
7.
Sanitaire Liquid Cleaning System
a. How it work?
b. Advantages
c. Case Studies
Why is Aeration so important?
Energy Usage of Typical WWTP
Aeration System can account for
50-75% of Plant Energy Usage
HVAC
4%
Pumping
20%
Lighting
2%
3
Misc.
12%
Aeration
62%
Types of Aeration Systems
Mechanical
Aeration
4
Jet Aeration
• Low Efficiency
•Low to Moderate
Efficiency
• High Maintenance
• Moderate Maintenance
Coarse Bubble
Diffused Aeration
Fine Bubble
Diffused Aeration
• Low Efficiency
• High Efficiency
• Low Maintenance
•Low Maintenance
Historical Development of Aeration Systems
Mechanical Aeration
1950s to 1970s
Mechanical and Coarse Coarse and Fine Bubble Fine and Ultrafine bubble
Bubble Aeration
Aeration
Aeration
1970s to 1980s
1990s to 2000s
2010s to 2020s
SAEs of Various Aeration Technologies
(standard conditions)
•
•
•
•
•
•
Fine Bubble (full floor coverage)
Fine Bubble (spiral roll)
Jet Aeration
Mechanical Aerators
Coarse Bubble
Aspirating Aerators
6.6 – 10.8 lbs.O2/BHP-hr
3.3 – 6.6 lbs.O2/BHP-hr
3.6 – 5.7 lbs.O2/BHP-hr
1.8 – 3.4 lbs.O2/BHP-hr
2.1 – 3.1 lbs.O2/BHP-hr
0.8 – 1.3 lbs.O2/BHP-hr
Data from ASCE WEF Manual of Practice 8: Design of Municipal
Wastewater Treatment Plants.
6
Mechanical Aeration
March 25, 2015
7
Where do we see these technologies?
• Small applications - 100 gpm or less
• Industrial applications with single tanks
• Sequencing Batch Reactors (SBR’s)
• Oxidation Ditches
March 25, 2015
8
Mechanical Aerator Types
Low Speed (20-60 rpm)
• Large Diameter Propeller
• Floating or Mounted on Bridge
• Gear Reducer Required
• Consider Concrete Platform cost
High Speed (300-1200 rpm)
• Small Diameter Propeller
• Floating
• Direct Drive
Submerged Turbines
• Low Speed
• Supplemented with Compressed Air
• Fixed Bridge Installation
• Requires Gear Reducers
Brush Aerators
• Low Speed
• Gear Reducer
• Used in Oxidation Ditches
• Limit Basin Configuration (shallow)
March 25, 2015
9
Mechanical Aerator Types (cont’d)
Hyperbolic Aerator
•
Efficiency is same as older mechanical
aerators (1.5 to 2.0 kg O2/kwh)
•
Mixing efficiency is similar to our Banana
blades
•
Capital cost is high
•
Capital cost should consider concrete
platform
March 25, 2015
10
Mechanical Aeration in Oxidation Ditches
• Low efficiency aeration
combined with low efficiency
mixing.
• Limited turn-up/turn-down
capability.
• Complex construction with
access bridges/platforms.
• Freezing/Splashing/Aerosol
issues associated with
mechanical aeration.
• Patented Processes = High
Capital Cost
11
Sanitaire Aeration Competition and Strategies
March 25, 2015
Converting Ditches from Mechanical
Aerators to Fine Bubble Diffused Aeration
1. Fine bubble + horizontal mixers result up
to 50% higher efficiency.
2. Independent control of mixing and
aeration allows energy input to be turned
down to match demand while
maintaining treatment.
Flygt BB Mixers
Sanitaire
Aeration
3. Oxidation ditches with fine bubble
aeration can be designed in deeper tanks
for reduced energy consumption and
space requirements in comparison to
mechanical aerators
4. Aerosols and the need to frequently
perform maintenance of mechanical
equipment in the basin are eliminated
Eco-Lift Video
Bioloop™ Advanced Oxidation Ditch
Conversion of Ditches with Mechanical Aerators to Fine
Bubble with Submersible Mixers
South Water Reclamation
Facility, Orlando, FL – 78 MLD
52% energy savings
Eunice, LA – 4 MLD
• 50% energy savings
• End of Compliance Issues
• Pushed More water through
Jet Aeration
March 25, 2015
14
Jet Aeration
•
Air and Mixed Liquor combined in Jet
Nozzle to create a water air plume to
provide mixing and oxygen transfer.
•
Can be used to provide mixing without
aeration.
•
Primarily used in SBR’s and some
industrial applications.
•
Jet Manufacturers promote high alpha
values and high oxygen transfer
efficiency.
•
Total Standard Aeration Efficiency
including both Blowers and Pumps is
similar to Coarse Bubble Aeration.
March 25, 2015
15
Jet Aeration
– Other Issues
• Limited turn-up/turn-down capability.
- Efficiency is based on a specific
air:water ratio.
• Extensive maintenance associated
with back-flushing of jet nozzles.
• Complicated piping/valve gallery
adds significantly to construction
cost of project.
• Maintenance of fiberglass jets.
Jet Aeration Piping/Valve Gallery
- Vibrational fatigue
- Erosion
- UV Damage
March 25, 2015
16
Tube Diffusers
March 25, 2015
17
Sanitaire Performance Test Facility
- State-of-the-art and unique test facility that allows for advanced performance testing
- Capability and facilities to do diffuser life-cycle testing
•Facility in operation since May 2010
•Tank Dim: 12ft wide x 22ft L X 28ft deep.
•Test to 24ft Submergence.
•Tank volume: 66,000 Gallons
•Time to fill: 2.5 hours
•Time to drain: 45 minutes
•Blower 1: 22 kW PD Blower
•Blower 2: 45 kW Screw Blower
•14 Droplegs
•19 Diffusers per drop
•Automated SCADA Control System
Test facility includes/featuring:
•Tank
•Aeration Droplegs and Control Valves
•Aeration Grids
•Control Station & Testing Laboratory
•Blower Room
•Boiler & Heat Exchanger
•Sodium Sulfite Mixing Tanks
•Dissolved Oxygen Probes
•Airflow Meters
Certified performance testing and PERFORMANCE GUARANTEES!
Tube Diffuser SOTE vs. Flux
Sanitaire SSII Diffusers
5% Difference
in SOTE
Typical Tube Diffusers
March 25, 2015
19
Why tube diffusers perform less efficiently?
•
•
•
Coalescence and coarse bubbling
Doesn’t happen at disc diffusers
Lower floor coverage causes higher flux rates
20
21
Fine Bubble Disc Aeration
Systems
Fine Bubble System Components
Dropleg
Air Main
Purge
Manifold
Supports
Distributor/Header/Line
Fine Bubble System Components / Materials
Pipework
• uPVC (Standard)
• cPVC (High Temperature)
• 304L Stainless Steel
• 316L Stainless Steel
Supports
• 304L Stainless Steel
• 316L Stainless Steel
Diffuser Assembly
• uPVC
• cPVC
• Polypropylene
Ceramic disc diffuser
• Introduced in 1978
• Over 8,000,000 diffusers in operation worldwide
• 20 year diffuser life
• Proven piping and support system
• Pressure monitoring and cleaning options available
Membrane disc diffuser
• Introduced in 1986
• Over 15,000,000 diffusers in operation worldwide
• Resistant to fouling
• On/off applications
• Proven piping and support system
FBDA Maintenance &
Liquid Cleaning Systems
Dynamic Wet Pressure (DWP)
DWP:
• This is the measurement of the headloss through a diffuser membrane.
• It is similar to transmembrane pressure (TMP) for hollow fiber membranes who
is familiar with filtration technologies.
Water Head on Membrane @ P3
Air @ P2
Air @ P1
Orifice Loss = P1 – P2
DWP = P2 – P3 = Headloss
P2 > P3
System Pressure
System Pressure:
• It is the total of piping losses, head of water on top of diffusers and DWP
SP = OL + PL + DWP + Head
Pipe Losses
Example:
Submergence = 15ft
DWP = 16 in w.c.
Pipe Losses = 22 in w.c.
Orifice Losses = 1.7 in w.c.
SP = 18 ft or 7.8 psi
Water Level
above diffusers
DWP
Orifice Loss
DWP Graph and Effects of Fouling
Fouled Diffuser
Clean Diffuser
• Fouled Diffusers will increase the system
pressure
0.5psi (13in.w.c. or 33cm w.c.) increase = $3 per diffuser per year*
•
Eddyville, IA = 10,000 diffusers
•
@ 1 scfm , the increase at this plant was 1 psi
•
So, they were spending an extra $60,000 per
year on energy cost.
Effect of Diffuser Cleaning on Headloss
Eddyville, IA MBR Plant with Ceramic Diffusers
4.50
4.00
Headloss (psig)
3.50
3.00
2.50
New
2.00
Pre-Cleaning
1.50
Post-Cleaning
1.00
0.50
0.00
0
1
2
3
Air Flowrate (SCFM)
4
Ceramic Diffuser Fouling Types
1.
Biofouling in the pores (rare)
How and Why?
•
•
•
•
2.
Ceramic diffusers runs only in continuous operation
Power failures
Biology enters in the pores and grows in there
Effects efficiency and increases headloss
Calcium Hardness fouling in the pores or on the
surface (more common)
How and Why?
•
•
•
•
Water Hardness, temperature
Excessive Polymer addition
Excessive heat build-up
Increases headloss
Membrane Diffuser Fouling Types
1.
Biofouling on the surface (rare)
How and Why?
•
•
•
•
2.
Bacteria attaches to the surface
Grows 1” to 2” thick layer causing coalescences of bubbles
Typically, mixing issues, too low air flow rates.
Air bumping is the solution
Calcium Hardness fouling in the on the surface
How and Why?
• Water Hardness, temperature, excessive heat
• Doesn’t affect operation
3.
Calcium Hardness fouling in the slits and backside
How and Why?
• Water Hardness, temperature, excessive polymer and heat
• On/Off operation
• Will increase Headloss
Water Hardness Map of the US
33
What does industry experts say?
34
What does it cost?
Extends the life expectancy of your diffusers.
35
How to Determine? – In Field
Pressure Monitoring System
Monitoring Panel
36
Connection Box
How to Determine – In Lab
In lab Services by Sanitaire
Available Cleaning Methods
1.
HCl Gas Cleaning – Developed by Sanitaire in late 1980s
•
•
•
•
•
2.
Full Purge liquid cleaning System – Developed by Sanitare in early 1990s
•
•
•
•
3.
In situ and does not interrupt operation
Older method to clean diffusers
Requires HCl gas tank and Nitrogen gas tank which is more expensive
More expensive equipment and all 316 stainless steel components
Effective method but requires more work to execute
In Situ but interrupts operation
Some fills all of the aeration piping with dilute acid
Uses much more acid solutions and more expensive
Medium effectiveness
Ex-situ Acid Bath solutions
• Requires draining the tank
• Acid is sprayed on the diffusers or diffusers are removed and submerged in acid solutions
• Spraying is ineffective, acid bath is effective
38
In-Situ Fine Bubble Diffuser Cleaning
•SANITAIRE HCl Gas Cleaning Process
• Cleaning agent injected into air stream
• Process air carries cleaning agent to diffuser
• Cleaning agent reacts with water in mixed liquor at
air/water interface, creating acid solution
• Solution dissolves acid soluble materials within the stone
• Biological matter killed by low pH
In-Situ Fine Bubble Diffuser Cleaning
In-Situ Gas Cleaning
• Good for Ceramic Diffusers
• Over 300 Successful Installations World-Wide
• Over 1.5 Million Diffusers Licensed
In-Situ Fine Bubble Diffuser Cleaning
• Albion, New York (Installed in 1988)
• Gas Cleaned Annually
• Plant Operators do actual Gas Cleaning
40
35
30
25
D.W.P.
20
inches
Before
After
15
10
5
0
E-1
W
1
Aeration Tank Number
2
E-2
What is Patent Pending LCS?
• Liquid acid cleaning is a partial fill acid cleaning system for cleaning membrane
and ceramic diffusers.
• Sanitaire tests diffusers (if possible) or looks at the system design to determine
the acid concentration and amount. .
• Air distributor pipe and manifold are filled with a dilute acid up to a certain depth.
• Acid will fumigate with hot air from blowers and go through the membranes as
gas.
• Concentrated acid is formed in the perforations and diffuser is cleaned.
43
Where to inject the liquid cleaning agent?
Cleaning Agent
Advantages of LCS
• You can use with membrane or ceramic diffusers
• Extends the operating life of diffusers
• Resets the diffusers to like-new conditions
• Works well and is evenly distributed over grid.
• Cheaper chemical and equipment cost.
• Low investment – High Return
• Safer than gas cleaning and high pressure cleaning systems
• Automation is possible
• Different from other liquid cleaning systems;
• They utilize high concentration, low quantity cleaning agents vs. we utilize low concentration,
high quantity
• This ensures equal distribution of the cleaning agent and cleans 100% of the diffusers
45
Case Study #1 – Kiel, WI
Problem:
• Kiel, WI WWTP utilizes 9” discs since 1997
• Original system was designed with a gas cleaning system
• Gas cleaning equipment reached its useful life after 17 years
• They needed new equipment and they evaluated Sanitaire LCS
Evaluation:
Criteria
Gas Cleaning
LCS
Corrosion
High
Low
Weather Consideration
Warmer seasons only
All year
Total Cleaning Time
2 days
2 to 4 hours
Hazardous Chemical
Training
Yes
No
Cost of Chemical
240 lbs x $8.81/lb = $2115
1620lbs x $0.45/lb = $744
Solution:
• We chose the liquid cleaning system mostly to get rid of the high hazards of the hydrogen chloride
gas to employees and public. The employees know and are trained in acid handling for other plant
processes so no new training was necessary. The time and money savings are much needed as the
plant ages and we have other maintenance items to attend to. The saving will be realized more do to
the waste characteristic and an increase to cleaning the aeration grids twice annually in the future.
Kris August, Superintendent
Case Study #2 – Eddyville, Iowa
•
•
•
•
Food Processing Plant in Eddyville, IA
MBR Plant
MLSS Concentration: 10,000 mg/l
Utilized Sanitaire 9” ceramic disc diffusers in 2008
• After 5 years of operation
• Very high back pressure on the blowers
• Design pressure – 7.6psig
• After diffusers are clogged – 9.5psig
• Blower motor started tripping
• They approached to Sanitaire
• Samples Sent
• Brown Deer, WI laboratory testing first
Fouled Diffuser from Eddyville, IA
Case Study #2 – Eddyville, Iowa Laboratory Analysis Results
• DWP – Dynamic Wet Pressure
• A measure of how much the diffusers are clogged and their efficiency
• Promising Results
Air Flowrate
per Diffuser
(scfm)
.50 scfm
1.0 scfm
2.0 scfm
3.0 scfm
Diffuser DWP
Before Cleaning
(inch)
30.9
47.1
98
111.7
Diffuser DWP
After Cleaning
(inch)
11.5
12.3
18.7
27.1
New Diffuser Recovery
DWP (inch)
(%)
5
6
7
8
75%
85%
87%
82%
Measuring diffuser DWP for different air flow rates at Brown Deer, WI laboratory
Case Study #2 – Eddyville, Iowa Full Scale Analysis
•
•
•
•
Xylem determined the cleaning agent type and calculated the volume required
Xylem applied the cleaning agent on full scale plant
After cleaning plant sent cleaned diffuser from their aeration basin
Over 85% recovery was achieved as laboratory results concluded
Effect of Diffuser Cleaning on Headloss
Eddyville, IA MBR Plant with Ceramic Diffusers
4.50
4.00
Headloss (psig)
3.50
3.00
2.50
New
2.00
Pre-Cleaning
1.50
Post-Cleaning
1.00
0.50
0.00
0
1
2
3
Air Flowrate (SCFM)
• Plant is back to normal operating conditions
• Not wasting energy anymore
• Scheduled to clean once a year
4
Total Care Service Maintenance Agreement
• Xylem offer a maintenance agreements, incorporating:
• Periodic Health Checks
• Periodic Liquid Cleaning Service
• Periodic Efficiency Evaluations
• Minimizing Fouling
• Optimising Performance
• Extending Operating Life
50
Questions?
Thank you!
51
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