Reverse Osmosis Life Cycle Costs Overview

3/4/2013
Reverse Osmosis
Life Cycle Costs
Peter Voss
Susan Berg
Reverse Osmosis Life‐Cycle Costs
Overview
Market Overview
Water is becoming a bigger deal for all of us
Macro trends/drivers
•
•
•
•
•
Increasing population growth & consumption
Reduced water quality & quantity
Increasing public awareness & understanding
Increasing use of chloramines by municipalities
Emergence of high efficiency water consuming appliances
Implications
• Water will become more expensive over time
• Water quality will deteriorate as supplies dwindle
• Alternative treatment methods needed… Like RO
1
3/4/2013
Impact of Water
Important to our customers & guests
Guest Satisfaction
• Improves beverage & ice quality
• Reduces off‐taste & odor
• Reduces spotting & filming on glassware
Operational Efficiency
•
•
•
•
•
Increased throughput
Reduced energy usage
Improved reliability
Reduced maintenance
Reduced downtime
Scale
Thickness
1/32”
Energy
Consumption
Increase1
8.5%
1/16”
12.4%
1/8”
25.0%
1/4”
40.0%
1 University of New Mexico Study & WQA Battelle Study (2009)
Modern Kitchen Equipment
Warranties contingent on meeting “water spec”
Typical water constituents
•
•
•
•
•
•
•
Dissolved solids (TDS)
Hardness (Ca/Mg)
Alkalinity
Chl i / hl
Chlorine/chloramine
i
Chlorides
Silica
Others
Treatment options
• RO often only way to meet equipment water spec
Peter Voss
Sr. R&D Program Leader, Ecolab Water Solutions
Experience
•
•
•
•
Ecolab: 2004‐Present
H.B. Fuller: 1992‐2004
University of Minnesota: B S Chemistry
University of Minnesota: B.S. Chemistry
Indiana University Kelley School of Business: MBA
Career Highlights
• 9 years in the water purification industry
• 15 years of polymer chemistry experience
• Holder of 9 US patents
2
3/4/2013
Reverse Osmosis Life‐Cycle Costs
Water Basics
Water Impurities
Water contains “stuff” that must be removed
Impurities
Suspended Solids
Bacteria
Dissolved Solids
Dirt/Silica
Organic
Grease/Oil
Removed By
Mechanical Filtration
Chlorine
Inorganic
Chloramine
Removed By
Carbon Filtration
Sodium (Na)
Calcium (ca)
Magnesium (Mg)
Nitrates
Removed By
Ion Exchange or RO
Particulate Removal
Mechanics of removing particles from water
Filtration Methods
• Mechanical (dead‐end)
• Particle larger than space between filter fibers
• Particle trapped in fibers
• Cross‐flow
Cross flow
• Reverse Osmosis (98%+ rejection)
• Nano‐filtration (50‐90% Rejection)
Effectiveness
•
•
•
•
Standard carbon filtration: 5.0 µm
Advanced carbon filtration: 1 µm
Reverse Osmosis: 0.0005 µm
Fun fact: Human hair = 100 µm
3
3/4/2013
Filtration Spectrum
Comparison of various water filtration solutions
Treatment Options
Common platforms used in foodservice arena
FILTRATION
SOFTENING
RO
Sediment
z
9
z
Chlorine
z
9
z
Hardness
z
z
z
Contaminant
Alkalinity
9
9
z
TDS
9
9
z
RO can be thought of as a very “tight” filter that fills the gap left by standard carbon filtration and water softening
Water Variability
RO typically used in high TDS/hardness areas
Customer water quality
•
•
•
•
•
Ecolab R&D water database
15‐20% samples > 500+ ppm TDS
80% samples > 7 grains hardness
All candidates for RO
RO often best (or only) solution
Customers with water quality specs
• Beverage companies
• Coffee companies
• Food service operators
4
3/4/2013
Reverse Osmosis Life‐Cycle Costs
RO Applications
RO Applications
Typical points of use within a kitchen
Brewed beverages
• Coffee, Tea, Espresso
• Improves product quality, clarity, & taste
Steamers & Combi‐ovens
• High‐temperature cooking applications
• Prevent scale & corrosion on heat transfer surfaces
Ice Machines
• Produce top‐quality crystal clear ice
• Prevent scaling & decrease maintenance costs
RO Applications
Steamers & Combi-ovens
Benefits
• Prevents scale buildup on heat transfer surfaces
• Ensures compliance with OEM warranty specs
• Reduces downtime & maintenance costs
• Extends equipment life
Guidelines for use
• TDS > 60 ppm
• Hardness > 5 grains
• Silica > 13 ppm
• Alkalinity > 20 ppm
• Chlorides > 30 ppm
• pH < 7.5
5
3/4/2013
RO Applications
Ice machines
Benefits • Crystal clear, pure, long lasting ice
• Reduced maintenance costs
• Improved beverage quality/clarity
Guidelines for use
• TDS > 300‐400 ppm
• Hardness > 10‐12 grains
• Issues with ice cube cloudiness
RO Applications
Brewed beverages (coffee | tea | espresso)
Benefits •
•
•
•
•
Improved beverage clarity
Longer holding time
Less scale buildup
Reduced maintenance costs
Extended equipment life
Guidelines for use
• TDS > 150‐200 ppm
• Hardness > 5 grains
Brewed Beverages
Vastly improved clarity & overall quality
Treated
10 NTU
Untreated
100 NTU
6
3/4/2013
Reverse Osmosis Life‐Cycle Costs
RO 101
Basic Terminology
Commonly used concepts & terms
Permeate (product water)
• De‐mineralized water that has passed through a membrane
• AKA: Product water
Concentrate (reject water)
• Water containing minerals/impurities filtered by membrane
l /
fl
db
b
Recovery
• % of feed water that becomes permeate (good water)
Rejection
• % of feed water that becomes concentrate (bad water)
Flux
• Permeate production of a membrane (GPD)
RO Membranes
Principle of operation
Reverse osmosis systems are designed to remove (reject) dissolved mineral salts, organic molecules and other impurities from water by forcing water to pass through a semi‐permeable membrane…
Feed Water
Membrane
Waste
(Reject)
Water laden with solids exits the system as waste water, called concentrate
Water Out
(Permeate)
Solids‐free water exiting the system is called permeate, and
can range from 40‐80% of influent water flow
7
3/4/2013
Typical RO System
Basic components
Always
Required…
Not Always
Present…
Heart of System…
Atmospheric or
Bladder Tank…
Not Always
Present…
Reverse Osmosis Life‐Cycle Costs
Factors Affecting
Life-Cycle Costs
RO Life-Cycle Costs
Controllable & uncontrollable factors
Controllable
• Pre‐treatment
• System recovery & reject rates
S t & j t t
• System configuration (single vs. multi POU)
• Line pressure vs. membrane pump
• Storage tank configuration
• Other uses for reject water
• Preventative maintenance/service
Uncontrollable
• Incoming water quality
I
i t t
t
• Incoming water temperature
• Treated water peak demand & daily usage/demand
• Desired/required effluent water quality (TDS)
• Reactive service
8
3/4/2013
Influent Water Quality
Impurities affecting RO performance/costs
Impurity
What is it???
Impact on Membranes
Silt, dirt, debris, etc.
Fouls membranes & impedes water flow
Chlorine &
Chloramines
Sanitizer fed by municipalities to kill micro‐
organisms
Degrades materials & adhesives used in membranes Hardness
Calcium (Ca)
Magnesium (Mg)
Combines w/alkalinity & forms scale on membranes
Decaying plant, animal, human matter
Fouls membranes & impedes water flow
Mineral contaminants that are not common but can occur
Requires special pretreatment to prevent membrane fouling
Sediment
Organics
Iron &
Manganese
Influent Water Quality
Impact on RO life-cycle costs
You get what you get…
•
•
•
•
Water quality dependent on source Surface water: Higher in suspended solids/organics
Ground water: Higher in dissolved solids
Either way: Must “deal” with it
Direct relationship between water quality & costs
• Water quality dictates level of pretreatment required
• Better water quality Ö less pre‐treatment Ö lower TCO
• Worse water quality Ö more pre‐treatment Ö higher TCO
Pretreatment
Balancing act… Pretreatment is not “free”
Pretreatment is non‐optional
• Required to protect critical membranes
Common forms of pre‐treatment
•
•
•
•
Mechanical filtration: Removes sediment, dirt, silt
Mechanical filtration: Removes sediment
dirt silt
Carbon filtration: Removes chlorine/chloramines
Ion exchange (softening): Removes hardness
Anti‐scalants: Chemically conditions hardness
Impact of good pretreatment on life cycle costs
• Achieve longer membrane life Ö lower costs
• Operate RO at higher recovery Ö lower costs
9
3/4/2013
System Recovery
Percent of incoming water permeate
% Recovery = Permeate / (Permeate + Concentrate) System‐1
System‐2
Feedwater (gpm)
2.0
2.0
Permeate (gpm)
10
1.0
15
1.5
Concentrate (gpm)
1.0
0.5
Recovery (%)
50%
75%
Feed Water
Membrane
Water Out
(Permeate)
Reject/Waste
(Concentrate)
System Recovery
Balancing the costs
High Recovery (60‐80% permeate)
• Less water to drain Ö lower water operating costs
• High Recovery Ö membranes more prone to plugging & fouling
• Shortened membrane life Ö higher membrane costs
Low recovery (30‐50% permeate)
• More water to drain Ö higher water operating costs
• Low Recovery Ö membranes less prone to plugging & fouling
• Extended membrane life Ö lower membrane costs
System Rejection
Focus on water quality requirements
High Rejection (98%+) Membranes
•
•
•
•
Higher costs
Very high quality permeate Less tolerant to poor pretreatment
M More prone to membrane fouling
t b
f li
Lower Rejection (90‐95%) Membranes
•
•
•
•
•
Lower costs
Slightly reduced permeate quality
Meets requirements of most food service applications
More tolerant to poor pretreatment
Less prone to fouling
10
3/4/2013
Desired Effluent Quality
Not all applications are created equal
Brewed Beverages
Steamers/Combi‐Ovens
Specialty Coffee Association (SCAA) Water Quality Standard
Treated Water Demand
Trade-off between system size & storage capacity
Water storage tanks are required to meet the “on‐
demand” water flow requirements of most food service equipment
Atmospheric tank
• Smaller foot print ‐‐ higher pressures with delivery pump
Accumulator tank (i.e. bladder)
• Larger foot print ‐‐ lower delivery pressures
Storage tank size relative to water needs/demand
• Smaller tank Ö Larger (costlier) RO but smaller footprint
• Larger tank Ö Smaller (cheaper) RO but larger footprint
Water Temperature
Key factor in performance of RO membranes
Inverse relationship between temperature & output
• As water temperature drops ‐‐ membrane output drops
• At 50°F, membrane output is 50% less than at 77°F
Must upsize for cold water
• Colder climates require RO systems with increased output and/or increased permeate storage capacity
• Systems should be sized for the coldest time of the year to consistently meet demand
• Larger system size Ö higher cost
11
3/4/2013
System Configuration
Single verses multi point-of-use systems
Single Point‐of‐Use
• Focus on water requirements of 1 appliance (i.e. steamer)
• Simplified sizing & less complexity
• Several systems may be required for complete coverage
Multi Point‐of‐Use
•
•
•
•
Treat several water consuming appliances with a central system
Water treatment cost spread over multiple pieces of equipment
Fully leverage the benefits of demineralized water
Requires greater understanding of water usage needs & patterns to properly size system
Alternate Uses For Reject
Collecting & reusing reject water can reduce TCO
Reject water is potable
• Not “bad” water
• Higher concentration of minerals vs. untreated water
Requires collection of reject water & (re)distribution
• Additional space required
• Trade‐off between on‐going expense (reject water) vs. upfront system cost
Service
Proper preventative service reduces TCO
Preventative service (scheduled)
• Pretreatment – proactive 6 month prefilter change‐out
• Proactive 1‐2 year membrane change‐out
• Routine monitoring of system insures proper system performance
Reactive service (wait until broken)
•
•
•
•
Membrane failure – potential equipment damage
Unexpected equipment downtime – lost revenue
Uncertain system performance
Expensive service 12
3/4/2013
Financing
Purchase upfront verses lease
Purchase (buy)
• Higher upfront capital costs
• Requires maintenance program or service agreement
• Potential variable monthly maintenance/repair expenses
Lease/Rent
• Lower upfront capital costs
• Preventative & reactive service typically included
• Fixed monthly expense with little/no variability
Reverse Osmosis Life‐Cycle Costs
Summary
(Rules of Thumb)
Rules of Thumb
• Smaller systems (<250gal/day), lower recovery = lower TCO
•
•
Water costs are relatively low vs. potential membrane / system failure costs
50% recovery = $30/month in added water costs vs. 75% recovery ($6/1k gallon)
• Higher recovery (60%+), better pretreatment = lower TCO
•
•
Anti‐scalant prefilter is small upgrade cost vs. membrane / system failure costs
Scale inhibiting prefilter = additional $100/6 months
• Higher Rejection 95%+(steamers), better pretreatment = lower TCO
• Line pressure RO membrane vs. high pressure membrane Ö lower TCO
•
•
Economical high output low energy membranes are readily available With adequate line pressure (50psi), membrane pump systems are not required
• Smaller water storage tank relative to water demands Ö higher TCO
•
Requires larger higher output RO with bigger membranes
13
Download PDF
Similar pages