WATER CONSERVING
TECHNOLOGY OPTIONS FOR
INSTALLATION USE
Richard Scholze and Annette Stumpf
U.S. Army Corps of Engineers
ERDC-CERL
Champaign, IL
US Army Corps
of Engineers
Engineer Research and Development Center
Water Conservation
Why Do It?
Delay or Avoid Expensive Water Supply and
Wastewater Treatment Capital Projects
Helps Protect Fundamental Natural Resources
Through Ecosystem Protection, Protect Current
Quality of Life and Provide for Future
Generations
Minimize Effects of Drought
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Federal Sector
Executive Order 13123
Requirements
Water Management Plan
Implementation of FEMP BMPs
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Selected Conservation
Opportunities
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Domestic Use
Administrative/Commercial/Institutional
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Toilets
Current Lowflow Designs Much Better
Dual Flush Toilets
Waterless Urinals
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Dual Flush Toilet
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Dual Flush Toilet Fixtures
Only Recently Actively Marketed in U.S.
4 New Manufacturers in 2004, Others Watching Marketplace
Costs Becoming Competitive
Do They Save water?
3 Study Summary
20-30% Savings in Water
Weighted Average Flush 1.1 to 1.3 gpf vs 1.6
Customer Satisfaction Positive, Liked Option
Advantage – Seldom Clogs
Disadvantage – Smaller Water Spot, Possible Streaking
Payback - 8.5 Years for $300 Toilet, 10 Flushes/day, Combined
W/WW Cost of $3.79/1000 gallons
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Waterless Urinals
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Waterless Urinals
Becoming Widespread (Thousands in Use)
Several Manufacturers
Focus on Non-Residential Installations
Concern Over Proper Maintenance
Ex. Presidio of Monterey
173 Urinals Replaced – Classrooms, Administrative
and Recreational Facilities in 48 Buildings
Expected Savings - 11,500 gal/day or 3 million
gallons per year
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of Engineers
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Food Service
• Pre-Rinse Spray Valves
• SOMAT System
• Boilerless Food Steamers
• Air-cooled Icemakers
• Water Conserving Dishwashers
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Pre-Rinse Spray Valves
Typical Restaurant/Food Service – Up to 50% of Dishwashing
Water Consumed by Pre-rinse Spray Valve to Remove
Food From Dishware, Utensils and Pans
Newer Units 1.6 gpm
Over 3.0 for Non-efficient Valves
Usually Use Heated Water
Traditional “Showerhead” Type Spray Pattern
Orifices Become Restricted with Time
New “Knife-like” Continuous Spray – More Efficient, Less
Mineral Buildup
Ex. Water savings 77,050 gal/year
Gas Savings 335 therms/year; 7600 kWh
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SOMAT Disposal System
What is It? Food Waste Pulping and Dewatering System to Replace Scraping
Trough and Garbage Disposal System in Kitchens
Uses Water to Move Material Scraped Off Plates to a Pulper Which Cuts Solid
Waste into a Slurry
Slurry Flows From Pulper to Water Extractor Unit Which Removes Water to
Produce Odor-Free, Semi-dry pulp
Extracted Water Returned to Feed Tray to Complete Closed-loop Cycle
Water Level Automatically Controlled
Small Amount 1-3 gpm Bled Off and Replaced
System Eliminates Need to Separate Food Scraps, Paper and Plastic Waste
Reduces Staff Time by Half
Ex. POM 2 Systems, 2 Bldgs. – Cuts Daily Water Consumption from 9,240 to
1680 gallons
Savings 2.76 Million gal/year
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SOMAT System
Pulper and Hydra-Extractor
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Boilerless Food Steamers
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Atmospheric Compartment Food Steamers – Connected to an
Incoming water Line and Utilize a Steam Boiler or Generator That
Injects Steam at a Constant Rate During the Cooking Event
To Maintain Atmospheric Pressure, Rejected Steam Goes into
Drain Requiring Additional Cooling Water
Boilerless Steamers Use a Water Reservoir in Bottom of Cooking
Compartment in Lieu of a water Connection – Manual Fill and
Drain. No Steam Leaves.
Better Energy Performance and Water Efficiency
Easier Cleaning
Now About 10 Different Manufacturers
Estimate of Savings – 500-1000 gallons per day plus Energy
Savings, 3 gph vs. 20 to 40 gph
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Boilerless Food Steamer
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High Efficiency Washers
• Most Are Front – Loaders
• A Few Top Loaders
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Marginally Meet Standard
CEE (Consortium for
Energy Efficiency)
Toploaders ½ to 1/3 Price
of Front Loaders
36% Less Water
60% Less Energy
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Common Area Laundry Rooms
Study
– In-Unit Washer – 11,800 gal/year
– Common Area Laundry Rooms 3600 gal/year per
Apartment
– 3.3 Times as Much Water
Why? Residents with In-Unit Washers Tend to Operate
Equipment More Often and Less Efficiently
Advantages – Savings in Gas, Electricity and Sewage,
Reduced Construction Expense, Increased Space in
Units
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Hospitals
• Steam Sterilizers
• Example – University of Washington
• Why – Steam Sterilizers Use Cold Water to Temper
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Condensate from Steam (212 F) to Keep Water Entering
Drain at or Below 140 F
Older Units – Constant Bleed of 1 gpm to Mix While Unit is
Hot Including Idle Time
Install Water Saving Kit – Device or Components That
Sense Effluent Temperature and Only Apply Water When
Necessary to Reduce Effluent Temperature
Evaluation – Payback Less Than 3 months
Tests Resulted in 68 to 98% Reduction
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Condensate
Local Example – San Antonio
Use Air Conditioning Condensate
Free Resource – High Quality, Distilled Water
If You Can Get to the Pipe, Catch It
Typical Home 5-10 gal/day
Larger Buildings Rule of Thumb 0.1 to 0.3 gallon per ton-hour
Collect – Residential Bucket Under Drain Line
Rout to Rain Barrel or Other Collection System
Use Gravity flow
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Condensate – Cont.
• Other Buildings
• Ex. 500 ton System @ 80 % Load (0.2 Factor) Produces 1.3
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gpm or 56,000 Gal/Month
Case Study- San Antonio Library
Produce 1 gpm (43,200 gal/month)
Garden 26,000 square feet
Collection System – 3 Interconnected Concrete Cisterns
(8400 gal capacity)
Collect from Sump Gravity Fed into Irrigation System
Total Cost $21,500, 1/3 that of Rainwater Harvest System
Another Example - River Center Mall – 12 MG of
Condensate Used for Cooling Tower Makeup
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Condensate – Cont.
Another Bldg. Captures 6.2 million gallons per year
Used for Boiler Feed Makeup water
Cost $19,000 Installed
Savings $26,000 / year
Payback – 11 Months
IOI – Possible Ordinance Mandating Collection
System in New Large Buildings
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Example Supermarket (CA)
Focus on Cooling
Average Concentration Ratio 2.45 Baseline
Cycles of Concentration – Approach 6, Water Reduction Negligible
Problems
Scale Prevention in Condensers
Wide Range of Scale Forming Minerals
Calcium Carbonate, Calcium Sulfate, Calcium Phosphate,
Magnesium Silicate
Biological Fouling
Corrosion
Tested 3 Processes
Only Effective Process was Alkalinity Control
Operated at 5.5 Cycles of Concentration
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Supermarket Cont.
Benefits
Reduced Water Use, Lower Water and Wastewater Charges
Reduced Electrical Use
Reduced Acid Washing, Life Extension of Cooling Tubes
B/C Ratio 2 to 4 for Water and Wastewater
Other Water Savings
Use High Efficiency Spray Nozzles and Aerators on All Hand
Sinks and Spray Tables
Eliminate Garbage Grinders
Replace Low Pressure Hoses with High Pressure Sprayers for
Washing
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of Engineers
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Options for the Reduction of
Outdoor Garden/Landscape Water
Use
Management Options
Turf maintenance
Turf maintenance, irrigation system
Maintenance, Irrigation Scheduling
Mulching in Ornamental Gardens
Soil Amendments (Compost)
Irrigation Scheduling
Irrigation/Soil maintenance
Lawn to go Dormant
Hardware Options
AutoRain Shut Off
Soil Moisture Sensors; Soil Probes
Improve Performance
Drip/Bubbler Irrigation
Gray Water
Rain Barrel Catchment
Landscape Design Options
Landscape Design
Turf Reduction
Choice of Plants
Potential Savings
(Percent)
10
20
20
20
25
65 to 75
90
10
10 to 30
40
50
Up to 100
Up to 100
19 to 55
19 to 35
30 to 80
From Gleick et al.
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of Engineers
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New Faucet Developments
Hydropower
Generator to
Recharge
Battery
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of Engineers
Uses PV Cell to
Power Optical
Sensor
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Summary
• Variety of Technologies and Techniques to Reduce Water
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Consumption
New Resource Soon Available
– Army Water Conservation Website
– Information on Policies, Technical Guidance, Case
Studies, Best Practices Within Army and Other Sectors
– Links to Information Sources
– Further Information Contact Author at 217-398-5590 or
email [email protected]
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of Engineers
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