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WATER CONSERVING TECHNOLOGY OPTIONS FOR INSTALLATION USE. Richard Scholze and Annette Stumpf U.S. Army Corps of Engineers ERDC-CERL Champaign, IL. Water Conservation. Why Do It? Delay or Avoid Expensive Water Supply and Wastewater Treatment Capital Projects

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Richard Scholze and Annette Stumpf

U.S. Army Corps of Engineers


Champaign, IL

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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


Water Management Plan

Implementation of FEMP BMPs

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Selected Conservation Opportunities

  • Domestic Use

  • Administrative/Commercial/Institutional

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Current Lowflow Designs Much Better

Dual Flush Toilets

Waterless Urinals


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Dual Flush Toilet

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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

Dual Flush Toilet Fixtures

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Waterless Urinals

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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

Waterless Urinals

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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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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

SOMAT Disposal System

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SOMAT SystemPulper and Hydra-Extractor

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Boilerless Food Steamers

  • 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 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


  • 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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  • Steam Sterilizers

  • Example – University of Washington

  • Why – Steam Sterilizers Use Cold Water to Temper 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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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 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


Scale Prevention in Condensers

Wide Range of Scale Forming Minerals

Calcium Carbonate, Calcium Sulfate, Calcium Phosphate, Magnesium Silicate

Biological Fouling


Tested 3 Processes

Only Effective Process was Alkalinity Control

Operated at 5.5 Cycles of Concentration

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Supermarket Cont.


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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Management Options Potential Savings


Turf maintenance 10

Turf maintenance, irrigation system 20

Maintenance, Irrigation Scheduling

Mulching in Ornamental Gardens 20

Soil Amendments (Compost) 20

Irrigation Scheduling 25

Irrigation/Soil maintenance 65 to 75

Lawn to go Dormant 90

Hardware Options

AutoRain Shut Off 10

Soil Moisture Sensors; Soil Probes 10 to 30

Improve Performance 40

Drip/Bubbler Irrigation 50

Gray Water Up to 100

Rain Barrel Catchment Up to 100

Landscape Design Options

Landscape Design 19 to 55

Turf Reduction 19 to 35

Choice of Plants 30 to 80

From Gleick et al.

Options for the Reduction of Outdoor Garden/Landscape Water Use

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New Faucet Developments

Hydropower Generator to Recharge Battery

Uses PV Cell to Power Optical Sensor

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  • Variety of Technologies and Techniques to Reduce Water 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 Richard.J.Scholze@usace.erdc.army.mil

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