An Advanced Urban Water Management Concept: Graywater Separation

1. An Advanced Urban Water Management Concept: Graywater Separation Sybil Sharvelle September 11, 2008

2. Separate Graywater Plumbing • Graywater is relatively clean compared to blackwater • On-site residential reuse • Landscape irrigation • Storage and coarse filtration • Toilet Flushing • Minimal Treatment • Pathogen inactivation • TSS reduction

3. Current Wastewater Management Energy & $$$ WWTP N & P Graywater Blackwater

4. Graywater Separation Green Energy Anaerobic Digester High N Low Pathogen Compost Graywater Blackwater

5. Advantages of Graywater Separation • Reduced load to wastewater treatment plant • Reduced capital costs • Reduced energy requirements • Water conservation • Preservation of source waters • Water quality improvements

6. Recent Current and Studies at CSU • Research on a residential graywater system • Review of the literature on “Long Term Effects of Residential Landscape Irrigation using Household Graywater • Pilot testing the Effects of Residential Irrigation using Household Graywater • Wetland treatment of graywater • Pilot studies on reuse of graywater from university residence hall

7. Need for Water Reuse Source: CO Department of Public Affairs, State Demographers Office, June 2003

8. Graywater Production Household Graywater Production (family of four, gpd) - Bath 4.8 - Shower 46.4 - Washer 60.0 - Faucets 43.6 - Other 6.4 TOTAL 161 gpd 1128 g/wk - Toilets 74 gpd 518 g/wk - Irrigation 610 g/wk (waters 300 plants or 1000 ft2 of grass) Source: AWWARF

9. Drinking Water Treatment $1.25/1000 gal Waste Water Treatment $2.40/1000 gal ResidentialReusePotential Greywater Generation of 87 gpcd Fort Collins Population 250,000 (2000 Census)

10. Graywater Quality Source: Eriksson et al., 2003

11. Application of Graywater for Household Irrigation Storage Tank Course Filter Household Graywater Drip Irrigation

12. Graywater System Irrigation well coarse screen

13. Graywater Irrigation

14. Pilot Testing on a National Scale

15. Application of Graywater for Household Irrigation • Many households use graywater for irrigation • Current regulations are not based on science • Legal in California, New Mexico, and Arizona (not Colorado) • In depth studies on fate of graywater constituents and effects to plant health required to make informed decisions about graywater irrigation • Study funded by WERF and US Soap and Detergent Association to Examine the Long Term Effects of Using Household Graywater for Irrigation

16. Graywater Irrigation Project

17. Graywater Irrigation Project • 3-year duration • Samples collected at households with systems in place for more than5 years • New systems installed at households in each state and monitored for three years • Parameters Studied • Surfactants • Antimicrobials • Pathogens • Plant health • General soil quality parameters

18. Some Forward Thinking at CSU • Treat graywater in wetlands and combine with stormwater runoff for reuse non-potable needs (decentralized treatment and reuse) • Blackwater collection and treatment for water reuseand energy generation

19. Location for Graywater Treatment Lagoons

20. Graywater, Labwater and Blackwater Lines in Atmospheric Sciences Laboratory at CSU

21. The Wetlands Under Construction

22. Planting the Wetlands

23. Latest Graywater Application to a University Residence Hall • One floor (14 residential units) plumbed with: • Graywater (sinks, showers, laundry) separated from blackwater • Toilets water supply separate from potable water lines • Experiments • Use raw (irrigation) water to flush toilets • Use conditioned graywater to flush toilets and for irrigation

24. Summary on Graywater • Graywater is a great source of water for reuse applications • Not highly contaminated • Graywater use for irrigation has many benefits • Water conservation • Contains important nutrients for plant growth • WERF funded research will provide ability to make informed decisions about graywater use for irrigation

25. Separate Graywater: What Happens to Wastewater Characteristics? Sources: Palmquist & Hanæus 2004 & Eriksson et al. 2003

26. Treatment Options • Aerobic • High removal of organic carbon, nitrification • Pathogens still present • Extensive disinfection required for reuse • High oxygen requirements • Anaerobic • Generation of methane – renewable energy • Pathogen inactivation • Water reuse after treatment (high nitrogen content) • Removal of organic carbon • Higher maintenance

27. A Word on Waste to Energy • Anaerobic digesters are well developed technology for conversion of high BOD wastes to energy • Generation of methane by bacteria from carbon under anaerobic conditions • Rise in prices and demand for renewable energy has resulted in renewed interest

28. Urban Applications • Anaerobic digesters good method for blackwater treatment when graywater is utilized for irrigation or treated by wetland • Water can be collected and treated for potential reuse • Can be combined with local industrial and food processing wastes for increased methane potential

29. Anaerobic Digestion Green Power Anaerobic Environment Cogeneration CH4 Acids  CH4 Organics  Acids Hot Water High BOD Waste High Nutrient Low Odor Waste

30. AD Energy Generation • For a neighborhood with 100 households, anaerobic digestion would produce enough energy to offset waste treatment energy requirements and 5% of energy requirements for the neighborhood • 3 persons per household • 60 gal/cap/day wastewater (40% blackwater) • Household Energy Use: 33,595 kWh / year • Supplement with other alternative energy sources (wind, solar, etc.)

31. Questions?