Environmental Perspectives and Issues
Environmental Perspectives and Issues Nicholas Ashbolt, Robert Bastian & Robert Goo Decentralized Water/Wastewater Reuse for Clean, Green and Smart Rural & Urban Communities Nags Head, NC, July 29th, 2009 Office of Research and Development Office of Water
Environmental aspirations • Closed loop systems (nutrients, energy, water)
–Global fossil P for agriculture is finite, must reuse –Systems with net zero energy balance –Off the water grid (yet centrally managed so robust) • High system resilience – watershed level water
balance –Aggressive infiltration of WW, stormwater and graywater can help ensure the integrity of the hydrologic system –Aquifer recharge for more sustainable landscapes 1
(connection between upland health and riparian health)
Development impacts on the Water Cycle
Alteration of the natural hydrologic cycle: Blue arrows represent the natural 2 system; Red arrows indicate short-circuiting due to piped systems. Courtesy of Kenneth Belt, USDA Forest Service, Baltimore, Maryland (NAS, 2008)
Water-Energy nexus US total water use
•Water and wastewater energy use for US cities consumes 5-10% national electricity production • 25-30% water utilities operating cost Carlson, S.W. and Walburger, A. (2007) Energy Index Development for Benchmarking Water and Wastewater Utilities. Denver: American Water Works Association Research Foundation. Subcommittee on Buildings Technology Research and Development (2008) Federal Research and Development Agenda for Net-Zero Energy, High-Performance Green Buildings. Washington D.C.: 3 Executive Office of the President of the United States.
Shortcomings of conventional waterborne sewage – ‘death by flushing’ 1868 river pollution commissioner (E. Frankland) 4
linear end-of-pipe technology
Top 15 categories of impairment requiring CWA 303(d) action
5
EPA, National Section 303(d) List Fact sheet (2004-2006) (http://iaspub.epa.gov/waters/national_rept.control)
Background - Hazards - Environmental impacts
6
Human & Ecological hazards in reuse waters Pathogens
Viruses
Bacteria
Parasitic protozoa
Chemicals
7
Cleaning agents
Pharmaceuticals
Design for the Environment (DfE) Safer Product Recognition Program • Chelating & Sequestering Agents –DfE prefers chelating agents with low toxicity and rapid biodegradation. Currently, inorganic phosphates that contribute to eutrophication, and NTA, a potential carcinogen, are not acceptable in DfE recognized products (should phase out in 3 y).
• Safer Detergents Stewardship Initiative (SDSI) to recognize companies that phase out the use of nonylphenol ethoxylate surfactantss. 8
www.epa.gov/dfe/pubs/formulat/formulator_review1.pdf www.epa.gov/dfe/pubs/projects/formulat/sdsi.htm
We need a paradigm shift Current: use water once & disposal
http://www.ecosanservices.org 9
Resource recycle instead of disposal
Options for households Integration of drinking water, wastewater & stormwater Irrigation
Energy recovery
Fertilizer
www.urbanwater.org
10
NPK reuse
Ashbolt et al. (2006) In: 2nd IWA Leading-Edge on Sustainability in Water-Limited Environments. WEMS vol 10, IWA Publishing, London.
Likely trends / Implications • Climate change:
–More intense storms, sewer overflows, outages –Hence off grid systems more resilient –Aging population, more prone to respiratory diseases via water aerosols (Legionellosis etc.) • Need to reduce greenhouse gases: –Move less water over longer distances/recycle, particularly reuse of greywater within homes • Renewable energy/recovery: –Utilize energy within ‘wastes’ / energy recovery –Urban agriculture / recycle of local nutrients 11
Environmental Issues with Water Reuse • Key negative issues • Salinity, boron and surfactants can alter soil properties, damage plants and contaminate ground water • Trace pharmaceuticals and personal care products (PCP) may impact on biota • Key positive issues • Reuse reduces water withdrawals and: • Enhances storm & ecological flow management • Enables nutrient recovery & reduces eutrophication problems • ‘Build-in’ control at home if local drinking/reuse waters
• Greening reduces urban heat island & GHGs 12
Sidebar on low P detergents • Phosphates vs other chelating agents (removes Ca2+ Mg2+ surfactant ppt)
– Used in household detergent formulations = 30-40% sewage P in 1970’s (when 11 mg/L sewage total P, but today at about 5 mg/L) – P causes eutrophication, as generally limited nutrient for growth of algae & cyanobacteria in freshwaters; most from agriculture • EPA limit in streams < 0.05 mg/L & lakes 15% sewage P from automatic dishwashing machines
• Alternatives – NTA-EDTA replacements phased out in Europe as nitrilotriacetate (NTA) is carcinogenic & EDTA is persistent – Citrates require more expensive enzymes to work – Zeolites not very effective – Phosphonates do not biodegrade but limited eutrophication potential • An argument that phosphates are necessary for high temp, high speed, high
13 alkaline commercial dish washing (may contribute < 0.9% P in sewage)
Litke, 1999
Sodium & Boron (B) are primarily from graywater • Laundry detergent is high
in sodium & B salts • Na disperses clay soils –which reduce drainage –Ca or Mg needed to remediate • Sodium adsorption ratio (SAR) of GW 2.8 - 6.0 –Long-term SAR > 4 can disperse clays in soils 14
Gross et al. (2005)
Boron is phytotoxic & Surfactants also cause soil hydrophobicity
• Boron (B) & Surfactants
– Detergents and soaps are the main sources of boron (B) and surfactants found in domestic effluents – B assayed by inductively coupled plasma (ICP), & anionic surfactants by the methylene blue active substances (MBAS) • The recommended B value for irrigation water varies between 0.3 and 1.0 mg.L–1 for non-tolerant plants (ANZECC, 1992)* – B in GW ranges 0.1-1.6 mg.L–1, suggesting possible negative effects to a variety of ornamental plants (Gross et al., 2005) • Surfactant concentrations in GW ranged between 29-60 mg.L–1 – Surfactants can alter soil properties and be toxic to plants at these concentrations (Bubenheim et al., 1997; Abu-Zreig et al., 2003) 15
*B toxicity review: Camacho-Cristóbal et al. (2008)
How to remove salinity? • Salinity affects the availability of crop water and
sodium causes clay soils to disperse • Naturally removed by rainfall/snowmelt leaching • If not, salts can be reduced by membrane treatments: –SAR values of secondary effluent, NF permeate, and RO permeate: 1.78, 4.67, and 0.72 respectively –The SAR value after NF (4.67) increased to more than twice that of the feed solution, whereas the SAR of the RO permeate decreased to 0.72 • Consequently, long-term potential harm if using NF treated secondary effluent for irrigation 16
Chang et al. (2005) Water Science and Technology 51:313-318.
Metals generally not phytotoxic • After 100 years of sewage
irrigation in Paris, metals accumulated: – Zn>Pb>Cu>As>Hg>Cd – Mostly in surface humics • Plant uptake levels generally under health limit Irrigation fields of Paris in 1900 Védry et al. (2001)
17
Year
Irrigated (Ha)
Irrigated (106m3/y)
1904
5,100
200
1950
5,000
100
1980
2,010
40
Also, no metal issues in bioretention cells (Davis et al. 2008)
Metals that may be phytotoxic or toxic to humans via food Metals in top soil after 100 years of application in Paris mg/kg
Cd
Cu
Hg
Pb
Zn
Top soil Limit
2.2
138
2.6
274
432
2
100
1
100
300
Metal bioavailability depends on pH of pore water Metals in various vegetables grown in the sewage amended soils
18
Védry et al. (2001)
Wastewater irrigated soils (90y) Mexico Person care products (Durán-Alvarez et al., 2009)
19
No evidence for soil accumulation, as degrade in soil
Take home messages:
US Domestic water use (AWWA/AwwaRF) 20
1) Soil application of wastewaters and in situ treatment appears to be much less impacting on the environment than riverine discharge 2) Provides for nutrient recovery 3) Local graywater reuse could reduce demand by > 50%
Other environmental benefits: water conservation & increased value • Local reuse of wastewater could save up to 70% on
water demand –So leaving more water for ecological services • Local groundwater recharge (via grass swales, infiltration basins etc.) enhance stormwater management & ecological services –Also provide amenity and increased property values
21
NRC (2008)
Energy & Greenhouse Gases • Water and wastewater facilities can be the largest single
energy user for many municipalities –Energy in wastewaters + municipal ‘wastes’ could balance it out (DW 1500 kWh/MG + WW 1200 kWh/MG) • Municipal wastewater treatment causes: –0.4% of total GHG emissions –3.0% of total anthropogenic methane & 2.2% N2O –Energy used in treatment yields 1.2% total US GHGs Inventory of Greenhouse Gas Emissions and Sinks 1990-2006 Subcommittee on Buildings Technology Research and Development (2008) Federal Research and Development Agenda for Net-Zero Energy, HighPerformance Green Buildings. Washington D.C.: Executive Office of the President of the United States. 22
Recommendations • Overall, strive to mimic natural systems & pre-
development hydrology –Need to promote decentralized to aid in reversing sprawl, car dependency, energy use & associated health issues –e.g. Cluster homes/apartments using park/garden treat’t • Technologies to:
23
–Enhance ground water infiltration –Divert urine and enable food/fecal energy recovery with residual fertilizers (NPK) back to agriculture • To enhance environmentally safe graywater reuse: –Phosphate-containing detergents need replacement with benign ‘building’ agents & surfactants –Use of low B detergents to evade phytotoxicity problem
References • Abu-Zreig, M., Rudra, R.P. and Dickinson, W.T. (2003). Effect of application of •
• • •
•
• •
24
surfactants on hydraulic properties of soils. Biosystems Engineering 84:363–372. ANZECC (1992). Australian Water Quality Guidelines for Fresh and Marine Waters. Australian and New Zealand Environment and Conservation council, Canberra, Australia. Bubenheim, D., Wignarajah, K., Berry, W. and Weydeven, T. (1997). Phytotoxic effects of graywater due to surfactants. J. Amer. Soc. Hort. Sci. 122:792–796. Camacho-Cristóbal, J.J., Rexach, J. and González-Fontes, A. (2008) Boron in plants: deficiency and toxicity. J. Integr. Pl. Biol. 50:1247-1255. Gross, A., Azulai, N., Oron, G., Ronen, Z., Arnold, M. and Nejidat, A. (2005). Environmental impact and health risks associated with greywater irrigation: a case study. Water Sci. Technol. 52(8):161-169. Litke, D.W. (1999) Review of Phosphorus Control Measures in the United States and Their Effects on Water Quality. Water Resources Investigations Report 99-4007. Denver, Colorado: U.S. Geological Survey. NRC (2008) Urban Stormwater Management in the United States. Washington D.C.: The National Academies. Védry, B., Gousailles, M., Affholder, M., Lefaux, A. and Bontoux, J. (2001) From sewage water treatment to wastewater reuse. One century of Paris sewage farms history. Water Sci. Technol. 43:101-107.
Environmental aspirations • Closed loop systems (nutrients, energy, water)
–Global fossil P for agriculture is finite, must reuse –Systems with net zero energy balance –Off the water grid (yet centrally managed so robust) • High system resilience – watershed level water
balance –Aggressive infiltration of WW, stormwater and graywater can help ensure the integrity of the hydrologic system –Aquifer recharge for more sustainable landscapes 1
(connection between upland health and riparian health)
Development impacts on the Water Cycle
Alteration of the natural hydrologic cycle: Blue arrows represent the natural 2 system; Red arrows indicate short-circuiting due to piped systems. Courtesy of Kenneth Belt, USDA Forest Service, Baltimore, Maryland (NAS, 2008)
Water-Energy nexus US total water use
•Water and wastewater energy use for US cities consumes 5-10% national electricity production • 25-30% water utilities operating cost Carlson, S.W. and Walburger, A. (2007) Energy Index Development for Benchmarking Water and Wastewater Utilities. Denver: American Water Works Association Research Foundation. Subcommittee on Buildings Technology Research and Development (2008) Federal Research and Development Agenda for Net-Zero Energy, High-Performance Green Buildings. Washington D.C.: 3 Executive Office of the President of the United States.
Shortcomings of conventional waterborne sewage – ‘death by flushing’ 1868 river pollution commissioner (E. Frankland) 4
linear end-of-pipe technology
Top 15 categories of impairment requiring CWA 303(d) action
5
EPA, National Section 303(d) List Fact sheet (2004-2006) (http://iaspub.epa.gov/waters/national_rept.control)
Background - Hazards - Environmental impacts
6
Human & Ecological hazards in reuse waters Pathogens
Viruses
Bacteria
Parasitic protozoa
Chemicals
7
Cleaning agents
Pharmaceuticals
Design for the Environment (DfE) Safer Product Recognition Program • Chelating & Sequestering Agents –DfE prefers chelating agents with low toxicity and rapid biodegradation. Currently, inorganic phosphates that contribute to eutrophication, and NTA, a potential carcinogen, are not acceptable in DfE recognized products (should phase out in 3 y).
• Safer Detergents Stewardship Initiative (SDSI) to recognize companies that phase out the use of nonylphenol ethoxylate surfactantss. 8
www.epa.gov/dfe/pubs/formulat/formulator_review1.pdf www.epa.gov/dfe/pubs/projects/formulat/sdsi.htm
We need a paradigm shift Current: use water once & disposal
http://www.ecosanservices.org 9
Resource recycle instead of disposal
Options for households Integration of drinking water, wastewater & stormwater Irrigation
Energy recovery
Fertilizer
www.urbanwater.org
10
NPK reuse
Ashbolt et al. (2006) In: 2nd IWA Leading-Edge on Sustainability in Water-Limited Environments. WEMS vol 10, IWA Publishing, London.
Likely trends / Implications • Climate change:
–More intense storms, sewer overflows, outages –Hence off grid systems more resilient –Aging population, more prone to respiratory diseases via water aerosols (Legionellosis etc.) • Need to reduce greenhouse gases: –Move less water over longer distances/recycle, particularly reuse of greywater within homes • Renewable energy/recovery: –Utilize energy within ‘wastes’ / energy recovery –Urban agriculture / recycle of local nutrients 11
Environmental Issues with Water Reuse • Key negative issues • Salinity, boron and surfactants can alter soil properties, damage plants and contaminate ground water • Trace pharmaceuticals and personal care products (PCP) may impact on biota • Key positive issues • Reuse reduces water withdrawals and: • Enhances storm & ecological flow management • Enables nutrient recovery & reduces eutrophication problems • ‘Build-in’ control at home if local drinking/reuse waters
• Greening reduces urban heat island & GHGs 12
Sidebar on low P detergents • Phosphates vs other chelating agents (removes Ca2+ Mg2+ surfactant ppt)
– Used in household detergent formulations = 30-40% sewage P in 1970’s (when 11 mg/L sewage total P, but today at about 5 mg/L) – P causes eutrophication, as generally limited nutrient for growth of algae & cyanobacteria in freshwaters; most from agriculture • EPA limit in streams < 0.05 mg/L & lakes 15% sewage P from automatic dishwashing machines
• Alternatives – NTA-EDTA replacements phased out in Europe as nitrilotriacetate (NTA) is carcinogenic & EDTA is persistent – Citrates require more expensive enzymes to work – Zeolites not very effective – Phosphonates do not biodegrade but limited eutrophication potential • An argument that phosphates are necessary for high temp, high speed, high
13 alkaline commercial dish washing (may contribute < 0.9% P in sewage)
Litke, 1999
Sodium & Boron (B) are primarily from graywater • Laundry detergent is high
in sodium & B salts • Na disperses clay soils –which reduce drainage –Ca or Mg needed to remediate • Sodium adsorption ratio (SAR) of GW 2.8 - 6.0 –Long-term SAR > 4 can disperse clays in soils 14
Gross et al. (2005)
Boron is phytotoxic & Surfactants also cause soil hydrophobicity
• Boron (B) & Surfactants
– Detergents and soaps are the main sources of boron (B) and surfactants found in domestic effluents – B assayed by inductively coupled plasma (ICP), & anionic surfactants by the methylene blue active substances (MBAS) • The recommended B value for irrigation water varies between 0.3 and 1.0 mg.L–1 for non-tolerant plants (ANZECC, 1992)* – B in GW ranges 0.1-1.6 mg.L–1, suggesting possible negative effects to a variety of ornamental plants (Gross et al., 2005) • Surfactant concentrations in GW ranged between 29-60 mg.L–1 – Surfactants can alter soil properties and be toxic to plants at these concentrations (Bubenheim et al., 1997; Abu-Zreig et al., 2003) 15
*B toxicity review: Camacho-Cristóbal et al. (2008)
How to remove salinity? • Salinity affects the availability of crop water and
sodium causes clay soils to disperse • Naturally removed by rainfall/snowmelt leaching • If not, salts can be reduced by membrane treatments: –SAR values of secondary effluent, NF permeate, and RO permeate: 1.78, 4.67, and 0.72 respectively –The SAR value after NF (4.67) increased to more than twice that of the feed solution, whereas the SAR of the RO permeate decreased to 0.72 • Consequently, long-term potential harm if using NF treated secondary effluent for irrigation 16
Chang et al. (2005) Water Science and Technology 51:313-318.
Metals generally not phytotoxic • After 100 years of sewage
irrigation in Paris, metals accumulated: – Zn>Pb>Cu>As>Hg>Cd – Mostly in surface humics • Plant uptake levels generally under health limit Irrigation fields of Paris in 1900 Védry et al. (2001)
17
Year
Irrigated (Ha)
Irrigated (106m3/y)
1904
5,100
200
1950
5,000
100
1980
2,010
40
Also, no metal issues in bioretention cells (Davis et al. 2008)
Metals that may be phytotoxic or toxic to humans via food Metals in top soil after 100 years of application in Paris mg/kg
Cd
Cu
Hg
Pb
Zn
Top soil Limit
2.2
138
2.6
274
432
2
100
1
100
300
Metal bioavailability depends on pH of pore water Metals in various vegetables grown in the sewage amended soils
18
Védry et al. (2001)
Wastewater irrigated soils (90y) Mexico Person care products (Durán-Alvarez et al., 2009)
19
No evidence for soil accumulation, as degrade in soil
Take home messages:
US Domestic water use (AWWA/AwwaRF) 20
1) Soil application of wastewaters and in situ treatment appears to be much less impacting on the environment than riverine discharge 2) Provides for nutrient recovery 3) Local graywater reuse could reduce demand by > 50%
Other environmental benefits: water conservation & increased value • Local reuse of wastewater could save up to 70% on
water demand –So leaving more water for ecological services • Local groundwater recharge (via grass swales, infiltration basins etc.) enhance stormwater management & ecological services –Also provide amenity and increased property values
21
NRC (2008)
Energy & Greenhouse Gases • Water and wastewater facilities can be the largest single
energy user for many municipalities –Energy in wastewaters + municipal ‘wastes’ could balance it out (DW 1500 kWh/MG + WW 1200 kWh/MG) • Municipal wastewater treatment causes: –0.4% of total GHG emissions –3.0% of total anthropogenic methane & 2.2% N2O –Energy used in treatment yields 1.2% total US GHGs Inventory of Greenhouse Gas Emissions and Sinks 1990-2006 Subcommittee on Buildings Technology Research and Development (2008) Federal Research and Development Agenda for Net-Zero Energy, HighPerformance Green Buildings. Washington D.C.: Executive Office of the President of the United States. 22
Recommendations • Overall, strive to mimic natural systems & pre-
development hydrology –Need to promote decentralized to aid in reversing sprawl, car dependency, energy use & associated health issues –e.g. Cluster homes/apartments using park/garden treat’t • Technologies to:
23
–Enhance ground water infiltration –Divert urine and enable food/fecal energy recovery with residual fertilizers (NPK) back to agriculture • To enhance environmentally safe graywater reuse: –Phosphate-containing detergents need replacement with benign ‘building’ agents & surfactants –Use of low B detergents to evade phytotoxicity problem
References • Abu-Zreig, M., Rudra, R.P. and Dickinson, W.T. (2003). Effect of application of •
• • •
•
• •
24
surfactants on hydraulic properties of soils. Biosystems Engineering 84:363–372. ANZECC (1992). Australian Water Quality Guidelines for Fresh and Marine Waters. Australian and New Zealand Environment and Conservation council, Canberra, Australia. Bubenheim, D., Wignarajah, K., Berry, W. and Weydeven, T. (1997). Phytotoxic effects of graywater due to surfactants. J. Amer. Soc. Hort. Sci. 122:792–796. Camacho-Cristóbal, J.J., Rexach, J. and González-Fontes, A. (2008) Boron in plants: deficiency and toxicity. J. Integr. Pl. Biol. 50:1247-1255. Gross, A., Azulai, N., Oron, G., Ronen, Z., Arnold, M. and Nejidat, A. (2005). Environmental impact and health risks associated with greywater irrigation: a case study. Water Sci. Technol. 52(8):161-169. Litke, D.W. (1999) Review of Phosphorus Control Measures in the United States and Their Effects on Water Quality. Water Resources Investigations Report 99-4007. Denver, Colorado: U.S. Geological Survey. NRC (2008) Urban Stormwater Management in the United States. Washington D.C.: The National Academies. Védry, B., Gousailles, M., Affholder, M., Lefaux, A. and Bontoux, J. (2001) From sewage water treatment to wastewater reuse. One century of Paris sewage farms history. Water Sci. Technol. 43:101-107.
