Producing Energy, Not Biosolids, Through Anaerobic Domestic Wastewater Treatment Perry L. McCarty, Jaeho Bae, Jeonghwon Kim, Po-Heng Lee Inha University, South Korea Stanford University, USA
INHA University, Korea, World Class University Research Team
Financial Support World Class University Program, Science and Technology, Ministry of Education, National Research Foundation of Korea Inha University Research Grant
Sustainability Using Wastewater as a Resource Water Industry Agriculture Domestic Use Fertilizing nutrients (N&P) Energy
Orange County Water District 2008 Wastewater Reuse (190,000 m 3 /d) Tertiary treatment using microfiltration, reverse osmosis, and ultraviolet/peroxide treatment
Water Recovery NEWater Singapore Five NEWater plants produce total of 550,000 m 3 /d
Treatment Energy Requirements kwh/m 3 Conventional Aerobic Activated Sludge Conventional Aerobic with Nitrification 0.6 0.8 Aerobic Membrane Bioreactor 1.0 Conventional Aerobic with RO 2.5
What is Best Reuse Option for Capturing All of Wastewater s Resource Potential? Water
Answer: Use for Irrigation Example:Water Reuse in Monterey County
Monterey Regional Water Pollution Control Agency Recovers Water, Energy, and Nutrient Resources Largest irrigated crop wastewater recycle in U.S. Produces 76,000 m 3 /day recycled water Irrigates 5,000 hectares Through anaerobic biosolids treatment and cogeneration, produces 50% of WWTP s energy needs No energy wasted for nitrogen oxidation all is used as plant fertilizer
Question Can we treat municipal wastewater 100% anaerobically to achieve net energy production while meeting effluent quality standards?
Wastewater as a Source of Renewable Energy Biogas (Methane) Formation Through Anaerobic Treatment Anaerobic Digestion, Elsevier (1981)
Advantages of Anaerobic Treatment A high degree of waste stabilization is possible Low production of waste biological sludge Low nutrient requirements No oxygen requirements Methane is a useful end product Public Works, Page 171, September 1964
Current Aerobic Sewage Treatment Anaerobic Digestion Heat Cogeneration (CHP) Electricity Heat Sludge Sludge Methane Cleansed Water Wastewater Primary Treatment Air Aerobic Secondary Treatment Membrane Filtration
Current Aerobic Sewage Treatment Anaerobic Digestion Heat Cogeneration (CHP) Electricity Heat Sludge Sludge Methane Energy User Cleansed Water Wastewater Primary Treatment Air Aerobic Secondary Treatment Membrane Filtration
Current Aerobic Sewage Treatment Anaerobic Digestion Heat Cogeneration (CHP) Electricity Heat Methane Sludge Sludge Aerobic Cleansed Water Wastewater Primary Treatment Out Membrane Filtration
100% Anaerobic Treatment Anaerobic Digestion Heat Cogeneration (CHP) Electricity Heat Sludge Methane Anaerobic In Cleansed Water Wastewater Primary Treatment Anaerobic Secondary Treatment Membrane Filtration McCarty, Bae, Kim, Environ. Science & Tech., 45:7100 (2011) Air Methane Stripping
Potential Benefits of 100% Anaerobic Treatment Significantly reduces energy requirement compared with aerobic treatment Produces more renewable energy as biogas Potential to be a net energy producer Greatly reduces production of secondary sludge thus results in significant reduction in sludge handling costs
Anaerobic Treatment of Industrial Wastewaters Objective High SRT and short HRT Clarigester Winery UASB Paper Mill CSTR with Recycle Sugar Beet Fluidized Bed Textile Filter Rum
Anaerobic Fluidized Bed Reactor Characteristices Good mass transfer Low clogging potential Combines high SRT with low HRT Good for low strength wastewaters Lidye Chemical Co., Taiwan Polyester Resin Wastewater 90% removal of 2000 3500 mg/l influent COD, 12 h HRT 20 m tall
Two Stage Anaerobic Fluidized Bed Membrane Bioreactor # Kim et al., Environ. Science & Tech., 45:576 (2011)
Reactors Being Evaluated at Inha University Shin et al., Bioresource Technology, 109:13 (2012) Anaerobic Fluidized Bed Reactor 35 o C, 200 mg/l COD, 17 min HRT, 17 kg COD/m 3 d 90 % Removal VSS Production 0.045 kg/kgcod
Fludized membrane Bioreactor at Inha University Anaerobic Fluidized Membrane Bioreactor (AFMBR)
Domestic Wastewater Treatment (25 o C) HRT: AFBR 1 hr, AFMBR 1.3 hr COD BOD 5 TSS AFBR Influent 235 105 93 Effluent 66 30 21 AFMBR Effluent 22 6 1 Overall % Rem. 91 94 99 Yoo et al., Bioresource Technology, 133 (2012) Bae et al., Proceedings, IWA Conference, Busan (2012)
Domestic Wastewater Treatment (25 o C) Additional Information 310 days of operation without need for membrane chemical cleaning or backwashing Electrical energy requirement: 0.047 kwh/m 3 Electrical energy from CH 4 : 0.098 kwh/m 3 Biosolids production: 0.05 gvss/gbod 5 Transmembrane pressure: 0.12 bar Membrane flux: 9 L/m 2 /hr Yoo et al., Bioresource Technology, 133 (2012) Bae et al., Proceedings, IWA Conference, Busan (2012)
Domestic Wastewater Treatment (Flux = liters/m 2 /h or LMH) Suction Pressure (Bar) 10 LMH 8 10 9 No fouling at 9 LMH for 70 days Time (Days)
Fluidized Bed Reactor 10 m 3 /day AFMBR Pilot Plant To Treat Bucheon, South Korea Primary Effluent Fluidized Bed Membrane Bioreactors Fluidized Bed Reactor Control Panel Flat Sheet Hollow Fiber
Conclusions Wastewater reuse for agriculture and landscape irrigation is best approach for resource recovery Anaerobic treatment produces energy and significantly reduces biosolids production Complete and efficient anaerobic treatment of domestic wastewaters now appears possible The anaerobic membrane bioreactor can produce high quality effluent for agricultural use, perhaps without further post treatment