Wastewater Treatment Trends in the 21st Century - George Tchobanoglous, University of California, Davis

Wastewater Treatment Trends in the 21st Century - George Tchobanoglous, University of California, Davis

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  WASTEWATER TREATMENT TRENDS Topics IN THE 21ST CENTURY Part-1 Some Global Trends Part-2 Uncontrollable Events and Unintended Consequences Water & Wastewater Management Summit Part-3 Future Challenges and Las Vegas, NV Opportunities May 3, 2012 George Tchobanoglous Department of Civil and Environmental Engineering University of California, Davis Part-1 Some Global Trends that will Impact of Urbanization on Plant Siting Impact Wastewater Treatment • Population Demographics Impact of urban spread Urbanization along coastal areas • Climate Change ( g (wetter/dryer) y ) Sea level rise Impact of storm events on WWTPs • Aging infrastructure Impact of Coastal Population Demographics Hyperion WWTP, Los Angeles, CA Urbanization Along Coastal Areas • By 2030, 60 percent of world’s population will near a coastal region • Withdrawing water from inland areas, transporting it to urban population centers, treating it using using it once and it, once, discharging it to the coastal waters is unsustainable. 1
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  Impact of SeaLevel Rise on Impact of Sea Level Stormwater Collection System Rise on Stormwater Collection System Courtesy City of San Francisco Courtesy City of San Francisco Climate Change: Impact of Intense Rainfall on Operation of WWTP Aging Infrastructure Challenges • Aging wastewater infrastructure, typical age 75 years, in large cities over 100 years old with excessive exfiltration • Flowrates have decreased over the past decade and will continue to decrease 1. Increased corrosion 2. Most conventional gravity sewer design equations no longer suitable 3. Increased mass concentration loading factors have impacted wastewater treatment facilities Part-2 Impact of Uncontrolled Events Impact of Sea Level Rise on Wastewater Management Infrastructure and Unintended Consequences • Uncontrollable events Natural disasters Climate change Chemical costs • Unintended consequences Treatment plant siting Water conservation Treatment plant hydraulics Energy usage 2
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  Impact of Conservationand Drought: Solids Deposition, H2S Formation, and At $0.03/kWh Energy Efficiency was not an Issue. Downstream Corrosion due to Reduced Flows Example: Excessive Headloss (Energy Loss) at Primary Sedimentation Tank Weir Part-3 Future Challenges and Opportunities • Paradigm shift in view of water • Alternative collection systems • Food waste management • Energy and nutrient recovery • Recycling through direct potable reuse • Integrated wastewater management New View of Wastewater: A Paradigm Shift Modified Collection System For Reduced Flow Rates (e.g., Conservation) WASTEWATER is a RENEWABLE and RECOVERABLE SOURCE OF ENERGY (heat and chemical), RESOURCES, RESOURCES and WATER 3
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  Wastewater and FoodWaste Management Options Energy Content of Wastewater Heat energy Specific heat of water = 4.1816 J/g •°C at 20°C Chemical oxygen demand (COD) C5H7NO2 + 5O2 5CO2 + NH3 + 2H2O (113) 5(32) Chemical energy (Channiwala,1992) HHV (MJ/kg) = 34.91 C + 117.83 H - 10.34 O - 1.51 N + 10.05 S - 2.11A Required and Available Energy for Wastewater Treatment, Exclusive of Heat Energy Energy Content of Wastewater • Energy required for secondary wastewater Constituent Unit Value treatment 1,200 to 2,400 MJ/1000 m3 Wastewater, heat basis MJ/10°C•103 m3 41,900 Energy available in wastewater for treatment Wastewater, Wastewater COD basis MJ/kg COD 12 - 15 (assume COD = 5 0 g/m3) 5.0 15 - 15.9 Q = [500kg COD/1000 m3) (1000 m3) (13 MJ/ kg COD) Primary sludge, dry MJ/kg TSS Secondary biosolids, dry MJ/kg TSS 12.4 - 13.5 6,000 MJ/1000 m3 • Energy available in wastewater is 2 to 4 times the amount required for treatment Alternative Technologies for Primary Treatment and Energy Recovery Heat Recovery from Wastewater SOURCE : City of Vancouver, Sustainability website retrieved from http://vancouver.ca/sustainability/neuTechnology.htm FALSE CREEK ENERGY CENTER 4
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  Alternative Wastewater Treatment Multiple Reclaimed Water Qualities Without Biological Treatment for DWM Systems Energy and product recovery Solids processing Enhanced Wastewater Management and Use of Existing Collection System For Water Reuse Through Urine Separation Source Separated Resource Streams Maximum recovery of nutrients Removal of trace organics (EDCs, etc.) Enhanced treatment with respect to residual nutrients and trace organics with less treatment complexity Reduced energy requirements Use of soil for advanced treatment of residual trace organics and unknown pathogens Enhanced protection of the environment Nutrients and Trace Organics in Domestic Examples of Urine Separation Fixtures Wastewater: A Case for Urine Separation Greywater 100 Greywater Greywater Feces 80 Feces Feces Composition, % 60 Relative Greywater distribution unknown, Urine preliminary 40 > 70% Urine Feces in urine and Urine urine 20 0 Nitrogen Phosphorus Potassium Volume Trace organics Wastewater constituent Source: Jönsson et al.(2000) Recycling Source Separated Human Urine. 5
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  Potential Impacts ofUrine Separation Nutrient Separation, Storage, and Recovery On Biological Wastewater Treatment From Individual Residence With US, After primary, Cell yield, Constituent mg/L mg/L mg/L BOD5 ~450 292 190 COD ~1050 525 - TSS ~500 500 150 - NH4-N 3 ~3 Req. N for Organic N 13 ~9 cell growth 23.5 TKN 16 ~12 P (biogenic) 3.3 2.3 Req. P P (other) 2.6 1.8 4.7 Urine Utilization in Indoor Wetland System Passive Water, Nutrient, and Energy Near Os, Norway Recovery System Factors Limiting Nonpotable and Indirect Potable Reuse Recycling Through Direct Potable Reuse Agricultural Irrigation • Large distance between reclaimed water and agricultural demand • Need to provide winter storage Landscape Irrigation • Dispersed nature of landscape irrigation • Cost of parallel distribution system Indirect Potable Reuse • Most communities lack suitable hydrology for groundwater recharge • Availability of nearby suitable surface storage 6
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  Microfiltration, Cartridge Filters,Reverse Osmosis, and Typical Flow Diagram Now Used for the Advanced Treatment (UV), OCWD Production of Purified Water Adapted from OCWD Planned Indirect and Direct Potable Reuse Driving Forces for Direct Potable Reuse • De facto indirect potable reuse is largely unregulated OCWD Groundwater Buffer • Infrastructure requirements limit reuse opportunities • Population growth, demographics, and global warming will result in unsustainable situation • Lack of an environmental buffer • Existing and new technologies can and will meet the water quality challenge • The value of water will increase significantly in the future Upper Occoquan, San Diego, CA (Proposed) • Stringent environmental regulations Surface Water Buffer De Facto Indirect Potable Reuse Integrated Wastewater Management With Decentralized, Satellite, Centralized Facilities Courtesy City of San Diego 7
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  Intercepted In-Building Self-Contained Water Recycle System Satellite Systems for Reclamation and Reuse Reclaimed water is used for toilet flushing, landscape irrigation, and cooling water Offsetting Potable Water Demand for Irrigation Review of Opportunities and Challenges (System has been in Operation for 25 Years, Upland, CA) • Energy and nutrients in wastewater under utilized • New models needed for retrofitting collection systems • New technologies will revolutionize WWTP • Direct potable reuse solves multiple problems with existing wastewater systems and future demographics • New integrated infrastructure needed for enhanced water reuse Courtesy D. Ripley The Future Replacement or repair of infrastructure with the same thinking and technology used to create it, will perpetuate the THANK YOU problems now experienced and create FOR LISTENING new problems problems. 8