Case Studies on Small Community and Decentralized Wastewater Treatment, Reuse and Management

Transcription

1 Case Studies on Small Community and Decentralized Wastewater Treatment, Reuse and Management Peter Haase, M.S., P.E., Inc. Wholly H2O Presentation 4/4/11

2 Presentation Outline Background & Project Experience Perspective on Decentralized and Small Community WW Projects Comparison of Alternative Wastewater Technologies Capital Costs O&M Costs EAC Sustainability Index Design and Management Considerations/Issues Case Studies TF + Wetland, California 2 Stage TF, California 3 Stage TF, California TF + Wetland, Fiji UASB, Pond + Wetland, Mexico What s next

3

4

5 Sustainable Decentralized Wastewater Management Appropriate technology - low cost, reliable, energy efficient, resource recovery, integrated to the site in design Supported by good O&M Monitoring and Evaluation: Service provider operational M&E Regulatory Oversight & Support Adaptive Management (AM) Fix what is not working Can it be fixed? Be ready for change Resource Recovery: Water recycling/reuse GHG and Energy recovery Nutrient recovery Goal is to create models that can be successfully emulated in different settings = Sustainability Technology Servicing M&E AM Resource recovery

6 Comparison of Alternative Treatment Technologies Compared Eight Technologies: Package Plants Two-Stage Trickling Filter Packed Bed (Gravel & Textile Filters) Extended Aeration System (activated sludge) Membrane bioreactors (MBRs) Sequencing batch reactors (SBRs) Oxidation ditches Land-Based Technologies Pond + FWS Wetland Trickling Filter + FWS Wetland Comparing: Capital Costs O&M Costs Equivalent Annual Costs Data Source: WERF Analysis of Existing Community-Sized Decentralized Wastewater Treatment Systems WAWTTAR Model, HSU, California, Inc., Santa Cruz

7 Comparison of Capital Costs SystemType Two-Stage Trickling Filter Packed Bed Extended Aeration SBR Oxidation Ditch MBR Pond + FWS Wetland Trickling Filter + FWS Wetland 5000 gpd $80,000 $95,000 $133,333 $100,000 $120, gpd $150,000 $163,000 $183,333 $590,000 $890,000 $450,000 $130,000 $160, gpd $300,000 $272,500 $253,333 $890,000 $920,000 $650,000 $190,000 $210, gpd $600,000 $560,000 $366,667 $1,800,000 $1,050,000 $1,200,000 $400,000 $450,000

8 Comparison of O&M Costs SystemType Two-Stage Trickling Filter Packed Bed Extended Aeration SBR Oxidation Ditch MBR Pond + FWS Wetland Trickling Filter + FWS Wetland 5000 gpd $11,592 $11,772 $22,608 WWTechnology Trickling Filter, Packed Bed Aerobic Treatment Units Land-Based Treatment $7,200 $8, gpd $11,967 $12,326 $25,308 $29,535 $22,627 $30,285 $7,500 $9, gpd $12,715 $13,434 $30,708 $34,185 $27,227 $35,685 $7,800 $10,000 % Operation and Maintenance Labor &Materials Energy gpd $14,962 $14,961 $43,158 $48,135 $36,427 $48,135 $8,100 $11,600

9 Equivalent Annual Costs ($/Yr) (20 Year Lifecycle Analysis) SystemType Two-Stage Trickling Filter Packed Bed Extended Aeration SBR Oxidation Ditch MBR Pond + FWS Wetland Trickling Filter + FWS Wetland 5000 gpd $17,095 $18,158 $31,570 $13,922 $16, gpd $22,201 $23,282 $37,631 $69,192 $82,449 $60,532 $16,238 $20, gpd $32,983 $31,750 $47,736 $94,007 $89,065 $79,375 $20,571 $24, gpd $54,748 $54,399 $67,804 $169,123 $107,003 $128,794 $34,986 $41,847

10 Key Design and Equipment Considerations System Redundancy & Backup Use duplex pumps Try to use the same pump size and model for multiple applications in system reduce complexity/keep it simple Provisions for backup power or gravity overflow Multiple reuse and disposal options design for at least 200% capacity Keep electricity and water separated Splice boxes out of risers Use appropriate pumps for specific applications Ease of operation and serviceability keep the skill of the operator in mind Expandability/adaptability consideration of changes preserve land area for future needs Efficacy in design select systems that meet the performance criteria Local and remote control and monitoring capability is critical

11

12 Case Study 1 San Lorenzo Valley School Complex Felton, Santa Cruz County, California School Complex preschool, elementary, junior high and high school 2,500 students + faculty/admin Onsite wastewater system - 15,000 to 20,000 gpd Regulated by CRWQCB San Lorenzo River Watershed Nitrogen TMDL requiring all large systems to reduce TN by 50% 1997 School District installed a FAST aerobic treatment system system did not meet TN requirement Key findings of 2001 Evaluation by FCE: Carbon:Nitrogen Ratio = 1:1 (BOD to TN = 120 mg/l as ammonia mostly urine) System had no provisions for flow equilization given the highly variable flows System used four 3 HP blowers (12 HP total) running 24/7 very energy intense High air flow led to odor issues no provisions for odor control Performance of FAST TreatmentSystematSLVSC BOD (mg/l) Total Nitrogen (mg/l) Influent Effluent Influent Effluent Date 9/ 18/ / 25/ / 27/ / 8/ / 11/

13 SLVSC Design Concept FCE recommended upgrade with two-stage trickling filter and two-pond FWS wetland. Power demand two ¾ HP Pumps running 12 hrs/day System constructed in 2004 with Project costs ~$270,000 Conversion of ammonia to nitrate via passive aeration through trickling filter and wetland Uptake of ammonia and nitrate by vegetation and bacteria in wetland Natural cycling of carbon from decaying plant matter Simple to operate, relatively low capital cost, reliable and low energy cost System is used by School s Watershed Academy for environmental education Creates wetland habitat on the property Energy Demand Comparison: FAST System = 12 HPx0.75 KW/HPx24hrs = 216 KWH/Day ~ $30/day or $900/month TF+FWS Wetland = 1.5 HPx0.75KW/HPX12hrs = 13.5 KWH/Day ~ $2/day or $60/month (@$0.14/KWH)

14 SLVSC Results Yr -Qtr Total Nitrogen Influent Effluent Precent (mg/l) (mg/l) Removal Influent (mg/l) BOD Effluent Precent (mg/l) Removal Influent (mg/l) TSS Effluent Precent (mg/l) Removal < <1 99 <1 99 <1 <

15 Case Study 2 Redwood Glen Salvation Army Camp Scotts Valley, Santa Cruz County, California Year round camp and conference center Population to 400 People Design Flows: Average 15,000 gpd Peak 30,000 gpd In San Lorenzo River Watershed 50% Nitrogen Reduction Onsite Wastewater System Installed Two-Stage Trickling Filter System in 2003 Treated Effluent used for irrigation of baseball field and ornamental landscaping Winter effluent to pressure dosed leachfields Stage 2 Trickling Filters Primary Clarifier 20,000 gallons Influe nt Recirculating Ball Valve Effluen t Stage 1 Trickling Filters Secondary Clarifier 10,000 gallons Pump Tank 5,000 gallons

16 Treatment Results and Layout Yr-Qtr Total Nitrogen (mg/l) Influent Effluent % Removal BOD(mg/L) TSS(mg/L) Influent Effluent Influent Effluent < <5 -< <

17 Case Study 3 - Prunedale Shopping Center North Monterey County, California Commercial shopping center constructed in the 1970s Onsite wastewater system using standard septic system High FOG load clogged leachfields High flows and use exceeded nitrogen loading requirements (40 grams/acre) set by Monterey County and Regional Water Board 20, 000 gpd FCE came in as peer review for a proposed three-stage trickling filter with 12 separate single purpose pump systems Revised plan for four duplex pump systems Stacked trickling filter and clarifier Internal and system wide recirculation 60% to 70% removal of TN 95 to 100% Removal of FOG Water Conservation reduced flows to ~10,000 gpd

18 Prunedale Flow Schematic Influe nt Recirculating Ball Valve Primary Clarifier 20,000 gallons Stage 3 Trickling Filters Stage 2 Trickling Filters Stage 1 Trickling Filters Pump Tank Final Effluen t Recirculating Pump Tank Recirculating Equilization/Pu Pump Tank mp Tank Tank 20,000 gallons Filter Media Baffled Clarifier Stacked Trickling Filter

19 Prunedale WWTS Results Date 9/ 15/ / 26/ / 23/ / 16/ / 7/ / 8/ 2011 BOD (mg/l) TSS(mg/L) Total Nitrogen (mg/l) Oil and Grease (mg/l) Influent Effluent Influent Effluent Influent Effluent Influent Effluent < < <

20 Case Study 4 - JMC Fiji Island Resort Savu Savu, Fiji Year round resort Onsite wastewater ~10,000 gpd Shallow groundwater Protection of corral reefs Nutrient removal Water reuse for landscape irrigation and constructed wetland Owner-build project Majority of Materials used were locally available Project Cost ~$80,000

21 System Layout & Installation Stage 1 Trickling Filters Stage 2 Trickling Filters Primary Clarifier 7,000 gallons Secondary Clarifier 4,000 gallons Influen t Pump Tank 5,000 gallons To irrigation Two-Pond Free Water Surface Wetland

22 JMCFIR Continued

23 Case Study 5 - Universidad Autonoma Oaxaca de Benito Juarez Ciudad de Oaxaca, Mexico Central public university in the City of Oaxaca, Mexico Demonstration project sponsored by the University School of Science with support from HSU and FCE Establish a full scale wastewater treatment system in the campus to be used for research, education, water reuse and passive recreation Satellite treatment system that diverts wastewater from the main sanitary sewer from the campus Project designed to treat approximately 20,000 gpd Three stage treatment train: UASB Advanced Integrated Pond FWS wetland ponds in parallel

24 Main Sewer Line System Schematic Effluent Pump Basin To irrigation Upflow Anaerobic Influent Sludge Blanket Pump Digestors (2) Station Modified Manway with diversion weir Free Water Surface Wetland Deep Anaerobic Zone Shallow Aerobic Zone Integrated Pond Design Free Water Surface Wetland Sludge Drying Beds

25 Benito Juarez Plant FWS Wetland UASB Integrated Pond Sludge Drying Bed

26

27 Al Fin