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Nutrient Issues at the Blue Plains WWTP February 2004
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Blue Plains Snapshot –Flow Design Annual Average: 16.2 m 3 /s (370 mgd) Peak: 43.8 m 3 /s (1 bgd) –Effluent Limits NH 3 :1.0 mg/l (May 1 to Oct 30) 6.5 mg/l (Nov 1 to April 30 TP: 0.18 mg/l BOD5/TSS: 5/7 mg/l
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Aerated Grit FeCl 3 Primary Sediment FeSO 4 Secondary AS Nitrification Filtration Dechlorination Potomac River Chlorination Chlorine Process Flow Diagram Pumping
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Blue Plains Nitrogen Control Efforts Goal: Reduce controllable loads of nutrients including nitrogen by 40% from the 1985 levels by the year 2000, and maintain those levels into the future Status: Nitrogen loads from Blue Plains declined by 7 million pounds per year from 1995 to 2003. The load was reduced by 49%, surpassing the Chesapeake Bay goal. This significant reduction was achieved through the use of Biological Nutrient Removal (BNR) Technology.
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Denitrification Process Selection u Lowest cost alternative for nitrogen removal - 1990 study –Bench testing showed promise –Low capital cost offsets operating costs u Process considered experimental - especially at this scale - Conduct pilot
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Denitrification Process Selection u Use excess capacity available in nitrification process u Conduct full plant study u Monitor results on both sides. u TN Goal 7.5 mg/L yearly average: –Winter: 8.58 mg/l –Summer: 5.55 mg/l
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Nitrification Facilities RAS Reactors Lime To Multimedia Sedimentation Basins WAS Secondary Effluent
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Denitrification Process RAS Reactors Lime To Multimedia Sedimentation Basins WAS Secondary Effluent Methanol
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IMA Shares at Blue Plains
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u Meeting Maryland and/or Virginia’s load allocations would require: –Additional treatment for a portion of the flow, as needed (Blended Effluent) –Significant capital expenditures u Meeting ALL BP users’ needs – under a regulatory program -- would require: –Plant-wide facilities upgrade –Major capital expenditures u Costs will depend on the level of nutrient reduction (Tier) that will be needed Nutrient Reduction Options @ Blue Plains
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Voluntary Program Estimated Costs (*) All WWTPs at their year 2000 levels (#) Blue Plains is at 7.5 mg/lit TN & 0.18 mg/lit TP; budget is for facilities needed to accommodate new digester effluent [$] Under NPDES permit requirement, the cost would be 30- 50% higher Nutrient Reduction Options at Blue Plains TierTN mg/litTP mg/litLife Time Budget I8.00(*)$0 II (#)8.001.00$30,000,000 III5.001.00$349,000,000 IV3.000.50$466,000,000 Total (cumulative) [$]$845,000,000
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Other Capital Costs Facing DCWASA u Ongoing 10 year Capital program –$1.8 billion –Infrastructure/plant rehabilitation –Technology enhancements supporting operational efficiencies u Proposed CSO Long-Term Control Plan –$1.265 billion over 15-25 years –Enhancement of water quality in tributaries of Chesapeake Bay, notably Anacostia River u Lead Service Replacement Issues u Emerging regulatory/security issues
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WASA’s CURRENT POSTURE u Meet all regulatory requirements u Continue strong support of state-by- state determination of methods to meet “caps” u Provide services to jurisdictions to assist in meeting their nutrient goals within Blue Plains capacity u Emphasize that DC’s primary appeal for federal assistance will be directed to the Anacostia CSO issue u Continue strong support of a VOLUNTARY (non-Regulatory) Nutrient Reduction Program
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