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Author      Title/Abstract      

Saving the Chesapeake Bay -- Planning for Less Than 3 mg/l Total N and 0.1 mg/l Total P -- the Lynchburg Regional WWTP Story
Author: John R. Bratby, Pete Schuler, Jose Jimenez, Denny Parker; Alvin Rucker (City of Lynchburg)
Date: 3/107
WEF/IWA Nutrient Removal Specialty Conference, Baltimore, March 2007

This paper describes work carried out to evaluate alternatives to allow enhanced nutrient removal at the Lynchburg Regional WWTP, to meet the regulatory initiatives agreed to by the Chesapeake Bay Program Partners in April 2003. For this purpose, the Virginia Department of Environmental Quality (VDEQ) identified four time-dependent tiered levels of effluent quality. Each successive Tier has more stringent effluent quality requirements. The highest Tier has annual average total nitrogen and total phosphorus levels of 3 mg/l and 0.1 mg/l, respectively. As part of the evaluation, alternative process flow schemes, basis of design requirements, capital cost estimates, O&M cost estimates, and net present value cost estimates were prepared, and advantages / disadvantages of the alternatives were compared. Process alternatives studied included: two-stage step feed activated sludge; three stage step feed activated sludge; a 5-stage Bardenpho based activated sludge process; and an integrated fixed-film - activated sludge (IFAS) based process. Of these, the two-stage step feed activated sludge process was found to be the most beneficial in terms of meeting long-term treatment objectives.