Strategies to Reduce Total Nitrogen

At the Neuse River WWTP, a four-stage BNR activated sludge process, with methanol addition, is used to achieve effluent total nitrogen below 3mg/L.

Recent expansions to the Culpeper Water Pollution Control Plant included two new circular five-stage biological nutrient removal tanks and denitrification filters. The plant has been achieving monthly total nitrogen averages of less than 2 mg/L since June 2011.

The Largo Wastewater Treatment Plant utilizes a 3-stage A2O (anaerobic-anoxic-aerobic) process followed by methanol-fed denitrification filters to achieve an average effluent total nitrogen concentration of 2.4 mg/L.

The Waynesboro Wastewater Treatment Plant has an influent BOD:TKN ratio of 5.5 and is able to meet annual total nitrogen and total phosphorus limits of 3 mg/L and 0.3 mg/L, respectively. The plant utilizes a 5-stage biological nutrient removal process with denitrification filters.

NEW YORK, NY – October 16, 2014) – Several Hazen and Sawyer engineers have co-authored an article appearing in the October issue of WE&T Magazine.

The article, adapted from an earlier WEFTEC manuscript, is titled “Traditional techniques, exceptional results: Reducing effluent total nitrogen to low levels using conventional strategies”. It examines factors and strategies that can be used to achieve effluent TN concentrations below 2.5 mg/L on an annual average basis using traditional technologies rather than more expensive advanced technologies. Several WRRFs, discussed in detail in the article, are achieving average effluent TN concentrations of less than 2.5 mg/L using only conventional technologies.

The authors include Rosalyn Matthews, Ryder Bunce, Joe Rohrbacher, Katya Bilyk, Paul Pitt, Ronald J. Latimer, and Wendell O. Khunjar, all of Hazen and Sawyer.

For more information, please visit the WE&T site or e-mail

Since our founding in 1951, Hazen and Sawyer has focused on two things: providing safe drinking water and controlling water pollution. Our range of services encompasses the planning, design, and construction management of water and wastewater-related projects – from clean water treatment, storage, and distribution to wastewater and stormwater collection, treatment, and reuse.

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