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Results of the Large-Scale Pilot Investigation of the DEMON® Nitrogen Removal System in Pierce County, Washington
Author: Adam Klein, Larry Ekstrom, Amanda Summers, Jiang Wan, Bernhard Wett, Chandler Johnson, Lynn Williams, Dave Newman, Kate Green and Henryk Melcer
Date: 10/12
WEFTEC 2012, New Orleans, LA, Sept. 29 – Oct. 3, 2012

A four-month pilot investigation was conducted from April to August 2011 to assess performance of the DEMON® nitrogen removal system treating dewatering centrate at the Pierce County Regional Wastewater Treatment Plant near Tacoma, Washington. The centrate is projected to contain an average of 1,100 kg/d ammonia-nitrogen at the design year. The pilot system was a 6,000 liter (L) sequencing batch reactor (SBR), which processed an average of 1,500 L/d of centrate. Ammonia and total inorganic nitrogen (TIN) removal rates of 81.6 and 78.4 percent, respectively, were achieved over a 30-day averaging period. An alkalinity addition trial at the end of the investigation yielded ammonia and TIN removal rates of 99.8 and 93.3 percent, respectively. The pilot investigation validated preliminary performance assumptions, and led to the development of a number of design criteria for full scale application.