Demonstration Of An Integrated Fixed Film Activated Sludge (Ifas) System For Enhanced Nitrification Using A New Free Moving Media
Between October 1995 and June 1998, a study was conducted at the Waterdown STP to evaluate IFAS options for reducing the cost of retrofitting larger plants in the province of Ontario for year-round nitrification. Cord media options were evaluated first, but significant detractors to this approach were encountered such as worm growth and flow short circuiting. As a result, a free-floating plastic media was investigated as an alternative IFAS approach. This paper reports on an evaluation of this approach at Waterdown that was initiated in April, 1997 and completed in June 1998. During the course of the study, extensive testing was conducted to monitor system performance. Aside from effluent characterization (ammonia, TKN, etc.), grab sampling at hourly intervals was conducted to monitor dynamic performance and off-line batch tests were conducted to assess media versus mixed liquor nitrification rates. The results showed that when the average mixed liquor temperature was 10.4'C, and the minimum was 8'C, essentially full nitrification was attained at a mixed liquor SRT of 3 days. The Waterdown study has demonstrated that the plastic freefloating media can provide excellent nitrification performance and fully realize the benefits of the IFAS concept.