The Lakeview WWTP and Clarkson WWTP in the Region of Peel will be expanded by 2006. The Ontario Ministry of the Environment has indicated its goal to achieve year round nitrification at these facilities. In light of potential benefits in terms of site capacity and capital costs, the Region initiated a demonstration study of the integrated fixed-film activated sludge (IFAS) technology, in order to determine whether full scale implementation of this process is a feasible solution to achieve the new nitrification criteria. One 14,000 m 3 /d conventional activated sludge (CAS) train at the Lakeview WWTP was retrofit with the IFAS technology. The full scale train construction was completed in August 2003, and media was added at that time. Unique features of the design, relative to other IFAS installations, were the relatively high velocity in the 3-pass aeration tanks, and the use of fine pore diffusers. The IFAS demonstration project at the Lakeview WWTP has been operating since October 2003. Important findings from the first few months of operation showed that stable nitrification performance can be consistently achieved in the IFAS train, at lower mixed liquor concentrations and clarifier solids loading rates than the parallel conventional activated sludge train. In addition, data suggests that mixed liquor from the IFAS train has better settling characteristics than the CAS process. With respect to the IFAS train design, there have been a few deficiencies identified in the demonstration that have led to operational and maintenance issues, and these must be considered carefully in a full scale design. A full-scale design must minimize potential for media accumulation on the sieve screens (and associated hydraulic bottlenecks), prevent all opportunity for media loss from the aeration basins and minimize potential for foaming. Adequate information is not yet available to date to support a decision on the future, full-scale implementation of the IFAS process at the Region's facilities. The demonstration project will continue through to spring 2005.

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Harnum, CET, City of Hamilton Tim Constantine, M.Eng., P.Eng., CH2M HILL 105 Commerce Valley Drive West, Markham, ON L3T 7W3 (905) 886 7022

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