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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The Region of Waterloo is in the process of implementing a number of recommendations from its 2007 Wastewater Treatment Master Plan through an extensive capital program (about $800 million) to upgrade its major wastewater treatment plants (WWTPs). These upgrades include the installation of off-site biosolids dewatering, commissioned in 2012, and other process upgrades at the Kitchener WWTP (122,000 m 3 /d rated capacity) to be completed by 2018.Kitchener's Plant 2 was retrofitted from an eight-cell completely mixed process with mechanical surface aeration to a single three pass fine bubble diffused aeration plant that includes a return activated sludge (RAS) reaeration zone to treat centrate from the off-site biosolids dewatering facility. The objective of the retrofit was to avoid increased ammonia discharges to the Grand River, replace old equipment, and improve plant performance. The initial study and conceptual design was approximately 24 months until commissioning of the upgrades.An overview of all the design and construction phases with the associated operational challenges is provided in this paper along with a detailed assessment of the plant's performance at two distinct periods of the year, with operation in warm and cold weather. The retrofitted bioreactor performed well during warm weather, but with the extremely cold temperatures observed in January 2014 (it was the fifth coldest month of January in the last 50 years in Ontario), ammonia started to increase and only partial nitrification was achieved. Poor performance during cold weather was attributed to operational problems experienced during the whole winter with the secondary clarifiers and RAS/waste activated sludge (WAS) control that prevented the operators to adjust the solids retention time (SRT) accordingly. Nevertheless, Plant 2 was still able to partially nitrify, showing that the process can be fairly resilient and keep nitrifiers functioning under less than optimum conditions. The main benefits of the retrofit/upgrade include increased capacity at lower cost and full nitrification. Additionally, there has also been an improvement in overall plant performance, both in terms of organic matter and nitrogen removal, with significant benefits to the water quality of the Grand River. Operational stability is yet to be achieved once secondary clarifier mechanisms and RAS/WAS pumping are upgraded.

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