A full-scale demonstration of an integrated fixed-film activated sludge (IFFAS) process with floating carriers has been conducted in Ontario, Canada, since August 2003. In this study, data collected on-site from July 2005 to December 2006 are analyzed and compared with the performance of a conventional activated sludge train operated in parallel. Both trains received similar loadings and maintained comparable mixed liquor concentrations; however, the IFFAS had 50% more biomass when the attached growth was considered.In the winter, the conventional train operated at the critical solids retention time (SRT) and had fluctuating partial nitrification. The IFFAS nitrified more consistently and had a doubled average capacity. In the summer, the suspended SRT was less limiting, and the benefit of IFFAS for nitrification was marginal.The lessons learned from the operational requirements and challenges of the IFFAS process (air flow, carrier management, and seasonal foaming) are discussed, and design recommendations are proposed for whole plant retrofit. Water Environ. Res., 81, 219 (2009).

A full scale demonstration project of an Integrated Fixed Film Activated Sludge process (IFFAS) with floating biofilm carriers has been operating at the Lakeview wastewater treatment plant (Ontario, Canada) since the fall of 2003. In this study, 18 months of data collected on site from July 2005 to December 2006 are analysed and compared to the performance of a conventional activated sludge (CAS) operated in parallel as a control. Both trains had similar loading and suspended solids concentrations, but the IFFAS had 50% more biomass.In the winter, the conventional train operated at the nitrifier washout limit and had unstable partial nitrification. The IFFAS had more stable ammonia removal, and a doubled average nitrification capacity. In the summer when the suspended SRT was less limiting, the difference between the IFFAS and the CAS nitrification performance was marginal. There are indications that the IFFAS train had slightly improved settling characteristics, but it cannot be established if they were due to the anoxic selector installed at the beginning of the train or to the fixed biomass itself. In this demonstration study, the performance benefits of the IFFAS technology were hampered by recurring operational issues including impaired carrier mixing, seasonal foaming in the winter, challenging carrier transfer during tank maintenance, and carrier containment failures.

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An integrated fixed-film activated sludge (IFFAS) process with four media cells is operating in parallel with a conventional activated sludge (CAS) train at Lakeview Wastewater Treatment Plant (Ontario, Canada). During winter 2007, an intensive sampling campaign was conducted to monitor the temporal and spatial variations of the nitrification capacity within the two plug-flow reactors. At the beginning of the six-week study, the CAS train was partially nitrifying, whereas the IFFAS train was nitrifying completely using the first two IFFAS cells only. Within one week, the CAS train lost nitrification because of a drop in solids retention time and pH caused by the onset of iron overdosing. When the IFFAS train received an iron spike, the carriers at the injection point (first cell) became ironcoated and lost 80% of their nitrification capacity. However, this train maintained its total nitrification capacity using the reserve capacity in the three remaining cells. Water Environ. Res., 81, 907 (2009).

An integrated fixed film activated sludge (IFFAS) process with four media cells is operating in parallel with a conventional activated sludge (CAS) train at Lakeview (Ontario). During the winter of 2007, an intensive sampling campaign was conducted to monitor the temporal and spatial variations of the nitrification capacity within the two plug flow reactors. At the beginning of the six week study, the CAS train was partially nitrifying, while the IFFAS train was nitrifying completely using the first two IFFAS cells only. Within one week, the CAS train lost nitrification due to a drop in SRT and pH caused by the onset of iron overdosing. When the IFFAS train received an iron spike as well, the carriers at the injection point (first cell) became iron-coated and lost 80% of their nitrification capacity. However this train maintained its total nitrification capacity using the reserve capacity in the three remaining cells.