Conversion from Contact Stabilization to Nitrification using Integrated Fixed Film Activated Sludge (IFAS) in The Colony, Texas

In early 2005, the City of The Colony, Texas, began construction of major modifications to its wastewater treatment plant to increase plant capacity and modify their existing contact stabilization basins. Due to the limitations of the existing process, the facility was not able to consistently nitrify ammonia. New ammonia limits of 3 mg/L would need to be met in addition to the expanded capacity. After evaluating process alternatives, the City chose to implement construction of an Integrated Fixed Film Activated Sludge (IFAS) system within their existing basin volume. Construction began in March 2005 and was completed in February 2007. Upon full scale implementation of the new IFAS basins, immediate improvement in treatment performance was noted and the plant was able to comply with ammonia discharge limits for the first time in its history. This manuscript includes discussion on startup and operational performance during construction and upon full scale implementation of the plant. In addition, first year operating data, discussion of startup related issues and impact of redworm predation on the IFAS media are also discussed.