Cold Weather Nitrification of Lagoon Effluent Using a Moving Bed Biofilm Reactor (MBBR) Treatment Process

Since 2000, the population at Johnstown, Colorado has increased over 22%, and shows no signs of slowing down. Faced with more residents and impending year round ammonia limits, the Town of Johnstown was forced to upgrade their wastewater treatment facility. The existing treatment facility in Johnstown consisted of three lagoons, whose main purpose was to achieve settling of total suspended solids and organic matter (BOD) removal. To meet the new increase in flows and nutrient limits, the Town of Johnstown had two choices: eliminate all existing lagoons and build a new conventional activated sludge facility, or continue to utilize the existing lagoons for organic matter reduction and add a down stream post-nitrification fixed film treatment system. By choosing the latter option, the Town of Johnstown managed to save about 50% of the cost of building a whole new plant. The post-nitrification MBBR was installed during the winter of 2003/2004 and brought online in June 2004. December 2004 to mid-January 2005, the average influent water temperature was 4.2°C, the MBBR treatment system removed an average of over 40% of influent NH3-N. In fact, the effluent NH3-N decreased by 35%, 42%, and 58% in December, January, and February, when compared with the same months in the winter prior to the installation of the MBBR treatment system. Throughout the warmer months, the MBBR treatment removed an average of 85% of influent NH3-N while the effluent BOD has been, on average, less than 1 mg/L, making it very easy for the plant to meet its permit requirements month after month.