Optimization of Nitrification Process By On-Line Monitoring of Nitrification Time Bill Roshong1, Sergey Maneshin2, Xin Yang2, George J.F. Lee2 1. EOS, Oaks WWTP, Oaks, PA. 2. BioChem Technology Inc., King of Prussia, PA. Abstract Nitrification has been a major concern in the wastewater treatment plant at Oaks, PA. While the plant has no problem removing up to 95% of the C-BOD and TSS, the operators at the plant have always been striving to achieve steady and consistent ammonia-N removal. This is especially true during the spring-summer transition when the ammonia discharge permit changes from 9 ppm to 3 ppm. In order to evaluate the constantly changing nitrification activity and nitrification capacity in the plant, Biological Activity Meters (BAM) manufactured by BioChem Technology, Inc. were used for on-line measuring of nitrification time (NT) in the aerobic zone. The measured NT was then compared with the hydraulic retention time (HRT) of the mixed liquor in the aerobic zone. When NT is shorter than HRT during the process, the NH3-N is completely removed. It was found that during the summer and fall periods, the utilization of only one train in the bioreactor was sufficient to bring NH3-N in the final effluent well below the discharge permit level. Therefore, the original two-train operation was converted to a single train operation for one month. Upon this conversion an energy savings of up to 50% on the mixers and 15% on air blowers was realized. During this one-train operation period, the plant had successfully treated an average daily flow (ADF) of wastewater equaling 6.25 MGD. This record can be used to support the application of an operation permit for increasing the treatment capacity of the plant. It can also be used to justify the decision of delaying or even avoiding future plant expansion.