Biological Activity Monitoring for Real Time Control of Biological Nutrient Removal: A Case Study Benedict R. Schwegler1, Terry J. Mah2, Xin Yang2, and Jaw F. Lee2 1. Walt Disney Imagineering, Glendale, CA 91221; 2. BioChem Technology, Inc., King of Prussia, PA 19406 Abstract Real-time, on-line monitoring of biological activity was evaluated for its usefulness as a process optimization and control tool. Continous monitoring of anaerobic and anoxic biological activity revealed several opportunities to improve process performance. Specifically, data acquired from biological activity meter (BAM) units suggested a process configuration change to enhance performance by limiting anaerobic phosphate release and optimizing biological denitrification. Periodic control of internal nitrified recycle flows, according to BAM data, maintained effluent nitrate concentration within discharge criteria. Better control has resulted in improved process stability and a reduction in operating costs. Further research and evaluation is ongoing to determine longer term the benefits of on-line process control.