Operational Improvements in a Biological Nutrient Removal Facility Using an Innovative Biological Activity Meter J. W. Hubbard1, R. C. Kirkpatrick1, J. F. Lee2 and B. R. Schwegler, Jr.3 1. Reedy Creek Energy Services, Inc., Lake Buena Vista, FL; 2. BioChem Technology, Inc., King of Prussia, PA; 3. Walt Disney Imagineering, Glendale, CA Abstract The Reedy Creek Improvement District (RCID) operates a biological nutrient removal (BNR) treatment facility that receives moderate seasonal variations in wastewater flow. This 5-stage Bardenpho facility has four identical process trains, each consisting of a series of cascading continuously stirred tank reactors. Upon plant commissioning in 1993, the influent wastewater flow averaged 7.5 million gallons per day (MGD), slightly higher than the 5 MGD estimated rating of each process train. Initial operations using both one and two process trains were unsatisfactory: effluent quality met permit guidelines, but the nitrogen (N) removal processes were unstable. In an attempt to better control biological N and P removal, we deployed BAM units at three locations in the BNR. A BAM is a small, computer-controlled, in situ batch reactor that can capture, isolate and analyze a sample of the mixed liquor. The BAM is equipped with an optical probe that measures biological activity based on microbial NAD(P)H fluorescence. We used data from the BAM unit to operate return activated sludge flows and the return location and flow rate of the internally recycled mixed liquor. Through process optimization, we have now successfully operated with one treatment train up to flows of 11 MGD, which in turn has provided substantial operational cost savings.