DESIGN OF A BIOLOGICAL NUTRIENT REMOVAL FACILITY

Butler County, Ohio is a rapidly growing County in southwestern Ohio. The Butler County Department of Environmental Services (BCDES) was faced with the need to upgrade their Upper Mill Creek Regional Water Reclamation Facility (UMCWRF) in order to meet increasingly stringent effluent requirements. These improvements were made by re-rating the two existing oxidation ditch processes and by optimizing biological nutrient removal with the augmentation and addition of anoxic tanks and anaerobic selector tanks. Wastewater treatment modeling with the use of the Bio Win™ simulator resulted in the ability to “fine tune” the design and decrease the original design volumes of the anoxic and anaerobic tanks. This resulted in the ability of BCDES to maintain the 16 million gallon per day (MGD) design capacity, meet the increased effluent requirements, and to eliminate existing 4.0 MGD capacity rotating biological contactors (RBCs) which were unable to meet the nutrient removal requirements. This paper details the steps and procedures followed to achieve the re-rating and increased nutrient removal necessary to meet the current requirements.