Case Study: Optimizing Biological Phosphorus Removal From An AquaSBR® System

The Middlbury Wastewater Treatment Plant located in Middlebury, Vermont treats domestic and industrial waste received from a local dairy and a brewery. Its original treatment system consisted of a flow-through activated sludge process with primary clarifiers, anaerobic digesters, and a four-train Rotating Biological Contactor (RBC) system. The RBC system was installed in 1980 but by the mid 1990s was plagued with mechanical failures. The plant was unable to meet its effluent requirements for BOD, TSS and Total Phosphorus. Since the plant was located in the center of town, the surrounding area was also burdened with odor problems from the facility’s primary clarifiers and aerated pre-equalization tank. Middlebury realized it was time to explore other secondary treatment technologies in order to alleviate its current problems and upgrade its facility to meet more stringent requirements.