Nutrient Recovery Performance and the Optimization of Biological Phosphorus Removal at the F. Wayne Hill Water Resources Center

The F. Wayne Hill Water Resources Center (FWHWRC) is Gwinnett County’s largest and most advanced wastewater treatment facility with a capacity of 60 MGD on a maximum month (MM) basis. The treatment plant utilizes enhanced biological phosphorus removal (EBPR) and chemical polishing to meet a stringent effluent total phosphorus (TP) discharge limit of 0.08 mg/L. Nutrients, mainly phosphorous, ammonia and magnesium bound up in the biological sludge are recovered at the facility using the OSTARA Pearl® process with WASSTRIP (Waste Activated Sludge Stripping To Remove Internal Phosphorus) via controlled harvesting of struvite. This also aids in the reduction of phosphorus recycle loadings on the liquid treatment train. This paper discusses a 7-month field optimization effort conducted to determine a biological reactor basin (BRB) operational configuration that would allow for improved enhanced biological phosphorus removal (EBPR) performance, with a reduction in the reliance of metal salt addition to the mixed liquor and tertiary filtration influent stream, especially during periods of reduced Nutrient Recovery performance.