The Brainerd Wastewater Treatment Facility (WWTF) is a Class A facility designed to treat an average wet weather flow of 6.0 MGD with a CBOD5 Influent concentration of 240 mg/L and a TSS concentration of 240 mg/L.
The Facility receives wastewater from the communities of Brainerd and Baxter. The Brainerd interceptor system consists of 2,745 feet of 20-inch force main, 587 feet of dual 20-inch river crossing main and 1,510 feet of 30-inch interceptor sewer.
The facility consists of a main lift station, which contains a mechanically cleaned bar screen and an aerated grit chamber, which pumps to the Facility Headworks building. This building contains two self-cleaning automatic fine screens, influent flow measurement, and a Pista-Grit grit removal system. The flow then goes into one of four Sequencing Batch Reactors (SBR) for secondary treatment. Biologically treated wastewater is decanted out of the SBR’s into one of two Effluent EQ Basins where it is pumped to disinfection, which consists of two banks of Ultraviolet (UV) bulbs.
Waste Activated Sludge (WAS) from the SBR’s accumulates in two Waste Sludge Holding Tanks (formerly two secondary clarifiers) before being thickened on one of two Gravity Belt Thickeners. The thickened WAS is used to feed two primary heated anaerobic digesters and is further treated in two secondary digesters prior to land application. Digested sludge is held in one of two Sludge Storage Tanks. Supernatant from the digesters is discharged to an aerated holding tank (decant aeration tank) and fed into the headworks of the plant during low flow conditions. Supernatant from the Sludge Storage Tanks is discharged to one of two non-aerated holding tanks and is also fed into the headworks building.
The Facility has a continuous discharge (designated SD 003) to the Mississippi River.
The Facility and the Main lift station are equipped with standby generator power.