The Activated Sludge Process
The City’s wastewater treatment plant is designed to receive 33,000 pounds per day of biochemical oxygen demand (BOD5) and 42,000 pounds per day of total suspended solids (TSS).
Unit processes utilized at the City’s treatment plant includes:
Primary and secondary clarification
Dissolved air flotation of waste activated sludge
Gravity thickening of primary sludge
Anaerobic digestion followed by centrifuge de-watering
The complete-mix mode of the activated sludge biological process is utilized for secondary treatment. The bio-solids, screenings, and grit are buried at the City’s sanitary landfill on a daily basis. The effluent of the City’s wastewater treatment plant is discharged into the Yellowstone River just downstream of the U.S. 87 E. Highway bridge.