Treatment Overview

Unit Processes

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:
  • Screening
  • Grit removal
  • Primary and secondary clarification
  • Disinfection
  • 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.