Biological treatment follows primary clarification where the aeration process converts remaining fine and dissolved organic pollutants into larger biological solids that can settle. Air is applied to the aeration tank contents which allows aerobic bacteria to assimilate pollutants contained in the wastewater. Ammonia is also removed in the aeration process. Final clarifiers follow the aeration process where the biological solids separate and settle from the wastewater as the velocity is decreased. Flow leaving the final clarifiers is directed to the disinfection process.
Chlorine is used to disinfect the plant effluent before it is discharged to the Town Branch Creek.
Sulfer dioxide is used to remove residual chlorine. Wastewater leaving the disinfection process flows over a cascade aerator which adds oxygen to the effluent. As wastewater is treated as described above, by-products are generated. Screenings and grit are dewatered and then delivered to a landfill. All sludges are thickened either by gravity thickening or centrifuge and then directed to the anaerobic digesters.