Wastewater Treatment Process

Basic Features of the Treatment Process

  • Aeration basins that provide for oxygenation and mixing of active microorganisms with raw sewage (the activation process).
  • A basin or clarifier to separate solids from the treated effluent. Effluent is the term for liquid discharged from a treatment plant.
  • Screens to remove debris from the raw wastewater as it enters the plant.
  • A system to return solids (also known as activated sludge) from the clarifiers back to the aeration basins.
  • A system to waste or remove excess solids from either the basin or clarifier thus controlling the solids mass.

Operational Controls

  • Controlling the oxygen level
  • Controlling the rate that activated solids are returned to the aeration basins
  • Controlling the rate that solids are withdrawn from the process

Functions of the Process, or Treatment

  • Oxidation of ammonia to nitrate
  • Removal of carbonaceous organic material
  • Removal of nitrate
  • Removal of phosphorus

Treated Water Is:

  1. Filtered to remove nearly all of the remaining solids
  2. Chlorinated to kill any potentially harmful microorganisms
  3. De-chlorinated to eliminate excess chlorine that could be harmful to natural organisms when the water is discharged into a stream
The chlorination and de-chlorination system is used from May through September each year when Coffee Creek, the stream into which the treated water is discharged, is likely to be used for recreational purposes.


Biosolids are sludge that is wasted or removed from the primary treatment process and pumped directly into a sludge lagoon. After spending a required amount of time in the sludge lagoons, biosolids are tested and applied to local farm land for crops such as bermuda grass or hay for stock feed.