Douglasville-Douglas County Water and Sewer Authority

"Award-Winning Service
For Our Local Community"

8763 Hospital Drive, Douglasville, Georgia 30134       P.O. Box 1157, Douglasville, Georgia 30133          (770) 949-7617    7:30 A.M. - 5:30 P.M. Monday - Friday

The Treatment Process


Sewage treatment is a multi-stage process to renovate wastewater before it reenters a body of water or is applied to the land.  The goal is to reduce or remove organic matter, solids, nutrients, disease-causing organisms, and other pollutants from wastewater.

Although WSA operates six wastewater treatment plants, for purposes of this website, our newest plant, the South Central Wastewater Treatment Plant, will be featured in the remainder of the wastewater treartment information.  You may tours the plant in person or take a narrated video tour.

Below is an aerial photo of the South Central Wastewater Treatment Plant showing the names of the buildings and structures.  Below the photo is a description of the treatment process as it moves through the plant and these structures.

You may download a flyer of this information.


  • Administration Building—The administration offices for the wastewater operations division, the plant control room, and the Authority’s central wastewater laboratory are housed here.
  • Influent Headworks Building—This building contains rotary drum screens used to remove paper and floating-type objects from the sewage followed by grit removal for heavier objects such as sand and grit.  The entire structure is enclosed, and air from the headworks is sent through scrubbers to remove potential odors.
  • Six Million Gallon Equalization Tank—This tank is used to provide steady, consistent flow into the treatment plant during rain events and periods of higher flows.  During high-flow events, the flow is stored in the tank and slowly released with a computerized-control valve.
  • Aeration Basins—The biological treatment of the wastewater is performed in this basin.  Bacteria breaks down organics and nutrients in the wastewater that would otherwise be harmful to the receiving stream.
  • Secondary Clarifiers—Flow from the aeration basin enters the clarifiers where the bacteria and solids in the wastewater are allowed to settle out while the treated water flows over the top to the next process.  Bacteria are recycled to the aeration basin to be used again.
  • Tertiary Flocculation and Clarifiers—An advanced treatment process where chemicals are used to further remove any remaining solids and nutrients from the wastewater.  The process causes the solids and nutrients to stick together where they will settle out in the clarifiers and can be pumped out for ultimate disposal.
  • Tertiary Filters—The treated water from the tertiary clarifiers flows through these filters to remove any remaining solids from the wastewater.
  • U.V. Tank—The Ultraviolet (U.V.) tank is where the treated water is disinfected by killing any remaining bacteria using ultraviolet light.
  • Post Aeration—Post aeration adds oxygen to the treated water as a final step prior to discharge to the Chattahoochee River.
  • Tertiary Treatment Building—Houses the controls, chemical feed pumps and chemicals necessary for the tertiary treatment process.
  • Solids Handling Area—This area consists of two parts.  A digester breaks down the solids, bacteria and chemical sludge removed from the treatment process to reduce the volume ultimately to be disposed.  The digested solids are then dewatered utilizing belt filter presses where polymers are added to further separate the solids and water.  The dewatered solids (now referred to as biosolids) are hauled to a landfill for ultimate disposal.
  • Service Water Pump Station—A portion of the treated wastewater flow is reused throughout the plant for wash down, chemical feed and the dewatering system.  This dramatically reduces the amount of potable water used at the plant.