Basic Operations

Activated Sludge Process

There are several different types of wastewater treatment systems; currently Warrensburg West and East Wastewater Treatment system's utilizes the Activated Sludge Process. The activated sludge process is used to convert non-settleable substances, in finely divided colloidal and dissolved form, into biological floc. This newly formed biological floc, termed sludge is removed from the system through sedimentation, thereby providing a high degree of secondary treatment.

Treatment Process

  1. The first step in the treatment process is to collect and convey the raw wastewater to the treatment plants for disposal.
  2. When the raw wastewater (Influent) reaches the treatment plant pumping station it is immediately pump to the headwork's for preliminary / primary treatment.
  3. When the influent wastewater reaches the headwork's, it enters the aerated grit chamber which consist of several units starting with the mechanically cleaned bar screen. This unit removes debris such as plastics, trash, rags, and other untreatable materials.
  4. The next preliminary treatment the influent receives is to remove inorganic material called grit. Grit consists of sand, rocks, and other large-sized relatively non-putrescible organic and inorganic substances. This material is removed by way of a collector and air lift pumps. These materials are dewatered and hauled to the land fill for disposal. Should the screenings and grit removal equipment fail other downstream processes may also fail.
Immediately following the preliminary / primary treatment the influent wastewater gravity flows to the biological Activated Sludge Process for secondary treatment which can remove 99% of the bacteria in the raw wastewater.


There are several types of modifications to the Activated Sludge Process; Warrensburg activated sludge process utilizes a fill and draw system known as Sequencing Batch Reactors (SBRs).
  1. The influent wastewater is introduced into one of the reactors for the fill portion of the treatment process.
  2. An adequate amount of biological floc (activated sludge) is maintained in the reactor along with sufficient dissolved oxygen (DO) to maintain aerobic conditions throughout the process.
  3. When such conditions have been accomplished the draw portion of the cycle begins, the influent valve is closed, mixing pumps and aeration equipment is turned off creating a quiescent zone so the activated sludge separates readily from the treated wastewater and settles to the bottom of the reactor tank
  4.  After a predetermined amount of time, usually 45 minutes, the effluent valve opens sending a portion of the treated wastewater (effluent) to the disinfection system then to the creek for final disposal, during this period another reactor will be in the fill process thus the name sequencing batch reactors.

Waste Activated Sludge

Because the activated sludge is constantly increasing in quantity as it removes organic material from the wastewater, and as microorganisms continue to grow, it is necessary to remove the excess quantity from the system, the sludge removed is termed waste activated sludge. To keep a proper amount of activated sludge under aeration the operators will pump the excess waste activated sludge to an aerated digester for proper digestion. After proper digestion of the waste activated sludge has been completed the terminology for the sludge becomes Biosolid's. Properly treated biosolid's is pumped to the Reed Reds for further treatment.


After being properly treated, the processed wastewater "effluent" from the West WWTF is discharged into Postoak Creek the East WWTF effluent is discharged into Bear Creek. Designated uses for Postoak Creek and Bear Creek are: Protection of Warm Water Aquatic Life and Human Health (AQL), Livestock and Wildlife Watering (LWW), and Whole Body Contact Recreation (WBC).