Operations

Land Application | Reclaimed Water | Discharge Info
 

Mission

The mission of the Operations Department is to accept all reasonable water borne wastes from the residences, businesses and industries in the District's service area. The Operations Department must operate the facility to handle the wastewater in a manner that safeguards the environment and enhances the area's water resources through the following steps.


Nitrification Treatment
Primary Treatment
 

Primary Treatment:

Screening of all waste-water to remove large objects like sticks, clumps of rags, cans, leafs and tissue paper. Grit removal where heavy inorganic such as sand, cinders, egg shells and etc... are settled and are then removed. Primary clarification is to separate solid particles from the liquid. The clarifier tanks provide a volume sufficient to create a quiescent flow zone. During this period of peaceful non-turbulent flow in a clarifier, solid particles are given a chance to settle to the bottom of the clarifiers while the clear clarified liquid is overflowed from the top. Settled solids are pumped from the bottom of the clarifiers to the Digesters for stabilization.


Secondary Treatment
Secondary Treatment
 

Secondary Treatment:

Primary effluent is mixed with the return biological life from the secondary clarifiers then evenly distributed between the four treatment tanks. This biological life will breakdown and absorb the waste in the wastewater into themselves.

Our Secondary system was designed for solids treatment which uses 1 pound of air for each pound of solids treated. Blowers are used to provide the air for the biological life to breathe.

Secondary clarifiers: The clarifier tanks provide a volume sufficient to create a quiescent flow zone. During this period of peaceful non-turbulent flow in a clarifier, biological life an solids produced in aeration system are given a chance to settle to the bottom of the clarifiers while the clear clarified liquid is overflowed from the top. The liquid proceed to the Nitrification Aeration Tanks for further treatment, a portion of the settled solids are pumped from the bottom of the clarifiers to the Digesters for stabilization. The rest of the settled biological life is return to the Secondary Aeration Tank to aid with the treatment of Primary Effluent.


Nitrification Treatment
Nitrification Treatment

Nitrification Treatment:

The Secondary effluent is evenly distributed between the five treatment tanks. The biological life will continue to breakdown and absorb the waste in the wastewater into themselves.

The Nitrification system was designed to treat ammonia in the waste water which will use 3 pounds of air for each pound of ammonia treated.

Nitrification clarifiers: The clarifier tanks provide a volume sufficient to create a quiescent flow zone. During this period of non-turbulent flow in a clarifier, biological life solids produced in the aeration system are given a chance to settle to the bottom of the Clarifiers while the clear clarified liquid is overflowed from the top. The liquid proceeds to the Aeration Tanks for further treatment, a portion of the settled solids are pumped from the bottom of the clarifiers to the Digesters for stabilization. The rest of the settled biological life is returned to the Aeration tank to aid with the treatment of Secondary Effluent.

 


Effluent Treatment
Effluent Treatment

Effluent Treatment:

A portion of the effluent flow becomes our plant process water. This water is pumped to our water tower which water is used in the process for chemical addition, flush water another process needs along with cleaning around the plant. Bleach is used to disinfect this water from May to November with Bisulfite being in used in the removal of any Bleach residuals. The flow leaves the plant though a cascade aerator which adds Oxygen to the cleaned wastewater before entering the Sangamon River.

Digester residuals also known as biosolids are applied to farmland as fertilizer.


Notable:

  • 8 of the Sanitary District of Decatur Operators are certified as Class 1 Wastewater Treatment Works Operators by the Environmental Protection Agency of the State of Illinois.
  • The district has received a Silver award from NACWA 4 times over the last 5 years, with 1 Gold award in that same time period. (Silver = less than 5 violations in a year, Gold = 0 violations in a year.)

 

Biological life used in treating wastewater:

Biological life used in treating wastewater

 

Land Application | Reclaimed Water | Discharge Info