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This schematic shows how wastewater moves through the Kennebunk Sewer District Plant as it is treated. Below is a brief explanation of each step. You can click on each title for a more detailed explanation and a picture.

Influent Sewer
Influent is a term used to describe the raw wastewater entering the treatment facility from the sewer collection system.

Screening and Grit Removal
The wastewater passes through a screen to remove rags and large debris.

Primary Clarifier
The screened, de-gritted wastewater then flows to circular sedimentation basins called primary clarifiers.

Activated Sludge / Rotating Biological Contactors Hybrid System
Secondary biological treatment designed to remove nutrients and dissolved organic material from the wastewater is provided by a rotating biological contactor (RBC) / activated sludge hybrid system.

Secondary Clarifiers
The “mixed liquor” from the RBC / activated sludge hybrid system enters circular secondary clarifiers (corresponding photo below) to facilitate gravitational separation of solids from the wastewater.

Flow from the secondary clarifiers is disinfected by injecting liquid chlorine (sodium hypochlorite) into the wastewater at the beginning of the chlorine contact tank.

Effluent Discharge to the Mousam River
The treated and disinfected final effluent is discharge to the Mousam River.

Biosolids Storage Tank
Sludge removed from the primary and secondary clarifiers is pumped into aerated storage tanks until it can be dewatered to produce biosolids.

Biosolids Dewatering
The sludge from the storage tank is chemically conditioned and squeezed by a machine called a screw press, which produces dewatered biosolids.