The four aerobic digesters stabilize primary and secondary sludge by oxidation to the point where it may be dewatered and thickened then transferred to the dewatering press.

Sludge is pumped from the primary and secondary clarifiers to the aerobic digesters (24'x24'x13'8") daily. SLudge is mixed with air and microorganisms in a state of near starvation so that they no only consume the available organic matter but alos consume each other producting carbon dioxide gas, water and stage sludge as end products. Clear to amber color supernatant is drawn from the digester surface through telescoping valves to the plant's influent sewer. Digested sludge is drawn from the bottom of the tanks with the sludge pump in the dewatering room where sludge is concentrated on the belt filter press.