On a timed basis, the waste activated sludge enters the gravity thickener. As sludge

accumulates and settles in the tank, water separates from the sludge and rises above the sludge. The liberated water is able to leave the tank easily due to the 9 foot tall screen. Solids are excluded from exiting the tank and they accumulate, settle, and compact.

Decant from the decant box is routed to the plant sewer system. The thickener sludge pump, located in the secondary pump room, take suction from the thickener tanks and pump the thickened sludge to the anaerobic digesters.