Sludge is wasted from a pit at the bottom of each tank and pumped to the dissolved air flotation thickener units. During summer months, all 3 pumps are operated continuously. During the winter months the pumps are operated 4 to 5 hours per day intermittently to maintain the desired wasting rate. The DAF system consists of two 352 square foot tanks, blowers and a polymer feed system. The DAF centrate is returned to the head of the plant.
Polymer is added to the sludge to aid in dewatering.
The thickened sludge is then pumped to the Aerobic Digester. Aerobic Digestion Effluent from the DAF units is pumped to two 47 foot square aerobic digestion tanks with a combined volume of 0.76 mg. They are aerated with submerged turbines and sparger rings. Blower air is cooled during the summer to decrease heat build-up in the tanks. A defoament is used to help prevent the build-up of foam.