The City of Vermilion’s wastewater treatment plant had an old centrifuge that was never utilized and was not operating. In order to dispose of the facility’s liquid sludge, the City trucked the sludge to a nearby community’s wastewater treatment plant for processing. When the permit for the nearby WWTP no longer allowed the facility to accept additional sludge, the City of Vermilion was required to evaluate alternatives to dewater and landfill its own sludge.
CT Consultants worked with the City to evaluate several sludge dewatering alternatives including belt presses, a rotary press and a centrifuge. A present worth analysis was prepared that compared the centrifuge to other dewatering equipment. Based on these results, the City ultimately selected the centrifuge alternative for which CT Consultants prepared the final plans and specifications.
The new centrifuge system consists of a progressive cavity pump that transfers polymer to a day tank, metering pumps that transfer polymer from the day tank to the centrifuge, a sludge conditioner and progressive cavity pump that transfers sludge to the centrifuge, the centrifuge itself and electrical controls that allow for interface operation of all of the equipment. Sludge is pumped from the secondary digester and mixed with an aqueous solution with polymer before entering the centrifuge. A sludge cake is produced containing a minimum of 20% solids. The dewatered sludge from the centrifuge drops into the conveyor where a horizontal screw evenly distributes dewatered sludge into a it into a roll-off container for transport to a landfill.