Dewatering system saves city money
It does not take long to realize that the Benbrook Water and Sewer Authority in Texas is a top-notch facility. The grounds are well kept, the equipment is spotless and the staff is professional.
When it was faced with an increased surcharge in 1995 based on the Total Suspended Solids and the Biochemical Oxygen Demand loading from the plant alum sludge discharge, it is not surprising that the facility began looking for alternative processing methods.
Determined to satisfied regulations for plant discharge, the staff began to research a cost-effective bag dewatering technology.
Benbrook located a bag dewatering system at the Benton Water Facility in Benton, Ark., that uses a Draimad sludge dewatering system for dewatering alum sludge solids and concentrating them in a disposable bag. The effluent discharged from the system was clear, and the sludge was packaged in a neat filter bag for disposal, all for a cost-effective rate of about two-and-a-half cents per gallon. The plant engineer designed a similar system to that in Benton.
The layout was straightforward since the basic unit package includes a stainless steel dewatering hood, a sludge pump, a tank for the stock polymer, a polymer feeding mechanism, an air pressurization system, a filter handling cart and a control system. Installation of the unit involved leveling, connecting the unit to a four-inch drain, plugging it into a 110 volt, 20 amp receptacle, assembling the necessary piping and connecting the polymer mixing tank to a garden hose feed.
The Benbrook system is presently operating one to two times per day with the bagged solids going directly to a 20-yard container for disposal in a landfill.
This article was written by Steven DeHart, technical consultant, Waterlink, Canton, Ohio.