Sludge characterization, removal, and dewatering

Abstract

In April 1988, E.I. du Pont de Nemours and Company retained the services of CH2M HILL to perform a sludge characterization study, treatability study, remedial design, and to provide construction management services during the remedial action for a slip containing wastewater sludge situated on the Baltimore Harbor. The slip contained an estimated 18,500 cubic yards of sludge that averaged 20 percent solids by weight. Organic compounds were the primary constituents in the sludge, with highest concentrations represented by benzene, ethylbenzene, toluene, and xylenes. During 1989 and 1990, the sludge was removed by a floating dredge, crane, and an air conveyance boom pumping system. A steel sheet pile wall was constructed around the slip to prevent the slip banks from collapsing during removal of the sludge. The sludge was treated using a cationic polymer of high molecular weight during flocculation, and a membrane filter press for dewatering. The sludge cake averaged 52 percent solids by weight. All sludgecake was disposed of offsite in a RCRA-permitted landfill.