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Sludge Dewatering <br /> The metal hydroxide sludges will have a water content of about <br /> 958 when they come out of the clarifier. This water content is <br /> too great for the sludges to be suitable for sale or disposal. <br /> These sludges, therefore, must be dewatered as much as possible <br /> before they can be stored, disposed of, or sold. <br /> The conventional plate-and-frame filter press is the most <br /> effective- filtration apparatus available. While other <br /> dewatering devices such as vacuum filters can only attain a <br /> water content of 708 , the plate and frame press can reduce <br /> water content from 958 to 508. <br /> Sludges that cannot be sold through the secondary metals market <br /> will be fixated with a Portland cement mixture and disposed. <br /> Portland cement is a good fixation agent and contingent upon <br /> the hazardous waste delisting procedure, the material produced <br /> may be disposed of in sanitary landfills. <br /> Copper Recovery <br /> Copper will enter the Facility in five forms. Bulk shipments <br /> of concentrated copper in acidic wastewater are treated by <br /> electrolytic recovery. Bulk shipments of chelated copper <br /> compounds in wastewater are first passed through an activated <br /> carbon column to remove the chelating agents and then are <br /> treated by electrolytic recovery. Copper concentrated on ion <br /> exchange resins during the treatment of copper wastewaters is <br /> flushed during resin regeneration with water, sulfuric acid and <br /> caustic soda. The resin regenerant solution containing copper <br /> is treated by electrolytic recovery. Copper cyanide complexes <br /> concentrated on ion exchange resins are treated in a similar <br /> manner. The resin is regenerated using caustic soda and water. <br /> The regenerant solution containing copper cyanide complexes is <br /> treated with sodium hypochlorite and caustic soda to oxidize <br /> the cyanide and then treated by electrolytic recovery. Finally <br /> bulk shipments of waste water containing copper cyanide <br /> complexes are treated to oxidize the cyanide and then <br /> transferred to the electrowinning tanks for electrolytic <br /> recovery. <br /> Wastewater from any and all of these treatments is neutralized <br /> and filtered to remove suspended solids before discharge to the <br /> sewer. <br /> Any wastewater containing copper that is too contaminated for <br /> economical electrolytic recovery is precipitated as copper <br /> hydroxide and resold. <br /> A-8 <br />