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Sludge Dewatering Cadmium Recovery <br /> The metal hydroxide sludges will have a water content of about Cadmium arrives at the Facility as cadmium cyanide complexes <br /> 95% when they come out of the clarifier. This water content is concentrated on ion exchange resins and bulk shipments of <br /> too great for the sludges to be suitable for sale or disposal. wastewater containing concentrated cadmium. The resin is <br /> These sludges, therefore, must be dewatered as much as possible regenerated with caustic soda and water then treated to oxidize <br /> before they can be stored, disposed of, or sold. the cyanide. The regenerant solution and the bulk shipments of <br /> wastewater are transferred to a small plating cell and the <br /> The conventional plate-and-frame filter press is the most cadmium is electrolytically recovered. Wastewater not <br /> effective filtration apparatus available. While other containing cadmium is neutralized, filtered and discharged. <br /> dewatering devices such as vacuum filters can only attain a <br /> water content of 70%, the plate and frame press can reduce Chrome Recovery <br /> water content from 95% to 50%. ; <br /> Bulk shipments of chrome in the hexavalent form are reacted <br /> Sludges that cannot be sold through the secondary metals market with sodium bisulfite for reduction to the trivalent form. <br /> will be fixated with a Portland cement mixture and disposed. ` Trivalent chrome is also concentrated on ion exchange resins. <br /> Portland cement is a good fixation agent and contingent upon k; The resin regenerant solution (produced by flushing with <br /> t caustic soda and water) and the reduced bulk shipment solutions <br /> he hazardous waste delisting procedure, the material produced <br /> may be disposed of in sanitary landfills. are treated by precipitation. The chrome hydroxide is <br /> dewatered and resold. Any waste waters from these treatment <br /> Copper Recovery processes that do not contain chrome are neutralized and <br /> filtered before discharge to the sewer. <br /> Copper will enter the Facility in five forms. Bulk shipments Zinc Recovery <br /> of concentrated copper in acidic wastewater are treated by <br /> electrolytic recovery. Bulk shipments of chelated copper Zinc cyanide complexes in bulk shipments of waste water and <br /> compounds in wastewater are first passed through an activated <br /> carbon column to remove the chelating agents and then are concentrated on ion exchange resins are treated to oxidize the <br /> treated by electrolytic recovery. Copper concentrated on ion cyanide after the resin is regenerated. The zinc is then <br /> precipitated as zinc hydroxide, fixated and resold or disposed. <br /> exchange resins during the treatment of copper wastewaters is <br /> flushed during resin regeneration with water, sulfuric acid and Wastewater generated during these treatment processes that does <br /> caustic soda. The resin regenerant solution containing copper not contain zinc is neutralized and filtered before discharge. <br /> is treated by electrolytic recovery. Copper cyanide complexes Nickel Recovery <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 Nickel enters the Facility as nickel in acidic wastewater and <br /> treated with sodium hypochlorite and caustic soda to oxidize concentrated on ion exchange resin. The bulk shipments of <br /> the cyanide and then treated by electrolytic recovery. Finally electroless nickel are run through an activated carbon column <br /> bulk shipments of waste water containing copper cyanide to remove the organic chelating agents present. The ion <br /> exchange resins are regenerated using sulfuric acid, sodium <br /> complexes are treated to oxidize the cyanide and then <br /> transferred to the electrowinning tanks for electrolytic chloride and water. The regenerant solutions and bulk <br /> recovery. shipments of both types are treated by precipitating the nickel <br /> as nickel hydroxide, dewatered, and resold on the secondary <br /> Wastewater from any and all of these treatments is neutralized metals market. Wastewaters from these treatments, not <br /> and filtered to remove suspended solids before discharge to the containing nickel, are neutralized, filtered and dishcharged. <br /> sewer. Lead Recovery <br /> Any wastewater containing copper that is too contaminated for <br /> economical electrolytic recovery is precipitated as copper Bulk shipments of wastewater containing lead and a lead <br /> hydroxide and resold. hydroxide sludge generated during in-plant treatment are the <br /> two forms of lead arriving at the Facility. The lead is <br /> precipitated from the wastewater as lead hydroxide. Both <br /> sludges are dewatered and sold if possible. Fixation and <br /> disposal is the other alternative. Wastewater generated during <br /> A-8 these processes, not containing lead, is neutralized and <br /> filtered before discharge. <br /> A-9 <br />