Metal finishing industry wastes

Q Treatment and Management of Metal Finishing Industry Wastes... 

E. Karlovic, The recovery of heavy metal hydroxides form metal finishing industries waste-waters by flotation with surfactants, M. Sc. Thesis, Faculty of Sciences of Novi Sad, Yugoslavia, Novi Sad 1977. 

DCNR, Metal Recovery Technologies for the Metal Finishing Industry, Fact Sheet, Office of Waste Reduction Services, Environmental Services Division, State of Michigan, Departments of Commerce and Natural Resources (DCNR), Lansing, MI, November 1993. 

In this section, the uses of water in the metal finishing industry are presented and the waste constituents are identified and quantified. 

Table 9.3 displays the ranges of flows in the metal finishing industry. Approximately 81% of the plants have flows between 1.9 and 57 m3/h (67-2000 ft3/h). For those plants with common metals waste streams, the average contribution of these streams to the total wastewater flow within a... 

Table 9.5 shows the concentrations of pollutant parameters found in the precious metals subcategory raw waste streams. The major constituents are silver and gold, which are much more commonly used in metal finishing industry operations than palladium and rhodium. Because of their high cost, precious metals are of special interest to metal finishers. 

Pollutant parameters and their concentrations found in the oily waste subcategory streams are shown in Table 9.9. The oily waste subcategory for the metal finishing industry is characterized by both concentrated and dilute oily waste streams that consist of a mixture of free oils, emulsified oils, greases, and other assorted organics. Applicable treatment of oily waste streams is dependent on the concentration levels of the wastes, but oily wastes normally receive specific treatment for oil removal prior to solids removal waste treatment. 

PRC Environmental Management, Hazardous Waste Reduction in the Metal Finishing Industry, Noyes Data Corporation, Park Ridge, NJ, 1989. 

Major sources of lead in Atlantic coast streams included wastes from metal-finishing industries, brass manufacturing, lead alkyl production, primary and secondary lead smelting, coal combustion, and manufacture of lead oxide. 

Recycling and resource recovery includes technologies that either directly use waste from one process as raw material for another process or recover valuable materials from a waste stream before the waste is disposed of. Some of the spent chemical process baths and much of the rinsewater can be reused for other plant processes. Also, process chemicals can be recovered from rinsewaters and sold or returned to the process baths. This section describes some of the recycling and resource recovery technologies available to the metal finishing industry. 

DHS. May 1988. Waste Audit Study Metal Finishing Industry. California Dept, of Health Services, Toxic Substances Control Division, Alternative Technology Section. Prepared by PRC Environmental Management, Inc. 

The restrictions on the land disposal of many wastes have increased the cost of hazardous waste disposal. The land disposal restrictions that affect metal fabricators have been in effect for several years. For example, the restrictions on the land disposal of liquid wastes containing toxic metals and/or acids began on January 1,1984 (Section 66905 CCR). These restrictions have caused increases in disposal costs since these wastes now require some form of treatment prior to land disposal. These increased waste disposal costs are viewed as a driving force for the metal finishing industry to implement waste reduction technologies. 

PRC Environmental Management, Inc. 1988. Waste Audit Study—Metal Finishing Industry. United States Environmental Protection Agency and California Department of Health Services, San Francisco, California. 

Electrolytic methods have been applied to the treatment of other metal waste streams generated in the electroplating or metal finishing industries. Pollution engineering processes have been designed and implemented for the removal of hexavalent chromium, trivalent chromium, nickle, copper, zinc and cadmium.Besides the Edwards patent, there seems to be no documentation of electrolytic methods for removal and recovery of mercury metal from waste streams. 

HAZARDOUS WASTE REDUCTION IN THE METAL FINISHING INDUSTRY... 

Reverse osmosis also serves some of the waste management and resource recovery needs in the metals and metal finishing industry. Effluent streams from mining and plating operations containing heavy metals, acids, and other chemicals can be treated with reverse osmosis to recover both the metal as its salt, and purified water for reuse. For metal ion recovery from dilute solutions, however, reverse osmosis faces competition from conventional solvent extraction, membrane-based solvent extraction, and its variant, coupled transport (see Section V.F.3). 

Waste treatment for the recovery of process materials such as metals for the metal finishing industries, and dyes used in the manufacture of textiles. 

Electrodialysis is a membrane-based process which can be used for separation, removal, or concentration of ionic species present in aqueous solutions. These operations are accomplished by the selective transport of ions through an ion exchange membrane under the influence of a direct current. One of the earliest applications of electrodialysis was the desalting of brackish water. However, since the 1970s, extensive studies have been performed on the application of electrodialysis for waste-water treatment, especially in the electroplating and metal-finishing industries. 

Hazardous Waste Reduction in the Metal Finishing Industry... 

Procedures Waste Minimization in Metal Finishing Industry California Department of Toxic Substances Control, 1991 distributed by U.S. Environmental Protection Agency, Pollution Prevention Information Clearinghouse. 

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