Electronics and metal finishing and processing

Abstract

This article provides a review of recent literature on water pollution control and wastewater treatment relating to electronics and metal finishing and processing industries. The review is organized into a number of sections providing information on regulatory issues, heavy metal removal technologies, cyanide treatment, metal cleaning and metal working fluid treatment, and pollution prevention and waste minimization case studies. REGULATORY ASPECTSSkefich (1999) discussed the US Environmental Protection Agency's (EPA) metal products and machinery (MP&M) effluent regulations. EPA estimated a reduction of toxic pollution of surface water by approximately 1 million pounds per year, and all MP&M wastewater control systems must comply with the regulations by the December 2002 deadline. Hayes (1999) examined environmental issues of specific importance to metal finishers. Various new and complex developments in the Clean Water Act, CleanAir Act, and hazardous waste regulations were discussed. Slanker (1999) provided a review of the ISO 14001 standard, which provides companies with the proper structure to implement an environmental management system. The U.S. EPA has indicated that metal finishing companies which adopt the standard may be more likely to avoid undesired governmental scrutiny and the resulting financial and legal penalties. Bode (1998) reported that the introduction of clear limits for the indirect discharge of heavy metals in Germany has greatly reduced the emissions from metal plating industry.Despite the more than 500 metal plating workshops within the Ruhr catchment area the current requirements for water quality of river water are met in the Ruhr. Madono (1999) pointed out that environmental issues have shifted from regional industrial pollution to city-type and living-oriented issues or global environmental issues.The environmental issues surrounding electronics industry, law regulations in Japan and Europe, and the efforts to promote the environmental activities in the industry and Sharp were discussed. The use of an environmental management system (EMS) was discussed and the concept of environmental performance was determined (Nagel, 1999). The environmental performance in a printed circuit board production facility was determined using 7 environmental indicators related to material use, use of aiding compounds, water use, energy use, emissions, waste and packing material. METAL TREATMENTMetal Precipitation. According to Weber (1999), the metal finishing industry discharges substantially more wastewater than any other industrial sector. Factors determining the selection of a treatment system include the pollutant type to be treated, the pollutant loading, the hydraulic flow rate, and the stringency of environmental regulations. Conventional wastewater treatment involves the use of chemicals to react with soluble pollutants to create insoluble by-product precipitants, which are removed by physical separation through clarification and/or filtration. A review of current chemical precipitation methods...