Electroplating and metal working processes cause pollution with heavy metals through discharge in rinse waters and through disposal of spent plating solution tanks. Most plating process water is used to cleanse the surface of the parts after each process bath. In order to maintain quality standards, the level of dissolved solids in the rinse water must be regulated and fresh water is added to the rinse tank to accomplish this. The overflow water is treated to remove pollutants and then discharged.

This is an area where ion-exchange resins can be employed. The use of special chelating resins will selectively remove the heavy metal such as copper and effectively concentrates the effluent. When the ion exchange resin is regenerated the regeneration effluent can typically contain 2-4% of copper which can then be precipitated in a conventional effluent treatment plant .

Trivalent chromium plating has become more and more important in recent years. Many electroplaters have come to realize that the operational advantages of trivalent chromium plating combined with substantially lower wastewater treatment costs make trivalent chromium an economic winner when compared to traditional hexavalent chromium plating baths.

In the past, however, one major limitation to the success of trivalent chromium plating has been the bath's sensitivity to relatively low levels of ionic, metal contaminants. The contaminants that have caused the most concern are copper, zinc and nickel. Copper and zinc have been reported to cause discoloration and poor coverage when present at levels of 20 ppm or more, while nickel causes problems at concentrations above 50 ppm. When contaminant metal concentrations reach unacceptable levels, the plating bath must be treated to restore proper bath performance.