Copper can be found in many wastewater sources including, printed circuit board manufacturing, electronics plating, plating, wire drawing, copper polishing, paint manufacturing, wood preservatives and printing operations. Typical concentrations vary from several thousand ppm from plating bath waste to less than 1 ppm from copper cleaning operations. Copper can be removed from wastewater by precipitation as an insoluble hydroxide salt or by ion exchange. Wastech designs and manufactures many types of metal precipitation systems including small and large batch type and a range of continuous flow treatment systems.
Precipitation of the insoluble cupric hydroxide salt is the most common form of treatment. This salt is formed by adjusting the pH of the water to about 9 to form the precipitate. The resulting precipitate can leave about 0.1 ppm of dissolved copper in solution if chelates are absent. If chelates are present, the final copper concentration can be much higher. When chelating agents are present, Wastech can design a treatment system using MetFloc chemistry. MetFloc HM-11 is used to break complexes and chelating agents and MetFloc HM-12 is used to precipitate the copper as well as most other heavy metals that may also be in solution. Wastech offers free lab testing of waste water samples to determine the best treatment procedure.
Ion exchange can be used to remove copper from wastewater. Wastech ion exchange systems are designed to treat plating rinse water with trace amounts of metals. The water is sent through cation and anion resin beds, along with activated carbon and/or media filtration to produce deionized water that can be returned to the process. The difference in a Wastech ion exchange system is that the resin is regenerated on-site, eliminating the need for bottle haul off. Since the regenerate waste will contain any copper and other metals removed during treatment, a vacuum distillation system can be used to concentrate the regenerate even further to reduce the amount of liquid waste hauled away. The purified water from the vacuum distillation system can also be returned to the process.
The equipment normally used for these processes is a batch treatment system for high copper concentrations (greater than 1000 ppm), continuous precipitation if the copper concentrations are less than 1000 ppm and the volume is greater than 5000 gpd. Ion exchange is feasible if concentrations are less than 20 ppm and the desired effluent requires low copper concentrations, less than 20 ppb.