Nickel is found in plating, metal pickling and metal cleaning wastewater. Like copper, non-chelated nickel can be precipitated as the hydroxide salt. It can also be removed by ion exchange in methods similar to copper. Precipitation of the insoluble hydroxide salt is the most common form of treatment. This salt is formed by adjusting the pH of the water above 10.5 to form the precipitate. If cyanide is present, it must be pre-treated before entering the Wastech treatment system. When other complexing 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 nickel 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 nickel and other heavy metals 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 nickel 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.