Removal of zinc from a wastewater of ammonium zinc chloride plating is difficult, because of the presence of highly concentrated ammonium ion. In this treatment, zinc was removed after the decomposition of ammonium ion with sodium hypochlorite. The breakpoint chlorination curve was obtained by the addition of sodium hypochlorite solution, where ammonium concentration should be nullified at the breakpoint. After this treatment, the residual zinc concentration was less than 0.5mg/l in the presence of aluminum or ferric ion (25-50mg/l).

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