Effect of Sodium Xylenesulfonate on Zinc Removal from Wastewater

Abstract

Based on new U.S. Environmental Protection Agency rules, many metal finishing and plating facilities have switched, or are evaluating switching, from solvent-based metal cleaning systems to aqueous (or alkaline)-based cleaning systems. Some of the constituents in the aqueous cleaners may inhibit metals removal in wastewater treatment processes. This study was conducted to evaluate the effects of sodium xylenesulfonate (SXS), a constituent of a common aqueous cleaner, on zinc removal from industrial wastewater using hydroxide precipitation. In addition, the effects of polyaluminum chloride (PAC) dosages used in the treatment plant were also evaluated. It was found that low levels of SXS did not significantly affect zinc removal. However, higher concentrations of SXS, especially when combined with greater than optimum levels of PAC, did significantly inhibit zinc removal through hydroxide precipitation.