Charged membrane ultrafiltration of heavy metals from nonferrous metal

Low-pressure ultrafiltration with negatively charged, noncellulosic membranes is shown to be a feasible process for the treatment and reuse of scrubber blowdown wastewater generated in the primary copper industry. Extensive laboratory-scale ultrafiltration data for actual wastewaters containing various heavy metals and sulfate are obtained in a thin-channel unit and are used to establish optimum values of the operational parameters. The design of a full-scale process (2.2 x 10⁶ l/day of wastewater), involving the optimum tapered module arrangement and multiple-pass water reuse, is established by computer simulation and recursive mass balance equations. Ninety-five percent water recovery and 73 to 97% removal of dissolved heavy metals (As, Se, Cu, Cd, Zn, Pb, Fe and Hg) and sulfate can be obtained with 2.9 x 10³ m² of membrane area at 5.6 x 10⁵ N/m² transmembrane pressure.