Combined Adsorption and Ultrafiltration Processes Employed for the Removal of Pollutants from Metal Plating Wastewater

This work investigated the use of combined sorption and ultrafiltration (UF) processes for the treatment of electroplating wastewater. The combined vermiculite - UF and bentonite - UF treatment schemes were assessed for their ability to remove nickel, zinc, organic, matter, and color. UF significantly reduced nickel and zinc concentration from wastewater at alkaline environment with removal efficiencies higher than 89% at pH >= 8 for both metals. Mineral addition increased metal removal efficiency to higher values (> 97% at pH >= 8). The presence of organic compounds and cations in wastewater limited the adsorption efficiency of minerals. Binary metal solutions suppressed the adsorption process for both nickel and zinc. The adsorption of metals on minerals was a multi-stage process where intraparticle diffusion was not the only rate limiting step. Isotherm examination showed that the best fit to the experimental data was obtained by the Langmuir model, and the three parameter models of Redlich-Peterson, Toth, and Sips converged to the Langmuir model. UF combined with minerals resulted in significant removal of organics and color. Furthermore, UF of wastewater resulted in limited membrane fouling.