Complexation-ultrafiltration process was employed to remove Ni( II ), Cu( II ), Zn( II ) and Cr( III ) from plating wastewater. Polyacrylic acid sodium (PAASS) as a water-soluble polymer was used for complexing the cationic forms of the heavy metals before filtration. The size of the complex has to be larger than the selected membranes so the complex can be retained. Permeate water is then purified from the heavy metals. Filtration experiments were performed with ultrafiltration membrane system, equipped with a polysulfone memebrane with a 10,000 Da cut-off. Different parameters, affecting the percentage rejection of the metals, such as pH, loading ratio, and permeate flux (FVC) have been investigated. The concentrated retentates were used further for the decomplexation, after the decomplexation, diafiltration experiments were carried out at pH 1.5 using dilute H2SO4 solution. All the four metals were found to be extracted from the metal-PAASS complexes with satisfaction. It was also found that the complexing performance of the PAASS regenerated did not change compared with the fresh PAASS. ? 2011 IEEE
