Experimental Study of Removing F–, PO4 3− and SO4 2− from Wastewater in Aluminum Surface Treatment Solution

Abstract

This paper treats aluminum surface treatment solution wastewater and adopts coagulation-chemical precipitation method (combination of CaO, PAC and PAM) to remove F–, PO4 3− and SO4 2− . The study explores an approach that can remove F–, PO4 3− and SO4 2− in the wastewater simultaneously. Through optimization and improvement of reagent dosage and reaction conditions, the treated wastewater reaches the national discharge standards. The experimental results show that the optimal conditions for removal of F–, PO4 3− and SO4 2− are: 1150 mg of CaO, 110 mg of PAC, 85 mg of PAM at pH 9 and a reaction temperature of 323 K for a reaction time of 30 min. After treatment, the concentration of F– is 4.30 mg/L, which is lower than discharge standards of fluoride-containing industrial wastewater (10 mg/L). The concentration of PO4 3− is 0.90 mg/L, lower than the second grade of discharge standard of phosphate-containing industrial wastewater (1.0 mg/L). The concentration of SO4 2− is 125mg/L, lower than the maximum of allowable concentration of sulfate in drinking water standards (250 mg/L).