Experimental Study of Removing F – , PO 4 3 − and SO 4 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 -, PO 4 3− and SO 4 2− . The study explores an approach that can remove F -, PO 4 3− and SO 4 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 -, PO 4 3− and SO 4 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 PO 4 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 SO 4 2− is 125mg/L, lower than the maximum of allowable concentration of sulfate in drinking water standards (250 mg/L).

Coagulation/flocculation process for marble processing plant effluent: Modelling and optimization through response surface methodology

“…Both of the coagulation and flocculation techniques imply the aggregation of suspended colloidal particles in water, their mechanism, and inducing agents are completely different. In the coagulation process, the hydrolyzable inorganic counterions are used, for example, aluminum, calcium, and iron. When the electrostatic repulsion between the colloidal particles are eliminated via adsorption and charge neutralization mechanism, the solid particles settle down and form a sludge blanket at the bottom of the system.…”