Treatment of heavy metal in the plating wastewater by electrocoagulation

Abstract

Abstract This present paper evaluated a batch electrocoagulation (EC) scale containing two flat aluminium plate electrodes to treat total Cr, Zn2+ in real plating wastewater taken from CX Technology company. Response Surface Methodology (RSM) and Design-Expert 12 software were applied to optimize the operating conditions with three main factors including current density, pH, and retention time. The control experiments using FeSO4 10% were performed to compare with the electrocoagulation method. The best treatment efficiency occurred at a current density of 16.93 A/m2, pH 9, and a 31-minute reaction. The conductivity did not significantly affect to the total Cr and Zn2+ removal but reduced energy consumption. The jar-test experiment result was obvious the optimal factors of the coagulation-flocculation encompassing pH 10 and 3 ml/L FeSO4 10 %. The treatment efficiency of total Cr and Zn2+ were 97.22±0.3 % and 99.53± 0.006 %, higher than others. The generated sludge in the electrocoagulation method was 2,031± 0.91 g/L, equal to 51.7 % sludge of the coagulation-flocculation method. The treatment cost by electrocoagulation was less than others.