Comparison of Electrocoagulation and Chemical Coagulation for Heavy Metal Removal

Abstract

Copper (Cu), chromium (Cr), and nickel (Ni) removal from metal plating wastewater by electrocoagulation and chemical coagulation was investigated. Chemical coagulation was performed using either aluminum sulfate or ferric chloride, whereas electrocoagulation was done in an electrolytic cell using aluminum or iron electrodes. By chemical coagulation, Cu-, Cr-, and Ni-removal of 99.9 % was achieved with aluminum sulfate and ferric chloride dosages of 500, 1000, and 2000 mg L-1, respectively. Removal of metals by electrocoagulation was affected by the electrode material, wastewater pH, current density, number of electrodes, and electrocoagulation time. Electrocoagulation with iron electrodes at a current density of 10 mA cm-2, electrocoagulation time of 20 min, and pH 3.0 resulted in 99.9 % Cu-, 99.9 % Cr-, and 98 % Ni-removal. The removal of copper, chromium, and nickel from metal plating wastewater was investigated by electrocoagulation and chemical coagulation. With both methods, the removal of these heavy metals increased with increasing aluminum and iron dosage. A comparison of the processes demonstrated the advantage of electrocoagulation in terms of costs and effectiveness. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.