Wastewater Treatment by Electrocoagulation: A comparative study using different anode materials

Abstract

This study investigated COD removal by electrocoagulation in both synthetic and real wastewater using different anode material. Experiments were conducted in a batch-scale EC cell using aluminium, iron and copper electrodes as anode and stainless-steel electrode as cathode. Effects of different parameters including pH (4, 7, and 10), time (10 to 60 min), voltage (3 to 12 V) were studied in order to evaluate the efficiency of electrocoagulation process. The initial synthetic COD concentration was 1000 mg/l. The highest COD removal efficiency of 97.7% was observed by aluminium electrode under the following conditions: pH = 7, time of 60 min, and voltage of 12 V. Moreover, it was observed that most of COD removal happened during the first 10 min (about 86%) then the removal rate decreased. For real wastewater, the highest COD removal efficiency was 91.9% which achieved by using aluminium electrode, pH =7.4, time of 60min, and voltage of 12 V. The results showed the feasibility of electrocoagulation process for the treatment of highstrength municipal wastewaters. ICEPTP 152-4 Effect of voltage on COD removalAs shown in figures 2, 3, and 4, the voltage and current have a main important role in increasing the removal efficiency at the same pH. By using Al electrode as anode with constant pH = 7, time 60 min, COD removal efficiencies were 92.4, 94.6, 95.9, and 97.7% at voltages of 3, 6, 9, and 12V, respectively. By using Fe electrode as anode under the same operating conditions, COD removal efficiencies were 91.1, 93.5, 95, and 96.8 respectively finally by using Cu electrode as anode the removal efficiency of COD was 90.3%, 92.9%, 94%, and 96% at voltages of 3, 6, 9, and 12V, respectively. The current induced at 3, 6, 9 and 12V were observed as 0.1, 0.3, 0.6 and 0.9 A, respectively.Current density determines both coagulant dosage and bubble generation rates and influences both solutions mixing and mass transfer at the electrodes [14]. COD removal efficiency increased with increase in voltage due to the increase in metal ions dissolute from anode. According to Faraday's law, as metal hydroxide increases, it adsorbs more COD. Also, it is well known that voltage and current density determines the production rate of coagulant, adjusts also bubble production, and hence affects the growth of flocs [5].