Arsenic removal from groundwater of Sivas-Şarkişla Plain, Turkey by electrocoagulation process: Comparing with iron plate and ball electrodes

In the present study, laboratory scale experiments were conducted with the air-fed electrocoagulation (EC) reactor using iron (Fe) ball and plate anodes in a batch mode to assess their efficiency in the removal of arsenic from Sivas Sarkisla groundwater (SSG). Effects of the operating parameters namely, initial pH_i (6.6-8.6), applied current (0.10-0.50 A), area of electrode (210-630 cm²), airflow rate (0-6 L/min) and operating time (0-20 min) for Fe ball and plate anodes on the removal efficiency of arsenic were investigated and operating costs for the treated SSG were calculated for each type electrode. The pH did not have significant effect on the arsenic removal in the pH range 6.6-8.6 for both type electrodes, but higher current density, airflow rate and lowest surface area of electrode led removal of arsenic rapidly from SSG. The optimum operating conditions determined to be pH 7.6, 0.30 A, airflow rate of 6 L/min, anode surface area of 210 cm² resulted in removal efficiency of 99.3% and operating cost of 1.55 $/m³ at 20 min (charge density of 360 C/L or 3.731 F/m³) for Fe ball electrodes and 96.9% and 0.101 $/m³ at 6 min (charge density of 108 C/L or 1.119 F/m³) for Fe plate electrodes, respectively. As a comparison, Fe plate electrodes performed better for reducing operating time from 20 to 6 min which affected the operating cost considerably. Both type electrodes in the EC were able to bring down arsenic concentration to <10 μg/L at the optimum operating conditions.