Evaluation of operating parameters with respect to charge loading on the removal efficiency of arsenic from potable water by electrocoagulation

Abstract

Charge loading is the most important parameter for controlling the reaction rate within electrocoagulation process (EC) which determines the coagulant production rate, and it may also serve as a design parameter for the process. In the present study, arsenic removal from potable water by a batch EC process using iron plate electrodes was investigated with respect to charge loading and effects of operating parameters such as current density, operating time, initial arsenic concentration, ratio of electrode surface area over volume (S/V), and electrode connection mode on removal efficiency of arsenic were evaluated. The results showed that arsenic concentration of 150 mu g/L in monopolar series (MP-S) electrode connection mode during the EC process decreased the arsenic concentration to less than 6 mu g/L corresponding to removal efficiency of 95.1% (under the limit set by the World Health Organization) at current density of 2.5 A/m(2), charge loading of 50 C/L, S/V of 10 m(2)/m(3) (ratio of electrode surface area over volume), EC time of 7.5 min. Arsenic removed capacity and charge dosage rate at the optimum operating conditions were 2.8 mu g As removed/C and 4.00 C/L/min. The adsorption of arsenic over electrochemically produced hydroxides and metal oxide complexes followed pseudo second-order adsorption model (r(2) > 0.94). Operating costs were affected with current density, electrode connection mode, S/V and initial concentration of arsenic from potable water. The operating cost at MP-S connection mode was calculated as 0.00075 s/m(3) at 150 mu g/L, 0.05 A, 7.5 min and 30 C/L. (C) 2016 Elsevier Ltd. All rights reserved.