Effect of operating conditions and ion contaminations on electro coagulation and oxidation processes for water quality improvement

Abstract

The objective of this study is to investigate the effect of ion contaminations and operating conditions on Electro Coagulation (EC) and Oxidation (EO) in turbidity and natural organic matter (NOM) removal. The experiments were conducted in 4 liters column. Ferrous and calcium were chosen as contaminated ions. The operating condition was varied in terms of initial pH and current density. 100 NTU turbidity and 70 mg/L NOM were synthesized from bentonite and humic acid (HA), respectively. The results showed that bipolar arrangement of electrodes with 2 cm gap was the optimal condition in terms of gas flow rate and electrode corrosive ratio (Qg/Loss) as well as the treatment performance. From kinetic study, turbidity was removed through destabilization mechanism while HA was removed faster by physical attractive force and sweep floc mechanism. The optimal operation time was found at 20 minutes. It was then selected for analyzing the effect of co-ions and operating conditions. Based on the result, calcium, ferrous, and initial pH were significant effect on turbidity removal while current density, initial pH, and ferrous were significant effect on HA removal. The optimal condition on turbidity removal was found at ferrous 1 mg/L, calcium 18 mg/L, initial pH 8, and current density 3.4 mA/cm2. HA was obtained at ferrous 25 mg/L, calcium 8 mg/L, initial pH 5, and current density 4 mA/cm2. The effluent of the worst condition of HA was then taken place for EO process. Aluminum cathode and conductive carbon coated onto graphite anode were the best condition for EO electrode material. The optimal condition was found at current density 5.5 mA/cm2 and operating time 20 minutes in monopolar arrangement for EO process to remove 37 mg/L HA.