Application of electrooxidation process for treating concentrated wastewater from distillery industry with a voluminous electrode

Experiments in a laboratory scale were carried out to reduce color and chemical oxygen demand (COD) in distillery wastewater by using electrooxidation processes. A cylindrical electrochemical reactor constructed in an axial configuration with 0.2 m diameter and 0.35 m height was employed in this study. Two materials including graphite particles and titanium sponge were used as the voluminous anodes. A cathode made from Ti/RuO2 was placed 0.04–0.05 m above the upper level of anode particles. Effect of parameters including initial pH of wastewater (1–5), time of dilution, current intensity (1–10 A), type of additive (H2O2 and NaCl), and additive concentration were investigated. The results indicated that the anode made from titanium sponge showed a higher potential to treat wastewater than the another one. The treatment in acidic condition (pH=1) provided the maximum oxidation of organic pollutants in wastewater. The presence of additives can promote the reduction of COD and color in wastewater approximately 89.62% and 92.24%, respectively. The maximum current efficiency was reached at the first 30 min and decreased slightly as electrolysis time proceeded due to the formation of passivation on the electrode surface. The energy consumption was obtained in the range of 2.82–4.83 kWh/kgCOD or 24.08–28.07 kWh/m3 wastewater depending upon the concentration of additive. The kinetics of COD reduction was the pseudo first-order reaction with a fast rate constant of 6.78 min−1.