Electrochemical oxidation of distillery wastewater by dimensionally stable Ti-RuO2 anodes

In this study, distillery wastewater (DWW) treatment was attempted via an electrochemical reactor (Cathode: Titanium and Anode: Ruthenium-oxide coated titanium (Ti-RuO2)) without the addition of external electrolytes. As a first step, the central composite design (CCD) experiments were carried out to investigate the effects of applied electric current (0.5-2 A), dilution of DWW (10-30 times) and inter-electrode distance (0.5- 2 cm) on COD removal and energy yield from DWW. The CCD experiments revealed that lower current density with a lesser inter-electrode distance and least dilution conditions were suitable to improve the energy efficiency for COD removal. Subsequently, the raw DWW was treated at a current of 0.5 A and an inter-electrode distance of 0.5 cm to increase energy yield. After 14 h of electrochemical treatment, 52% COD and 92.4% colour were removed from the DWW. Under this condition, the energy yield of reactor was found to be 177.4 mg COD/Wh with a specific current consumption of 1.48 Ah/g COD. Moreover, the BOD/COD ratio of treated raw DWW was increased from 0.25 to 0.57, which shows that electrochemical oxidation could be adopted as a pre-treatment before biological DWW treatment. Although the energy requirement for electrochemical treatment was high, it could reduce the footprint of wastewater treatment plant and better management of DWW. (C) 2020 Elsevier B.V. All rights reserved.