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

Abstract

Abstract 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.