Electrochemical pretreatment of textile effluents and effect of electrode materials on the removal of organics

The aquatic environment around the textile industries in India was severely affected due to continuous discharge of effluents. In order to avoid further deterioration, the pollution control board of Tamil Nadu, India has enforced zero discharge concepts throughout the state. Consequently, most of the industries have opted membrane technology to recover water. The present study was aimed to find out the efficacy of electrochemical techniques as pretreatment methods to reverse osmosis (RO). The textile wastewater was initially treated by electrocoagulation to remove the suspended solids. After the electrocoagulation, the wastewater was further treated by electrooxidation for COD removal. Mild steel as anode was found to be effective for coagulation of suspended solids. For electrooxidation, graphite and RuO2/IrO2/TaO2 coated titanium were used as electrodes. The efficiency of these electrode materials was evaluated in terms of chemical oxygen demand (COD) removal, instantaneous current efficiency (ICE) and electrooxidation index (EOI). The COD was removed to the extent of 90-93% using graphite and 54% with RuO2/IrO2/TaO2 coated titanium electrodes. The current efficiency of 40% and 11% was achieved with graphite and RuO2/IrO2/TaO2 coated titanium respectively. The degradation of organics was followed using GC-MS and the reason for incomplete degradation of organics in the presence of RuO2/IrO2/TaO2 coated titanium was discussed. (C) 2009 Elsevier B.V. All rights reserved.