Treatment of textile wastewater is a known pollution control challenge for environmental engineers. Various organic compounds in these effluents undergo chemical as well as biological changes, consume dissolved oxygen, and destroy aquatic life. Some dyes and their degradation products are also carcinogens and toxic. It is necessary to treat dye effluents prior to their discharge into the receiving water stream to meet the stringent environmental regulations.
In this work, batch electrotreatment of aqueous dyeing effluents of two different industrial dyes have been investigated in a desktop set up. Experiments were conducted with 200 mg/l individual dye concentration of methylene blue (MB) and Eosin Yellowish (EY). Electrotreatment with current density up to 10.4 mA/ cm2 and operating time up to 75 minutes with graphite electrodes materials has been investigated. Effluents were tested for decolorization and reduction of COD (chemical oxygen demand). COD reduction and decolorization has not been found to progress in the same proportion because decolorization possibly occurs due to some of the dye molecules breaking into intermediate organic molecules. Energy consumption during treatment per kg of COD reduction, starting with 200 mg/l dye solutions, was 272.7 KWh/m3 and 625 KWh/m3 for MB and EY respectively. A mathematical model of the process has been proposed and validated with experimental results.
Key words: electrotreatment, dyeing effluents, decolorization, COD reduction, energy consumption
