A Novel Method for Efficient Electrochemical Treatment of Actual Dyeing Wastewater With Energy Saving

Abstract

Electro-oxidation is a promising technology for wastewater treatment with bio-refractory organic and nitrogen pollutants; however, the high energy-demanding hinders its wide application. In this study, a novel method by regulating the significant parameter during electro-oxidation process timely for actual dyeing wastewater treatment with energy saving was studied. Operating factors (i.e., flow rate, initial pH value, electrode distance, and current density) were investigated for chemical oxygen demand (COD) and ammonia removal, and results indicated that current density was the key factor which obviously influenced the electrochemical performance. Indirect oxidation by active chlorine was then confirmed as the main reaction pathway for pollutants oxidation, and the relationship between the current density and the generation of active chlorine was established, suggesting that a large part of the generated active chlorine was not utilized effectively. Subsequently, a novel method by variation of current density timely based on the reaction mechanism was proposed; results indicated that, with similar pollutant removal efficiency, energy consumption could be reduced from 31.6 kWh/m3 to 20.5 kWh/m3. Additionally, the novel system was further optimized by Box-Behnken design: COD and ammonia removal efficiencies could reach 71.8% and 100% respectively, and energy-demanding could be reduced by 45.6%.