Hybrid Fenton-electrochemical reactor and system as post-treatment of textile wastewater

Abstract

Textile effluents contain different kinds of chemical additives and mostly are treated by biological processes. However, COD, ammonium, and color cannot be removed completely from wastewater. Decolorization agents are commonly used as a post-treatment method, although high cost and hazardous sludge byproduct are often reported as their main weaknesses. This study proposes a hybrid system of Fenton and electrochemical to replace the costly decolorization agents, as it is low-cost and highly efficient with no sludge production. This system consists of one cylindrical reactor with a working volume of 50 L and 12 pairs of Ti/RuO2 mesh cylinder and graphite carbon rod electrodes. It was also equipped with wastewater tank, pump, power supply, mixer, pH meter, and ammonia meter. The effects of wastewater volume, potential, retention time, pH, mixing speed, ferrous sulphate and salt concentration on COD, ammonium, and color removals were investigated and discussed. This system was able to reduce color, COD, and ammonium significantly in 15 min for 96 %, 64 %, and 77 %, respectively, at 4000 mg/L salt concentration, 30 mg/L ferrous sulphate, pH 4, 90 rpm mixing speed, and 6 V potential. pH was increased to 6.18; 6.73; 7.25 and 7.36 after 15, 30, 45 and 60 min, respectively. A circulatory system was applied to improve pollutants removal efficiency and electrochemical oxidability index as well as to reduce energy consumption. In terms of reactor performance and operating cost, this system is deemed feasible and applicable as a post-treatment method to support anaerobic-aerobic unit of textile WWTP.