Electrochemical treatment of a real textile wastewater using cheap electrodes and improvement in COD removal

Abstract

Abstract Various types of dyes and other hazardous pollutants used in the textile industry are one of the leading pollutants of surface water. In this study, real textile wastewater was electrochemically treated with two different electrode combinations (graphite/graphite and iron/graphite) by changing the anode electrode type. Then, comparison studies were carried out by adding Fe2+ or H2O2 to these combinations to improve Chemical Oxygen Demand (COD) removal. Current density (5, 7.5, 10 mA cm− 2), initial pH (2.5–8), and electrochemical (EC) oxidation time (0-120 min) were investigated to determine the optimum electrooxidation conditions. The results showed that in the electro-oxidation (EO) process, 100% colour removal, and 75.39% COD degradation efficiencies were achieved at pH 5.5, current density (I) 7.5 mA cm − 2, and electrolysis time (t) 40 min. In the peroxi-coagulation (PC) process, 89.41% colour removal, and 74.28% COD degradation efficiencies were achieved at pH 3, current density 7.5 mA cm − 2, and electrolysis time 120 min. In the EO + Fe+ 2 and PC + H2O2 processes, 99.9% colour removal efficiencies, 96.38 and 90.63% COD degradation efficiencies were reached at pH 3, current density 7.5 mA cm − 2, and electrolysis time 40 min., respectively. In systems using EO, PC, EO + Fe2+and PC + H2O2, energy consumption, and operating cost were estimated as 2.85, 2.34, 0.54, 0.62 kWh m− 3, and 0.304, 0.249, 0.199, 3.466 US$ m− 3, respectively. Among all processes applied in the study, the most efficient one in terms of COD removal performance, energy, and cost is the (EO + Fe2+) system.