Treatment of textile industry wastewater by electrocoagulation coupled with electrochemical advanced oxidation process

Abstract

The present study deals with the treatment of real effluents, containing a mixture of reactive dyes (mainly methylene blue), by electrocoagulation (EC) coupled with electrochemical advanced oxidation processes (EAOPs) such as peroxi-coagulation (PC), anodic oxidation (AO), and electro-Fenton (EF), individually. To choose the right treatment process, the key criteria should be higher degradation efficiency and minimal energy consumption. Textile effluents are physico-chemical characterized and the operating parameters i.e. the initial pH, the current density, and the electrolysis time, were investigated. Wastewater treatment energy consumption was evaluated for each combined process. The results highlighted high efficiency of electrochemical processes in effective degradation of organic pollutants at the optimum operating conditions. Among the electrochemical advanced oxidation processes tested, sequential EC-EF treatment was being preferred and quite effective since it provided electro generated hydroxyl radical OH especially when using the boron-doped diamond. Thus, removals of 97%, 100% and 100% for, respectively, TOC, turbidity and color removal were achieved by using the EC-EF combined process. Energy consumption values were evaluated for textile dye decolorization as 0.45–1.5 kW h kg−1 of the removed TOC, depending on the applied current density. Regarding the efficiency level and the operating cost, the EC-EF combined process offers many advantages allowing the reuse of the treated water for other purposes.