Electrochemical technology for the treatment of real washing machine effluent at pre-pilot plant scale by using active and non-active anodes

Abstract

Real effluent of washing machine is one of the major sources of microplastics and fabrics in municipal and surface water. The effluents constitute large volume of wastewater with different surfactants since every household and industries nowadays use washing machine rather than traditional hand washing.In this work, a real effluent of washing machine was treated by electrooxidation (EO) in a pre-pilot plant scale electrochemical flow reactor using active (Ti/Pt) or non-active (boron doped diamond (BDD)) anodes and Ti cathode. The effect of anode material (Ti/Pt or BDD) and the applied current density (16.6, 33.3 and 66.6 mA cm−2) on the decay of the organic matter, in terms of chemical oxygen demand (COD) during the electrochemical treatment was examined using the as-received effluent or by adding Na2SO4 as supporting electrolyte (as auxiliary in the conductivity). A decreased in organic matter (COD) was always observed when an increase on the applied current density was achieved at both anodes; however, BDD anode showed a well-defined trend as well as higher removal efficiency at all current densities studied when compared to Ti/Pt. Besides, faster and higher COD decay was attained by adding Na2SO4 to the real effluent compared to as-received effluent regardless of anode material used. Active chlorine species were also electrochemically produced at both anodes from the Cl− ions in the real effluent, contributing to the elimination of the pollutants. The mineralization of organic matter in the effluent was also determined, obtaining >90% of total organic carbon (TOC) reduction after 360 min with BDD anode at 33.3 and 66.6 mA cm−2. Based on the achieved results, EO is an efficient and effective treatment approach for the remediation of organic micropollutants in washing machine effluent especially with BDD anode.