Electrochemical Advanced Oxidation Processes: An Overview of the Current Applications to Actual Industrial Effluents

Many human activities result in the production of wastewater. Usually, physical, chemical and biological processes are successfully combined for the treatment of municipal wastewater, attaining good removal efficiencies. However, some industrial processes introduce anthropogenic recalcitrant pollutants in wastewater that are quite difficult to remove or degrade using conventional means and that should be removed due to their hazardousness. In such cases, the application of an Advanced Oxidation Processes (AOP) uses to be a good and/or promising alternative to attain an appropriate effluent. These processes rely on generating hydroxyl radical, which is a powerful oxidant that mineralizes efficiently pollutants contained in wastewater. In this review, we focus on the use of electrochemical methods to produce hydroxyl radical, using directly or indirectly electrochemical technology, within the so-called Advanced Electrochemical Oxidation Processes (EAOP). These processes include electrochemical, sonoelectrochemical and photoelectrochemical technologies and this work describes the fundamentals, main cases studied in the literature related to actual industrial waste treatment and tries to help in the elucidation of the range of applicability of each technology.