Employing electro-peroxone process for industrial wastewater treatment: a critical review

Recently, the electro-peroxone process has advent rapidly as an efficient and new electrochemical advanced oxidation process (EAOP) to treat pollutants, which is operated through in situ generations of H2O2 from cathodic O-2 reduction during the ozonation process. The electro-generated hydrogen peroxide leads to the improvement in ozone transformation to hydroxyl radical; hence, the electro-peroxone can considerably improve the treatment performance, total organic carbon (TOC) mineralization, and reduction of ozone-resistant emerging pollutants compared with the traditional ozonation process. Moreover, the main disadvantage of the traditional ozonation process for water treatment is bromate generation during the treatment of bromide-containing water sources, which can be remarkably decreased by the application of this technology. Additionally, because of its enhanced kinetics of contaminant degradation, electro-peroxone offers a more secure, time-efficient, energy-saving, and effective alternative for the reduction of emerging pollutants, compared with different ozone-dependent AOPs including traditional UV/O-3 and peroxone (O-3/H2O2) methods. Hence, it can offer a suitable, eco-friendly, and cost-effective approach to markedly enhance the efficiency of the current ozonation process. This paper reviews the principles of the electro-peroxone process and compares its efficiency with other methods. The essential reaction mechanisms and experimental parameters that are crucial to the operation, realization, and design of the electro-peroxone, including ozone dosage, applied current, injected ozone flowrate, electrolyte type, electrode setup, solution pH, and type of cathode and anode on electro-peroxone efficiency, are investigated. Moreover, the application of electro-peroxone for water and wastewater treatment is explored. Finally, the challenges in wide-ranging application of electro-peroxone, the future research direction, and its incorporation in wastewater and water treatment systems for viable application are discussed.