The electro-peroxone process for the abatement of emerging contaminants: Mechanisms, recent advances, and prospects

The electro-peroxone (E-peroxone) process is an emerging electrochemical advanced oxidation process (EAOP) that combines ozonation with in situ cathodic hydrogen peroxide (H2O2) production to drive the peroxone reaction for water and wastewater treatment. Over the past several years, the E-peroxone process has quickly emerged as a promising EAOP for the abatement of emerging contaminants (ECs) in water. Because of the enhanced ozone (O-3) transformation to hydroxyl radicals (center dot OH) by electro-generated H2O2, the E-peroxone process can considerably increase the efficiency and decrease the energy demand for the abatement of ozone-resistant ECs compared with conventional ozonation. Meanwhile, the E-peroxone process can substantially mitigate the formation of bromate during the treatment of bromide-containing water, which has been a major concern of conventional ozonation for water treatment. Hence, by simply installing electrodes in ozone contactors, the E-peroxone process can remarkably enhance the performance of water and wastewater treatment in various aspects. Compared with other ozone-based AOPs such as the conventional peroxone (O-3/H2O2) and UV/O-3 processes, the E-peroxone process also represents a more convenient, cost-effective, energy-efficient, and safer option for EC abatements. This paper reviews recent research of the E-peroxone process, with focus on the abatement of ECs in real water matrices. The fundamental reaction mechanisms that are essential to the understanding, design, and operation of the E-peroxone process are described. The abatement of various ECs in natural water and wastewater by the E-peroxone process are critically reviewed. The challenges in scaling-up the E-peroxone process and integrating it in water and wastewater treatment trains for practical applications are discussed. (C) 2018 Elsevier Ltd. All rights reserved.