Insights into the flow-through electrochemical system in water and wastewater treatment: Influential factors, advantages, challenges, and perspective

Abstract

Adopting electrochemical advanced oxidation processes (EAOPs) in flow-through filtration systems will be an asset in achieving (waste)water treatment goals in the near future, owing to their simplicity of application, enhanced mass transfer, and low energy use. This review discusses the recent treatment of contaminants of emerging concern (CEC), influencing factors, benefits and challenges, and prospects for flow-through electrochemical reactors (FTER). The research effort has mainly driven the electrochemical oxidation (EO) methods to treat organic pollutants from synthetic wastewater in the past decade. However, FTER has revealed some limitations in a working system, suggesting the need for more experimental research and practical applications. The integrated processes and multi-stage electrochemical flow-through systems with novel materials development should exemplify an efficient and applicable method for (waste)water treatment. The establishment of the multi-stage flow-through systems efficiently reduces the overvoltage and prevents the difficulties associated with higher current, such as energy loss and high running costs. In addition, extensive research on hydrodynamic features and current distribution models should provide the residence time and current density across the system. Some studies on chloride-based electrolytes have shown that electrodes in FTER can prevent chloride conversion to chlorate and perchlorate at low current densities. However, one of the toughest challenges is reducing the production of these products during electrochemical processes. At least, the current status of the FTER operating process is thoroughly discussed and reflected upon. Then, prospects are presented to understand working mechanisms and maintaining systems. We believe that this review will furnish a worthy insight into the sustained application of FTER in environmental water treatment.