Critical review on the pulsed electrochemical technologies for wastewater treatment: Fundamentals, current trends, and future studies

In wastewater treatment, conventional electrochemical technologies (ETs) suffer from several limitations, including a low Faraday efficiency, high energy consumption, and poor long-term performance. The implementation of pulsed electrochemical technologies (P-ETs), through the application of pulsed currents with periodically switching potentials, have been proved to be the effective means of enhancing wastewater treatment efficiency and mitigating energy consumption. There has been considerable interest in the field of P-ETs. However, a systematic review of this topic is currently absent. Here, a comprehensive overview of the current state-of-the-art progress on P-ETs for wastewater treatment is discussed in detail. Pulsed electrocoagulation, pulsed electro-oxidation, pulsed electro-fenton, pulsed electrocatalytic nitrate reduction, pulsed electrodialysis and pulsed discharge plasma were classified for the first time based on their reaction mechanisms and system designs. Important operational and design parameters affecting the cost-effectiveness of all P-ETs were reviewed, including the fundamentals, applicable conditions and even optimization strategies for enhancing the process performance. Furthermore, the challenges encountered by P-ETs are presented, and effective strategies to overcome the key technical limitations are systematically proposed. Overall, the prospect of the P-ETs is attractive, and this review provides valuable insight into the systematic understanding and potential value of P-ETs in wastewater treatment.