Electrochemical advanced oxidation processes towards carbon neutral wastewater treatment: A review

Electrochemical advanced oxidation processes (EAOPs) have been widely studied in efficient wastewater treatment for achieving high degradation efficiency of pollutants even at the expense of high electric energy consumption and carbon emissions. This development is inconsistent with the initiative of carbon neutrality. Despite the growing numbers of published papers on EAOPs, there is still a lack of guidelines regarding carbon neutral wastewater treatment, thus hampering efforts to achieve sustainable development of EAOPs and attain carbon neutrality. This review systematically summarized recent advances of EAOPs and the potential strategies for developing carbon neutral wastewater treatment. The mechanisms, performance, and defects of recent developed EAOPs via improving electrodes, catalysts and processes were discussed systematically. The effective strategies including energy conservation, material savings, carbon dioxide reduction reaction (CO2RR), and mineralization mitigation were presented in detail. To conserve energy, the review also investigated the power supply capacity, degradation efficiency and costs in transforming renewable energy into electric energy for EAOPs operation. The wind turbines and photovoltaic cells (PVCs) performed better than fuel cells and triboelectricity nanogenerators (TENGs). Furthermore, the review explored the carbon offset potential of EAOPs by combining with CO2RR. The carbon offset factor ranged from <1 % to ∼10 %. In addition, specific strategies and challenges in developing carbon neutral EAOPs were summarized and discussed. This review was expected to constitute a baseline for the development of EAOPs towards carbon neutral wastewater treatment.