Efficiency and mechanism of photoelectrocatalytic system powered by constructed wetland-microbial fuel cell for the treatment of refractory wastewater

Abstract

Constructed wetland-microbial fuel cell (CW-MFC) offers a dual benefit of wastewater treatment and energy recovery from wastewater to generate electricity. The optimization and application of this electricity have garnered significant attention in recent years. In this study, we utilized the electricity generated by CW-MFCs to power a photoelectrocatalytic (PEC) system designed to enhance the degradation of refractory wastewater contaminants. We investigated the efficiency of Rhodamine B (RhB) wastewater degradation using a CW-MFC coupled PEC system under varying bias voltages supplied by the CW-MFC. The results demonstrated that the CW-MFC-PEC coupled system exhibited superior degradation efficiency for Rhodamine B under a bias voltage of 0.6 V. Compared to TiO₂ adsorption, electrocatalysis (EC), UV photodegradation, and UV-TiO₂ photocatalysis (PC), the degradation rate of the CW-MFC-PEC coupled system increased by 93.29 ± 1.6%, 89.41 ± 1.49%, 59.34 ± 0.06%, and 16.4 ± 2.46%, respectively. Further investigation by free radical capture experiments verified that activated substances including hydroxyl radical (•OH) play a crucial role in the catalytic degradation process. This study demonstrates that the electricity generated by CW-MFC can be used for photoelectrocatalysis to improve the efficacy of wastewater treatment, presenting a novel method for treating highly concentrated organic wastewater and refractory wastewater simultaneously.