Enhanced sulfamethoxazole degradation by electrode material modification in microbial electrochemical system

Electrode modification was recognized as an effective strategy for enhancing the performance of microbial electrochemical systems. In this study, the cathode material was modified by introducing conductive polymer (3,4-ethylene dioxythiophene, PEDOT)-modified carbon fiber (CF) and MnO₂-modified granular activated carbon (GAC) electrodes to improve the removal efficiency of sulfamethoxazole (SMX) from water and to explore the mechanisms underlying microbial electrochemical action that facilitated SMX degradation. The results showed that, compared to the control group, the specific capacitance of the PEDOT/CF group and the MnO₂/GAC group was increased by 100.2 F·g-1 and 197.4 F·g-1, respectively. Additionally, internal resistance was reduced by 335 Ω and 684 Ω, while the average current was increased by 56.8% and 57.4%, respectively. As a result, SMX removal efficiencies were enhanced by 11.8% and 12.9%, respectively. Microbial community analysis revealed that the cathode surfaces were enriched with electroactive and degradation-dominant microorganisms. Combined with an analysis of SMX degradation products, these findings demonstrated that the modified electrodes exhibited enhanced electron transfer capabilities, promoting redox reactions and ultimately facilitating the degradation of SMX.