Impact of in-situ bioelectric field on biogas production, membrane fouling and microbial community in an anaerobic membrane bioreactor under sulfadiazine stress

The treatment of swine wastewater (SW) using an anaerobic membrane bioreactor (AnMBR) shows significant potential for energy recovery. However, antibiotics in SW, such as sulfadiazine (SDZ), can inhibit microbial activity, leading to reduced operational efficiency and severe membrane fouling. This study investigated the performance of an integrated microbial fuel cell (MFC)-AnMBR system under various SDZ concentrations, focusing on methane production, membrane fouling, and microbial community dynamics. Results showed the bioelectric field in the MFC-AnMBR improved COD removal by 2.8%-7.3%, enhanced methane production by 12.5%-35.5%, and reduced volatile fatty acids (VFAs) accumulation by 35.3%-56.1% under SDZ stress, compared to a conventional AnMBR (C-AnMBR). Meanwhile, the bioelectric field reduced soluble microbial products (SMP) by 6.3%-43.0%, extracellular polymeric substances (EPS) by 21.9%-43.3% and extended the membrane fouling cycle by over 36 days than C-AnMBR under SDZ stress. Microbial analysis revealed that SDZ stress caused a 2.8%-7.8% reduction in methanogen populations within the MFC-AnMBR, 0.5%-3.0% higher than in the C-AnMBR due to the bioelectric field's influence. Moreover, the bioelectric field enriched p__Chloroflexi, which may help mitigate membrane fouling. In conclusion, the bioelectric field significantly enhances the overall performance of AnMBR systems under SDZ stress, improving energy recovery and membrane fouling resistance.