Assessing the Long-Term performance of an integrated microbial fuel Cell-Anaerobic membrane bioreactor for swine wastewater treatment

To improve the performance of an anaerobic membrane bioreactor (AnMBR) treating swine wastewater, an integrated microbial fuel cell (MFC)-AnMBR was constructed and operated for 185 days at organic concentrations of 3000–––12000 mg/L to investigate the effect of the in-situ bioelectric field on organic removal, methane production, system stability and membrane fouling. Results showed that MFC-AnMBR achieved up to 99.0 % chemical oxygen demand (COD) removal at all organic loads with the maximum methanogenic capacity of 0.21 L/gCODremoved. Compared to conventional AnMBR, MFC-AnMBR shortened the start-up period by 15 days, improved the COD removal by 8.7 ± 1.5 % and methane production by 54.2 ± 37.8 %. In the presence of the bioelectric field, the concentrations of soluble microbial products (SMP) and extracellular polymeric substances (EPS) were reduced by 52.7 ± 10.9 % and 15.7 ± 10.9 %, respectively. Notably, the bioelectric field extended the membrane life cycle by more than 40 days. Facilitated by the bioelectric field, the abundance of g_Methanothrix and g_Brooklawnia (capable of electron transfer with g_Methanothrix) in MFC-AnMBR were increased by 29.5 % − 48.7 % and 8.2 % − 10.8 %, respectively, greatly enhancing the methanogenic performance. Furthermore, the bioelectric field inhibited the growth of membrane-fouling bacteria (p_Bacteroidota and p_Firmicutes) and promoted the proliferation of membrane-fouling-mitigating bacteria p_Actinobacteria on the membranes. Overall, the integrated MFC-AnMBR system exhibited an excellent long-term operation performance when treating swine wastewater at different organic loads. This provided a promising strategy for stabilising and efficiently treating swine wastewater.