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 gMethanothrix and gBrooklawnia (capable of electron transfer with gMethanothrix) 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 (pBacteroidota and pFirmicutes) and promoted the proliferation of membrane-fouling-mitigating bacteria pActinobacteria 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.