A new integrated single-chamber air-cathode microbial fuel cell - Anaerobic membrane bioreactor system for improving methane production and membrane fouling mitigation

Abstract

A novel integrated single-chamber air-cathode microbial fuel cell - anaerobic membrane bioreactor (ScMFC-AnMBR) system was designed. It involved an anaerobic membrane bioreactor (AnMBR) and a single-chamber air-cathode microbial fuel cell (ScMFC) being constructed in a common reaction chamber to enhance methane production and reduce membrane fouling in the AnMBR. Results indicated that ScMFC-AnMBR delivered a stable micro-bioelectric field environment with a voltage output of 95 ± 4 mV. Compared with conventional AnMBR (C-AnMBR), methane production using this system increased by 35.89%. Soluble microbial product (SMP) and extracellular polymeric substances (EPS) dropped by 65.3% and 43.1%, respectively. Particularly, the transmembrane pressure (TMP) in the operating cycle was in a slow growth status with the maximum value of only 18.5 kPa. The bioelectric field helped aceticlastic methanogens (Methanosaeta) replace hydrogenotrophic methanogens (Methanobacterium) as the dominant methanogens via electron transfer under a closed-circuit scenario. As syntrophic bacteria of methanogens (Syntrophobacter, Smithella and Syner-01) and exoelectrogens of Desulfovibrio were selected by the bioelectric field and gained a stable foothold, bio-foulant (Megasphaera) was significantly reduced. The complex microbial synergism in ScMFC-AnMBR greatly improved the methanogenic performance, thus effectively alleviated membrane fouling and prolonged the operation cycle of the system. Demonstrated here is the feasibility of practical application.