Low electric field assisted surface conductive membrane in AnMBR: Strengthening effect and fouling behavior

Abstract

• The novel surface conductive membrane as cathode mitigated membrane fouling. • A unimodal pattern of SFR led to flocs on the surface of membrane to gel layer. • Basophilic methanogens and metabolic activity were influenced by electricity. • High specific surface area and biocompatibility contributed to form MEC system. This study investigated the possibility of using a novel type of surface conductive hollow fiber membrane during the Anaerobic membrane bioreactor process (AnMBR). In particular, the membrane fouling control mechanisms of Surface electric field AnMBR (S-AnEMBR) were evaluated through comparing with the operation of Conventional AnMBR (AnMBR) and Electric field AnMBR (AnEMBR). Results showed that S-AnEMBR had longer running time, stronger anti-fouling capability, and more stable Total organic carbon (TOC) removal efficiency. And S-AnEMBR could extend the running time of the rapid fouling phase (Stage 2). Electrochemical analysis and microbial community analysis showed that enhanced electron transfer in S-AnEMBR accelerated the decomposition of organic matter and further improved acidification efficiency from 83.75% to 234.78%, indicating the methane concentration ranged between 24.56 mmol/L and 36.99 mmol/L. Cake layer compression was reduced because significant changes were observed in increased particle size and more negative Zeta potential. In addition, basophilic methanogens (48%) were enriched at cathode, which improved electrochemical activity of carbon electrode biocathode and promoted anaerobic digestion. Therefore, it was found that S-AnEMBR was more conducive to controlling the properties and structure of the gel layer, and further achieving the resistance towards protein and polysaccharide adhesion in membrane. This work demonstrated that the surface conductive hollow fiber membrane possessed good anti-fouling ability in AnMBR, and provided an alternative membrane material for AnMBR application.