Impacts of electric field-magnetic powder coupled membrane bioreactor on phenol wastewater treatment: Performance, synergistic mechanism, antibiotic resistance genes, and eco-environmental benefit evaluation

Abstract

A novel electric field-magnetic powder coupled membrane bioreactor (EM-MBR) was constructed, which was superior on improvement of phenol treatment performance and sludge characteristics, and mitigation of membrane fouling. EM-MBR enhanced the phenol degradation via the improvement activity of phenol degrading enzymes. The EPS contents and SVI of EM-MBR were significantly reduced by 49.3 % and 58.7 % than that of the conventional MBR, respectively. Moreover, EM-MBR successfully reduced fouling rate by 57.0 %, delaying the membrane resistance. The EPS contents were positively correlated with the SVI and fouling rate, implying that the sludge settleability was strengthened by improving the properties of EPS with the assistance of electromagnetic, thus mitigating the membrane fouling. Microbial co-occurrence network demonstrated that EM-MBR enriched phenol-degrading and EPS-degrading genera correlated to Fe redox cycle. Furthermore, the activation of the antioxidant system in the EM-MBR resulted in the suppression of reactive oxygen species (ROS) generation, consequently impeding the dissemination of antibiotic resistance genes (ARGs). Co-occurrence patterns of MGEs and ARGs revealed that intercellular binding facilitated by ist and Integrase may account for the horizontal transfer of ARGs. The reduction of unit capital costs (15.63 %), running costs (53.00 %), and total average carbon emissions (15.18 %) indicated that EM-MBR was environmentally beneficial.