Low-maintenance anti-fouling and phosphorus removal of an electro-MBR with Fe anode-cathodic membrane

Frequent membrane cleaning and chemical phosphorus removal increase the maintenance burden of membrane bioreactors (MBRs), greatly limiting their application in decentralized wastewater treatment. Herein, an electrochemical MBR (electro-MBR) integrating a Fe anode and a membrane cathode was constructed to simultaneously alleviate membrane fouling and enhance phosphorus removal using a low-maintenance method. Compared with conventional MBR, coagulation by Fe ions released from the sacrificial anode coupled with electrostatic repulsion from the cathodic membrane significantly mitigated membrane fouling in the electro-MBR. The coagulation significantly increased the sludge floc size, favoring the generation of a porous cake layer, and enhanced phosphorus removal by 69.0% without the addition of chemicals. The electrostatic repulsion impeded the adhesion of foulants, particularly extracellular polymeric substances (EPS), onto the conductive membrane. The EPS deposited onto the membrane surface declined by 31.5% under the synergistic effect of coagulation and electrostatic repulsion. Additionally, the applied electric fields increased microbial species diversity and enhanced the adaptability of biochemical systems to water quality variations. The service life of the membrane module in the electro-MBR was extended by 3 times, and the dosing coagulant was replaced by a sacrificial Fe anode with a working life of 600 d, resulting in 66.7% decrease in maintenance costs. This study suggests a low-maintenance method to achieve anti-fouling and phosphorus removal and promotes the development and application of MBRs.