Unraveling synergistic mechanisms of bioelectrocatalytic methane enhancement and membrane fouling alleviation via composite anodic membrane assembly in anaerobic bioreactor treating purified terephthalic acid wastewater

The efficient anaerobic treatment of purified terephthalic acid (PTA) wastewater is constrained by the recalcitrance of toxic aromatic pollutants and biomass washout/loss. To address those limitations, an electrochemical anaerobic membrane bioreactor (EC-AnMBR) integrated with a composite anodic membrane was designed and developed, and the dual functionalities in simultaneous bioenergy recovery and membrane fouling mitigation were evaluated. Results revealed that synergistic chemical-electrochemical cleaning significantly improved operational efficiency. EC-AnMBR achieved the highest methane production of 1422 ± 129 mL·L⁻¹_reactor·d⁻¹, representing an 18.7 % increase compared to the conventional reactor at a hydraulic retention time (HRT) of 20 h. Electrochemical oxidation degraded key components of extracellular polymeric substances (EPS) stickily deposited onto membrane surface, induced the formation of porous network-like matrix, and reduced transmembrane pressure escalation rate by 47.0 %, thereby reinforcing the anti-fouling ability of membrane. Microbial community analysis revealed that bio-electrochemical regulation facilitated the electroactive properties of microbial aggregates, enriching syntrophic aromatic compound degraders (Syntrophus, Syntrophorhabdus and Pelotomaculum), thereby improving contaminant degradation efficiency. Additionally, acetoclastic and hydrogenotrophic methanogenic pathways (Methanosaeta, and Methanolinea) were augmented at the cathode surface, thus elevating methane production. Mantel test analysis further indicated that the composition of sludge EPS served as a critical factor influencing methane productivity and membrane fouling rate, with Sludge-PS_TB-EPS, Sludge-PN_LB-EPS, and Sludge-PN_TB-EPS identified as the primary controlling factors. These findings collectively substantiate the novel EC-AnMBR's dual advantages in refractory pollutant removal and bioenergy recovery, providing a promising approach for industrial aromatic wastewater treatment with simultaneous energy recovery.