Polyaniline derived carbon membrane and its in-situ membrane fouling mitigation performance in MBR based on metal-free electro-Fenton

An electro-enhanced membrane bioreactor (EMBR) was constructed with polyaniline-based carbon (PAC) separation membrane as the membrane-electrode, which could realize the in-situ electro-generation and activation of H2O2 to ·OH depending on the graphitic and pyridinic N as active sites without metal catalyst. After the continuous operation of the bioreactor for 74 days, approximately 77.41% irreversible membrane fouling occurred on the electrochemically enhanced membrane, which was less than that on the control membrane (85.96%). The ·OH oxidation combined with electrostatic barrier formed by -1.0 V enhanced PAC membrane suppressed the extracellular polymeric substances deposition on membrane. After operation, the strength of total cell, proteins, β-polysaccharides and α-polysaccharides on the membrane without bias were 5.17, 4.32, 9.65 and 16.31, respectively. In EMBR, the corresponding strength were 2.03, 3.35, 2.15 and 6.73. After calculation, the unblocked pores accounted for 35.3% and 78.5% of the total membrane surface in MBR and EMBR, respectively, indicating the fouling was alleviated obviously. Meanwhile, the EMBR owned a satisfactory wastewater treatment effect with average effluent chemical oxygen demand and NH4+-N around 18.98 mg/L and 0.68 mg/L. The successful implementation of this strategy achieved a green and metal-free method for ·OH production with electrochemical effect for membrane fouling control in MBR.