Polypyrrole Modified Stainless Steel Mesh Membrane Electrode In Integrating Membrane Bioreactor With Microbial Fuel Cell

Integrating membrane bioreactor (MBR) with microbial fuel cell (MFC) is an innovative and promising technique. Combining two reactors effectively can overcome their own shortcomings. MBRs are advantageous in better water quality, lower sludge production, less sludge cost over other conventional wastewater treatment, but its fouling problems require higher energy consumption, while MFCs not only recover energy with increasing capacity and efficiency, but also have high potential and technical feasibility in effectively treating various industrial wastewaters. Thus, the integration provides a great possibility of application in MBR. The present MBR and MFC studies mainly focused on three aspects,(1) the reactor configuration,(2) different kinds of electrode materials,(3) the mechanism of MBR/MFC system.This paper mainly focused on the modification of cathode membrane materials. Polypyrrole is conductive polymer and it can modify stainless steel mesh. Anthraquinone compounds can be used as catalysts to promote oxygen reduction reaction (ORR). Polypyrrole(PPy) doped with AQS (sodium9,10-anthraquinone-2-sulfonate) and ARS (sodium3,4-dihydroxy-9,10-anthraquinone-2-sulfonate, Alizarin Red’s) were used as the catalysts to modify stainless steel mesh via constant-potential electropolymerization. The electrocatalysis experiment was carried out in a three-electrodes system. The modified cathode membranes increased the degradation of (MB) methylene blue (>90%,1h, while the control had a degradation rate of41%). Additionally, modified stainless steel meshes helped in achieving good antifouling properties. After applying an electric field at0.2v/cm, the cumulative volume increase for PPy, PPy/ARS, PPy/AQS modified membrane was18.8%,19.2%and1.5%respectively.Then, the modified membranes were used in MFC for wastewater treatment and enhancing the current generation. The power densities when using PPy/AQS, PPy/ARS and PPy/SO42-were13.93mW/m2,7.36mW/m2and5.58mW/m2respectively. In contrast, using the stainless steel mesh, it was just2.34mW/m2. Additionally, the internal resistance decreased greatly after modification. Next, the modified membrane modules were applied in self-designed MBR/MFC system. The cell potential and power densities exhibited the same trend as in this MFC system. Most importantly, the increase in power density for PPy/AQS, PPy/ARS and PPy modified SSM was respectively31.37,27.06and23.7times that for the blank SSM in integrated MBR and MFC system. The new system has a good wastewater treatment potential. The effluent was clean without odor. The COD removal rate reaches more than95%; NH4+-N removal rate can reach90%, pH fluctuates around8. Turbidity is very low. At last, another membrane module was put into the MBR/MFC system. However, the cell potential increased while the power densities decreased. Overall, the new MBR/MFC system demonstrates great application potential and economic feasibility in effective removal of COD and NH4+-N nutrients, obtaining better effluent qualities and increasing energy recovery.