Preparation Of Conductive Microfiltration Membrane And Its Application In Electric-MBR

Membrane bioreactors(MBR)have been widely used for wastewater treatment and reclamation,due to their many advantages.However,the membrane fouling problem in MBR directly affects membrane flux,membrane effluent quality,process energy consumption and system operation.In recent years,many studies have found that MFC coupled MBR and electric field membrane bioreactor can improve the efficiency of membrane treatment performance,and alleviate membrane fouling.In these systems,the applied electric field,microbial power generation efficiency,etc.were closely related to the conductive properties of the membrane.However,the conventional polymeric membrane commonly has not conductivity,while the metal membrane that has a good electrical conductivity has large pore size and limited rejection capabilities.Therefore,it is highly expected to prepare a conductive membrane possessing both excellent electrical conductivity and filtration performance.In this study,the optimal membrane modification method and ionic liquid doping material were selected,and accordingly,ionic liquid BVIMBF4 was used to dope the conductive polymer monomer pyrrole.Two base membrane,polyvinylidene fluoride membrane(PVDF)and ceramic membrane,were successfully in-situ oxidatively polymerized.The performance characteristics and surface morphology of the modified membrane were systematically compared,and the results showed that the polymer adhered evenly to the base membrane and was stable under the neutral and acidic circumstances.The conductivity of the modified membrane was significantly improved,as the resistivity of the modified PVDF and the modified ceramic membrane was as low as 9.76?·cm and 346.70?·cm,respectively.The pore size and porosity of the modified membrane were analyzed,which were found rather comparable to the base membrane,with an apparently improved membrane surface hydrophilicity.Upon the application of mimute electric field,the modified membrane displayed quite good anti-fouling performance for bovine serum albumin filtration.Meanwhile,with an applied positive electric,the modified conductivity membrane could effectively remove charged metal ions.The flux decline rate of conductivity membrane reduced by about 30%compared with those of base membrane,while their flux was rather similar.By employing the conductivity membrane into an electric-MBR and applied electric field,when the electric fields was small in the MBR,the differences of the removal rates of COD,NH4~+-N and TP between modified membrane system and the base membrane system were less than 4%,both in PVDF membrane reacter and ceramic membrane reactor.The MBR sludge showed a higher specific oxygen uptaking rate than that of the basement membrane system,and the specific resistance of the sludge was lower.The sludge floc structure was more compact and induced a low fouling rate.Under the action of the electric field,the TMP of the membrane grows slowly,and the membrane fouling caused by the cake layer and the clogging inside the membrane were greatly reduced.The above experimental results show that certain electric field strength has positive significance for mitigating membrane fouling,but when under a high electric field intensity the activated sludge activity in the MBR is destroyed,and the stability of the degraded pollutant is reduced.Therefore,the electric field strength should be controlled within a certain range.The size and contrast of the PVDF membrane and the ceramic membrane,the anti-pollution performance of the modified PVDF membrane is more obvious.