| Ultrafiltration technology is widely used in wastewater treatment,but membrane biological fouling is still a difficult problem to solve.Electrochemical coupled membrane filtration technology is a new research direction in the field of water treatment,conductive membrane can achieve the intercection of pollutants,and applied voltage can adjust the interaction between pollutants and membrane,can effectively inhibit the attachment and reproduction of pollutants on the membrane,so as to effectively alleviate the problem of membrane fouling.In view of the above problems,the following work has been carried out:（1）By optimizing the content of carbon nanotube whiskers（CNTWs）,the thickness of conductive layer,the content of polyvinylidene fluoride（PVDF）in conductive layer and the content of polyvinylpyrrolidone（PVP）in conductive layer,CNTWs-PVDF conductive composite membrane with good conductivity and stable mechanical properties was prepared by two-step phase inversion method.（2）Using Pseudomonas aeruginosa（PAO1）as a biological pollutant,the anti fouling properties of electrochemically coupled CNTWs-PVDF conductive membrane on live bacterial solution,dead bacterial solution and"dead bacteria+extracellular polymer（EPS）"solution were studied.The results show that CNTWs-PVDF conductive membrane has good anti fouling effect on the above three solutions under applied voltage,but the anti fouling effect on living bacteria solution is the most obvious,and the anti fouling effect on"dead bacteria+EPS"solution is the weakest.Under three influent conditions,after six cycle continuous filtration experiment,the membrane specific flux（J/J0）of conductive membrane under applied voltage of-1.5V was increased by 30%,17%and 7%respectively,the irreversible fouling accumulation rate was reduced by 40%,20%and 16.6%respectively,and the irreversible resistance value(Rir)was reduced by 31.2%,39.8%and 21.6%respectively.（3）Laser confocal microscopy（CLSM）、protein and polysaccharide content calculation、Zeta potential measurement、average particle size distribution and three-dimensional fluorescence spectroscopy（3D-EEM）were used to analyze the anti fouling mechanism of conductive membrane.The results showed that the electronegativity of living bacteria was the strongest,The strong electrostatic repulsion between bacteria and electric membrane with negative conductivity significantly inhibited the irreversible attachment and accumulation of bacteria on the membrane.Compared with the dead bacteria solution alone,although the electrostatic repulsion between the"dead bacteria+EPS"solution and the conductive membrane is stronger,because the soluble organic fouling component of"dead bacteria+EPS"is significantly higher than that of the dead bacteria solution,the anti fouling performance of the charged conductive membrane to the"dead bacteria+EPS"solution is the worst.（4）The results show that when a high negative high voltage（-10V）is applied to the membrane surface for a short time,the electrostatic repulsion force and hydrogen evolution reaction will further promote the bacteria to stay away from the membrane surface,which is conducive to reducing the irreversible fouling of the membrane surface.However,the effect of further voltage increase is no longer obvious.When a strong positive voltage is applied to the membrane surface（+10V,+20V）,most of the bacteria on the membrane surface are killed after 5min,which means that in the long-term operation process,the regular application of short-term positive voltage to the conductive membrane can significantly inhibit the proliferation of bacteria on the membrane surface,so as to inhibit the rapid development of membrane biological fouling. |
