ED performance, it is needed to enhance the monovalent anion permselectivity and anti-fouling properties included anti-organic, anti-inorganic and anti-biofouling of anion-exchange membranes -AEMs-. In our previous study, we succeed to improve the antiorganic fouling by a surface modification with dopamine solution which formed a negative layer on the membrane surface1-. In addition, polydopamine -PDA- coating increased a monovalent anion permselectivity, which positively affect on inorganic fouling resistance2, 3-. In this work, we attempted to investigate the effect of PDA coating on biofouling of AEM and evaluated its impact on ED process performance. In this study, Neosepta AMX -Astom Corp., Tokyo, Japan- was modified with PDA coating using different dopamine concentrations. The effect of PDA coating on AMX membrane surface was evaluated by a static adhesion test using P.putida, as a model gram-negative bacteria, due to its high adhesion property. The bacteria that attached on the membrane surface was observed using confocal laser scanning microscopy -CLSM-. Then, the total cell volume and coverage percentage were calculated using COMSTAT software. The results showed that the number of bacteria attached on the membrane surface significantly decreased by PDA modification and found that 0.1 kg/m3 is an optimal concentration of dopamine. Moreover, biofouling during ED operation was evaluated using bacterial suspension with 0.05 M NaCl as a feed solution. It was evaluated by the increase of transmembrane potential due to the increase of electric resistance of membrane caused by biofouling. The voltage did not change during ED operation even for unmodified membrane. It indicates that DC itself also decreases biofouling. Thus, biofouling may scarcely occur in a real ED operation. For further investigation, fouled membranes were then observed by scanning electron microscope -SEM-. The coverage percentage was determined by analyzing the SEM images. The results revealed the coverage was minimum for a surface modified with 0.1 kg/m3 of dopamine concentration whitch is the same as the static adhesion test and the organic fouling1-. Therefore, PDA layer sufficiently improves ED performance of AMX membrane.

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