Polydopamine coating - Surface modification of polyester filter and fouling reduction

To develop a high flux and antifouling membrane to be used in membrane bioreactor for water pretreatment, a low cost polyester filter cloth was modified by coating with polydopamine (PDA), based on the easy self-polymerization and strong adhesion characteristics of dopamine (DA) under mild conditions. The apertures and surface morphological changes were characterized using SEM. The influence of the modifying conditions such as coating time and DA concentration on the membrane properties was investigated. It was found that the most reasonable modification conditions to obtain the best antifouling performance are 1.5 g/L DA concentration and 24 h coating time. There was 142.67% increment of the stable flux during filtrating yeast suspension for the PDA modified membrane under the best conditions compared with that of the original membrane. The result showed that the PDA modified filter membrane has higher flux, excellent antifouling properties and good stability. The stable flux increase in the short-term test in MBR was ∼36% after PDA coating. The results of the relatively longer term experiments in MBR indicate that the membrane modified by PDA reduced the membrane fouling in active sludge, especially the irreversible fouling. This work provides a simple method of modifying low cost filter membrane for better antifouling properties and potential application in MBR.