Inhibition of algae-induced membrane fouling by in-situ formed hydrophilic micropillars on ultrafiltration membrane surface

Inhibiting algae-induced membrane fouling has become an extremely challenging work in algae-laden water treatment. In this study, we developed a novel Polyvinylidene Fluoride (PVDF) ultrafiltration membrane to inhibit algal fouling by in-situ formed four-arms star poly(styrene)-block-poly(ethylene oxide)monomethacrylate (FAS-PS-b-PEGMA) micropillars on membrane surface via nonsolvent induced phase separation technique. Morphology characterization revealed that the protruding micropillars were formed on membrane surface after the addition of FAS-PS-b-PEGMA. The formation of micropillars affected phase separation behaviors, resulting in more porous membrane structure. Surface analyses suggested that the hydrophilic PEGMA chains of the amphiphilic copolymers were enriched onto the surfaces of micropillars, and endowed the modified membranes with higher hydrophilicity and lower electronegativity. The excellent permeability and antifouling properties of the modified membranes were demonstrated by gravity-driven filtration of Microcystis aeruginosa solution. Especially for M5 membrane, the stable permeation flux was more than 5 times than that of the control membrane. The flux decline ratio was only 51.3%, which was much lower than the control membrane (80.1%). Furthermore, the analyses of fouling layer further confirmed that the micropillars could inhibit the accumulation of algae cells on the membrane surface. This study provides a one-step strategy on the modulation of ultrafiltration membrane preparation, modification and performance for algae-laden water treatment.