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Electrically conductive membrane possesses a remarkable performance in antifouling with the assistance of applied external electric fields. However, its widespread application is hampered due to the poor properties of existing conductive membranes, such as low conductivity and inadequate strength. The present study demonstrates a novel in-situ combination approach for the fabrication of a highly conductive carbon nanotube (CNT)/polyvinylidene fluoride (PVDF) membrane. During membrane fabrication, the casting solution film was pre-mantled with a CNT layer before the occurrence of polymer precipitation, thereby ensuring a natural and tight in-situ mergence between the CNT layer and supporting PVDF. The obtained CNT/PVDF membrane was characterized in terms of physicochemical properties and filtration performance. An electrically-enhanced cross-flow filtration system was devised to evaluate the antifouling performance of the pristine PVDF and CNT/PVDF membranes. Compared with the pristine PVDF membrane, the CNT/PVDF membrane possesses a greater electrical conductivity and a higher permeability. The incorporation of the CNT layer led to a completely different surface composition in terms of elemental components and functional groups. Being used as a cathode, the CNT/PVDF membrane exhibited a remarkable antifouling performance in the presence of external electric fields, and performed better in a 0 V/2 V-pulsed mode as compared with a 2 V-constant mode. This in-situ combination method provides a simple and practical approach for the fabrication of composite conductive membranes, suggesting promising applications in various membrane-fabrication areas. [ABSTRACT FROM AUTHOR]

Polymeric flat-sheet membrane (FS) and ceramic flat-tubular membrane (CM) are the most widely-used membranes in anaerobic membrane bioreactor (AnMBR). However, fouling mechanism on FS and CM were rarely compared before and needed to be deeply illuminated. In this work, distinction of irremovable fouling formed on polyvinylidene fluoride FS and Al 2 O 3 CM in AnMBR treating municipal wastewater was studied. Lab-scale AnMBR operation showed that FS presented severer irremovable fouling and faster fouling rate. Foulants characterization revealed that irremovable fouling of FS was composed of more organics (FS = 0.91, CM = 0.35 g-TOC/m2-membrane) and biomass (FS = 47.3, CM = 8.65 × 1010 cell/m2-membrane), leading to gel layer loosely structured. Conversely, irremovable fouling of CM contained more inorganics (FS = 0.08, CM = 0.55 g/m2-membrane), facilitating dense gel layer with larger specific filtration resistance. Membrane cleaning tests found that gel layer on FS was efficiently removed by NaClO, while gel layer on CM was loosened by NaClO but destructed by citric acid. NaClO/NaOH both reduced resident bacteria, whereas increased the proportion of live cells. Irreversible fouling on FS involved more organics while more inorganics on CM. Irreversible biofouling could utilize citric acid as substrate for metabolism and proliferation. This study not only helps to probe fouling mechanism with different membrane materials, but also aids to develop differentiated effective cleaning strategy to corresponding membrane modules. Image 1 • Loosely structured gel layer on polymeric membrane contains more organics and biomass. • Dense and robust gel layer on ceramic membrane comprises more inorganics. • Gel layer on polymeric membrane is removed by NaClO degrading organics. • Gel layer on ceramic membrane is loosened by NaClO but destructed by citric acid. • NaClO reduces biomass on both membranes but increases the proportion of live cells. [ABSTRACT FROM AUTHOR]