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  • PDMS-coated porous PVDF hol...
    Sethunga, G.S.M.D.P.; Karahan, H. Enis; Wang, Rong; Bae, Tae-Hyun

    Journal of membrane science, 08/2019, Letnik: 584
    Journal Article

    This report demonstrates the fabrication of a composite hollow fiber membrane that efficiently recovers dissolved methane (dCH4) from anaerobic wastewater treatment effluents via membrane contactor (MC) process. We first fabricated highly porous hollow fiber membranes (∼85% porosity) using polyvinylidene difluoride (PVDF). Then, we coated the whole structure (bulk), or lumen side of PVDF supports with polydimethylsiloxane (PDMS), a hydrophobic polymer possessing high gas permeability. The adjustment of the concentration of PDMS precursor mix could effectively serve for tuning the performance characteristics of MC membranes and helped suppress membrane wetting, a major performance-reducing factor. Despite their denser skin layers, the lumen-modified membranes demonstrated superior dCH4 recovery flux. Mass transfer analyses have confirmed the importance of preserving bulk porosity while coating the membrane surfaces. The long-term performance tests performed using actual anaerobic effluents suggested that the PDMS coating did not accelerate fouling, such that the lumen-modified MC membranes showed an almost steady flux for 8 days with an anaerobic membrane bioreactor effluent. A high-strength effluent, obtained from an up-flow anaerobic sludge blanket reactor, induced faster fouling. However, we observed only a ∼20% flux decline in a 10-day operation. Thus, we propose that the designed PDMS-PVDF composite membranes are promising for industrial practices. Display omitted •We prepared PDMS-coated PVDF porous hollow fiber membranes for membrane contacting.•Both lumen- and bulk-modified PVDF membranes were successful in methane recovery.•Lumen-modified PDMS-PVDF membrane outperformed commercial PP and PDMS membranes.•Lumen-modified PVDF achieved long-term performance with actual anaerobic effluents.