Hydrophobic-hydrophilic janus membrane for membrane aerated biofilm reactor: improvement of oxygen transfer efficiency and biofilm attachment

초록

Addressing the dual demands of membrane aerated biofilm reactors (MABRs) for high oxygen transfer rate and robust biofilm attachment, this study reports an asymmetric wettability Janus polyvinylidene fluoride (PVDF) membrane fabricated via a one-sided differential modification strategy. This approach enables independent regulation of the membrane's bilateral surface properties: the hydrophobic side was constructed by blending hydrophobic nano-silica nanoparticles (HSiNPs) with polydimethylsiloxane (PDMS) to enhance aeration and oxygen transfer, while the hydrophilic side was modified via in-situ polydopamine (PDA) coating to promote biofilm adhesion. This design avoids performance trade-offs inherent in conventional full-membrane modifications. Characterization revealed that the Janus membrane exhibited a water contact angle of 41 f 1 degrees on the hydrophilic side and 124 f 2 degrees on the hydrophobic side, with a bubble point pressure of 0.01 f 0.001 MPa. The oxygen transfer rate (OTR) reached 2.75 times that of the pristine PVDF membrane, with a difference of no more than 1% compared to that of the hydrophobic membrane. During 30-day continuous MABR operation, a dense biofilm of 330 f 15 mu m formed on the hydrophilic side, with biofilm attachment increasing by 26.0% to 26.2 f 1.3 g/m2 compared to the pristine membrane. The COD removal rate achieved 91.8 f 0.6%. By coupling asymmetric wettability with surface micro-nano structures, this strategy synergistically optimizes hydrophobicside oxygen transfer and hydrophilic-side biofilm performance, overcoming the limitations of single-property modified membranes. This work provides an advanced membrane material solution for high-efficiency MABR systems.

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