Continuous Fabrication of PDMS / PSF Hollow Fiber Composite Membrane for Membrane Aerated Biofilm Reactor

ABSTRACT

The membrane aerated biofilm reactor (MABR) is a novel wastewater treatment technology that combines biofilm technology and gas separation membrane technology. The hollow fiber (HF) composite membrane combines the benefits of a porous membrane with those of a dense membrane, which shows promise in the development of robust aerators. Polydimethylsiloxane (PDMS) emerges as an ideal membrane material for MABR processes. However, a few papers have reported the continuous fabrication of PDMS HF composite membrane. In this work, the continuous fabrication of the PDMS/polysulfone (PSF) HF composite membrane for MABR was first presented by thermal curing process. A series of curing parameters for the PDMS were determined by fabricating PDMS/PSF flat sheet composite membranes. The coatability of the PDMS coating solution stored at low temperatures was also investigated. In the continuous fabrication of PDMS/PSF HF composite membranes, it was found that glycerol, used as a pre‐wetting agent, caused defects, which were related to the special structure of the HF membrane. Consequently, the strategy of filling the membrane pores with a glycerol aqueous solution and then removing the water prevents the PDMS coating solution from intruding the membrane pores in the support layer, thus continuously preparing the defect‐free PDMS/PSF HF composite membrane. Furthermore, the interfacial adhesion between the PDMS layer and the PSF support was improved by optimizing the extraction time to control the depth of pore intrusion. In this paper, a PDMS/PSF HF composite membrane with a burst pressure of more than 200 kPa, an O ₂ permeance of about 20–40 GPU, an O ₂ /N ₂ selectivity of about 2.1 and an oxygen transfer rate (OTR) of 5.6 g/m ² d was successfully prepared. The PDMS/PSF HF composite membrane demonstrated considerable potential for OTR (oxygen transfer rate) and great potential for the application of MABR.