Fabrication of knitted Polyethylene/SiO2 composite membrane modules for one-step microfiltration and particle removal in wastewater treatment

Sewage treatment efficiency is affected by the membrane module design. In this study, SiO2 was employed as additives in the formation of polyethylene/SiO2 hollow fibre composite membranes using the thermally induced phase separation (TIPS) method. This approach effectively addressed the limitations of pure polyethylene hollow fibres, such as poor network pore structure and low flux. The investigation revealed that the addition of SiO2 enhanced gas flux by 30%, increased porosity by 20%, and provided a commendable tensile strength of 2.1 MPa, suitable for weaving knitted composite membrane module. The voids of the membrane module facilitated particle filtration and microfiltration through micropores of the composite membrane, successfully integrated into a one-step wastewater treatment process. The knitted composite membrane module's particle filtration process effectively intercepted all particles A (size > 30 μm), and the microfiltration process rejected particles B (1.3 < size <15 μm). During these processes, the rejection rate of talc powder in the membrane module was as high as 90%, and the gas flux was remained at 1200 L·m−2·min−1. The strategy of knitted composite membrane modules demonstrates versatility in applications and has the potential for expanding the design to various microporous hollow fibre materials for diverse separation purposes.