The mystery of ‘air resistance’ in submerged hollow fiber membranes: A controllable 'irreversible fouling'

Abstract

In recent years, with the widespread application of membrane separation technology, the influence of the 'air resistance' phenomenon on membrane filtration performance has gained increasing attention. This study investigates the mechanism of 'air resistance' in the formation of membrane fouling. The results show that 'air resistance' not only significantly reduces membrane flux but also increases the 'irreversible resistance' of the membrane, which negatively impacts the long-term stable operation of the membrane.In this study, highly sensitive fibre bragg grating (FBG) sensing technology was used to monitor the vibrational performance of hollow fiber membranes in real-time, confirming the important role of membrane vibration in controlling 'air resistance'. Quantitative analysis showed that the air content in the membrane was reduced by approximately 52.08% after optimizing the vibration parameters.Additionally, a comparative study of membrane surface modification revealed that outer surface modification was more effective than inner surface modification under fouling conditions, with reductions of about 23.64% and 6.89%, respectively.This study demonstrates that the effect of 'air resistance' can be effectively reduced by adjusting operating parameters and membrane modifications, enabling a more accurate assessment of the nature and extent of actual membrane fouling. It lays the foundation for future research on membrane fouling and the development of smarter, more efficient filtration systems, which will improve the economics and sustainability of water and wastewater treatment.