Surface grafting of polyvinyl alcohol (PVA) cross-linked with glutaraldehyde (GA) to improve resistance to fouling of aromatic polyamide thin film composite reverse osmosis membranes using municipal membrane bioreactor effluent

Abstract

Membrane surface modification is a favourable method to handle fouling during wastewater treatment processes. In this study, grafting of polyvinyl alcohol (PVA) through cross-link with Glutaraldehyde was applied to a thin film composite reverse osmosis membrane to enhance the resistance to flux decline. The analytical analyses attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy were performed to evaluate the impact of surface modification. Biofouling using Escherichia coli (E. coli) bacterial solution and fouling tests using a bench scale reverse osmosis system with a simulated secondary effluent from a membrane bioreactor were used to assess the impact of the surface modification initiated on antifouling properties of the membrane. It was shown that the morphological structure and the chemical properties of the membrane were altered, whereas the pure water flux slightly decreased after modification. Although a slight decrease of salt rejection was observed, the membrane resistance to fouling improved and the biofouling model used revealed the anti-biofouling capacity of the membrane. The flux decline and flux recovery ratios improved with an increase in PVA concentration. The sterilization ratio increased from 33.8 to 36.8% and the pure water flux decline decreased from 46.04 to 25.94% after modification.