Design of a New pH Switch Hollow Fiber Membrane and Analysis on Its Anti-Fouling Performance in a Membrane Bioreactor

Abstract

This paper designs a pH switch hollow fiber membrane made from polypropylene (PP) in a membrane bioreactor (MBR). The polyacrylic acid (PAA) was grafted onto the surface of the PP membrane surface by continuous ultraviolet (UV) grafting, creating the pH switch PP-g-PAA membrane. Then, the membrane was put into a bioreactor which ran continuously 90 days. Both the original PP membrane and the proposed PP-g- PAA membranes were used in the MBR, and cleaned by physical and chemical methods. The two membranes were analysed by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), field emission scanning electron microscopy (FESEM), atomic force microscope (AFM), and laser granularity distribution analyser. The results show that the new membrane achieved lower TMP and longer physical backwashing period than the original PP membrane, indicating that it has better hydrophilic and anti-fouling performance. The PP-g-PAA membrane performed a perfect switch effect in chemical backwashing, especially acid washing. Most of the pollutants clocked in membrane pores were cleaned by chemical backwashing thanks to the pH switch effect. The good performance of the PP-g-PAA membrane in the MBR system promises a low energy consumption and a long membrane life.