Highly effective antifouling performance of PVDF/graphene oxide composite membrane in membrane bioreactor (MBR) system

Abstract

A composite microfiltration membrane, prepared by blending polyvinylidene fluoride (PVDF) and hydrophilic graphene oxide (GO) nanosheets, was successfully used in a submerged membrane bioreactor system. Scanning electron microscopy (SEM), contact angle measurements, and X-ray photoelectron spectroscopy were used to determine the surface properties of GO modified PVDF membrane. To compare the composite membrane with a commercial PVDF membrane, the critical flux, fouling behavior, membrane resistance, and anti-fouling properties against extracellular polymeric substances (EPS) were studied. Higher critical flux was obtained by PVDF/GO composite membrane due to the change of surface characteristics. The PVDF/GO composite membrane demonstrated sustained permeability, lower cleaning frequency, and filtration time that was three times longer than that of the PVDF membrane. In terms of anti-EPS accumulation, the PVDF/GO composite membrane showed lower membrane resistance, particularly, lower pore plugging resistance than the PVDF membrane. Fewer amounts of EPS, specifically polysaccharide accumulated on the composite membrane surface due to the introduction of GO nanosheets. The SEM and confocal laser scanning microscope images showed that the cake layer on composite membrane was looser and thinner than that of commercial PVDF membrane. Consequently, membrane surface was exposed, resulting in the maintenance of high permeability over a long period of time.