Membrane fouling is a major problem in membrane bioreactors (MBRs).In this study,membrane fouling caused by membrane rejection and adsorption was study.Filtration tests indicated that membrane rejected SMP,causing membrane pore blockage and then forming a gel layer.Batch adsorption experiments showed that adsorption of SMP onto PVDF membrane was a spontaneous physical adsorption process.Meanwhile,the absolute value AG of adsorption of SMP onto D3520 was higher than that of adsorption of SMP onto PVDF membrane,so SMP preferentially adsorbed onto D3520 rather than PVDF membrane.Thus,the effect of ARs on reducing the SMP concentration was investigated.It was found that,6 g ofD3520 was suitable for adsorption of SMP.This physical adsorption involved extal film diffusion,intra-particle diffusion,and surface adsorption.The Redlich-Peterson isotherm model performed best in terms of describing this equilibrium data.The mechanism of membrane fouling mitigation was verified by MBR simulation system.A case study of AR-MBR system was conducted.The results showed that addition of D3520 can effectively alleviate the development of membrane fouling.