Fouling behaviour of membranes with different characteristics by urban wastewater secondary effluent.

Fouling behaviours and antifouling properties of polyvinylidene fluoride (PVDF) ultrafiltration membranes blending with polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP) and polymethyl methacrylate (PMMA) had been investigated using the secondary effluent as the filtration medium. The results demonstrated that the antifouling properties of membranes using PVA and PVP as the additives were generally stronger than those using PMMA. Additives PVA and PVP could effectively improve the structural property and hydrophilicity of the membrane and result in an outstanding antifouling property. A dense membrane surface could prevent low molecular foulants from entering into the membrane pores, depositing on the membrane with a loose spongy layer and penetrating into the internal macropore structure. The not fully generated internal macropores on the membrane surface were trend to be plugged, which resulted in serious flux decay and the membrane fouling was irreversible. Filtration cake formed on the membrane due to concentration polarization, which caused membrane flux decline and high flux recovery after cleaning.