Insights into the roles of membrane pore size and feed foulant concentration in ultrafiltration membrane fouling based on collision‐attachment theory

Abstract Membrane property and feed characteristics play critical roles in membrane fouling. This paper aims to clarify the roles of membrane pore size ( φ ) and feed foulant concentration ( C b ) in ultrafiltration fouling induced by polysaccharides. The fouling behaviors were expounded by collision‐attachment theory, where the rate of membrane fouling is mainly determined by collision frequency ( JC b ) and attachment efficiency ( γ ). At the initial fouling stage, rapid flux decline was observed at large φ or high C b due to the great JC b and/or γ . At the later fouling stage, there existed a nearly identical maximum stable flux attributing to the same JC b and γ , which was independent of φ and C b . Moreover, the smaller φ can lead to less foulants passed through the membrane and thus more foulants attaching on the membrane, while the higher C b can give rise to more foulants on both the membrane surface and in the permeate. The results presented in current study provide fundamental basis in understanding membrane fouling. Practitioner points Collision‐attachment theory was employed to expound the UF fouling behavior. Rapid flux decline occurred at large membrane pore size or high feed foulant concentration in the initial fouling stage. Membranes with different pore size or feed foulant concentration had an identical flux at the latter fouling stage. Lowering membrane pore size or increasing feed foulant concentration can lead to more foulants attaching on the membrane surface.