Interaction mechanisms and predictions on membrane fouling in an ultrafiltration system, using the XDLVO approach

The extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) approach was used to predict the mechanisms and control of membrane fouling in an initial ultrafiltration (UF) phase. The polymeric UF membranes – made of polyvinylchloride (PVC) – were selected to investigate membrane fouling, by means of filtering water samples that differed in terms of organic colloid composition and pH. Results indicated that membrane fouling was ameliorated as the total interaction energy increased. Van der Waals (LW) interaction energy predominated when the distance between the membrane surface and organic colloids was >5 nm while short-range acid–base (AB) interaction energy was a key contributor to total interaction energy over short distances (<2.5 nm). The size of colloids was the lowest in the water sample with a humic acid (HA)/fulvic acid (FA) ratio of 1:2. This sample also had the highest negative interaction energy, indicating that it had the lightest level of membrane fouling. Increased pH resulted in an increase in total interaction energy, which alleviated membrane fouling. Prechlorination resulted in an increase in total interaction energy of the water sample, indicating that the use of feed water (for ultrafiltration) that had been pre-oxidized using chlorine, could reduce membrane fouling, due to characteristic changes in organic matter.