Mathematical modeling of flux decline in ultrafiltration

Studies were conducted to investigate membrane fouling in Ultrafiltration (UF) of emulsions and suspensions. A laboratory scale plate and frame cross flow membrane filtration setup was fabricated and installed. Oil and gelatin were used to make the emulsion and suspension as feed. The feed was pumped to the UF cell at a cross flow velocity of 1 m/s and a temperature of 30 °C. It was found that development of membrane fouling is a dynamic process of two distinctive stages. Pore blocking is dominant resistance at initial period of UF and cake resistance begins to dominate following the initial pore blocking. The results show that cake layer resistance increases with increasing feed concentration and transmembrane pressure. UF of oily emulsions and dilute gelatin suspensions, which produce highly compressible cake (gel) layers, were studied under constant pressure and constant feed concentration, respectively. In this research, a new model which is a modified cake layer filtration model was developed. Model predictions show an excellent agreement with experimental data.