Scientific Contributions

In cross-flow ultrafiltration permeate flux has three types of flow regimes. Initially it has a transient regime with a decreasing permeate flow rate. Then it attains a steady state, and the flux reaches a plateau. In the third stage the flow rate becomes independent of applied pressure and is called the limiting flux. In this paper a general membrane fouling modeling was developed that accounts for internal clogging, partial and total clogging, cake deposition and cake deposition with retroflux for any type of filtration; and it is validated with the experimental data of cross-flow ultrafiltration of suspensions containing suspended solids and oil droplets. A relationship for the limiting flux was developed using the experimental data. The fouling was then quantified and linked to the operational parameters. The main operating parameter affecting the filtration process was temperature. Indeed, this determined the droplet and particle size distribution, which is found highly dispersed at any temperature leading to standard deviations of the same order of magnitudes as or even larger than the mean diameters. The major limiting processes that controlled the fouling were evidenced and explained by mean droplet size and size distribution. A systematic study of the influence of the different operational parameters on the transient filtration rate is presented for different temperatures.