In order to control membrane fouling, a batch ultrafiltration was used to study the reduction in membrane permeability in turbulent now. A model of the process was developped on pilot plant as function of time, taking into account the non uniformities in now, cake deposits along the length of the channel. The model predictions compared to the experimental results for ultrafiltration of bentonite solutes shows a goad agreement. The effect of I transmembrane pressure on the filtration has been studied.