A combined model for the prediction of the permeation flux during the cross-flow ultrafiltration of a whey suspension

In the dairy industry, whey protein is concentrated by means of cross-flow ultrafiltration. In this membrane process, the thickness of the cake layer is assumed to be controlled by the shear stress exerted by the feed flow. In our prior work, we developed a model for the cross-flow ultrafiltration of a whey suspension that incorporated the effect of this shear stress. In this study, the model is extended to consider the permeation process as two periods determined by the dominant factor controlling the filtration resistance. In the first period, pore blockage dominates while in the latter, cake deposition is dominant. The models for each period were combined using the results of the model for the first period as the initial conditions for the second period. The combined model was compared with experimental results of cross-flow ultrafiltration. Results show that the permeation process was well described under the conditions of this study by the combined model and the possibility of the application of the model to the cross-flow ultrafiltration system was indicated.