Evaluation of fouling resistances during the ultrafiltration of whey model solutions

In the last decades, the ultrafiltration of whey has grown in importance as a “green” technique. However, since fouling is an important drawback, researchers focused on its prediction by mathematical models. In this work, three ultrafiltration membranes of different molecular weight cut-offs and materials were used to ultrafilter whey model solutions of different protein concentrations. As a novelty, a resistance-in-series model that accounts for the time evolution of the fouling resistances was considered. The results demonstrated that the higher the protein and salt concentrations in the feed solutions were, the greater the fouling degree was. The resistance-in-series model was accurately fitted to the experimental data for each membrane and feed solution used. The results showed that the resistance due to adsorption dominated the first minutes of operation, while the membrane characteristics (surface roughness and hydrophilicity/hydrophobicity) played an important role in the growth of the cake layer.