Comparison of filtering models for milk substitutes

Membrane-based methods of filtering are becoming increasingly popular in the food industry, but membrane fouling significantly affects filtration performance, making the characterisation of fouling mechanisms critical. This study examined the applicability of three mathematical models. The resistance-in-series model divides the total resistance into membrane resistance, reversible resistance and irreversible resistance. The Hermia models distinguish four basic blocking mechanisms, namely complete blocking, standard blocking, intermediate blocking and cake filtration. The Makardij model analyses the flux-reducing or -enhancing effects. In the experiments, different models were investigated and compared. The feed solution was two milk substitute drinks (soy and oat) that were ultrafiltered under different operating parameters (transmembrane pressures: 0.05–0.1 MPa, stirring rate: 100–400 min−1). By fitting the data to the models, the most characteristic blocking mechanism and the rate constant that most influenced flux could be determined.