Synthetic membrane fouling causes a progressive reduction in flux and separation performance. Fluid dynamic gauging (FDG) is a technique that has application in the measurement of the thickness and deformation behavior of soft fouling layers deposited on a substrate. In this project we report the use of FDG as a tool to improve our understanding of synthetic membrane fouling phenomena relating to the filtration of food based materials. The FDG has been used to track the thickness of the cake layer during the microfiltration of a 45º Brix molasses solution using a 1.5 micron polysulphone (Psf) membrane.

Results are presented simultaneously tracking the thickness of cake and the permeate flux during the filtration of a molasses feed. To validate the measurement technique, different values of cross flow velocity (CFV), temperature and transmembrane pressure were tested to determine the effect on cake thickness measurements.

The Carman-Kozeny equation has been used to determine the theoretical porosity of the deposit (size of particles ranging from 1 to 10 microns) whilst taking into account thickness of deposit and flux.

Results indicate that the FDG can be applied to study food-based deposition on permeable surfaces in cross-flow microfiltration with some reliability. FDG has been found to be a sensitive to variations in operating parameters during filtration. Operating conditions have to be carefully chosen to minimize the effect of membrane fouling. The future uses of the FDG will include an evaluation of concentration polarisation, critical flux, and particle sweeping phenomena.