The application of fluid dynamic gauging in characterising cake deposition during the cross-flow microfiltration of a yeast suspension

► Cake thickness was measured in situ and in real time during microfiltration. ► FDG was used to estimate thickness and cohesive strength of yeast cakes. ► Yeast cakes of thickness ca. 255 and 250μm were identified after 30min fouling. ► The cake's resilience to fluid shear was inversely proportional to its thickness. ► After erosion, a persistent cake layer resistant to stresses >30Pa was identified. Fluid dynamic gauging (FDG) has been used to study cake fouling during cross-flow microfiltration of inactive Saccharomyces cerevisiae yeast suspensions through a 5μm nominal pore size mixed cellulose ester membrane. Cake thickness was measured in situ and in real-time during fouling, for which an initial growth rate of ca. 0.81μms−1 was observed at TMP=35mbar and Reduct=1000. The thickness increased asymptotically to a terminal value of 130μm, limited by the FDG process. Although it influences the evolution of the cake thickness, FDG can nevertheless be used to perform strength tests on preformed cakes, by imposing controlled shear stresses to the surface and measuring the thickness following deformation. Cake deformation via incremental increases in shear stress demonstrated that the cake's resilience to tangential fluid shear was inversely proportional to its thickness. It was found that preformed cakes over 250μm thick were deformed by shear stresses