INITIAL TRANSIENT EFFECTS DURING CROSS-FLOW MICROFILTRATION OF YEAST SUSPENSIONS

In order to better understand the effect of transient filtration param eters on the filtration performance during cross flow microfiltration of yeast suspensions, a laser distance sensor was used to measure on-l ine the height of the filter cake in a specially designed flat channel module. The data obtained with an accuracy of +2 mu m were used to fi t a model describing the build-up of the filter cake and the related f lux decline. The model is based on a volume balance over the deposited particles, with the flux of the particles back into the concentrate s tream proportional to the average cross flow velocity at the centre of a particle placed on the surface of the filter cake. An empirical bac k transport coefficient was introduced to fit the data to the model. T he results showed that with yeast suspensions membrane fouling is limi ting the filtration performance. Also the performance cannot be improv ed by transient pressure conditions generated by an alternation of the flow direction in the module.