Determination of filtration characteristics of yeast suspension based upon multistage reduction in cake surface area under step-up pressure conditions

The step-up pressure filtration experiments of yeast suspension were conducted by using a specially designed filter equipped with a cylinder in which the inner cross-sectional area decreases with the height in stages. The filtration characteristics such as the average porosity and average specific filtration resistance for a variety of filtration pressures were accurately determined from only one test by measuring the variation with time of the filtrate volume in the step-up pressure experiment on the basis of the sudden reduction of the filtration area in the filter cake surface. The relations obtained from step-up pressure filtration experiments were fairly consistent with those from a series of constant pressure filtration experiments. The compression-permeability cell data representing the local values of the porosity and specific filtration resistance as functions of the local solid compressive pressure were evaluated based upon the data of the average values of the porosity and specific filtration resistance thus obtained. It is expected that the method is distinctly efficient as an alternative to the conventional compression-permeability cell measurements.