Structure Compression in Cake Filtration

Abstract
The relationship between filtrate flow rate, cake liquid content, and cake structure compression is investigated for compressible structures in cake filtration. It has been observed that when the pressure is above a critical value, the filtrate flow rate is nearly independent of filtration pressure for highly compressible cake structures. In this study the specific resistance of waste-activated sludge is investigated and the critical filtration pressure, above which filtrate flow rate is independent of pressure, is found to be 0.02 bar, a value well below that used in dewatering processes. Local values of any point within the cake of specific resistance and liquid content are important to characterize the behavior of compressible structures in cake filtration. It is, however, difficult to make local measurements in the cake structure. Therefore, the local properties are often determined from overall sludge filtration parameters by calibration of mathematical models for cake filtration. These models requir...