Prediction of Diatomite Filter Cake Resistance

Improved diatomite filtration equations for flat and cylindrical septa were recently developed and can be used to predict filter performance. However, the use hinges on knowledge of empirical filter cake resistance indices. Over 200 actual pilot and plant-scale filter runs have been analyzed to test the validity of the equations and to develop typical prediction equations for filter cake resistance. The results indicate that the filtration equations give excellent results in describing the head loss-time relationship during a filter run with either flat or cylindrical septa. A prediction equation for filter cake resistance index is presented. It is adequate to predict the filter cake resistance for various raw waters. For most waters, the index can be correlated to the ratio C_S/C_D (suspended solids concentration over body feed concentration). For some waters, however, the correlation is improved If C_S and C_D are treated as Independent variables. The filtration equations and the filter cake resistance prediction equations have been used to optimize filtration plant design.