CROSS-FLOW MICROFILTRATION CHARACTERISTIC S OF DILUTE SUSPENSIONS WITH BINARY MIXED SOLIDS

The crossflow microfiltration characteristics of a dilute suspension c ontaining binary suspensoids with different degrees of filterability a re studied under constant pressure. In addition, correlations between filtrate flux and solids mixture ratio are used to investigate the req uirements of material added to the main body of suspension to aid effi cient crossflow filtration. Empirically, the reciprocal flux is sigmoi dal in time with its behavior indicating that there are two stages: in itially crossflow medium filtration, and then thin-cake filtration. Th ree major factors controlling the earlier stage are confirmed: concent ration, mixture ratio, and relative force of sweeping and capturing of solids. If these conditions are within a certain level, the earlier s tage ceases and thin-cake filtration covers the entire process. The fi nal steady-state flux is related to many operating variables in terms of the shear stress on the cake layer and the coefficient of constant pressure filtration by considering the intensive dependence of the Bur on the mixture ratio. Finally, it is established that for high-rate m icrofiltration combining body feed with crossflow operation, materials yielding marked sweeping of fouling as well as those producing highly permeable cake can be effectively used regardless of the poor filtera bility in static filtration.