DYNAMIC MICROFILTRATION OF DILUTE O W EMU LSION IN ROTATING CYLINDRICAL MEMBRANE-FILTER/

The microfiltration of an oil-in-water emulsion, where only the water permeates through a ceramic membrane at constant pressure, is done usi ng a rotating cylinder type of dynamic filter. Its suitability for the efficient filtration of the dilute emulsion consisting of drops small er than 7 mu m is examined, and a flux-controlling factor for the eval uation of the filtration performance is proposed. The rotational micro filtration of the O/W emulsion shows a gradual reduction in flux initi ally, and then a roughly uniform value of final flux, in a manner simi lar to that of a conventional solid-liquid slurry. The time dependent change in unsteady flux at an earlier stage is formulated in the form of a filtration rate equation with a dynamic coefficient(defined as th e ratio of static to dynamic cake resistance); this coefficient being estimated as a power-function of filtrate volume. The final steady sta te flux at the later stage is related to a number of operational varia bles in terms of a controlling factor composed of the shear stress on the fouling surface and the coefficient of constant pressure filtratio n, considering the intensive dependence of the flux on the high compre ssibility of the extremely low permeable fouling-layer. It is confirme d that, due to a powerful sweeping force acting on the residual foulin g-layer, the rotating cylinder -type membrane filter can be applied ef fectively to high-flux microfiltration of poorly filterable oil-water systems.