CROSS-FLOW MICROFILTRATION OF OIL-IN-WATER DISPERSIONS USING SURFACE FILTRATION WITH IMPOSED FLUID ROTATION

Surface filters, consisting of asymmetric pore channels that passed di rectly from one side of the filter to the other, were made into tubula r crossflow microfilters of 14 mm internal diameter. For some tests th e filter tubes contained tightly fitting helices of pitches: 14, 42 an d 70 mm. Thus rotational flow was induced and deposition of oil drops suspended in water was minimised. The filters provided total oil rejec tions of up to 97%. For all the tests the operating permeate flux was standardised at 200 l m(-2) h(-1), and transmembrane pressure was adju sted in order to achieve this. However, in the case of filtration with the helical inserts the pressures remained constant at the initial va lues. Hence these filtrations were run under conditions of both consta nt flux and pressure. When filtering with the more open side facing th e challenge dispersion, the transmembrane pressure was approximately 5 0% of that given when filtering in the opposite configuration. The tra nsmembrane pressures were low, values ranging from 3 to 9 kPa for the filtrations employing helices. (C) 1998 Elsevier Science B.V.