DESIGN OF A CROSS-FLOW MICROFILTRATION UNIT FOR STUDIES OF FLUX AND PARTICLE-TRANSPORT

This paper describes the design. construction, and performance of a cr ossflow microfiltration rig that allows accurate measurement and contr ol of transmembrane pressure (TMP), crossflow velocity, permeate flux, and the amount of particle deposition. The rig uses the uniform TMP c oncept, which allows the TMP to be independent of the position along t he membrane. The performance of the rig filtering a well defined parti cle suspension is reported. It was found that both flux and amount of matter deposited reached constant values after about an hour. The leve l of the steady-state flux was found to depend on the pH of the suspen sion, and to increase with increasing pH. The correlation observed bet ween flux and amount of matter deposited suggested that the void fract ion of the cake is not dependent, or only slightly dependent on pH; th e observed differences in Bur being caused by differences in thickness of the cake, not by differences in void fraction.