Design of a crossflow microfiltration unit for studies of flux and particle transport

This paper describes the design. construction, and performance of a crossflow microfiltration rig that allows accurate measurement and control of transmembrane pressure (TMP), crossflow velocity, permeate flux, and the amount of particle deposition. The rig uses the uniform TMP concept, which allows the TMP to be independent of the position along the membrane. The performance of the rig filtering a well defined particle suspension is reported. It was found that both flux and amount of matter deposited reached constant values after about an hour. The level of the steady-state flux was found to depend on the pH of the suspension, and to increase with increasing pH. The correlation observed between flux and amount of matter deposited suggested that the void fraction of the cake is not dependent, or only slightly dependent on pH; the observed differences in Bur being caused by differences in thickness of the cake, not by differences in void fraction.