Determination of particle-release conditions in microfiltration: a simple single-particle model tested on a model membrane

A simple single-particle model was developed for cross-flow microfiltration with microsieves. The model describes the cross-flow conditions required t o release a trapped spherical particle from a circular pore. All equations are derived in a fully analytical way without any fitting parameters. For e xperimental verification of the model ultra-thin microsieves of uniform por e size and distribution were used. The release of trapped particles (polyst yrene spheres and yeast cells) was determined by flux measurements as well as by in-line observation through a microscope. The results show that the m odel gives a fairly good indication of what cross-flow should be applied to keep the pores free for the conditions specified in this paper. In additio n it provides us with a simple rule of thumb for the design of cross-flow m odules for microsieves. It describes which geometrical demands have to be m et to enable filtration without pore blocking, again for the conditions spe cified in this paper. (C) 2000 Elsevier Science B.V. All rights reserved.