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 to release a trapped spherical particle from a circular pore. All equations are derived in a fully analytical way without any fitting parameters. For experimental verification of the model ultra-thin microsieves of uniform pore size and distribution were used. The release of trapped particles (polystyrene spheres and yeast cells) was determined by flux measurements as well as by in-line observation through a microscope. The results show that the model 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 addition it provides us with a simple rule of thumb for the design of cross-flow modules for microsieves. It describes which geometrical demands have to be met to enable filtration without pore blocking, again for the conditions specified in this paper. (C) 2000 Elsevier Science B.V. All rights reserved.