Separation of enzymes and yeast cells with a vibrating hollow fiber membrane module

In this work it is shown that the vibrating microfiltration hollow fiber membrane module is able to separate macromolecules (the enzyme Fungamyl produced by Novozymes A/S) from bakers yeast suspensions at a very low transmembrane pressure, at a very low cross-flow velocity and with a high enzyme transmission. The critical flux is determined at different degrees of module vibration. The critical flux increases as the vibration frequency and amplitude is increased. The correlations between the critical flux and the average membrane surface shear rate are found. For a pure 1% Fungamyl solution the correlation is J(crit) = 2.10((gamma) over bar (s))(0.38), and for a 1% Fungamyl solution with 5 g/l suspended bakers yeast the correlation is J(crit) = 1.79((gamma) over bar (s))(0.32). These correlations are compared to the correlation J(crit) = 8.22((gamma) over bar (s))(0.26) from filtrations of 19 g/l bakers yeast suspensions from an earlier study with the same apparatus. The powers to which the shear rate is raised are all around the same value (around 1/3) and describe the degree of dependency between the critical flux and the average surface shear rate. The term multiplied to the shear rate depends on the feed fluid composition. Below the critical flux high enzyme transmission is observed whereas above the critical flux the transmission decreases dramatically as the fouling resistance increases. (c) 2006 Elsevier B.V. All rights reserved.