Separation Science and Technology, Vol.40, No.6, 1213-1225, 2005
Flux enhancement by introducing turbulence effect for microfiltration of Saccharomyces cerevisiae
Numerous studies have proven that the existence of turbulence effect could promote flux enhancement in the crossflow microfiltration channel. These turbulence effects can be generated by the introduction of turbulence promoters like helical baffles. Helical inserts reduce hold-up in the feed channel; increase fluid velocity and wall shear rates; and produce secondary flows or instabilities. The aim of this work was to investigate the influence of turbulence effects in the feed channel on permeate flux during the microfiltration of Saccharomyces cerevisiae solutions. Tubular, single channel ceramic membranes with a nominal pore size of 0.2 mu m were used. Variations of the helical baffle geometries, which are the number of turns per baffle length, were investigated. It was found that the insertion of helical baffles managed to increase the permeate flux. The optimum number of turns is four turns per 50 mm, which demonstrated the lowest cake resistance, R-c, and highest permeation flux, J, for particular transmembrane pressure, Delta P. The increment of permeation flux reaches 88.2% while the cake resistance is reduced to 70.62% compared to the run without baffles.
Keywords:turbulence effects;microfiltration;reduced cake resistance;helical baffles;Saccharomyces cerevisiae