Dependence of Saccharomyces cerevisiae filtration through membrance on yeast concentration

Abstract

Filtration of baker’s yeast in an isotonic solution through a 0.45 micron membrane was investigated for yeast concentrations in the range 0.14 – 51 g/L at filtration pressures between 40 and 80 kPa. Yeast filtration through membranes depends on applied filtration pressure and on slurry concentration. It was found that for a yeast volume fraction in suspension above 0.06 the porosity of the yeast cake becomes weakly dependent on the suspension concentration. For highly diluted suspension the specific cake resistance approaches to the minimum value, which is sensitive to the filtration pressure. Correlation functions of the cake porosity and specific cake resistance were obtained in the investigated concentration range. It was found that the Kozeny-Carman coefficient is increased with increasing applied pressure. Both filtration pressure and slurry concentration can be subject of process control. In the range of moderate yeast concentration, manipulation of filtration pressure and of slurry concentration might increase the filtrate flux. Obtained results and assumptions made indicate that complex behavior of yeast cake at high slurry concentration can be further described within the framework of conventional model by increasing complexity of subsystems due to aggregation effect.