Get access

Modeling the influence of slurry concentration on Saccharomyces cerevisiae cake porosity and resistance during microfiltration

Authors

  • Manuel Mota,

    1. IBB, Institute for Biotechnology and Bioengineering, Centro de Eng. Biológica, University of Minho, 4710-057 Braga, Portugal
    Search for more papers by this author
  • Michael C. Flickinger

    Corresponding author
    1. Dept. of Chemical and Biomolecular Engineering, Golden LEAF Biomanufacturing Training and Education Center, North Carolina State University, Raleigh, NC 27695
    • Dept. of Chemical and Biomolecular Engineering, Golden LEAF Biomanufacturing Training and Education Center, North Carolina State University, Raleigh, NC 27695
    Search for more papers by this author

Abstract

Filtration of an isotonic suspension of baker's yeast through a 0.45-μm membrane was studied at two different pressures, 40 and 80 kPa, for yeast concentrations ranging from 0.14 to 51 kg/m3 (dry weight). For a yeast volume fraction above 0.06 (∼21.8 kg/m3), the porosity of the yeast cake is less dependent on the suspension concentration. For highly diluted suspensions, the specific cake resistance approaches a minimum that depends on the filtration pressure. Correlation functions of cake porosity and specific cake resistance were obtained for the concentration range investigated showing that the Kozeny–Carman coefficient increases when the applied pressure increases. Both filtration pressure and slurry concentration can be process controlled. In the range of moderate yeast concentration, the filtrate flux may be increased by manipulating the filtration pressure and the slurry concentration, thereby improving the overall process efficiency. The complex behavior of yeast cakes at high slurry concentration can be described by a conventional model as long as part of yeast cells are assumed to form aggregates, which behave as single bigger particles. The aggregation effect may be accounted for using a binary mixture model. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012

Ancillary