It is required to recover active extracellular enzymes from a completed fermentation medium that also consists of proteins (<200,000 molecular weight cut-off (MWCO)) and bacterial cells (1-2 μm). A cross-flow 0.35 μm microfiltration (MF) with retentate recycled back to the fermenter will be used over a period of 5 hours during which time flux is assumed to decline linearly. After 5 hours, assuming 95% of the bacteria are retained and given the additional information below,
It is required to recover active extracellular enzymes from a completed fermentation medium
that also consists of proteins (<200,000 molecular weight cut-off (MWCO)) and bacterial cells (1-2
μm). A cross-flow 0.35 μm microfiltration (MF) with retentate recycled back to the fermenter will
be used over a period of 5 hours during which time flux is assumed to decline linearly.
After 5 hours, assuming 95% of the bacteria are retained and given the additional
information below, what is the concertation of bacteria remaining in the fermenter and what area,
in m2 , of MF membrane is needed?
Initial bacterial concentration = 1.2 gdcw /L (dcw = dry cell weight)
Volume of medium at the beginning = 15 m3
Volume of medium left in the fermenter after 5 hours filtering = 1 m3
Initial (starting flux) = 6.5 x 10-5 m sec -1
Final flux (after 5 hours of filtering) = 3.9 x 10-5 m sec -
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