Disk Stack
Centrifuge
Rachel Robitaille
Recovery Process
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Centrifugation is the first step in the recovery of
the insulin precursor from the fermentation broth
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The goal of the recovery is to obtain a stable
intermediate product for further processing
Principles of the Fermentor
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The fermentor is inoculated as a fed-batch
process
3 days later the culture is grown as a continuous
fermentation in a simple medium containing
yeast extract as its main nitrogen source
The yeast secretes the insulin precursor into the
fermentation broth, making disruption of the
S.Cerevisiae cells unnecessary
The insulin precursor is recovered from the
fermentation broth on a continuous basis
Principles of the Centrifuge
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Disk type centrifuges
consist of a vertical
stacks of thin disks in the
shape of cones
The sedimentation takes
place in the radial
direction in the space
between adjacent cones
This reduces the settling
distance and increases
the rate at which the
material is separated
Centrifuge Variables
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Disk Stack Centrifuges may contain 2 or 3 disks.
Ours will have 2 in order to remove the solid
yeast cells from the liquid broth
They can process batch or continuous feeds
Very effective at removing solids but do not
account for dissolved solids or heavy metal
species in solution
Specifications
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Assuming a batch process, the centrifuge would
need to be able to hold at least 650,000 L
Assuming a continuous process where the
amount of feed in one day is equivalent to that of
a batch process, the centrifuge would need to be
able to hold at least 8000 L.
 Approx
100 L would be expelled as solid waste
containing yeast cells
 The rest would go into the supernatant stream
containing 98% of the insulin precursor
Economics
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Suppliers
 Over
53 companies in the US that sell
centrifuges
 Centrifuge Solutions Inc (CSI) sell high speed
disk centrifuges for applications in the food,
chemical and pharmaceutical industries
Alternatives