Disk Stack Centrifuge

Rachel Robitaille

Recovery Process

Centrifugation is the first step in the recovery of the insulin precursor from the fermentation broth

The goal of the recovery is to obtain a stable intermediate product for further processing

Principles of the Fermentor

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

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

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

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

SuppliersOver 53 companies in the US that sell

centrifugesCentrifuge Solutions Inc (CSI) sell high speed

disk centrifuges for applications in the food, chemical and pharmaceutical industries

Alternatives