Biomedical Engineering Reference
In-Depth Information
Figure 3.10. Stainless steel cell filtration system for concentrating Dhc cultures. The concentra-
tion system consists of tubular ceramic membranes contained within stainless steel shells. The
individual membrane units are connected in series and water from the culture passes through the
membranes and is captured in the shell and disposed. Concentrated culture is transferred back to
the fermentor (background ) and the culture recirculated through the system until the desired
concentration factor is achieved.
after concentration demonstrated only small changes in activity during concentration. For
example, specific activity of two cultures tested were 24 and 16 mg PCE/h
g DWT before
concentration and 23 and 15 mg PCE/h
g DWT after concentration, respectively. Because the
concentration process results in approximately 90% reduction in culture volume,
it also
removes ~90% of any metabolic byproducts remaining in the culture broth.
Cell concentration also allows standardization of
Dhc
concentrations and activity of
culture batches. That is, the concentrated cultures can be diluted to a predetermined
Dhc
concentration, allowing producers to deliver consistent cultures and allowing users to develop
more reliable estimates of the volume of culture needed for field applications. It is worth noting
that some culture biomass will be unrecoverable from the ceramic membranes, because some
cells will be trapped in any retained liquid or will adhere to the membranes. However, given the
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