Industrial Biotransformations

5.4 Biocatalyst Recycling and Recovery
in an ideal plug-flow reactor (diffusion = 0) and all the concentrations will not change
with time in the steady state (accumulation = 0). Just by exchanging t for s, Eq. (33) can
be also used for the plug-flow reactor to determine the residence time necessary to reach
a desired conversion:
s ˆ‰SŠ 0
R x
0
1
v
dX (34)
5.3.1.3 Mass Balance in a Continuously Operated Stirred Tank Reactor
The concentration of substrate S within the reactor is affected by convection as well as by
reaction. There is no diffusion between different volume elements (diffusion = 0) and in
the steady state the concentrations will not change with time (accumulation = 0). The
mass balance is simplified to:
0 ˆ
d‰SŠ
dt
ˆ ‰SŠ ‰SŠ
0
s
‡ v S (35)
The residence time that is necessary to reach a desired conversion can be determined by
Eq. (36):
s ˆ‰SŠ 0
1
v
5.4
Biocatalyst Recycling and Recovery
dX (36)
To facilitate downstream processing or increase the turnover number of the catalyst, it is
often beneficial to remove the catalyst from the reaction solution and recycle it. Several
approaches for the recycling and recovery of the catalyst are feasible (Fig. 5.10).
immobilization two-phase system membrane reactor
Fig. 5.10 Catalyst recycling and retention.
135