and product concentrations in each of the organic and aqueous phases with time.
Biocatalyst inhibition terms due to either specific substrate/product effects or the effect of
biocatalyst exposure to the organic interface are not included. The advantage of such a
model, even if numerical values of each parameter are not known, is that it highlights the
important reactor operating parameters. These include substrate and product distribution
coefficients, mass transfer coefficients, the interfacial area available for mass transfer and
the concentration and kinetic constants of the biocatalyst. All of these need to be
experimentally determined in relation to the design and operation of a two-liquid phase
stirred-tank reactor. Similar models have been developed in the case of microporous
(Molinari et al., 1997) and dense-phase (Doig et al., 1998) membrane reactors and the
liquid-impelled loop reactor (Tramper et al., 1987). Recent work has also shown that
biosurfactants produced by some
Figure 5.3 The effect of aqueous phase
substrate concentration on the initial
reaction rate of toluene oxidation by
Pseudomonas putida ( ), benzyl
acetate hydrolysis by pig liver esterase
( ) and hydrocortisone ∆
1-
dehydrogenation by Arthrobacter
simplex ( ). Redrawn from Woodley
and Lilly (1994). Toxic effects of
toluene not shown.
Advances in the selection and design of two-liquid phase biocatalytic reactors 131