Multiphase Bioreactor Design

Figure 5.4 Mass transfer-reaction

model for a reaction occurring in the

aqueous phase and a biocatalyst

exhibiting Michaelis-Menten kinetics.

Nomenclature: A, interfacial area; E,

enzyme concentration; Km, Michaelis

constant; k, mass transfer coefficient;

M, molecular mass; m, equilibrium

distribution coefficient; P, product

concentration, S, substrate

concentration; t, time; V. volume.

organisms in two-liquid phase systems as a response to solvent exposure, will have a
critical influence on a number of the model parameters such as the solute mass transfer
coefficients and the interfacial area available for mass transfer (Schmid et al., 1998b;
Kollmer et al., 1999).

Reactor Operation

As previously indicated, knowledge of the location of the reaction within the biocatalytic
medium is of key importance for reactor selection and design. One method for
elucidating this is a set of experiments carried out in a defined, flat liquid-liquid interface
apparatus known as a Lewis cell (Woodley, 1990b; Woodley et al., 1991a). In such a
device the rate of mass transfer of substrate from organic to aqueous phase under defined
conditions can be measured and thus a mass transfer coefficient obtained. These data can
be combined with measurements of aqueous phase biocatalyst kinetics (measured in all
aqueous phase solution with dissolved levels of poorly water-soluble organic substrate

Multiphase bioreactor design 132