Multiphase Bioreactor Design

CHAPTER FOUR

DESIGN AND MODELLING OF

IMMOBILISED BIOCATALYTIC

REACTORS

BRUNO S.FERREIRA^1 , PEDRO FERNANDES1,2 AND JOAQUIM

M.S.CABRAL^1

(^1) Centre for Biological and Chemical Engineering, Institute Superior
Técnico, Av. Rovisco Pais, 1049–001 Lisboa, Portugal
(^2) Universidade Lusófona de Humanidades e Tecnologies, Av. do Campo
Grande, 376, 1749–024 Lisboa, Portugal

ABSTRACT

Immobilised biocatalysts can be effectively employed in a wide variety of

reactor configurations. High concentrations of the biocatalyst can be used,

thus allowing high volumetric productivities. Furthermore, the biocatalyst

is easily separated from other components in the reaction mixture,

simplifying downstream processing. The process integration thus

achieved can lead to lower production costs. However, in order to render

the use of immobilised biocatalysts effective, an adequate understanding

of the interrelationship between mass transfer and reaction kinetics is

required to allow rational design of the bioreactor. In the first part of this

chapter, expressions describing the effect of internal or external mass

transfer effects and different kinetics on the overall reaction rate are

presented. In the second part of the chapter, the main features of different

reactor configurations are discussed and their design equations are

presented.

BIOCATALYST IMMOBILISATION AND PERFORMANCE

Introduction

The use of immobilised biocatalysts in laboratory studies, in analytical and medical
applications and in large-scale industrial processes is presently a widespread technique.
Immobilisation can be defined as the confinement of a biocatalyst inside a bioreaction
system, with retention of its catalytic activity and stability, and which can be used
repeatedly and continuously. Table 4.1 lists some advantages and limitations which can
arise from the use of immobilised biocatalysts.