Multiphase Bioreactor Design

CHAPTER SIX

ENZYMATIC MEMBRANE REACTORS

DUARTE MIGUEL F.PRAZERES AND JOAQUIM M.S.CABRAL

Centre for Biological and Chemical Engineering, Institute Superior

Técnico, Av. Rovisco Pais, 1049–001 Lisboa, Portugal

ABSTRACT

Membrane bioreactors have been increasingly used in past years to

perform numerous enzymatic catalysed transformations. The unique

characteristics of these multi-functional reactors that integrate biocatalysis

and membrane separation, have made them an alternative to more

conventional reactors such as fixed or fluidised beds. The aim of this

chapter is to provide an updated overview on the topic of enzymatic

membrane bioreactors. The first sections review the basic concepts,

classification, advantages and problems associated with enzymatic

membrane reactors. Different applications that have been described in the

scientific literature in the last 20 years are then presented and discussed.

Finally, some comments on the current state of the art and future

prospects of this area are outlined.

Keywords: Membrane Reactor, Ultrafiltration, Enzymatic Reactors,

Process Integration, Process Intensification, Bioreactors

INTRODUCTION

Process intensification has been defined by chemical engineers as “...the development of
novel apparatuses and techniques that, compared to those commonly used today, are
expected to bring dramatic improvements in manufacturing and processing, substantially
decreasing equipment-size/production capacity ratio, energy consumption, or waste
production, and ultimately resulting in cheaper, sustainable technologies” (Stankiewicz
and Moulijn, 2000). This concept can be easily translated and applied to processes in
Biochemical Engineering. This chapter describes a particular type of process-intensifying
system, i.e. enzymatic membrane reactors that have been used for some years in the
specific area of Enzymatic Engineering.
An enzyme catalysed transformation of substrates into products can be carried out
either in homogeneous or heterogeneous systems. The separation of the final products
from the unreacted reagents and, in homogeneous catalytic systems, the separation of the
catalyst from the reaction mixture, is a necessary step that increases the general
complexity and cost of the process. Furthermore, an efficient use of the biocatalyst
usually demands the transformation to be carried out continuously. Membrane reactors
are special units designed to meet these needs, constituting an attempt to integrate the