Multiphase Bioreactor Design

CHAPTER ELEVEN

PULSING BIOREACTORS

JUAN M.LEMA, ENRIQUE ROCA, ANGELES SANROMÁN, M.JOSÉ

NÚÑEZ, M.TERESA MOREIRA AND GUMERSINDO FEIJOO

Department of Chemical Engineering, Institute of Technology, University

of Santiago de Compostela, Av. das Ciencias s/n, E-15706 Santiago de

Compostela, Spain

ABSTRACT

The application of external energy in the pulsing form has for a long time

been a common practice to improve mass transfer rates in chemical

engineering units. This chapter reviews the different types and

applications of pulsed bioreactors, pointing out most especially the use of

the elastic membrane pulsator (EMP). Considering the hydrodynamic

behaviour, pulsed bioreactors coupled with an EMP display a lower axial

dispersion than non-pulsed ones. Besides, pulsation overcomes a series of

problems usually associated with the use of packed-bed bioreactors:

difficulty of gas supply (aeration); retention of the gas produced in

fermentation processes within the bed; and clogging of the bed by

excessive microorganism growth. Examples concerning the enzymatic

hydrolysis of starch solutions, the alcoholic fermentation by immobilised

cells and the continuous production of ligninolytic enzymes by

filamentous fungi are presented.

Keywords: Pulsation; Packed-bed; Starch hydrolysis; Alcoholic

fermentation; Immobilised cells; Filamentous fungi; Ligninolytic

enzymes; Bioreactor

TYPES AND APPLICATIONS OF PULSING DEVICES

The application of external energy in the pulsing form has, for a long time, been a
common practice to improve mass transfer rates in chemical engineering units. The
general principles about pulsing columns were established by Van Dijk (1935), who
developed several systems to improve the efficiency of solid-liquid extraction processes
at the Royal Dutch/Shell Laboratory in Amsterdam, in the 1930’s. Since then, a number
of techniques, based on several principles, have been developed and adapted for their
application to very different fields.

Types of Pulsing Devices

In general, pulsing equipment may be classified into two different types: