Design of Fermentation Processes

Abstract

In all the previous chapters the bioreactor has been invisibly present, waiting in the wings for a cue to enter central stage. The discussion of rate measurements in chapters 3 and 5 and of kinetics in chapters 6 to 8 would not have been meaningful without the short introduction to basic mass balancing for stirred tank reactors in steady state (chapters 3 and 5) and extended to include also transients in Chapter 7. Now the bioreactor itself will be given full attention. The kinetics of Chapter 7 will be used as part of the description of the behavior of typical reactor configurations used in the laboratory and in industry. Steady state- and transient operation of bioreactors will be the main subject of the present chapter, and optimization problems, typical topics of texts on chemical reaction engineering, will be treated. In particular we shall solve the mass balances for the most popular reactor configurations and look for the maximum productivity (q p ) max rather than for the maximum specific productivity (r p ) max . Also optimal start-up procedures for bioreactors are discussed, and it will be shown how stability of the process can be assured and how infection of the culture or spontaneous mutation of the producing strain will influence the outcome of the process