Fundamental Bioengineering

15Control of Bioprocesses

Jakob Kjøbsted Huusom

Summary

The fundamental principles for control of biochemical processes are presented. Through examples, the selection of manipulated and controlled variables in the classical reactor configurations is discussed, so are control objectives and the challenges in obtaining good control of the bioreactor. A number of typical control loops are given for different objectives, for example, for control of the growth of the organism or the environmental condition that surrounds it. Then, follows a brief introduction to the general principles of process control, the PID control algorithm is discussed, and the design and effect of tuning are shown in an example. Finally, a discussion of novel, model-free control approaches for bioreactors is provided.

15.1 Introduction

As in any other field of control and operation, the purpose of bioprocess control is to ensure that the plant operates as designed, that is, produces the demanded amount of product within specifications while minimizing consumption of energy, process water, and other resources. The process should operate safely and produce only a minimum of waste streams.

Hence, the aim is to achieve the desired performance of the process despite the presence of process disturbances. This implies monitoring the state of the bioreactor using direct and/or indirect measurements (the so-called soft sensors) as described in Chapter 14. To impose a manual or an automatic actuation on the process, ...