Fundamental Bioengineering

16Scale-Up and Scale-Down

Henk Noorman

Summary

As described in Chapter 11, the scale-up of a process from laboratory scale, through pilot scale, and finally to the large industrial scale is far from easy. Mixing of the medium is necessary to minimize gradients of substrates, but intensive mixing may become very costly. Sparging of the medium with, for example, oxygen may lead to operation in flow and reaction regimes that change drastically with power input and scale, and a gas–liquid contact pattern that was found to be excellent in small scale may prove to be inadequate in large, industrial scale. To gain a qualitative or semiquantitative insight into the major effects of scale-up, a design philosophy based on scale-down of the large-scale operation to a smaller scale has been developed. One starts by defining the desirable large-scale process conditions to give a product that has certain characteristics, such as quality, yield, ease of downstream processing, and so on. Then one constructs a smaller scale version in which these characteristic properties can be examined as a function of the process conditions. This chapter describes how the proper large-scale performance can be achieved through well-designed scale-down experiments, using regime analysis, compartment models, and other engineering models by which the desired qualities of the product in large scale can be studied.

16.1 Introduction

It is the ultimate purpose of a bioengineer to design and implement bioprocesses ...