Chapter 4 - Mixing in Fermentation Processes

Abstract

Mixing in the fermentation industry involves a large number of different kinds of operations. There are many kinds of laboratory mixing requirements, mixing involved in seed tanks, and the agitation involved in the typical large size fermentation tanks in the production plant. Besides this, there are many auxiliary tanks, a few of which are involved in changing pH in the harvesting and recovery steps, and the many types of mixing operations that are carried out auxiliary to the main fermentation system. The fermentations themselves have many different characteristics, from the traditional mycelial fermentation to the many viscous type processes and the low viscosity bacterial type. This chapter discusses the general use of mixing in all these operations and some of the basic principles involved that apply to a wide variety of fermentation characteristics. It presents a summary of some concepts regarding the mechanisms of flow and fluid shear and discusses their applications. It shows a typical velocity from a radial flow impeller blade as measured by a high frequency response probe, such as a hot wire velocity meter, hot film velocity meter, or a laser doppler velocity meter.