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Bioreactions
A handful of basic bioreactor designs is used to produce a wide range of products, from antibiotics to foods to fuels. Here's how to pick the best options for your application.
Traditionally, microbiologists have played the dominant role in bioreaction development, with assistance from those in multiple disciplines, including biochemists, geneticists and chemical engineers. And while the fermentation process - the precursor to modern bioreactions - has been used since prehistoric days, the major advancements of the last half century have had as much to do with technology as with biology. It is our objective to illustrate the relevance of established chemical engineering practices and processes as they apply to today's bioreaction engineering, as chemical engineers make further inroads into a field once thought to be the sole domain of biology-based scientists.
This article will discuss the key engineering issues in bioreactor design and operation, focusing on the similarities between traditional chemical reactor engineering and bioreaction engineering. Our objective is not to trivialize the field of biological-based processes; it is simply to demonstrate that strong parallels exist between the two fields. In fact, we will also discuss the key differences that must be taken into consideration for successful bioreactions. In so doing, we will provide chemical engineers with increased confidence in applying their knowledge and experience with chemical reactors to bear on the issues and opportunities available in bioreactor engineering.
The distant and recent past
Long before anyone understood the concept of bioreaction, humans were taking advantage of its results. Bread, cheese, wine and beer were all made possible through what was traditionally known as fermentation - a little-understood process, successful more by chance than design. It was, in fact, the failure and frustration of French vintners who found they were too often producing vinegar not wine, that led the famous French chemist and microbiologist Louis Pasteur to study the fermentation process at their request.
What Pasteur discovered was that fermentation occurred as a result of the biological activity of a microscopic plant called yeast. When unwanted microbes infiltrated the wine and "fed"on the alcohol produced by the yeast, the microbes left behind distasteful and harmful wastes, which ruined the wine's flavor. Pasteur's work laid the foundation for bioreactors as we know...