Preface

Bioseparations has developed as a significant, separate discipline within the general field of biochemical engineering. Bioseparations involves the separation and purification of compounds of biological origin, which are derived from cells grown in bioreactors or from cells contained in animal or plant tissue. The biotechnology industry, which originated in the late 1970s, gave added importance to bioseparations because many of the products of biotechnology are proteins that often are difficult to purify and frequently must be purified to homogeneity or near homogeneity, leading to high costs. Practitioners of bioseparations include biochemical engineers and biochemists in the pharmaceutical, biotechnology, food, and chemical industries. This new text focuses on the science and engineering aspects of bioseparations and is designed for juniors, seniors, and graduate students. The book is also intended to be useful for practitioners in industry.

The first chapter contains introductory material in two parts, the first of which is basic information about biochemistry. Bioprocess engineers need to know about the physical properties of the materials they must purify, which include antibiotics, vitamins, and vaccines, and, in the field of biotechnology, proteins, nucleic acids, antibodies, subcellular particles, and whole cells. An understanding of cell structure and function is necessary for the intelligent choice of early postfermentation processes. The second part of this chapter is a brief review of engineering analysis, which is used in various forms throughout the book.

Because we believe that good analytical methods are the foundation of any effort to develop, optimize, and then operate and troubleshoot any bioprocess, the introductory chapter is followed by a chapter on analytical methods. A good understanding of analytical methods is important for anyone involved in bioseparations process development or production.

The important unit operations are thoroughly covered in separate chapters that follow (Chapters 3–10), and the order of the chapters is similar to the order in which the operations are used in a typical bioseparations process. The approach in each of the chapters on unit operations is to start with a qualitative description indicating the importance and general application of the unit operation, describe the scientific foundation of the operation, develop the necessary mathematical theory, and finally describe the applications of the theory in engineering practice with an emphasis on design and scaleup.

In deciding on the subject matter in each of the chapters on unit operations, we have been guided by a desire to emphasize the aspects of unit operations that are most important as applied to bioseparations at the commercial scale. For example, we have not discussed all methods of industrial drying, just those that are the most important in general for drying bioproducts; nor have we included details concerning unit operations currently used primarily in the laboratory, such as preparative electrophoresis.

Acomprehensive treatment of bioseparations process design (Chapter 11) follows the unit operations chapters and focuses on how to integrate the individual unit operations in developing a process design that is the "best" among several plausible alternatives. The use of a process simulator (SuperPro Designer; Intelligen, Inc., Scotch Plains, NJ) is illustrated to analyze and evaluate the production of three biological products—citric acid, recombinant human insulin, and monoclonal antibodies. All the problems in this chapter are intended as open-ended assignments, which can be worked either with or without a biochemical process simulator. The use of a bioprocess simulator, however, will greatly facilitate the process analysis, including generating flowsheets, carrying out material balances, and analyzing costs. It is recommended that students have 6 to 8 weeks to complete their problems.

SuperPro Designer is our strong preference for a biochemical process simulator that can handle batch as well as continuous processes. A functional evaluation version of SuperPro Designer can be accessed at the website www.intelligen.com. A site license (one time fee) of SuperPro Designer can be obtained at a discount for courses at universities adopting Bioseparations Science and Engineering

Illustrative example problems are included within the text throughout Chapters 1 to 11. The purpose of these examples is often to show how to apply previously presented theory; in some cases, the theory is extended to other situations. One way that these examples can be effectively used in the classroom is by using the "thinking aloud pair problem-solving" (TAPPS) method, where one student is the problem solver and talks through the example and the other student is the listener who questions and prompts the solver to keep talking, giving clues if necessary.

Numerous problems developed for this book are given at the ends of Chapters 1-11. These problems are intended to help the student both understand and be able to apply the material presented. A few of the problems are deliberately underspecified or of an open-ended nature. The problems can be assigned as out-of-class homework or can be tackled in class by students working in groups (of two, three, or four, depending on the complexity of the problem). Groups in class respond to the task in the following way: (1) each student formulates his or her answer, (2) students share their answers with their partner or partners, (3) students listen carefully to partner's or partners' answers, and (4) groups create a new answer that is superior to each member's initial formulation through the process of association, building on each other's thoughts, and synthesizing.

The practicum (Chapter 12) describes a set of bioseparations experiments that has been thoroughly tested by students (University of Colorado). A few selected experiments, or all of them, could be used in a course on bioseparations.

Additional information supporting this textbook and bioseparations in general can be found at the website www.biosep.ou.edu. Material at this website includes new problems and examples, which are added periodically; links to useful databases (such as for proteins); and links to manufacturers of bioseparations equipment and supplies.