References biochemical reactors

It has not been possible to cover all aspects of the principles of fluidization. A number of comprehensive texts on fluidized bed behaviour are available and inevitably I have drawn heavily on these. The reader who wishes to go into greater depth about the fundamental mechanisms at work in fluidized beds should consult those works by Davidson and Harrison (1971), Botterill (1975), Davidson, Clift and Harrison (1985), Kunii and Levenspiel (1991) and more recently Gibilaro (2001). Full references can be found at the end of Chapter 1. In addition, I have concentrated on gas-solid fluidized beds somewhat to the exclusion of liquid-solid fluidization although an indication of how particulate fluidization can be applied to biochemical reactors is given in Chapter 7. 

One of the most important biochemical reactors is the fermentor. We provided a simple example of a batch fermentor in Chapter 4. But there are many other types including continuous, batch, and fed-batch. There are some other useful references in the literature.16-17... 

The estimation algorithms were tested in a variety of numerical and experimental studies, characteristic of the operation of biochemical reactors. The general conclusion is that the obtained on-line estimates of b, s andyare in excellent agreement with the true values or the of f-line measured values of the above variables. In the interest of space, the reader is referred to a forthcoming publication (12) for the details and further elaboration on the results. Their basic characteristics are discussed below. 

A bioreactor or fennenter is a chemical reactor in which microbes (e.g., bacteria or yeast) act on an organic material (referred to as a substrate) to produce additional microbes and other desired or undesired products. A schematic diagram of a bioreactor is - given in Fig. 15.9-1. Mass balances for a biochemical reactor or fermenter are slightly... 

Another specific but important application of the CSTR is in biochemical reactor systems, for both evaluation of kinetic parameters in the laboratory and in commercial operation. The CSTR in such applications is most often referred to as a chemostat. Let us consider, then, the analysis for a typical unstructured culture of micro-organisms. Recall the general form of mass balance, equation (4-51),... 

Increased conversion and product purity are not the only benefits of simultaneous separation during the reaction. The chromatographic reactor was also found to be a very suitable tool for studying kinetics and mechanisms of chemical and biochemical reactions. Some recent publications describe the results on investigation of autocatalytic reactions [135], first-order reversible reactions [136], and estimation of enantioselectivity [137,138]. It is beyond the scope of this chapter to discuss the details, but the interested reader is referred to an overview published by Jeng and Langer [139]. 

A bioreactor is a reactor in which enzymes or living cells catalyze the biochemical transformations. It is frequently called a fermenter whether the transformation is carried out by living cells or in vivo cellular components (enzymes). Fermentation originally referred to the metabolism of an organic compound under anaerobic conditions. However, modem industrial fermentation includes both aerobic and anaerobic cultures of organisms. Currently, bioreactor and fermenter can be regarded as synonyms. 

It often becomes necessary in biochemical reactions to continuously add one (or more) substrate(s), a nutrient, or any regulating compound to a batch reactor, from which there is no continuous removal of product. A reactor in which this is accomplished is conventionally termed the semibatch reactor (Chapter 4) but is referred to as a fed-batch reactor in biochemical language. The fed-batch mode of operation is very useful when an optimum concentration of the substrate (or one of the substrates in a multisubstrate system) or of a particular nutrient is desirable. This can be achieved by imposing an optimal feed policy. 

In this type of reactors, the gas and the liquid phase flow over a fixed bed of catalysts. The fixed bed reactors can be mainly classified into three types, (i) co-current down-flow of both gas and liquid phases (ii) downward flow of liquid with gas in the countercurrent upward direction and (iii) co-current up-flow of both gas and liquid. Reactors with co-current down-flow of gas and liquid is called as trickle bed reactors (TBR) and the co-current up-flow reactors are also referred to as packed bubble column reactors. Trickle bed reactors, wherein, the liquid reactant trickles down concurrently along with the gaseous reactant, over a fixed bed of catalyst pellets finds its application in wide variety of chemical, petrochemical and biochemical processes along with its application in waste water treatment. The examples of application of trickle bed reactors are given in detail in several monographs. (Satterfield (1975), Shah (1979), Al-Dahhan (1997) and Saroha (1996)). These include oxidation, hydrogenation, isomerisation, hydrodesulfurisation, hydroprocessing. These types of reactors are also applicable for esterification reactions (Hanika (2003)). 

As noted earlier, different nomenclature has grown up in different branches of science and engineering. For example, in biochemistry and biochemical engineering, a reactant is referred to as a substrate. Continuous stirred-tank reactors frequently are used to study cell growth and to produce commercial quantities of cells. However, it is very likely that the reactor will he called a chemostat, not a CSTR. 

The aim of this contribution is to show the application of fundamentals of thermodynamics to biochemical engineering. The connection between different measurements is inspected at the reactor scale. The reader is referred to references [6,7] for a discussion of notations and terminology. 

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