Performance of the CSTR with Simple Kinetics

In a completely mixed continuous flow reactor, the composition is thought to be uniform throughout the reactor, and is the same as in the exist stream (cf. Fig. 3.30). Applying the law of conservation of mass (cf. Equ. 2.3) to a CSTR yields Equ. 3.90 for the steady state. The dilution rate D is reciprocal to the mean residence time of a fluid (7). 

Accumulation = input — output reaction and for biomass X and substrate S 

As a consequence of Equ. 6.4, the definition of growth rate /x in a CSTR at steady state is given by = D (Equ. 3.91). This fact is most important for practical application of the CSTR in microbial culture techniques. It means that this reactor configuration functions as a differential reactor (cf. Sect. 4.4.1), and it enables the direct measurement of a biological reaction rate (e.g., growth rate) without mathematical manipulation of the measurements. 

The practical consequence from this statement is that can be controlled by the amount of nutrient fed to a constant-volume CSTR. This system is called realstat or chemostat, a name that refers to the constant chemical 

A modified turbidostat scheme has recently been proposed, as have other control schemes such as pH auxostat, CTR, OTR, and OUR control (Agrawal and Lim, 1984). 

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