Bioreactors Monod equation

While the Monod equation is an oversimplification of the complicated mechanism of cell growth, it often adequately describes fermentation kinetics. The Monod kinetic parameters can be determined by making a series of ideal continuous stirred-tank bioreactors, which will be discussed later. Table 19.6 shows the typical values of the Monod s kinetic parameters when glucose is a limiting substrate. 

The Monod equation is not the only unstructured, nonsegregated empirical model of bioreactor cell growth. Others can be found in the summaries provided by Bellgardt (2000a), Dunn et al. (2003), or Nielsen et al. (2003). 

Because (1 + r — rC) < 1, it is possible to operate the system at dilution rates greater than the maximum growth rate. Utilizing the Monod equation, the following expressions for the growth limiting substrate, 5, system effluent biomass concentration, and biomass concentration in the exit stream from the bioreactor, X, are obtained ... 

Merchuk JC, Asenjo JA. 1995. The Monod equation and mass transfer. Biotechnol Bioeng 45(l) 91-94. Mikola M, Seto J, AmanuUah A. 2007. Evaluation of a novel Wave Bioreactor ceUbag for aerobic yeast cultivation. Bioprocess Biosyst Eng 30 231-241. 

The growth rate for cells in a bioreactor can follow a variety of growth equations. Monod kinetics is represented by part (1) of Problem 8.3. A substrate-inhibition growth rate is given by (see Shuler, 1988) ... 

The first term on the right can be recognized as the Monod form of the specific growth rate (p). One can rearrange equation (13.3.12) to obtain an estimate of the volume of bioreactor necessary to bring about a reduction in the concentration of the limiting substrate (e.g., BOD) from Sq t0 2-... 

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