Monod kinetic parameter determination

Respiration inhibition kinetics analysis (RIKA) involves the measurement of the effect of toxicants on the kinetics of biogenic substrate (e.g., butyric acid) removal by activated sludge microorganisms. The kinetic parameters studied are max> the maximum specific substrate removal rate (determined indirectly by measuring the maximum respiration rate), and Ks, the half-saturation coefficient [19]. The procedure consists of measuring with a respirometer the Monod kinetic parameters, Vinax and Ks, in the absence and in the presence of various concentrations of the inhibitory compound. 

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. 

It was considered a stirred tank reactor where the Desulfovibrio Alaskensis (DA) bacteria growth is carried out. The DA bacterium is a sulfate reducing bacteria used, in this case, to degrade some undesirable sulfate compounds to sulfides. It was previously determined that the Monod s kinetic equation adequately describes our reactor [2], where its kinetics parameters were determined via standard methodology in a batch culture [3]. 

Sue proposes to analyze these data to determine whether or not her analysis yields kinetic parameters for a Monod rate law that are consistent with the parameters reported in Example 11.1 of J. M. Santamarfa, J. Herguido, M. A. Mendndez, and A. Monzdn, Ingenien a de Reactores, Editorial Sintesis, Madrid, 1999. Does the Monod model provide a good fit of the data Comment on your faith in the vahdity of the kinetic parameters that you would determine from the fit of an appropriate form of the following equation to the data ... 

Plotting l/dn(s/so) versus [ln(l + ad)lt] by assuming values for a, and iterating this procedure until linearization appears, leads to the estimation of kinetic parameters (see Figs. 4.22 and 4.23). A variant of this procedure, which also starts from the integrated form of the Monod equation, is used for determining Kg for a discontinuous process from the position of the inflection point of the growth curve (Meyrath and Bayer, 1973). 

The domination of microbial growth kinetics by the Monod equation has led to the development of techniques to determine the constants Ks and fim used in that equation. Whilst n is in fact dependent on other parameters, such as temperature and pH, in the usual case these are specified, and a design procedure requires values of the Monod constants under these conditions. The yield coefficient Y will also be required in order to link calculations of microbial growth to substrate concentrations. 

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