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Experimental Study of Biodegradation of Ethanol and Toluene Vapors

Experimental Study of Biodegradation of Ethanol and Toluene Vapors

Experimental Study of Biodegradation of Ethanol and Toluene Vapors

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most commonly applied, unstructured model for microbial growth. We have assumed<br />

that the growth kinetics on ethanol is described by the Monod equation:<br />

μe,maxSe<br />

μ =<br />

(5-56)<br />

K + S<br />

s<br />

e<br />

where<br />

μe,<br />

max<br />

is the maximum specific growth rate when S e >>K s . Figure 5-10 shows the<br />

variation <strong>of</strong> μ as a function <strong>of</strong> S e (ethanol mass concentration). In the Monod model, K s<br />

is the empirical value which represents the limiting substrate concentration at which the<br />

specific growth rate is half <strong>of</strong> its maximum value. That is, it separates the plot <strong>of</strong> μ<br />

versus S e into a low-substrate-concentration range where the specific growth rate is<br />

strongly dependent on S e , <strong>and</strong> a high-substrate-concentration range where μ is more or<br />

less independent <strong>of</strong> S e . In general,<br />

μ<br />

μ = for S e K s <strong>and</strong> Se<br />

K<br />

s<br />

Specific growth rate, h -1<br />

0.6<br />

0.5<br />

0.4<br />

0.3<br />

0.2<br />

0.1<br />

0<br />

Se = Ks<br />

0 5 10 15 20 25 30 35 40<br />

<strong>Ethanol</strong> concentration, g/L<br />

Figure 5-10. Effect <strong>of</strong> ethanol concentrations on the specific growth rate <strong>of</strong> P. putida<br />

according to the Monod model<br />

120

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