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Experimental Study of Biodegradation of Ethanol and Toluene Vapors

Experimental Study of Biodegradation of Ethanol and Toluene Vapors

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discharged from the other end. The flow pattern in the ideal reactor is plug or piston<br />

flow with no back mixing. The performance equation <strong>of</strong> a single plug flow reactor for<br />

the substrate can be obtained from the material balance as:<br />

V<br />

F<br />

S<br />

= −∫<br />

S<br />

f<br />

dS<br />

r<br />

s<br />

(2-18)<br />

2.4.5 Reactors for Biochemical Processes (Bioreactors)<br />

Many factors such as cost <strong>of</strong> equipment, scale <strong>of</strong> production, stability <strong>and</strong> safety,<br />

that can affect the choice <strong>of</strong> an optimum reactor. The most important single factor is the<br />

reaction kinetics. A poor choice <strong>of</strong> reactor type can increase the cost <strong>of</strong> reactor<br />

construction <strong>and</strong> operation as much as two orders <strong>of</strong> magnitude. For example, the<br />

volume <strong>of</strong> a CSTR reactor needed for 99% conversion for a first order reaction (or even<br />

zero <strong>and</strong> second order) is as much as 100 times more than a plug flow reactor<br />

(Levenspiel, 1972). However, the nature <strong>of</strong> many biochemical reactions resembles<br />

autocatalytic reactions which strongly favours the use <strong>of</strong> CSTRs instead <strong>of</strong> plug flow<br />

reactors (Levenspiel, 1972).<br />

31

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