Experimental Study of Biodegradation of Ethanol and Toluene Vapors

For the kinetic model of ethanol as sole substrate, the Monod model was used as
the rate controlling equation for growth metabolism:
r
x
μe,maxCe
= μ C
x
= C
x
(5-34)
K + C
e
e
To allow for maintenance requirements, Equation (5-34) is coupled with Equation (5-
15), and the expression for ethanol conversion rate becomes:
dC
1
μ
C
e
e,max
e
− = ( )( )
max
dt Yxe
K
e
+ Ce
C
x
+ m C
e
x
(5-35)
Similarly, for the kinetic modeling of benzyl alcohol as sole substrate, the following
substrate inhibition model is assumed to apply (Luong, 1987):
r
x
μ C C
= )
b,max
b
b n
μ C
x
= (1 − ⋅ C
x
(5-36)
K
b
+ Cb
Cb,max
The benzyl alcohol conversion rate is obtained by coupling Equations (5-30) and (5-36):
dC
1
μ
b
b,max
b
b n
− = ( )( )(1 − )
max
dt Yxb
K
b
+ Cb
Cb,max
C
C
⋅ C
x
+ m C
b
x
(5-37)
For parameter estimation purposes, nine independent sets of batch experiments
were conducted with different initial ethanol concentrations (0.10, 0.12, 0.17, 0.18 and
0.26 C-mol/L), and with differential initial benzyl alcohol concentrations (0.048, 0.069,
0.14, and 0.18 C-mol/L) added into the reactor at time zero. Measurements of the
concentrations of ethanol and biomass were obtained in the first five sets of
experiments, and concentration measurements were performed for benzyl alcohol and
biomass in the last four sets of experiments at certain time intervals throughout the
reactions.
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