Experimental Study of Biodegradation of Ethanol and Toluene Vapors

φ ⋅ Y + φ ⋅ Y = ( −φ
) + m C
(5-48)
e
max
ex
T
max
tx
x
et
x
Coupling with the parameters obtained from Equations (5-38) and (5-39), the maximal
yield coefficients of ethanol and toluene were found to be 0.59 and 0.41, respectively:
max 3δ
− 0.5
Y ex
=
= 0.59 (5-48a)
K + 2δ
− 0.635
and
max 12δ
Y tx
=
= 0.41 (5-48b)
7( K + 2δ
− 0.635)
In Equation (5-48),
( −
F(
C
− C
x x0
φ
x
) =
=
V
)
μC
x
, thus the concentration of biomass can
be determined as:
C
x
1 max
tx
et
= max
⋅ ( φe
⋅Yex
+
T
⋅Y
( μ + m )
φ
)
(5-49)
In Equation (5-49),
Q( yin
− yout
) F(
Ce0 Ce
)
φ −
e
=
+
, (5-49a)
V
V
Q( yin, T
− yout,
T
) F(
CT
0
− CT
)
φ
T
=
+
, (5-49b)
V
V
φe
and φT
can be then calculated from the measured data in the experimental studies.
Coupling Equations (5-49), (5-49a) to (5-49b) with Equation (5-48a) and (5-48b), the
maintenance for biomass growth in steady state bioremediation of mixed toluene and
ethanol was then predicted as 0.027 ± 0.001 (C-mol/L/C-mol h) by applying the
experimental data at steady state (Figure 5-8). This maintenance term is higher than that
(0.010 ± 0.001 C-mol/C-mol h) for bioremediation of ethanol as sole carbon source in a
continuous operation. This is caused by the stress of metabolizing toluene, a more toxic
substrate.
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