Experimental Study of Biodegradation of Ethanol and Toluene Vapors

5.6.4 Theoretical Predictions of Continuous Steady State Removal of Benzyl Alcohol
and Toluene Mixtures
For growth with the benzyl alcohol/toluene mixture, toluene acts as a growth
inhibitor only (Bailey and Ollis, 1986; Chang et al, 1993; Bielefeldt and Stensel, 1999).
The growth on the mixture of benzyl alcohol and toluene follows the two-compound
inhibition equation (Bailey and Ollis, 1986) which agrees with the metabolic model that
applied with the data for benzyl alcohol/toluene bioremediation:
μ
C
C
max b
b n
μ =
(1 − )
(5-72)
Cb
+ K
b
( 1+
I / K
i
) Cb,
max
where μ max = μ e,max , I = liquid concentration of a competing compound (mg/L) and K i
is an inhibition constant (mg/L). In this case, I = C t ,
K i
= 1.71mg
/ L for toluene was
used (Chang et al., 1993). For benzyl alcohol (see Table 5.2): μ = 0. 42 h -1 , and
K b
= 0.289g
/ L .
The biomass concentration can be predicted by:
m
C
x
1 max
tx
bt
= max
⋅ ( φb
⋅Ybx
+
T
⋅Y
( μ + m )
φ
)
(5-55)
φ
b
and φ T
represent the net amount of benzyl alcohol and toluene that flows into the
system (In-Out), and they are calculated using the following equations:
F( Cb0 Cb
)
φ −
b
=
(5-55a)
V
Q(
yin,
T
− yout,
T
) F(
CT
0
− CT
) Q
φ
T
= +
= ( yin,
t
− yout,
t
) − DCT
(5-49b)
V
V V
Therefore, the expression of biomass concentration becomes:
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