Environmental Engineering Reference
In-Depth Information
Growth of RHA1 (
fcb
) on 4-CBA
in the Presence of Fe(II) Compounds
5
1e + 8
4
1e + 7
3
1e + 6
2
1e + 5
1
1e + 4
0
1e + 3
0
10
20
30
40
Time (hr)
cfu/ml w/10 mM FeSO
4
& 10 mM FeS
cfu/ml w/20 mM FeS
cfu/ml 4-cba Only Control
10 mM FeSO
4
& 10 mM FeS
[4-cba] w/20 mM FeS
[4-cba] in 4-cba Only Control
Figure 6.20
Effect of Fe(II) on growth of RHA1(
fcb
).
LB400(
ohb
)Rif+ and RHA1(
fcb
)Rif+ freshly grown cells were added to a
final density of 10
4
cells/ml in K1 media with 2-CBA or 4-CBA, or 2 m
M
2-CB or 2 m
M
4-CB with either 20 m
M
FeSO
4
, 10 m
M
FeSO
4
+ 10 m
M
FeS,
10 m
M
FeS, or an Fe-free control. The pH of each treatment was adjusted to
~7. The results of studies using CBAs as growth substrates indicate that
FeSO
4
and FeS do not appear to adversely affect either organism. Given these
results, the anaerobic-stage FeSO
4
treatments used to stimulate anaerobic
dechlorination should not affect the activities of either aerobic organism in
soil.
6.4.2 Microbial-surfactant compatibility experiments
A number of research groups have evaluated the use of surfactants to
enhance the bioremediation of hydrophobic organic compounds (HOCs),
including phenanthrene and naphthalene (Laha and Luthy, 1991; Tsomides
et al., 1995). However, these studies have yielded mixed results, showing
either enhancement, reduction
,
or no measurable effect on contaminant bio-
degradation following surfactant addition (Rouse et al., 1994). These con-
flicting results are due, in large part, to the complex interactions that may
occur between surfactants, microorganisms, the solid phase, and the con-
taminant(s) of interest.
A series of batch reactor experiments was first conducted to determine
the effects of surfactants on the growth and survival of two biphenyl-degrad-
ing strains of bacteria, gram-positive
Rhodococcus erythreus
strain NY05 and
