Biomedical Engineering Reference
In-Depth Information
a
b
4.0
10
11
20
10
11
BMW4
BMW2
10
10
3.5
10
10
3.0
15
10
9
10
9
2.5
10
8
10
8
2.0
10
10
7
10
7
1.5
10
6
10
6
1.0
10
5
5.0
10
5
0.5
10
4
10
4
0.0
0.0
1000
1000
-100
0
100
200
300
400
-100
0
100
200
300
400
Days
Days
c
d
10
3.0
Bioaugmentation #2
BMW6
BMW8
10
10
10
10
2.5
8.0
Bioaugmentation #1
10
6
2.0
10
6
6.0
1.5
10
5
10
5
4.0
Start
Up
1.0
10
4
10
4
2.0
0.5
100
0.0
0.0
100
-100
0
100
200
300
400
-100
0
100
200
300
400
Days
Days
Figure 5A.1. Concentration of VOCs and Dhc at the second row of monitoring wells of a field
demonstration system at Fort Dix, New Jersey. The monitoring wells were located 20 ft down-
gradient of the recirculation system injection wells. The system employed four recirculation loops
that were inoculated with enough Dhc culture to theoretically achieve 10
8
Dhc/L (BMW2), 10
7
Dhc/L
(BMW4), 10
6
Dhc/L (BMW6), and native Dhc only (BMW8). Bioaugmentation events were as identi-
fied for BMW6. Shortly after the first bioaugmentation event, pH in the aquifer exceeded pH 9 due
to a system failure, so a second inoculum was applied to the site as indicated. Symbols represent
TCE (○), DCE (□), VC (
e
), Ethene (
▪
), and Dhc (
).
predicting remediation performance with different inoculum amounts was verified during the
field study (Schaefer et al.,
2010a
).
Also notable from the Fort Dix field experiment data is significant transport and apparent
growth of
Dhc in situ
. These results are consistent with previously described field results and
the results of laboratory studies as described above.
Dhc
levels in the actively dechlorinating
treatment loops were in the range of 10
7
-10
9
Dhc
/L. The results from this demonstration
indicate that there is no simple relationship between numbers and activity. Rather, the migration
of injected
Dhc
cultures, and subsequent treatment of dissolved chlorinated ethenes, is highly
dependent upon a relatively small fraction of the
Dhc
population that is mobile in the
subsurface (because they readily detach from the solid surfaces). The rate at which these
mobile
Dhc
increase is dependent upon the growth rate of the injected (and primarily immobile)
Dhc
, which do not migrate a substantial distance into the soil. In addition, based on the model
simulations and sensitivity, the
Dhc
detachment and growth rate may be more important for
determining overall bioaugmentation success than initial
Dhc
dosage or the utilization rate
(Schaefer et al.,
2010
a; Torlapati et al.,
2012
).
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