sented in Table 4. The average concentration was
Table 4. Results of loading process.
found to be 32.4 g/g, with a relative standard de-
TCE
viation of 31% and a range from 21.0 to 57.1 g/g.
Loading
concentration
The data show that, with the exception of columns
time
in clay
1 and 2 for round 1 and columns 1 and 2 for round
(g/g)
Round
Column
(hr)
2, the TCE concentration in the clay sorbent was
1
1
88
43.5
very reproducible. The average concentration,
2
88
57.1
excluding these runs, which resulted in extreme
3
74
32.4
values, was 31.0 g/g, with a relative standard
4
74
36.6
2
1
140
21.0
deviation of 13%. The low concentration found for
2
140
22.2
columns 1 and 2 in round 2 was attributed a long
3
54
30.9
holding time (10 days) between the loading of the
4
54
23.5
columns and the remediation of the sorbent. No
3
1
50
32.2
suitable explanation could be attributed to the
2
50
33.6
3
48
28.6
high concentrations found for round 1, columns 1
4
48
26.9
and 2.
Bioremediation of sorbent
all of the loading curves. The first three loadings
During the remediation phase, water samples
were run for 88, 74, and 140 hours, respectively.
were collected and analyzed daily for TCE, phe-
The other three were run for approximately 50
nol, and chloride. Clay samples were collected and
hours each. The average amount of time required
analyzed for TCE every third day. Although the
to achieve the "loaded" mark was approximately
concentration of TCE was monitored in both the
36 hours.
water and the clay during the remediation process,
To evaluate the reproducibility of the loading
the system's performance was primarily evaluated
process, we examined the initial TCE concentra-
on the basis of the clay data because our objective
tion of the clay sorbent prior to starting the remedi-
was to rejuvenate the clay for reuse. The TCE in the
ation phase. Results of the loading process are pre-
25
Column 1
20
Column 2
15
10
5
0
12
0
2
4
6
8
10
16
14
Time (days)
a. Concentration vs. time.
Figure 9. Remediation curves for TCE in clay for round 2, columns 1 and 2.
10
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