RESULTS AND DISCUSSION
mL/min and samples were collected every 15
minutes for the first hour. In addition, we decided
Loading
Skid 1 was initially loaded at a flow rate of 240
that distilled water would be used while setting
mL/min, and the first effluent samples were col-
the loading flow rates. The time required to set the
lected after 2 hours. The data showed that the
flow accurately was nearly 30 minutes. If the con-
effluent concentration was already 40% of the
taminated groundwater had been used during this
influent and had risen to near 60% after 4 hours of
time, then loading of the columns would have
loading (Fig. 7).
been started, confounding the description of the
This suggested that the loading curve had a
loading curve.
very sharp rise in the first hour. Data also suggested
The data from the five subsequent loadings
that the contact time between the groundwater and
show that the loading curve indeed has a very
the clay sorbent was too short to retain sufficient
sharp rise in the first few hours, then starts to level
TCE. As a result, the flow rate was reduced to 120
off after about 6 hours. Figure 8 is representative of
80.80
0
70.70
0
60.60
0
50.50
0
40
40.0
30.30
0
Column 1
20.20
0
Column 2
Figure 7. Initial loading
curves for columns 1 and 2.
10.10
0
0.00
0
10
20
30
40
50
60
70
80
90
100
Time (hr)
.00 0
10
.00 0
9
.00 0
8
.00 0
7
.00 0
6
.00 0
5
.00 0
4
Figure 8. Third loading
.00 0
3
curve for columns 1 and 2.
Column 1
.00 0
2
Column 2
.00 0
1
.00 0
0
10
20
30
40
50
60
Time (hr)
9
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