Environmental Engineering Reference
In-Depth Information
100
100
80
80
60
60
40
40
20
20
0
-1
0
-1
0
1
2
3
4
0
1
2
3
4
log Cr (ppb)
log TCE (ppb)
100
100
80
80
60
60
40
40
20
20
0
0
0
1
2
3
0
1
2
3
log VC (ppb)
log
cis
-DCE (ppb)
FIGURE 6.3
Cumulative% distribution diagrams for Cr, TCE,
cis
-DCE, and VC. Filled circles (up gradient);
open triangles (down gradient) and open circles (in wall).
There are few PRB case studies which can be compared to the Elizabeth
City site. Flury et al. (2009) described the 4-year performance of a granu-
lar iron PRB installed in Willisau, Switzerland, for Cr
VI
contamination.
Unfortunately, the Flury et al. (2009) study does not provide any analysis of
Cr uptake or removal efficiency. However, their results suggest that Fe cor-
rosion processes and the build-up of thick deposits of Fe hydroxides on the
Fe surfaces primarily limit the long-term effectiveness of the Willisau PRB.
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