Environmental Engineering Reference
In-Depth Information
14
12
10
Sand
Karri bark
Pine wood chips
Pine sawdust
8
6
4
2
0
0
50
100
Distance along column (cm)
FIGURE 7.6
Concentration of nitrate (as N) along the length of each column experiment.
200
180
160
Sand—DOC
140
Karri bark—DOC
120
Pine wood chips—DOC
Pine sawdust—DOC
100
Sand—TOC
80
Karri bark—TOC
60
Pine wood chips—TOC
40
Pine sawdust—TOC
20
0
0
2
4
Time (days)
6
8
FIGURE 7.7
Concentration of soluble organic carbon and total organic carbon from the four columns.
as well as a strong organic odor, which corroborates the high concentrations
of DOC. As the amount of DOC in the effluent of the denitrification PRB was
a concern, owing to potential passivation of the ZVI, it was decided that the
shredded aged Karri bark was not appropriate for the PRB system and was
omitted from further testing.
As the carbon source will degrade over the life span of the PRB, it is impor-
tant that some sand is used in the PRB's construction to provide long-term
structural integrity of the barrier. A second round of column tests was
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