Environmental Engineering Reference
In-Depth Information
100
Zn
Cu
Pb
90
80
70
60
50
40
30
20
10
0
1
2
3
4
5
6
Layers
Fig. 2
Column C1: metal mass ratio
70
70
Zn (pH2)
Cu (pH2)
Pb (pH2)
Zn (pH6)
Cu (pH6)
Pb (pH6)
60
60
50
50
40
40
30
30
20
20
10
10
0
0
1
2
3
4
5
6
1
2
3
4
5
6
Layers
Layers
Fig. 3
Layer relevance in overall heavy metal retention at pH2 and pH6
percentage of these metals are release from the filter media at pH6, as presented in
Fig.
2
. The relevance of each layer in the overall retention of Zn, Cu and Pb, at pH2
and pH6, for column C1 is depicted in Fig.
3
.
At pH2 all the reactive layers are equally relevant. At pH6 the retained heavy
metals decrease for higher depths. High retention of Cu and Pb in the top layer
suggests the occurrence of precipitation and particulate retention, favorable condi-
tions in terms of groundwater protection.
Column C2
In this column, with the reactive layers with 5% of kaolinite and 95% of sand, the
heavy metals retained were considerably higher than those in column C1. In the
reactive layers heavy metals retention, at pH6, vary from 12% for Zn to < 5% for
