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. 6
Column C3: metal mass ratio
70
70
Zn (pH2)
Cu (pH2)
Zn (pH6)
Cu (pH6)
Pb (pH6)
Pb (pH2)
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. 7
Layer relevance in overall retention of Pb at pH2 and pH6
Heavy metals released at pH6 are lower in the bottom layers, which is a favorable
result when looking for groundwater protection (Fig.
7
).
Conclusion
Results obtained for chemical desorption allow evaluation of the heavy metals
retention in each layer and their environmental availability at pH6.
In column C1, with a sand filter medium, a significant amount of retained metals
is released at pH6.
In columns C2 and C3 with reactive filter media, high retention efficiencies were
found. The environmental availability results obtained were 12-18% for Zn and
lower than 5% for Cu and Pb.
