Environmental Engineering Reference
In-Depth Information
correlation (R2 = 0.98) at 1,000 mg CO
3
2−
/L. At the lower carbonate concentrations,
0.1 and 10 mg/L, the correlation is less valid (R2 = 0.14 and 0.35 respectively).
It was concluded that the metals will only be precipitated as carbonates at
extremely high carbonate concentrations. The carbonate concentration was 0.47
mg/L from the measurement of alkalinity for the old sludge in water solution.
At the lower carbonate concentrations, more relevant for natural water in contact
with the sludge, other mechanisms such as sorption are more likely to occur.
The CHEAQS data base was unable to make the calculations for V and Mo, and in
the second simulation Pb could not be dealt with by the software.
Conclusions
The results show that blast-furnace sludge has a good ability to remove the majority
of the studied metals at pH 7-9. It is therefore recommended for use as a sorption
material for water contaminated by metal, but the risk of the leaching of V and Cs
should be investigated in each case. The slightly lower capacity of the old sludge
and the use of real leachate should be taken into consideration when laboratory
results are applied to real-life environments. The leaching of Cs and the lower
capacity of the old sludge to remove Mo and V should be noted. For further studies,
column experiments with real contaminated leachates are recommended for the
investigation of the material's behavior under flowing conditions.
Acknowledgements
SSAB Merox AB in Oxelösund is gratefully acknowledged for financial
support. We also wish to thank Hanna Friberg and Therese Stark at Merox, as well as environmental
consultant Kristina Hargelius who initiated the project, for their valuable help and support.
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