P. Theodoratos et al., The use of municipal sewage sludge for the stabilization of soil contaminated by mining activities, J HAZARD M, 77(1-3), 2000, pp. 177-191
The ability of municipal sewage sludge to immobilize Pb, Zn and Cd containe
d in contaminated soil originating from a former mining area in Lavrion, Gr
eece was investigated. The soil was cured with sewage sludge in various pro
portions. The stabilization was evaluated primarily by applying chemical te
sts and complemented by the performance of additional biological tests. App
lication of the U.S. EPA Toxicity Characteristic Leaching Procedure (TCLP)
on the stabilized mixtures proved that Pb, Zn and Cd solubility was reduced
by 84%, 64% and 76%, respectively, at 15% w/w sludge addition, while a 10%
w/w addition was sufficient to reduce Pb solubility below the U.S, EPA TCL
P regulatory limit. The results of the extraction using EDTA solution showe
d the same trend, resulting in 26%, 36% and 53% reduction in the Pb, Zn and
Cd extractable fractions, respectively. Speciation analysis of the treated
soils revealed a significant decrease in the mobile fractions of heavy met
als, which was attributed to their retention in sewage sludge by adsorption
and organic complexation mechanisms. For the assessment of possible phytot
oxicity, experiments including growing dwarf brans in the treated soil was
carried out. It was Found that sewage sludge addition had a positive effect
on plant growth. Furthermore, the Pb and Zn uptake of plant leaves and roo
ts was reduced, while Cd uptake was unaffected by the sludge treatment. The
results of this study support the hypothesis that municipal sewage sludge
is a potential effective stabilizing agent for contaminated soil containing
Pb, Zn and Cd. (C) 2000 Elsevier Science B.V. All rights reserved.