| CHROMIUM LEACHABILITY FROM STABILIZED/SOLIDIFIED SOILS UNDER MODIFIED SEMI-DYNEMIC LEACHING
CONDITIONS
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| Deok Hyun Moon† |
| W. M. Keck Geoenvironmental Laboratory Center for Environmental Systems Stevens Institute of Technology Castle Point on Hudson, Hoboken, NJ 07030, USA |
Corresponding Author:
Deok Hyun Moon ,Tel: 201-216-8097, Fax: 201-216-8212, Email: dmoon@stevens.edu
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Received: August 18, 2005; Accepted: December 18, 2005. |
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| ABSTRACT |
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The effectiveness of fly ash-, quicklime-, and quicklime-fly ash-based stabilization/solidification (S/S) in chromium (Cr) contaminated soils was investigated using modified semi-dynamic leaching tests. Artificial soil samples composed of kaolinite or montmorillonite contaminated with chromium nitrate (4000 mg Cr3+ kg"1 of solid) were prepared and then subjected to S/S treatment using quicklime, fly ash, or quick lime-fly ash. The effectiveness of the treatment was evaluated by assessing the cumulative fraction of leached Cr3+ as well as, by computing the effective diffusivity (Dt) and the leachability index (LX) of the treated samples. The reduction in Crj4 release for the untreated samples was more pronounced in the presence of montmorillonite, which was attributed to sorption. Treatment with quicklime, fly ash, or quick lime-fly ash was significantly effective in reducing CrJ* release most probably due to the formation of pozzolanic reaction products and Cr(OH)3 precipitation. The most effective treatment was observed in montmorillonite-sand soil samples treated with quicklime-fly ash (99.8% removal). The mean De decreased significantly and the mean LX was greater than 9 for all treated samples, indicating that the treated soils were acceptable for "controlled utilization". The mechanism controlling Cr3+ leaching from all treated samples during the first 5 days appeared to be diffusion. |
| Keywords:
chromium (CrJ ) | leachability index (LX) | quicklime | semi-dynamic leaching test | stabilization/ solidification (S/S) |
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