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Journal of Microwave Power
and Electromagnetic Energy (JMPEE) |
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TITLE |
Microwave Treatment of Hazardous
Wastes: “Fixation” of Chromium in Soil [PDF] |
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AUTHORS |
E. Sedhom,
L. Dauerman, G. Windgasse
1992 27 2 81-86 |
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Abstract It has been found that chromium
(hexavalent)-impregnated soil treated in a microwave
field can be rendered non-hazardous as defined by federal regulations. Another requirement for feasibility
effecting site remediation by any technology is that the heavy metal does not
become leachable in the future. That it is possible to prevent leaching
after treatment was demonstrated by spectroscopic studies. The hexavalent
chromium phase in the chromium-impregnated soil became non-detectable;
chromium reappeared in two new crystalline phases: chromite
(FeCr2O4) and chromic oxide (Cr2O3),
respectively. It is the appearance of
the chromite phase which suggests the following
model to guide the development of microwave-based processes to treat this
class of hazardous wastes cost-effectively:
The hematite phase, initially present in the soil, is “lossy”, and absorbs microwave energy; this phase can
interact with the dichromate phase in the presence of other soil constituents
to effect the formation of a non-hazardous phase. This type of interaction should be more
cost-effective than soil vitrification because the
expenditure of energy should be less.
In contrast to physical stabilization processes, the possibility of
subsequent leaching of a hazardous nature is eliminated. This model leads to general guidelines for
the development of microwave-based processes to remediate soils contaminated
with a heavy toxic metal: (a) Determine if a “lossy”
native mineral is present: (b) Determine is this “lossy”
native mineral interacts with the toxic heavy metal within the soil matrix to
form a non-harzardous substance. Key
Words: Hazardous wastes, Soil, Microwave, Fixation, Chromium |
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