ACERC
Abstracts - 1998 |
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Research
Area 3: Fine Particles
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Trace Metals Behavior During
the Thermal Treatment of Paper-Mill Sludge
Holbert, C. and Lighty,
J.S.
Accepted for publication, Journal of Waste Mgt. (1998)
The objective of the present
study is to investigate trace metals (Cd, Cr, and Pb) behavior during thermal
treatment of sludge wastes. Paper mill sludge spiked with extraneous amounts
of Cd, Cr, and Pb was subjected to different thermal regimes using two different
bench-scale reactors. Metals retention in the resultant ash is discussed, as
is the influence of structural modifying additives. Ash is characterized according
to leachability tests to determine the environmental availability of the trace
metals and provide insight as to the extent of metals immobilization within
the ash matrix. The bulk of the ash appears to be supermicron particles composed
of individual fragments with no evidence of localized sintering effects. Cadmium
and chromium partitioning behavior is similar for both reactors, with metal
retention by the ash strongly influenced by treatment temperature. Lead behavior
exhibits significant differences between the two reactors. Under fully oxidizing
conditions, 95 to 100% of the lead is retained by the ash and occurs as an immobilized
form resistant to leaching using a strong mineral acid. Structural modifying
additives did not increase metals retention or decrease metals leachability
from the ash matrix. Alternatively, these additives appear to have a detrimental
effect upon metals immobilization by the ash.
