1998
Research Area 3: Fine Particles
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.
1998
Research Area 3: Fine Particles
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.