Decontamination of fly ash and used lime from municipal waste incinerator using Thiobacillus ferrooxidans
The purification of incinerator gases produces large quantities of fly ash and used lime [a combination referred to as air pollution control residues (APCR)], both of which contain elevated levels of metals. This paper describes biological solubilization assays utilizing Thiobacillus ferrooxidans to leach metals from APCR to render them nonhazardous. The multistage solubilization process involves an alkaline aqueous phase that removes some Pb. In the second phase, the APCR are acidified to pH 4 with H{sub 2}SO{sub 4}, then inoculated with a bacterial culture that has been acclimated in the presence of 2% Fe (FeCl{sub 3}). Several rinses and decantings achieve removal of the leachable metals. The final step involves the addition of Ca(H{sub 2}PO{sub 4}){sub 2} and an increase in the treatment pH prior to the final filtration. Viability of thiobacilli in APCR was poor. Despite this problem, the removal of Pb was 35.9%, 46.0%, and 68.7%, which demonstrates greater metal removal with increased APCR contamination. Zn removal varied from 68.2% to 79.5%, which was positively correlated to the level of residue contamination, whereas Cu was removed in the proportions of 26.9% to 68.2%. Cadmium removal appeared to be independent of the level of Cd in the APCR; Cd was removed to the greatest degree, with a variation of 92.0% to 94.7%. The treated APCR were tested using four different leachate tests.
- Research Organization:
- INRS-Eau, Sainte-Foy, Quebec (CA)
- OSTI ID:
- 20001030
- Journal Information:
- Environmental Management, Vol. 24, Issue 4; Other Information: PBD: Nov 1999; ISSN 0364-152X
- Country of Publication:
- United States
- Language:
- English
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