Effects of injected activated carbon and solidification treatment on the leachability of polychlorinated dibenzo-p-dioxins and dibenzofurans from air pollution control residues of municipal waste incineration.
To assess the effectiveness of the injected activated carbon, cement, and sulfur-containing chelating agent in controlling polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) release from the surface of air pollution control (APC) residues, this study examined the leachability of PCDD/Fs from APC residues generated by municipal solid waste incinerators. Results showed that PCDD/Fs were stably retained in the APC residues when the samples were leached with acetic acid solution. Highly chlorinated PCDD/F homologues (i.e., hepta- and octa-CDDs and CDFs) were relatively easy to leach. The leaching percentages of PCDD/Fs from raw APC residue samples containing activated carbon were smaller than those from samples without activated carbon, especially when n-hexane was used as the leachant. These results indicate that the flue gas injected activated carbon not only controls PCDD/F emissions, but also suppresses the leachability of PCDD/Fs from the APC residues. Solidification/stabilization (S/S) processes with 30wt% cement and 5wt% sulfur-containing agent can additionally decrease the leachability of PCDD/Fs with humic acid. Using n-hexane as the leachant, S/S processes increased the leachability of PCDD/Fs. Various low chlorinated PCDD/F congeners were moreover leached out of the APC residue samples, markedly increasing the leachate toxicity. The enhancement of leachability and toxicity owing to S/S processes may negatively impact the environment when APC residues are exposed to nonpolar organic solvents.
Hsi
Hsing-Cheng
HC
Department of Safety, Health and Environmental Engineering, National Kaohsiung First University of Science and Technology, No. 2, Juoyue Road, Nantsu, Kaohsiung 811, Taiwan, ROC. hchsi@ccms.nkfust.edu.tw
Wang
Lin-Chi
LC
Yu
Tsung-Hsien
TH
D000395:Air Pollutants, Occupational / Q000032:analysis*; D000465:Algorithms; D001572:Benzofurans / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D017745:Incineration; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D012037:Refuse Disposal; D012995:Solubility; D013624:Taiwan
D000395:Air Pollutants, Occupational; D001572:Benzofurans; D000072317:Polychlorinated Dibenzodioxins; D011108:Polymers; C016068:polychlorodibenzofuran; D002606:Charcoal