Influence of residual carbon on the decomposition process of PCDD/Fs in MSWI fly ash.
In heating treatment of fly ash to reduce PCDD/Fs, cooling process is important to inhibit de novo formation of PCDD/Fs. In this study, assuming that residual carbon is the dominant factor of de novo synthesis, the relation between PCDD/Fs and residual carbon was examined. Firstly, by using MSWI fly ash which was treated in an actually operated facility, both the content of PCDD/Fs and residual carbon were decreased as heating temperature increased. At temperatures higher than 400 degrees C, the reduction rate of residual carbon was higher than 20% and more than 95% of PCDD/Fs was decomposed. In order to simulate a heating treatment process, fly ash was heated at different temperatures and gas atmospheres, oxygen or nitrogen. Heated fly ash was placed for 2 h at 300 degrees C in oxygen to promote de novo synthesis, or cooled immediately. As a result, good correlation between PCDD/Fs and residual carbon was found, therefore it was shown experimentally that residual carbon was the main factor for PCDD/Fs formation by de novo synthesis in fly ash.
Kakuta
Y
Y
Recyclable Resources Assessment (TAKUMA Endowed) Laboratory, Hokkaido University, Kita 13 Nishi 8, Kita Ku, Sapporo 060-8628, Japan. ytkakuta@eng.hokudai.ac.jp
Matsuto
T
T
Tanaka
N
N
Masuda
T
T
D001272:Atmosphere; D001572:Benzofurans / Q000032:analysis / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D003031:Coal; D060729:Coal Ash; D000072338:Dibenzofurans, Polychlorinated; D004784:Environmental Monitoring; D005740:Gases; D007220:Industrial Waste; D052638:Particulate Matter; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis; D013696:Temperature
D001572:Benzofurans; D003031:Coal; D060729:Coal Ash; D000072338:Dibenzofurans, Polychlorinated; D005740:Gases; D007220:Industrial Waste; D052638:Particulate Matter; D000072317:Polychlorinated Dibenzodioxins; D012989:Soil Pollutants; D002244:Carbon