Enrichment of PCDDs/PCDFs in the cooling system of municipal solid waste incineration plants.
This study measured the levels of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/PCDFs), destroyed or formed in combustors and re-synthesized in cooling systems. For the proper control of PCDDs/PCDFs in municipal solid waste (MSW) incinerators, three grate-type MSW incinerators were selected, two of which had boilers, and one of which had a water spray tower (WST) as a cooling system. At the combustor outlets, dusts were in the range of 1640-4270 mg/Sm3 and PCDDs/PCDFs were in the range of 0.103-2.619 ng-TEQ/Sm3, showing the different values according to the grate structure of combustor and the flow direction of flue gas. After the flue gases passed through the cooling system, PCDDs/PCDFs at the waste heat boiler (WHB) outlets were enriched to levels that were 10.8-13.6 times higher than those at the furnace outlets, but PCDDs/PCDFs at the WST outlet was reduced to 5% of the level found at the furnace outlet. The emission patterns, such as the ratio of PCDFs to PCDDs, the ratio of gaseous-phase to particulate-phase PCDDs/PCDFs, and the compositional percentiles of each 2,3,7,8-substituted congener varied according to the types of air pollution control devices (APCDs). Reducing re-synthesis in the cooling system rather than enhancing the removal efficiencies of the APCDs seems to be more effective for lowering the levels of PCDDs/PCDFs in MSW incineration plants.
Kim
Sam-Cwan
SC
National Institute of Environmental Research (NIER), Environmental Research Complex, Kyungseo-Dong, Seo-Ku, Inchon 404-170, Republic of Korea. kscnier@me.go.kr
Lee
Kil-Chul
KC
Kim
Ki-Heon
KH
Kwon
Myung-Hee
MH
Song
Geum-Ju
GJ
D000393:Air Pollutants / Q000032:analysis; D001572:Benzofurans / Q000032:analysis*; D000072338:Dibenzofurans, Polychlorinated; D017745:Incineration / Q000295:instrumentation*; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis; D012037:Refuse Disposal / Q000295:instrumentation*
D000393:Air Pollutants; D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D000072317:Polychlorinated Dibenzodioxins