| Summary: | 碩士 === 國立中央大學 === 環境工程研究所 === 91 ===
Many studies indicate that both municipal waste incinerators (MWIs) and the industrial activities containing combustion processes are important sources of PCDD/F emissions. Local studies indicate that dioxin in ambient air originates mainly from electric arc furnaces. Electric arc furnaces (EAFs) have been identified as the major sources of PCDD/F emissions in Taiwan.
Two kinds of EAFs including the direct evacuation system and the building evacuation system are selected for measuring the dioxin emission. Results indicate that the PCDD/F concentration of stack gas in EAF-A was 22.50 ng/Nm3, and the total Toxic Equivalent Quantity (TEQ) concentration was 1.72 ng I-TEQ/Nm3. The PCDD/F concentration of stack gas in EAF-B was 2.19 ng/Nm3, and the TEQ concentration was 0.14 ng I-TEQ/Nm3. This result showed that the direct evacuation system emitted more dioxin than the building evacuation system. The other results obtained on gas/particulate partitioning of PCDD/Fs in EAFs indicate that more than 90% in the particulate-phase before the flue gas passed through APCD. The emission factor of EAF-A is 11.62 ng-I-TEQ/kg-product, while 7.36 ng-I-TEQ/kg-product is found for EAF-B. 1,2,3,4,6,7,8-HpCDF, OCDD and OCDF were the major contributors of the dioxin concentrations in each phase and the percentage of PCDD/F in particulate phase increases with the chlorination level of the PCDD/F congeners. The distributions of total Toxic Equivalent Quantity (TEQ) concentrations on 2,3,4,7,8-PeCDF at each sampling site were about 50%.
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