戴奧辛為已知毒性最強之持久性有機污染物之一，近年來先進國家陸續進行非鐵金屬二次冶煉業煙道氣及廢棄物戴奧辛濃度及物種分佈探討，以瞭解全廠戴奧辛之生成及流佈狀況，提供源頭減量及製程改善之建議。研究對象銅二次冶煉業使用三組不同原料配比進行比對，三組銅合金產品原料以「電解銅」為主要原料、以「廠內回收之銅廢料」為主要原料及以「廠外回收之銅廢料」為主要原料；鋁二次冶煉業同樣使用三組不同原料配比進行比對，三組鋁合金產品原料以「鋁切削料」為主要原料、以「輪胎之鋁圈」為主要原料及以「鋁下腳料」為主要原料。在使用不同原料進行冶煉情況下，兩產業之煙道氣及廢棄物戴奧辛各物種濃度分佈百分比相似，同一物種毒性當量濃度貢獻度亦相近。PCDD佔總毒性當量濃度貢獻量之1~2成，PCDF佔總毒性當量濃度貢獻量之8~9成，PCDF之同源物為優勢物種。PCDD以12378-PeCDD及2378-TCDD為優勢物種，PCDF以23478-PeCDF及234678-HxCDF為優勢物種。比較銅二次冶煉業及鋁二次冶煉業戴奧辛濃度，銅二次冶煉業之生成濃度(2.92~12.4 ng I-TEQ/Nm3)明顯較鋁二次冶煉業(0.14~0.25 ng I-TEQ/Nm3)為高，兩產業因戴奧辛物化特性，易於微粒表面生成，因此多存在於固相。隨著空氣污染防制設備收集煙道氣中微粒，固相戴奧辛濃度也隨之下降(0.13~0.40 ng I-TEQ/Nm3)，使後續煙道氣排放戴奧辛能符合法規標準(1.0 ng I-TEQ/Nm3)，相對而言，集塵灰之PCDD/F毒性當量濃度為0.466~28.8 ng I-TEQ/g，已超過有害事業廢棄物認定標準1.0 ng I-TEQ/g，需注意其後續處理。 Dioxin is one of the most toxic persistent organic pollutants (POPs). In recent years, many countries are investigating the concentrations and distributions of dioxin in the stack gas and wastes from nonferrous secondary metal smelting industries to understand its generation and distribution. With the above-mentioned information, they are able to make suggestions for the source reduction and process modification. This study aims to compare the characteristics of dioxin generation from secondary copper smelting industry with three different feedstock compositions, which are primarily composed of copper, copper scrap recycling in plant and copper scrap recycling plant outside. As for aluminum secondary metal smelting industry, the characteristics of dioxin formation with three feedstock compositions that mainly consists of aluminum cutting material, tire aluminum ring and aluminum scraps are investigated. Even if the feedstock ratios are different, the results indicate that the contributions of dioxin congeners in stack gas and waste are similar. Moreover, the international toxicity equivalency concentration contributed by the same species are close as well. 10-20% of the international toxicity equivalency concentration is from PCDD while the rest is attributed to PCDF. PCDF is the dominating species. The dominating species for PCDD and PCDF are 12378-PeCDDand 2378-TCDD, and 23478-PeCDF and 234678-HxCDF, respectively. Furthermore, the dioxin concentration from copper secondary metal smelting industry (2.92~12.4 ng I-TEQ/Nm3) is significantly higher than that from aluminum secondary metal smelting industry (0.14~0.25 ng I-TEQ/Nm3). For both industries, dioxin tends to accumulate on the particle surface because of its physical and chemical properties. Therefore, dioxin is mostly distributed in solid phase. While the particles in stack gas are collected by the air pollution control equipment, the dioxin concentration in solid phase decreases as well (0.13~0.40 ng I-TEQ/Nm3) and it meets the emission standard (1.0 ng I-TEQ/Nm3). In contrast, PCDD/F concentrations based on toxic equivalent in fly ashes ranged from 0.466 to 28.8 ng I-TEQ/g. That is significantly higher than the standard for the hazardous industrial waste regulated by Taiwan EPA. Hence, how to properly dispose of highly dioxin contaminated fly ash remains a great concern.
