| 摘要: | 垃圾焚化飛灰因含有高濃度之重金屬與戴奧辛，被歸類為毒性有害事業廢棄物。本研究以批次與動態溶出兩種方式，探討台灣地區都市垃圾焚化廠飛灰中重金屬與戴奧辛之溶出潛勢與對環境可能造成之影響，並藉由不同溶液探討不同環境介質對於飛灰中重金屬與戴奧辛溶出之影響。本研究並以飛灰穩定化試驗探求適合之螯合劑，進而增加飛灰穩定化之能力。批次溶出試驗結果顯示A廠飛灰在四種溶液（HAc、acid rain、humic acid、SDBS）中，Pb之溶出濃度分別為：21.6、19.3、16.7、16.0 mg/L，均超過法規標準（5 mg/L）；B廠飛灰只於醋酸溶液中，Pb、Cu及Cd之溶出濃度超過法規標準。而兩廠飛灰之PCDD/Fs溶出以高氯數物種為主（如HpCDD、OCDD等）；PCBs溶出則以3,3’,4,4’-TCB、2,3’,4,4’,5-PeCB與2,3,3’,4,4’-PeCB為主。動態溶出試驗結果顯示A廠飛灰在四種溶液中，重金屬之溶出濃度皆以Pb最高，其次依序為Zn、Cu、Cr、Cd。Cd在界面活性劑溶液中之溶出濃度最高，而Zn、Pb、Cu及Cr則在醋酸溶液中之溶出濃度最高。在PCDD/Fs方面，飛灰受醋酸溶液長時間（13天）流洗，導致其結構受破壞，而增加其PCDD/Fs之溶出濃度。在PCBs方面，則發現有其他PCB之物種溶出（與批次溶出之結果相比），如：3,3’,4,4’,5-PeCB、2,3,3’,4,4’,5-HxCB與2,3,3’,4,4’,5,5’-HpCB。飛灰穩定化試驗結果顯示以無機硫系（A廠）或磷酸鹽系（B廠）搭配水泥之重金屬穩定化效果較佳，而穩定化對降低戴奧辛之溶出有些許之助益。The MSWI fly ash which contains high concentrations of heavy metals and dioxins has been classified as hazardous waste. In this study, batch and dynamic leaching procedures were used to explore the leaching behaviors of heavy metals and dioxins in the fly ash generated from MSWI. Heavy metals and dioxins leached from different solutions are assessed, and different chelating agents are tested for higher stability of MSWI fly ash. The results of batch leaching procedure indicate that the leached Pb concentrations of the plant A were 21.6, 19.3, 16.7 and 16.0 mg/L for HAc, acid rain, humic acid and SDBS as solvents, respectively. These concentrations all exceeded the regulated standard (5 mg/L). The leached Pb, Cu and Cd concentrations of the plant B exceeded the regulated limit, but only occurred in HAc solution. Highly chlorinated PCDD/Fs were observed in the leachates of fly ash, accounting for more than 80% of PCDD/Fs. In addtion, 3,3’,4,4’-TCB, 2,3’,4,4’,5-PeCB and 2,3,3’,4,4’-PeCB were also observed in the leachates of the fly ash. The results of dynamic leaching procedure indicated that the leached Pb concentrations of the plant A was the highest, followed by Zn, Cu, and Cr, whereas Cd was the lowest. In the SDBS solution, the leached Cd concentrations was the highest. On the other hand, the leached Zn, Pb, Cu and Cr concentrations were the highest in HAc solution. The structures of fly ash were destroyrd due to the long-term washing (13 days) of fly ash were washed by HAc solution, resulting in the increase of PCDD/Fs concentrations leached from the fly ash. 3,3’,4,4’,5-PeCB, 2,3,3’,4,4’,5-HxCB and 2,3,3’,4,4’,5,5’-HpCB were also observed in the leachates of the fly ash, compared with the results of batch leaching. Adding inorganic sulfide (A plant) or phosphate (B plant) along with cement results in the best stabilization effect in treating the fly ash. We also found there was some stabilization effect for dioxins of fly ash. |
