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年度	103	專案性質	實驗性質
專案類別	研究專案	研究主題	整治
申請機構	國立中央大學	申請系所	環境工程研究所
專案主持人	張木彬	職等/職稱	教授
專案中文名稱	同時處理土壤中戴奧辛、五氯酚及汞之整合性技術開發(第二階段)
中文關鍵字	戴奧辛；汞；五氯酚；污泥；裂解；回收
專案英文名稱	Integrated Approach for Simultaneous Removal of Dioxin, PCP and Mercury in Contaminated Soil (2nd)
英文關鍵字	Dioxin；Mercury；PCP；Sludge；Pyrolysis；Recovery
執行金額
執行期間	2013/11/25 至 2014/11/24
計畫中文摘要	中石化安順場址不管是在污染物形態、污染物數量與污染物濃度均為國 內外罕見，受污染土壤之戴奧辛（PCDD/Fs）、五氯酚（PCP）與汞含量均遠 遠超過管制標準；而此種包含不同超高濃度毒性物質之複合式污染型態，是 相當棘手的污染整治場址。本團隊於 102 年度之研究已獲致初步成果，本年 度則針對超高濃度戴奧辛污染土壤（249,000 ng-TEQ/kg）、超高濃度汞污染 土壤（1,860 mg/kg）及含汞污泥（2,220 mg/kg）等三種不同基質進行熱處理 試驗。在熱處理效能方面，土壤及汞污泥中戴奧辛及總汞去除效率隨著熱裂 解模組操作溫度及停留時間的提升而上升，戴奧辛及五氯酚的破壞效率可達 98%以上，總汞的脫除效率最高達 99%以上。為期 12 天的長時間系統操作 試驗結果顯示操作於 750oC 且停留時間在 60 分鐘以上時，可確保處理後土 壤及汞污泥中之戴奧辛/總汞濃度符合我國土壤污染管制標準（戴奧辛：1,000 ng-TEQ/kg；汞：20 mg/kg）。 排氣控制方面，高效袋式集塵器可有效去除粒狀物，集塵器出口粒狀物 濃度可穩定維持在 3 mg/Nm3 以下；驟冷塔對戴奧辛及汞之去除效率皆隨冷 凝溫度降低而提昇，90%以上的汞被捕集回收，在冷凝液中可發現汞珠（元 素態汞）的聚集。在流動床式活性碳吸附塔方面，本計畫採用 3 層活性碳床， 在 1 cm/day 之活性碳質床更新率下即可有效維持排放濃度符合法規標準，但 因實際操作上，土壤濃度變動性高，故建議以 2 cm/day 為佳。經過高效袋式集塵器、驟冷塔及流動床式活性碳吸附塔處理後，排氣中戴奧辛及汞濃度皆 低於我國最嚴格之排放標準（五氯酚 500 μg/Nm3、戴奧辛 0.1 ng-TEQ/Nm3、 汞 50 μg/Nm3）。由於汞污泥在熱處理過程中會產生高濃度的 SO2，而濕式洗 滌塔分別採用 NaOH 及 Na2CO3 吸收液對於氣流中 SO2 均可達到 96%以上的 去除效率，並符合固定污染源最嚴格之排放標準（SO2 <100 ppm）。 本研究建立活性碳再生系統，採流動床式理念設計，活性碳吸附床中的 球狀活性碳因重力往下移動至再生系統中，無氧條件下隨著反應時間增加， 對戴奧辛及五氯酚的破壞效率愈高，對吸附於活性碳之戴奧辛及五氯酚的破 壞效率可達 98%以上，對於總汞可達 99%以上的脫除效率，由於再生系統出 口端含有高濃度的汞蒸氣，可將廢氣導回驟冷塔之入口端，藉由汞珠的回收 將其去除，整個熱裂解系統中並無含汞廢棄物或汞污泥的產生，更能達到污 染減量之目的。
計畫英文摘要	In this case study, contaminated soil containing extremely high concentrations of PCP, PCDD/F and mercury in An-shun site is selected for remediation test. Different characteristics of these contaminants have caused the difficulty of effective remediation. For better remediation of contaminated soil in An-shun site, a continuous pyrolysis system (CPS) is designed and applied in this study. In 2013, CPS had been proved for effective removal of PCDD/Fs and mercury from contaminated soil. In this stage, contaminated soils with extremely high PCDD/F and mercury concentrations, which are 249,000 ng-TEQ/kg and 1,860 mg/kg, respectively, and mercury-containing sludge (2,220 mg/kg) are selected for treatment by CPS. Regarding the removal efficiencies achieved with CPS, PCDD/Fs and mercury are efficiently removed with increasing operating temperature of CPS and retention time of contaminated soil. At 750oC and 60 minutes retention time, destruction efficiencies of PCDD/Fs and PCP are higher than 98% and removal efficiency of mercury is higher than 99%. After long-term test with 12 days, good performance of CPS is still effectively maintained and the residual concentrations of PCDD/Fs and mercury in remediated soil are lower than the promulgated limits of Taiwan (PCDD/Fs: 1,000 ng-TEQ/kg; Mercury: For air pollution control devices, baghouse (BH), quench tower (QT), multi-layer adsorption system (MAS) and wet scrubber (WS) are adopted for controlling air pollutants discharged from CPS. BH can efficiently remove particulate matter and maintain <3 mg/Nm3 of particle concentration in the exhaust after BH. 90% mercury is recovered by QT and elemental mercury significantly aggregates in the condensate of the QT. Regarding to MAS, three layers of bead-shaped activated carbons (BACs) are adopted in this study and replacement rate of 2 cm-BAC/day is suggested for effective emission control. BH, QT and MAS can efficiently remove PCDD/Fs and mercury to meet the emission limits (0.1 ng I-TEQ/Nm3 for PCDD/Fs and 50 g/Nm3 for mercury). However, SO2 is significantly found in the exhaust of CPS with the remediation of mercury-containing sediment. WS with NaOH or Na2CO3 as absorbent can efficiently remove more than 90% SO2 in the exhaust of the MAS. For continuous operation of MAS, a system for BACs’ regeneration is built with moving bed system. At oxygen-free condition (N2 as carrier gas), increasing retention time is useful to enhance destruction efficiencies of PCDD/Fs and PCP adsorbed on BACs (>98%) and removal efficiency of mercury adsorbed on BACs (>99%). Although vaporized mercury is discharged from the regeneration stream of BACs, exhaust of regeneration system is introduced into the flue gas before quench tower. Vaporized mercury can be efficiently recovered. Finally, CPS applied in this study can efficiently remove PCDD/Fs, PCP and mercury from contaminated soil and APCDs can also efficiently control the pollutant emission. Furthermore, secondary pollutants including BACs waste and condensate from quench tower are not discharged from CPS+APCDs. Experimental results indicate that the CPS+APCDs developed in this study is a powerful and environment-friendly remediation technology for removing PCDD/Fs and mercury from contaminated soil and sediment.