Combination of Membrane Substrate Feeding Bioreactor and Zero-valent Metal Reduction Technology - Dechlorination of TCE by Immobilized Autotrophic Hydrogen-bacteria and Zero-valent Iron
|關鍵字:||零價鐵;脫氯反應;氫氣自營菌;三氯乙烯;含氯有機化合物;TCE;zero-valent iron;dechlorination;autotrophic hydrogen-bacteria;TCE;chlorinated hydrocarbon||公開日期:||2009||摘要:||三氯乙烯（TCE）為地下水中最常被發現的污染物之一，其對生物和環境的危害相當大，也具有很高的致癌潛勢。本研究的目的在於探討零價鐵與氫氣自營菌共包埋對去TCE降解的去除效率，以及此生物－化學合併處理系統對TCE之去除是否具有加成效果。在批次反應中可證實加入的氫氣可以有效加速零價鐵之催化脫氯作用，也可有效降低鐵腐蝕量；此外，由於脫硫微生物所產生的硫化鐵也有助於TCE與cis-DCE脫氯還原，合併系統的總去除效率明顯優於零價鐵與氫氣自營菌去除速度之總和，MFSB批次試驗結果也顯示合併系統對TCE的去除效果為傳統零價鐵的3.2倍。續流管柱試驗為本研究模擬於地下水層中以零價鐵－氫氣自營菌去除TCE的效率探討，結果顯示此合併處理系統不但具有較佳的TCE去除能力，對於含氯中間產物也能有效降解，達到100%轉化為無氯產物之目標；此外，於長時間操作下，本系統並無傳統零價鐵去除效率遞減的問題，證實可以有效實際應用在受TCE污染之場址進行現地復育。
Trichloroethylene (TCE) is the most ubiquitous chlorinated compound found in groundwater contamination. The objective of this study was to evaluate the dechlorination rate (from an initial concentration of 180 μmol per liter) and synergistic effect of combining commercial Fe0 and autotrophic hydrogen-bacteria in the presence of hydrogen during TCE degradation process. In the batch test, the treatment using Fe0 in the presence of hydrogen (Fe0/H2) showed more effective dechlorination and less iron consumption than Fe0 utilized only (Fe0/N2), meaning that catalytic degradation had promoted transformation of TCE and the iron was protected by cathodic hydrogen. The combined use of Fe0 and autotrophic hydrogen-bacteria was found to be more effective than did the individual exercise even though the hydrogen was insufficient during the batch test. By the analysis of XRPD, the crystal of FeS transformed by sulfate reducing bacteria (SRB) was detected on the surface of iron after the combined treatment. The synergistic impact was caused by FeS precipitates which enhanced TCE degradation through catalytic dechlorination. The dechlorination rate coefficient of the combined method in MFSB was 3.2-fold higher than that of iron particles individual used. Additionally, the continuous column study showed the combined method improved the TCE degradation efficiency and accumulation of cis-DCE in long-tern operation. Results from batch and continuous column experiment revealed that the proposed combined method has the potential to become a cost-effective remediation technology for the chlorinated-solvent contaminated site.
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