不同基質於地下水中傳輸與三氯乙烯生物移除之比較

含氯有機溶劑為土壤及地下水中常見之重質非水相溶液(dense non-aqueous phase liquids, DNAPLs)污染物，其中又以三氯乙烯(trichloroethylene, TCE)為地下水中最常見之含氯有機污染物，常可存在數十年以上。於90年代中期後，藉由滲透式反應牆之設置，現地加強式生物整治法已廣泛應用於處理地下水中含氯污染物整治。然而定期施作營養基質雖加速生物反應速度，亦造成水井阻塞及酸化問題，衍生基質傳輸效果不佳、水質惡化及操作維護費用增加等議題。因此，本研究將藉由進行基本物化特性分析及管柱流通性試驗，探討四種不同基質( 基質A ~ D)於地下水中之傳輸，並篩選兩種基質進行批次試驗，藉由處理受三氯乙烯污染之地下水，評估基質於應用上之可能性。依據物性分析結果可知，基質A及D於放置72小時後並無明顯分層，溶液之油滴皆為球型型態，平均粒徑範圍為0.4 ~ 0.6 μm，而基質B及C則有明顯分層且平均粒徑較大( 大於3 μm)，黏度亦較大，然四種基質之界達電位測值皆為負值，可減少吸附於土壤表面之可能性。由流通性試驗之結果，顯示基質A及D傳輸性最佳，應可長效且穩定提供微生物營養鹽。於批次試驗期間，使用基質D之組別之降解速率最快，於30天的試驗中可降解地下水中88%之TCE。此外，藉由添加碳酸鈉及碳酸氫納做為緩衝溶液，不僅可有效維持pH於中性，並且有利於還原脫氯微生物生長。

關鍵字

三氯乙烯；現地加強式生物整治；傳輸；批次試驗；還原脫氯

並列摘要

Chlorinated solvents, which are regarded as dense non-aqueous phase liquids (DNAPLs), are commonly observed in soil and groundwater contamination. Tetrachloroethene (TCE), particularly, is one of the most persistent chlorinated organic contaminants in groundwater that can last for decades. In-situ enhanced bioremediation was quickly adopted during the mid-1990s to treat dissolved chlorinated solvent plumes by creating permeable reactive barriers. However, due to the periodical injection of donor substrates, the enhanced biological reactions result in low well efficiency and acidified groundwater, accompanying issues of poor transportation of donor substrates, groundwater quality eruption and increased cost of operation maintenance. Thus, the objective of this study is to compare the transport ability between four donor substrates (Substrates A ~ D) and realize these donor substrates' biodegradation ability by performing the physical properties analyses and column circulation test. After the above analyses and experiments, two out of four donor substrates were selected to conduct batch experiment. The accessibility of these substrates for in-situ remediation was also evaluated. According to the physiochemical analyses, no obvious layer was observed for Substrates A and D within 72 hours. The droplets of these substrates are sphere with the radius ranging between 0.4 ~ 0.6 μm. In contrast, Substrates B and C have obvious layers and large average radius (＞ 3 μm). The viscosity of Substrates B and C is also larger than Substrates A and D. The negative zata potentials of four substrates can reduce the absorption onto the surface of soil. Based on the results of circulation test, Substrates A and D have the ability to fast transport within the soil column, suggesting the persistent and stable release of the substrates for the growth of microbial population. The using of Substrate D can rapidly reduce the concentration of TCE up to 88% during the period of batch experiment. Furthermore, the addition of sodium carbonate and sodium bicarbonate can act as pH buffer to maintain groundwater within neutral pH and be beneficial for the growth of reductive dechlorination bacteria.

並列關鍵字

tetrachloroethene ； in-situ enhanced bioremediation ； transport ； batch experiment ； reductive dechlorination

國際替代計量

不同基質於地下水中傳輸與三氯乙烯生物移除之比較

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