以生物可分解之界面活性劑沖洗法整治受DNAPL污染之地下水

Application of Biosurfactant Flushing on the Remediation of TCE-contaminated Groundwater

蔡在唐(Tzai-Tang Tsai) ； 高志明(Chih-Ming Kao) ； 梁書豪(Shu-Hao Liang) ； 葉琮裕(Tzung-Yuh Yeh) ； 黃文彥(Wen-Yan Huang)

《界面科學會誌》 29卷3&4期 (2007/12) Pp. 111-125

https://doi.org/10.30020/JCCIS.200712.0001

摘要

近年來陸續發現因含氯有機溶劑被不當儲存及處置而導致之地下水污染事件，如桃園RCA場址、台灣氯乙烯場址及高雄大寮福德廟場址等，各場址均暴露出重質非水相液體（dense non-aqueous phase liquid, DNAPL）污染的嚴重性及整治之迫切性。由於DNAPL污染場址之整治具有相當高之困難度，而傳統之整治方式（例如抽取處理法及空氣灌入法）僅針對溶解相之地下水污染進行處理，並無法有效移除DNAPL造成之污染源，使整治時程延長且整治經費提高。本研究之主要目的為探討不同土壤質地與有機質含量對地下水沖洗效率之影響、不同界面活性劑種類與濃度之增溶與移除效率評估以及模擬傳統抽取處理（地下水沖洗）接續界面活性劑沖洗之處理成效。本研究以含氯有機物中最常被使用之三氯乙烯（trichloroethylene, TCE）為目標污染物，結合傳統抽取處理法（pump and treat）與生物可分解之非離子型界面活性劑沖洗技術（biosurfactant flushing），以加速DNAPL在地下水層的溶解與移除，縮短地下水整治時間。其中，所使用之界面活性劑均為食品級與生物可分解，包括：Simple Green（簡稱SG）、Tween 80以及Triton-100。批次實驗結果顯示，在受TCE污染之含水層中，使用地下水沖洗可移除40至50%之TCE；而地下環境對TCE移除效率之影響因子主要有土壤質地與有機質含量。在界面活性劑沖洗結果顯示，界面活性劑沖洗之TCE移除效率比單獨以地下水沖洗之效率佳。當以界面活性劑沖洗9個Pore Volumes（簡稱PV）後，TCE之移除效率為75至95%，較傳統抽取法（地下水沖洗）之TCE移除效率（約45%）高。實驗結果亦顯示，使用之界面活性劑濃度越高，TCE之移除率越佳。雖然0.1wt% Tween 80與0.1 wt% TritonX-100對TCE之沖洗效率（91.8%與96.9%）略優於0.1 wt%SG（89.8%），但在環保與成本之考量下，SG之成本較低且生物分解性較佳，因此建議可優先使用於場址之整治。另在土壤管柱實驗中也進一步發現結合地下水與0.1 wt% SG沖洗法可移除90.3%以上之TCE。本研究之成果將可提昇與改善現地應用之可行性，且未來在現地整治受DNAPL污染之地下水時，可用SG進行DNAPL之沖洗。

關鍵字

界面活性劑沖洗法 ； 抽取處理法 ； 地下水污染 ； 重質非水相液體 ； 三氯乙烯

並列摘要

The industrial solvent trichloroethylene (TCE) is among the most ubiquitous chlorinated compounds found in groundwater contamination. The objective of this study was to improve the efficiency of conventional pump-and-treat system on the remediation of TCE-contaminated groundwater by applying the biosurfactant flushing. In the first part of this study, three different surfactants including Tween 80, Triton X-100, and Simple Green^TM (SG) were evaluated for their effectiveness on TCE extraction in bench-scale experiments. Results indicate that after nine pore volumes of surfactant flushing, approximately 91.8%, 96.9%, and 89.8% of TCE (initial concentration = 40 mg/L) was removed when 0.1 wt% Tween 80, 0.1 wt% Triton-100, and 0.1 wt% SG was applied, respectively. Results also reveal that only 40% of TCE removal was observed if no surfactant was applied during flushing. Although SG shows less treatment efficiency, it was selected for the following column study based on the effects that SG is more biodegradable and cost effective. Results also show that higher treatment efficiency can be obtained when higher surfactant concentration was applied. Moreover, soil organic content and soil permeability would affect the treatment efficiency significantly. Results from the column experiment indicate that approximately 90% of TCE could be removed after groundwater extraction followed by surfactant flushing (0.1 wt% SG). The combination of pump-and-treat and surfactant flushing technologies would amount of surfactant used, and thus, the remedial cost can be minimized. Results from this study will be useful in designing a practical in situ biosurfactant flushing system to remediate TCE-contaminated groundwater.

並列關鍵字

Biosurfactant flushing ； Pump-and-treat ； Groundwater contamination ； DNAPL ； Trichloroethylene