EPA-95-U1U4-04-001

095

1,250 千元

2006/03/03

2006/11/30

高志明

永續發展室(停用)

林燕柔

國立中山大學

土壤及地下水

整治列車系統、重質非水相溶液、三氯乙烯、地下水污染

Treatment Train System, Dense Non-Aqueous Phase Liquid, Trichloroethylene (TCE), Groundwater Contamination

葉琮裕

蔡在唐

075254419

d933030003@student.nsysu.edu.tw

由於受DNAPL (dense non-aqueous phase liquid, 重質非水相溶液)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DNAPL污染進行處理，並無法有效移除DNAPL造成之污染源，造成整治時程之延長及整治經費之提高。我們在本計畫中所研發之三階段整治列車系統，可有效同時移除DNAPL污染源並處理溶解相之地下水污染，而此整治列車系統之研究成果預期將可作為規劃設計DNAPL污染場址整治系統之重要參考依據。在本研究中，我們以三氯乙烯(trichloroethylene, TCE)為目標污染物，而研究計畫所提出之三階段之整治方式包括第一階段之界面活性劑之沖排(surfactant flushing)，第二階段之高錳酸鉀氧化及第三階段之生物整治牆系統。當第一階段之處理效率降低後，即進行第二階段之高錳酸鉀氧化處理，以氧化殘留於地下水中之TCE。我們預估此二階段之整治將可去除超過90%以上之TCE去除率，而剩餘之TCE將應用生物整治牆之方式進行降解去除。由批次試驗結果可發現，本計畫所採用之整治列車系統確實可在經濟與技術可行性考量下，有效移除地下水中之TCE。而前兩階段之物化程序如本計畫預期，移除與降解地下水中90%以上之TCE；而剩餘10%之TCE可由生物整治牆降解至符合地下水管制標準。此外，由地下水沖排之批次試驗結果可知，以未加界面活性劑之地下水沖排可移除40至50%之TCE，此結果顯示在使用界面活性劑沖排前若先以地下水進行沖排(如現地pump and treat處理)，應可降低整治成本。研究結果亦顯示土壤有機質將影響TCE之移除效率，而以含有界面活性劑之沖排受TCE污染之地下水確實比以無界面活性劑之地下水沖排獲得較佳之處理成效。所使用之兩種界面活性劑Tween 80與Triton X-100之沖洗效率略優於第三種界面活性劑Simple Green (簡稱SG)，但在環保(SG有較佳之生物分解性)與成本雙重考量下，本計畫決定使用SG(成本為其他二種界面活性劑之1/3至1/4)進行後續之管柱試驗。在高錳酸鉀氧化批次試驗方面，經過假一階反應動力參數推算後發現，當有添加0.1 wt% SG於高錳酸鉀氧化TCE之系統時，其反應速率常數皆高於未添加SG之系統。因此添加SG對於高錳酸鉀氧化地下水中之TCE有正面效果，主要原因為SG可增進增進高錳酸鹽傳輸及提昇氧化速率之功能。研究結果顯示，在96 mg/L高錳酸鉀處理5 mg/L TCE之系統中，高錳酸鉀耗損速率常數及氯離子產生量可佐證添加SG確實有助於提昇高錳酸鉀脫氯降解TCE之效率。綜合批次試驗之成果得知，本計畫所提之整治列車系統確實可在經濟與技術可行性考量下，有效移除地下水中之TCE。較佳之整治列車系統處理40 mg/L地下水之組合程序依序為(1)地下水沖排，(2)以0.1 wt% SG移除在土壤/地下水中之TCE，(3)利用含有0.1 wt% SG之96 mg/L [MnO4-]溶液，脫氯降解未被界面活性劑移除而殘留在地下水中之TCE，(4)同時注入好氧性污泥與糖蜜構成生物整治牆以降解剩餘之TCE。我們以較佳之整治列車系統組合程序進行管柱試驗，發現第一階段地下水及界面活性劑之沖排可達到90%之TCE去除率；而第二階段之高錳酸鉀(添加 0.1 wt% SG)氧化可再去除7.2%之TCE，殘留之TCE將可由第三階段之生物整治牆去除，使TCE污染之介質達到完全整治之目標。針對受TCE污染之土壤與地下水所建立之整治列車系統概念的設計研發，不僅是一條可行的方向，亦是普遍受到業界認同。因此，未來在市場上應有相當不錯之佔有率。此外，就其設計理論推斷，此技術對整體環境之負面影響應是相當低，故此技術在市場上應有相當程度之競爭力。

整治列車系統、重質非水相溶液、三氯乙烯、地下水污染

KM-99977749-1.pdf

0MB

[期末報告]公開版

2007/3/1 上午 12:00:00

Soil and groundwater at many existing and former industrial areas and disposal sites is contaminated by halogenated organic compounds that were released into the environment. Halogenated organic compounds are heavier than water. When they are released into the subsurface, they tend to adsorb onto the soils and cause the appearance of DNAPL (dense-non-aqueous phase liquid) pool. Thus, a combination of several different treatment technologies is required to remediate DNAPL contaminated soil and groundwater. Among those halogenated organic compounds, trichloroethylene is more difficult to treat compared to other organics. Thus, TCE is used as the target compound in this study, . The objective of this study is to assess the potential of combining three different treatment processes to clean up DNAPL contaminated sites. In this study, a concept of “treatment train” has been proposed. The first remedial phase applies surfactant flushing to remove the major amount of DNAPL in the groundwater. Thus, more than 50 to 60% of the TCE can be reduced in groundwater. After the flushing with the surfactant, the groundwater permeability would decrease due to the clogging. This would be minimized after the subsequent oxidation process. The second phase is the chemical oxidation process applying potassium permanganate (KMnO4) technique. Approximately 20 to 30% of the remaining TCE could be reduced after the oxidation process. The residual 10 to 20% of the TCE would be remediated by the third process, which is biological permeable reactive wall. In the first surfactant flushing stage, three different surfactants were evaluated including Tween80, Triton X-100, and Simple Green (SG). Results from the bench-scale study indicate that Tween80 and Triton X-100 had higher TCE removal efficiencies. However, SG is selected for the following column study based on the effects that SG is more biodegradable and cost effective. Results from the oxidation experiments show that higher TCE oxidation efficiency was achieved when 0.1 wt% of SG was mixed in potassium permanganate solution. This is due to the effects that SG is able to enhance the transport of potassium permanganate, and thus, enhance the oxidation efficiency. TCE oxidation can be further confirmed by the analyses of chloride concentrations and rates of potassium permanganate consumption Results of this study will aid in designing a system for field application. The proposed treatment scheme would be expected to provide a more efficient and cost-effective alternative to remediate TCE contaminated sites. The following operational steps are recommended for the future application on TCE contaminated sites: flushing with site groundwater, followed by SG (0.1 wt%) flushing, and oxidation by potassium permanganate containing with 0.1 wt% SG. Results from the column experiment indicate that approximately 90% of TCE could be removed after the groundwater and surfactant flushing. The potassium permanganate (KMnO4) oxidation is able to remove 7.2% of the remaining TCE. The residual TCE could be further remediated via the biological permeable reactive wall process. Thus, more than 97% of initial TCE could be removed using the three-stage treatment scheme. Results of this study will aid in designing a system for field application. The proposed treatment scheme would be expected to provide a more efficient and cost-effective alternative to remediate TCE contaminated sites. This developed remedial scheme can also be applied for other DNAPL contaminated sites. Because the developed integrated remediation system is able to remediate the TCE contaminated soil and groundwater effectively, this system would be accepted as a sound technology in the remediation market. Moreover, this system would not cause any adverse impact on the subsurface environment, and thus, it would be a more environmentally friendly technology compared to other technologies currently in use.

Treatment Train System, Dense Non-Aqueous Phase Liquid, Trichloroethylene (TCE), Groundwater Contamination