以竹炭結合過硫酸鹽氧化法處理受汽油及含氯有機物污染之地下水

土壤及地下水受到油品及含氯有機溶劑污染已是一廣泛且嚴重之問題。本研究以竹炭結合過硫酸鹽氧化法處理受汽油及含氯有機物污染之地下水，本研究之主要目的包含：(1)評估竹炭在不同條件下及竹炭結合過硫酸鹽氧化法系統對三氯乙烯(trichloroethylene, TCE)、苯(benzene)及甲基第三丁基醚(methyl tert-butyl ether, MTBE)之吸附能力，並探討其吸附模式及機制；(2)評估不同過硫酸鹽濃度及竹炭結合過硫酸鹽氧化法在水相及泥漿相系統下對TCE之去除能力；(3)探討過硫酸鹽濃度及竹炭結合過硫酸鹽氧化系統對自由基生成之影響；(4)探討不同過硫酸鹽灌注方式現地處理TCE之成效；(5)評估過硫酸鹽於地下水層中之持久性及影響半徑；(6)評估過硫酸鹽對現地微生物及場址性質之影響；及(7)以分子生物技術觀察整治過程中現地微生物數量及族群之變化。批次吸附實驗結果顯示，竹炭具有吸附TCE、苯及MTBE能力，吸附效果依序為TCE > 苯 > MTBE，且其吸附符合擬二階動力模式。等溫吸附模式模擬結果，竹炭吸附水中之TCE、苯及MTBE符合Langmuir等溫吸附模式，TCE、苯及MTBE之最大吸附量分別為24.78、23.14及6.94 mg/g，RL值介於0.0474 至0.1025間，因此可知此吸附作用是屬於有利吸附。氧化實驗結果顯示，過硫酸鹽濃度越高，TCE、苯及MTBE去除所需時間越短。竹炭結合過硫酸鹽之批次實驗結果顯示，雙系統可增進TCE、苯及MTBE之去除。竹炭結合過硫酸鹽雙系統中MTBE降解副產物甲酸第三丁基酯(tert-butyl formate, TBF)及第三丁基醇(tert-butyl alcohol, TBA)之生成量較少，顯示將竹炭添加於過硫酸鹽系統中，可提供一定的吸附能力，有效降低MTBE降解副產物之濃度。自由基鑑定結果顯示，在過硫酸鹽系統及竹炭結合過硫酸鹽雙系統中，同時存在硫酸根自由基及氫氧自由基。不同過硫酸鹽濃度對現地微生物及TCE降解之影響實驗結果顯示，添加1、2、3及5%之過硫酸鹽氧化劑對現地微生物生長抑制影響不大。研究結果顯示，竹炭之添加可增進污染物去除。建議未來應用於現地整治時，可以整治牆方式進行吸附/氧化雙系統整治，或初期先以竹炭吸附污染物達到吸附飽和後，再添加氧化劑進行處理，以有效整治受污染之地下水。現地試驗結果顯示，未灌注過硫酸鹽前，P143及P146兩口井之TCE濃度分別為0.264 及0.361 mg/L，總菌落數分別為6.1 × 103及4.4 × 104 CFU/mL。不同灌注程序(一次全量灌藥及兩次平均灌藥)結果顯示，5%過硫酸鹽可將P143 (兩次平均灌藥)及P146 (一次全量灌藥)井中之TCE降解至濃度低於地下水第二類管制標準(< 0.05 mg/L)，但隨著井中過硫酸鹽濃度消耗後，TCE濃度慢慢回升，其原因可能為上游污染持續進入試驗區所致。在過硫酸鹽灌注後傳輸擴散距離方面，在P146之過硫酸鹽可擴散至P145，距離為4.5公尺；P144距離為4公尺至TW-38，距離為3.6公尺。5%過硫酸鹽最長可於地下水層中維持14天。灌藥後第二天，P143及P146之總菌落數分別為2.4 × 103及1.8 × 103 CFU/mL，略呈下降之趨勢。當過硫酸鹽濃度降低時，總菌落數有回復之趨勢。現地試驗結果顯示，一次全量灌藥方式可維持過硫酸鈉於地下水中的持久性，增進三氯乙烯之整治效率。本研究之成果將可提供相關受污染場址進行整治之參考。

關鍵字

三氯乙烯；苯；甲基第三丁基醚；竹炭；過硫酸鹽；自由基

並列摘要

In this study, the treatment of gasoline and chlorinated organic-contaminated groundwater using bamboo charcoal coupled with persulfate oxidation was evaluated. The main objectives of this study were to: (1) evaluate the adsorption capacity of bamboo charcoal for trichloroethylene (TCE), benzene, and methyl tert-butyl ether (MTBE) and the adsorption kinetics and mechanism of the contaminant removal by bamboo charcoal bamboo charcoal coupled with persulfate and the removal kinetics of the contaminants；(2) evaluate the feasibility of TCE removal by persulfate , bamboo charcoal coupled with persulfate in aqueous phase and slurry – phase system；(3) evaluate the EPR free radical identification by persulfate concentration and bamboo charcoal coupled with persulfate system；(4) different persulfate oxidation processes to remediate TCE contaminated groundwater；(5) evaluate the persistence of persulfate in the aquifer and determine the radius of influence (ROI) of persulfate delivery；(6) assess the impacts of persulfate on indigenous microorganisms and site conditions; and (7) evaluate the variations of in situ bacterial community and groups during remediation. Results of the batch adsorption experiments show TCE , benzene and MTBE removal efficiency increased with increasing charcoal dosage. TCE,benzene and MTBE adsorption onto charcoal fit well with the pseudo-second- order model . Results of the Isothermal adsorption model simulation show TCE , benzene and MTBE on adsorption compare to Langmuir isotherm , indicating the monolayer of organic compound contaminated onto the adsorbent. The highest adsorption capacities of bamboo charcoal for TCE , benzene , and MTBE were 6.94、24.8 and 23.1 mg/g , RL = 0.0474 to 0.1025 , that this adsorption is a favorable adsorption. Results of the oxidation experiments show that TCE , benzene and MTBE degradation rates were positively related to persulfate concentrations. Results of this study show that it is feasible to remediate TCE , benzene and MTBE –contaminated using bamboo charcoal coupled with persulfate oxidation. Results of Test shows TCE concentrations and microbial numbers in Wells P143 and P146 were 0.264 and 0.361 mg/L, and 6.1 × 103 and 4.4 × 104 CFU/ mL, respectively, before persulfate was injected. The results from the pilot study show that TCE could be removed effectively by one-stage and two-stage injection of 5% persulfate. However, TCE concentrations rebounded after persulfate was consumed, probably due to the transport of TCE from the upgradient area. The ROI of persulfate injection ranged from 3.6 to 4.5 m. In addition, it was observed that persulfate persisted for 14 days in the aquifer. After persulfate was injected, the total bacterial counts in P143 and P146 slightly decreased to 2.4 × 103 and 1.8× 103 CFU/ mL, respectively, while total dsDNA decreased significantly. When persulfate was consumed, the numbers of total bacterial counts and dsDNA were recovered. The results reveal that one-stage injection would enhance the persistence of persulfate and the removal of TCE in the subsurface.