To explore the technical skills of MTBE which is degradable underground

[[abstract]]臺灣地下儲槽的洩漏物質主要為成品汽柴油，其中汽油中含有的苯(Benzene)、甲苯(Toluene)、乙苯(Ethylbenzene)、二甲苯(m.p-Xylene、o-Xylene)以及為了增加辛烷值而添加的甲基第三丁基醚(MTBE)，這些物質於水中的溶解度高，故一旦發生洩漏，很容易隨著地下水而傳播，造成地下水汙染，成為整治時最棘手的問題。對於部分正經營中之工商場址(如加油站、生產工廠)或是不易及時進行工程作為的待清理 (Clean up)場所，採行現地處理，特別是生物處理工技有其重要性。有鑑於此，如何開發出一套符合現場需求、節能、環保的整治方式，有效解決這類易隨地下水文波動的汙染物，便成為相當重要的課題。因考量在受有機物汙染的地下環境中，常會在現地誘發生長出能利用該有機物的微生物菌群，然而往往受限於地下環境氧氣不易傳輸的事實，缺乏最終的電子接受者而限縮了現地原生微生物降解有機汙染物的速率，進而造成汙染物的殘留、蓄積而汙染土壤。故本研究以生物刺激的方式，加速現地微生物的降解反應，先以瓶杯試驗，針對可降解MTBE的現地微生物進行優厚培養，加強生物降解MTBE的能力並進行生物刺機條件研就透過微型試驗方式，以受MTBE與BTEX汙染之場址(MB場址)及僅有MTBE汙染之場址(M場址)兩個不同場址的現地地下水為基質，進行不同營養源配方的生物刺激實驗，針對頑強化合物MTBE進行個別探討，結果發現場址特性的影響，對MTBE降解是很關鍵的，在MB場址中，不論是否添加生物刺激營養源，對於地下水中原先就存在的BTEX都有很好的降解效率，但MB場址對於MTBE的降解效果無顯著提升；M場址中僅存在MTBE汙染物，但觀察到MTBE可在實驗後6~14天內幾乎完全降解，轉化率達99%，並且證明此為微生物降解反應。最後將實驗所的結果，應用至某儲油場之汽油污染場址，先由污染情況調查，找出BTEX及MTBE污染團塊，並針對BTEX存在區域，配合實驗室的綠色複方灌注進行生物刺激，施用綠色複方後，苯濃度從一開始的0.1 mg/L降解至0.03 mg/L，而甲苯、乙苯、二甲苯均降至低於偵測極限，同時由下游MTBE污染團塊部份，灌注調整溶氧複方，刺激生物反應，使整個場址的MTBE濃度從3mg/L降解至約0.2 mg/L。本研究的放大作業模式，歸納一個策略性的生物刺激手段，透過適當的監控與複方調配現地生物刺激，可有效控制地下水汽油汙染對環境的衝擊。[[abstract]]The leaking substances of the underground storage tanks in the gas station were usually gasoline and diesel. Benzene, Toluene, Ethylbenzene, m.p-Xylene, o-Xylene (BTEX) and methyl tert-butyl ether (MTBE) were the main components in gasoline. In particular, these compounds were dissolved in water easily, therefore, they also could be transferred into groundwater easily when the underground storage tanks leaked. How to remove these compounds from groundwater was a very important issue.In this study, the bio-stimulation was proposed for increasing the degradation of these contamination in groundwater. The microorganism source of the bio-stimulating nutrient agent for the bio-stimulation was obtained from the MTBE contaminated groundwater. Two contaminated groundwater were selected as test sites to evaluate the efficiency of the bio-stimulation, one site was contaminated by MTBE only (M sample) and another one was contaminated by BTEX and MTBE (MB sample). The results show the characteristic of the contaminated was the most important factor for the MTBE removal efficiency. In the MB sample, whether or not to add the bio-stimulating nutrient agent, we could observed the high removal rate of the BTEX, but it was not effective for the MTBE degradation. On the other hand, in the M sample, 99% MTBE was degraded around 6 – 14 days, it means that MTBE could be degraded by some especial microorganism in specific environment. Finally, this bio-stimulating nutrient agent was used in the actual gasoline contaminated site. The benzene concentration was reduced from 0.1 mg/L to 0.03 mg/L, and the concentration of toluene, ethylbenzene and Xylene were reduce to below detection limit. In particular, MTBE concentration was reduce from 3 mg/L to 0.2 mg/L. It was confirm the feasibility of bio-stimulation for degrading the BTEX and MTBE in the contaminated groundwater