本研究採樣於疑似受TCE污染場址之現地土壤，由批次實驗探討現地土壤原生菌或額外添加甲苯分解菌（Pseudomonas putida F1）時，在好氧環境下，以甲苯為誘導基質，生物降解袪除地下水中三氯乙烯（Trichloroethylene, TCE）和氯乙烯（Vinyl chloride, VC）的可行性與降解機制。此外，以生物刺激的方式，利用土壤管柱模擬建構於地下飽和含水層之生物反應牆，探討應用現地土壤原生菌，整治受TCE和VC污染之地下水的可行性。 批次實驗結果發現，當添加100 mg/L甲苯於土壤原生菌時，TCE袪除率可達87％，驗證土壤原生菌可以甲苯為生長基質，產生甲苯加氧酵素，以好氧共代謝的方式袪除TCE。此外，P. putida F1對甲苯與TCE的降解率，均高於土壤原生菌，當添加100 mg/L甲苯時，P. putida F1對TCE共代謝袪除率可提升至94％。然而，若將P. putida F1植種至土壤中，P. putida F1會與土壤原生菌相互競爭甲苯基質，導致影響降解效果，TCE的降解率下降至89％。另一方面，當土壤原生菌以VC為唯一碳源時，可直接好氧降解VC，其降解率約為60％，此外，本研究實驗結果亦發現，在土壤原生菌降解VC的同時，若提供50和100 mg/L的甲苯，對VC降解率的提升並沒有明顯的幫助，顯示土壤原生菌無法以甲苯為基質，以好氧共代謝的方式祛除VC，至於是否有其他合適之好氧共代謝基質，可被土壤原生菌利用於代謝VC，仍需進一步驗證。 土壤管柱實驗主要包括三部分，（1）土壤原生菌管柱好氧直接氧化VC，（2）土壤原生菌管柱好氧共代謝TCE和（3）外添加P. putida F1之土壤管柱好氧共代謝TCE。在管柱操作0~20天，由於甲苯加氧酵素不足或微生物代謝活性低，使得各管柱均發生污染物貫穿現象，且污染物的生物袪除作用主要發生在管柱前端，同時，隨著操作時間的增加，污染物貫穿至出流端的濃度遞減。當管柱操作至30天時，管柱前端5cm處，對污染物的袪除率均可達99％以上，顯示管柱前端進入操作穩定期，此時生物降解作用最為旺盛。此外，在TCE與VC的好氧降解過程中，並未觀察到其他含氯中間產物的生成或累積。 The biodegradation and removal of trichloroethylene (TCE) and vinyl chloride (VC) in groundwater under aerobic condition by indigenous soil cells and toluene-degrading cell (Pseudomonas putida F1) were investigated in this study. A series of batch experiments using toluene as co-substrate to induce toluene dioxygenase (TDO) for co-metabolizing of TCE and VC were carried out. In addition, bioremediation of TCE and VC in contaminated saturated aquifer were studied by laboratory scale column tests, which were designed to simulate the bio-barriers under the conditions of enhancing activity of in-situ soil cells by bio-stimulation. Batch experimental results showed that the indigenous soil cells and P. putida F1 could effectively co-metabolize TCE with 100 mg/L toluene added and the removal efficiency of TCE was 87% and 94%, respectively. However, when P. putida F1 seeded to soil, the TCE removal efficiency decreased from 94% to 89% due to the competition for toluene between P. putida F1 and indigenous soil cells. Additionally, indigenous soil cells could utilize VC as a sole carbon source and the removal efficiency of VC was around 60%. It also found that the supplement of exogenous primary substrate, e.g. toluene, did not increase the degradation of VC in this study. Thus, further studies are needed to figure out if any other compatible co-substrate could enhance the co-metabolize degradation of VC by indigenous cells. Soil column tests included (1) indigenous soil column for aerobic oxidation of VC, (2) indigenous soil column for aerobic co-metabolism of TCE and (3) indigenous soil column with adding P. putida F1 for TCE co-metabolism. The test results indicated that TCE and VC would breakthrough along the columns during the initial start up period due to the lack of induced toluene dioxygenase or the low activity of microorganisms. Moreover, the dominant biodegradation occurred in the front end of the column after 20 days of operation. It observed that the concentrations of TCE and VC in the column effluent decreased with the increase of the operation time. The removal efficiencies of TCE and VC were greater than 99% after 30 days of operation. As a result, the soil columns could effectively biodegrade the contaminants when the growth of microorganisms approached to steady phase. In addition, no other chlorinated byproducts were detected while TCE and VC were biodegraded.
