以不同氧化劑結合生物復育法處理受柴油污染土壤之研究

Treatment of diesel-contaminated soil by different oxidants coupled with bioremediation

邱婉婷(Wan-Ting Chiou)

指導教授 ： 陳谷汎

國立暨南國際大學/科技學院/土木工程學系/碩士(2011年)

https://doi.org/10.6837/NCNU.2011.00198

摘要

近年來，石化產品汽油、柴油及其他化學成品等高污染性的有機化合物在儲存和運輸方面十分頻繁，而造成環境污染之事件層出不窮，對於生態環境所造成的影響甚鉅。本研究利用化學氧化法結合生物復育法整治受油品污染場址，並藉由分子生物技術評估各種氧化劑對降解污染物之優勢菌種是否造成不利之影響。在本研究中，我們選擇一受總石油碳氫化合物(主要為柴油)污染之場址為研究對象(TPH大約4,000 mg/kg)，針對過硫酸鈉、過錳酸鉀及過氧化氫氧化法對油品之去除效率，不同氧化劑對現地微生物數量及族群變化之影響進行評估，期能發展一迅速且有效之結合性整治方法。實驗結果顯示，現地微生物確實有降解柴油之能力，且營養鹽的添加有助於促進柴油之降解。在不同濃度氧化劑(1%，3%，5%，10%之過硫酸鈉、過錳酸鉀、過氧化氫)添加之柴油降解試驗中，可發現三種氧化劑皆可有效降解柴油。添加低濃度氧化劑時(1%)，對現地微生物生長之影響較小。當過硫酸鈉濃度高於3%時，微生物數量明顯降低；當過硫酸鈉濃度達10%時，所有現地微生物皆會死亡，其原因應為 pH下降所致。過錳酸鉀低濃度的添加雖對現地微生物之生長抑制較不明顯，但隨過錳酸鉀濃度添加增高，實驗過程中總菌落數生長較慢，推測可能為過錳酸鉀產生之副產物阻礙土壤中物質之傳輸，及初始氧化劑濃度提高影響微生物之生長。過氧化氫實驗組別結果顯示，1%過氧化氫在添加初期不會造成總菌落數下降，當過氧化氫濃度達10%時，所有現地微生物皆會死亡。實驗結果顯示，在低濃度氧化劑存在時，微生物的生長狀況較佳，微生物的數量增加亦顯示，在有氧化劑的條件下，微生物可能利用柴油或柴油之降解副產物為碳源生長。因此，柴油濃度之下降可能為化學氧化劑及微生物共同作用所致。
菌相分析結果顯示，約有13株菌與柴油之降解有關。隨著氧化劑濃度增高，多數現地微生物皆會被破壞，使得菌相趨為單調。此結果顯示，在高濃度氧化劑添加下，具耐受氧化劑能力之微生物為總菌落數貢獻之主要來源。因此，在化學氧化系統中，總菌落數的增加並非意味著所有可降解柴油之優勢菌群數量的增加。研究成果顯示，在化學整治成效與對現地土壤中之菌相最小擾動之考量下，建議氧化劑的添加劑量為1%至3%；若要縮短整治時程則建議以5%劑量之添加，惟使用過硫酸鹽時，需考慮pH之控制。在氧化劑逐漸消耗後期，建議添加營養鹽以利後續生物復育之進行。本研究成果將有助於設計一套迅速且有效之整合性整治方法，提供受石油碳氫化合物污染場址整治之用。

關鍵字

柴油 ； 過硫酸鹽 ； 過錳酸鉀 ； 過氧化氫 ； 生物復育法 ； 化學氧化法 ； 分子生物技術

並列摘要

Contamination of soil and groundwater by petroleum hydrocarbons has become a serious and widespread environmental problem. In this study, persulfate, permanganate, and hydrogen peroxide oxidation coupled with bioremediation was applied to remediate a diesel-contaminated site (TPH = 4,000 mg/kg). Additionally, molecular biotechnology was used to evaluate possible adverse effects of persulfate, permanganate, and hydrogen peroxide on predominant in situ microorganisms.
Results show that indigenous microorganisms were capable of degrading diesel. In addition, diesel removal was enhanced with the addition of nutrient solutions. Concentrations of diesel could be decreased effectively by different oxidants under various concentrations (1%, 3%, 5% and 10% of the selected oxidants). The experimental results show that the addition of 1% oxidants had fewer adverse effects on the growth of in situ microorganisms. When the concentrations of persulfate reached 3%, the total counts of in situ bacteria were significantly decreased. The death of all of the in situ microorganisms was observed because of low pH values under 10% of persulfate addition. Although the inhibition of bacterial growth was less in the permanganate oxidation system, the decrease of the total bacteria counts was also observed with increased permanganate concentrations. This might be caused by the decrease of substrate transport due to the production of MnO2 or higher initial concentrions of permanganate. The growth of in situ microorganisms was not inhibited with the addition of 1% hydrogen peroxide. However, the application of 10% hydrogen peroxide resulted in the death of all of the in situ microorganisms. The results reveal that the growth of microorganisms was better under lower oxidant concentrations. Moreover, the increase of microorganisms with the presence of oxidants indicates that in situ microorganisms might use diesel or the oxidating byproducts of diesel as carbon sources to support their growth. Therefore, the removal of diesel could result from the contributions of both chemical oxidation and biodegradation.
Results of PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) analysis show that a total of 13 predominant strains could relate to the biodegradation of diesel. Most of the in situ microorganism species were destroyed with the increased oxidant concentrations. This indicates that under high oxidant concentrations, the numbers of bacteria were mainly contributed by the microorganisms, which were tolerant to the oxidants. Thus, the increase of the bacteria counts in chemical oxidation systems does not indicate the increase of the predominant diesel-degrading bacteria. The results obtained from this study suggest that 1% to 3% of oxidant addition was more suitable for the simataneuos occurrence of chemical oxidation and biodegradation. The addition of 3% or 5% oxidants could also be considered to shorten the remediation process of the combined systems. However, pH should be controlled while persulfate is applied. Furthermore, nutrients could be added to enhance bioremediation after the concentrations of the oxidants become lower. Results of this study will be helpful in designing practical systems using chemical oxidation coupled with bioremediation to remediate petroleum hydrocarbon-contaminated sites.

並列關鍵字

Diesel ； persulfate ； permanganate ； hydrogen peroxide ； bioremediation ； chemical oxidation ； molecular biotechnology

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