跳到主要內容 :::

年度	108	專案性質	實驗性質
專案類別	模場試驗	研究主題	整治
申請機構	國立高雄師範大學	申請系所	生物科技系(所)
專案主持人	陳士賢	職等/職稱	教授
專案中文名稱	以超高溶氧奈米氣泡水強化現地生物整治技術試驗計畫
中文關鍵字	超高溶氧奈米氣泡水,現地生物復育技術,石化污染場址
專案英文名稱	Field Study of Enhanced Bioremediation by Injection of Water Saturated with Nano – scale Oxygen Bubbles
英文關鍵字	Nano – scale Oxygen Bubbles,Enhanced Bioremediation,PetroChemical Contaminated Site
執行金額	1,200,000元
執行期間	2018/1/10 至 2019/11/30
計畫中文摘要	本研究目的為開發一新穎現地好氧生物整治技術，應用奈米氣泡顆粒小、持續時間較長的特性，利用水力控制使氣泡通過微小的土壤間隙，使微生物可獲得氧氣，透過奈米氣泡配合抽、注井場，提升地下水中的溶氧，刺激地下環境中的微生物在好氧環境下分解石化污染物，另一方面也突破目前氣提法(air sparging)中曝氣影響半徑不足的問題，開發出一新穎之本土化的石化場址現地生物整治技術。 研究主要分為實驗室試驗以及污染場址模場試驗等二個部份，實驗室試驗區分為管柱與砂箱試驗等二個部份以收集操作參數，透過觀察奈米氣泡水的傳輸情況，了解高濃度溶氧停滯及消散之情形，同時建立系統操作參數基線資訊、監測技術與方法。模場試驗則是選取高雄市大社工業區中的某石化污染場址進行技術試驗，設計抽、注井場與循環井場，利用模場試驗方法，建立與發展超高濃度溶氧奈米泡水現地生物整治技術的操作參數與方法，開發一完整之新穎整治技術，提升我國土壤及地下水污染整治技術水平。 管柱實驗顯示飽和溶氧水垂直狀態下之溶氧較不易消散。以高濃度氣體溶解裝置循環製造高溶氧水，製程時間選擇為30分鐘，溶氧濃度大於40.9 mg/L，而高溶氧水在開放與密閉系統中的溶氧量皆維持在一定濃度，長期觀察20天後溶氧無顯著差異。高溶氧水之水平管柱實驗顯示，注水後之24小時溶氧劇烈減少，從27 mg/L降至10 mg/L，但此後溶氧減少即趨於和緩，在歷經120小時後高溶氧水仍能維持原溶氧之80%以上。高溶氧水在垂直管柱中傳輸亦會造成溶氧損失，注入水經滯留時間24小時後溶氧劇烈減少，從27 mg/L降至9 mg/L，但此後溶氧減少即趨於和緩，滯留時間120小時後所偵測的溶氧值8.54 mg/L，仍是高於常溫飽和溶氧水。以長60公分、寬51公分、高65公分之砂箱進行傳輸試驗，砂箱每15公分處放入一支篩管，各篩管在第一天之溶氧降低最多，在96小時後，溶氧僅剩原始之40%，第四天至第十六天其溶氧減少呈現趨緩，且從距離對應天數來看，不同距離之溶氧量消散速度不同。 本計畫之裝置、監測井及注水井於2018年8月建置完成並且完成試車，而於2018年9月7日進行土壤及地下水採樣並建立該模場之基線資料。模場區域土壤採樣點位編號分別為S1、S2及S3，每個樣點採樣深度為4至6公尺，每50公分為一單位。土壤之酸鹼值約介於6.54至7.72，平均為7.40，氨氮約為0.018－0.027%，平均為0.015%；磷約為241－444 mg/kg，平均為390 mg/kg。6個樣本之菌相Shannon-Wiener多樣性指標是介於6.91－7.11之間，其中以樣點S2深度4－5 m與5－6 m的土壤之菌相多樣性最高，樣點S3深度4－5 m的土壤最低。比較3個採樣點土壤中菌相差異，S2樣點土壤中平均觀察菌種數與不同深度間差異高於S1與S3樣點，且S2樣點土壤中菌相多樣性亦高於S1與S3樣點。地下水採樣點位編號分別為GW1、GW2、GW3、MW1及MW2，本場址之地下水水位為2.07－2.33米，而溫度、酸鹼值及溶氧均差異不大，應為同一區域之水源，故其數值較為相近，ORP之檢測數據則為-2.30－84.4 mV，EC之測值則為435 µs/cm。5個樣本之菌相Shannon-Wiener多樣性指標是介於4.94與6.74之間，其中以GW3的菌相多樣性最高，MW2次之，MW1最低。比較注入井與監測井菌相之差異，注入井平均觀察菌種數與組間差異高於監測井，且注入井菌相多樣性亦高於監測井。 模場試驗於2018年10月8日開始進行高溶氧水注入試驗，此階段分為三個月進行，第一個月每日注水8小時，灌注量為每日2.4 m3，第二個月開始每日注水12小時，灌注量為每日3.6 m3；2018年12月12日開始進行每日注水時間為24小時不間斷注水，灌注量為每日7.2 m3；整體而言MW2在採用8 hr/day、12 hr/day間歇注入頻率中，溶氧上升幅度較小；而在連續24小時注入高溶氧水後，MW2之溶氧有大幅度的提升，然而後續因考量24小時持續灌注高溶氧水可能會造成菌相稀釋效應，故於2019年06月18日開始調整每日注水時間為12小時。 本計畫建立環境指標，對比灌注一年期間前後的目標污染物檢測數據可得知，經過一年的注水後，苯的濃度從最初基線調查之198－266 mg/L降至ND－15.1 mg/L，而在基線建立中超過地下水管制標準之乙苯，其濃度也從最高5398 mg/L降至1.25－639 mg/L，而甲苯、苯乙烯在採樣中大多未檢出，雖然苯及乙苯仍超過地下水管制標準，但經過這一年的試驗，污染物濃度已大幅下降，在五個井位均呈現此趨勢，但乙苯及苯仍具高濃度，尤其乙苯仍是主要污染物，在地下水樣品中常有純相出現，至於污染物濃度大幅下降是灌注水稀釋或生物降解作用旺盛何者貢獻較多甚難判斷。 本計畫完成建立現場微生物指標，無論是任一口監測井所採集之地下水，其細菌物種數皆隨著持續加入高溶氧水後逐漸增加，特別是MW1監測井，其地下水中細菌物種數增加速度與數量皆高於MW2監測井，可能是MW1監測井較靠近於注入井GW1 (相距0.3 m)而能獲得較多之氧氣所致。菌相分析顯示同時加入高溶氧水可能促進同一類型菌種大量生長，而使得兩口監測井地下水中菌相差異度減小。石化污染物降解菌添加試驗，污染物濃度仍呈現下降，在五個井位均呈現此趨勢。在技術應用的可行性上，本研究立基於水力控制方法，因此只要水文地質環境適宜，便可以應用本研究所發展之技術。 目前奈米氣泡水於土壤及地下水污染整治之研究於國內外應用亟少，本計畫為一創新性之研究，期望可透過本研究之成果，擴大奈米氣泡水於我國土壤及地下水污染整治工作的應用。
計畫英文摘要	Microbubble (MBs) and nanobubble (NBs) technologies have drawn great attention due to their frequent applications in water treatment, biomedical engineering, and nanomaterials in recent years. In particular, the focuses were on degradation of toxic compounds, water disinfection, and cleaning/defouling of solid surfaces including membrane from environmental aspects. The main purpose of water pretreatment is to reduce biological, chemical and physical loads in order to reduce the running costs and increase the treated water quality. In this context, air MBs/NBs as a pretreatment means has been shown to be highly beneficial for downsizing the water/wastewater treatment plants and improving the quality of product water. Use of oxygen NBs has been anticipated due to their extremely high bioactivity and mass transfer efficiency. It is reasonable to consider that NBs would have great potential implication in soil and groundwater remediation. Hence, the objective of this study is to develop the use of NBs in petroleum hydrocarbon contaminated site to facilitate and enhance bioremediation processes. Laboratory experiments were conducted to investigate flow of discrete microbubbles through a water-saturated porous medium by column and sand box experiments in the first year study. NBs was release from a diffuser, move upward through a column filled with packed soil. Outflowing bubbles were collected for flux measurements. The scaling behaviors between the gas (bubble) release rates and various characteristic parameters of the bubble plume, including plume tip velocity, plume width, and breakthrough time of the plume front will be quantified. The experiments also revealed circulations of ambient pore water induced by the bubble flow. The results of column experiments indicated that loss of dissolved oxygen (DO) in air-saturated water was about 1 mg/L after 72 hours. After 120 hour of retention time in the packed column, DO loss in air-saturated water was about 1.90 mg/L. Vertical columns tended to retain oxygen for longer time than horizontal one. Dissolved oxygen was measured to be 40.9 mg/L after nano-scale oxygen bubble was produced for 30 min. Longer exposure time did not significantly increase the level of DO. DO depletion was not observed in either open or closed system after 20 days when dissolved oxygen level in the water was raised by nano scale bubble. Dramatic depletion of DO from 27 mg/L to 10 mg/L was observed in the first 24 hours of the column experiment. After the time period, the depletion was slow down. After 120 hours, DO was maintained higher than saturated water of room temperature. Forty percent of DO depletion was observed after 96 hours in the sand box experiment. However, the depletion was slower between 4 to 16 days. Field study was conducted since August 2018. Test zone with injection and extraction ewellls were designed and employed in a petroleum hydrocarbon contaminated site in Kaohsiung. Injection of NBs was conducted in the test zone with three injection wells and two monitoring wells. Injection of high DO water was 8 hours per day in the first month. It was increased to 12 hours per day in the second months. Finally, continuous injection of 24 hours was performed. After the long term practice, injection of high DO water of 12 hours was recommended because the whole day injection of high DO water may potentially dilute the dissolved phase contaminants and dilute the populations of microorganisms in the subsurface environment. Grondwater monitoring of pH, dissolved oxygen, nutrients and change of population/diversity of microorganisms was performed. Retention time of NBs, concentration of dissolved oxygen, and change of petroleum degrading bacteria species was observed monthly. After the one year injection practice of high DO water, the apparent concentrations of target contaminants were declined. Benzene was reduced from 198 to 266 mg/L to not detectable to 15.1 mg/L. Though concentration of ethylbenzene in groundwater decreased from 5398 mg/L to 1.25-639 mg/L, it remained the major contaminant. The degradation mechanism is unclear due to potential impact of dilution of groundwater by injection or high rate of biodegradation. It is anticipated that functions of enhanced bioremediation can be achieved through injection and circulation of NBs by field practices. The results of microorganism diversity indicated that bacteria species tended to increase with long term injection of high DO water. Petroleum-degrading bacteria (Enterobacter tabaci) was applied in the site for enhanced bioremediation. The concentrations of target contaminants were decreased. This study serves as a leading project for future investigations to employ nanobubbles in the field of soil and groundwater remediation.