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年度	112	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	國立中山大學	申請系所	環境工程研究所
專案主持人	高志明	職等/職稱	教授
專案中文名稱	應用綠色化學及生物吸附劑整治氟化物污染場址：技術開發及現地模場試驗
中文關鍵字	地下水污染, 氟化物, 綠色吸附劑, 生物吸附, 現地整治
專案英文名稱	Application of innovative chemical and biological sorption adsorbents to cleanup fluoride-contaminated groundwater: Technology development and pilot-scale studies
英文關鍵字	Groundwater contamination, fluoride, adsorbent, biosorption, in situ remediation
執行金額
執行期間	2022/9/1 至 2024/8/31
計畫中文摘要	地下水中氟鹽(fluoride)污染主要源自地質礦物溶解釋出及工業廢水貯存洩漏，攝取過量則會導致骨骼及神經等方面疾病。因此，現地長效化學及生物吸附工法為經濟可行且環境友善的綠色整治方式，可有效在被動及低成本模式下達到場址整治及風險管控目標。本計畫主要目標為：(1)開發創新之長效氟化物化學及生物吸附技術；(2)建立所開發技術的理論和反應機制；及(3)將所開發的技術予以模組及實場化，達到氟化物污染場址整治目標。主要工作為：(1)開發鎂基改質綠色吸附劑(包括造粒骨材及微米粉材)；以不同環境變因進行氟化物吸附試驗以及吸附動力計畫，以評估對氟化物吸附效益；(2)由氟化物污染場址篩選可有效生物吸附氟化物之菌株，利用分子生物技術進行菌種鑑定，並評估此菌株針對氟化物之生物吸附機制及影響因子；(3)針對所製備之化學吸附劑開發現地應用技術及針對所篩選分離之生物吸附菌株開發固定化製備技術，以達到實場應用目標；(4)選定一受氟化物污染場址進行現地試驗，評估化學及生物吸附技術實場應用之效益及長效性；(5)利用分子生物技術進行菌量及菌相分析，建立氟化物場址生化代謝及特徵基因和優勢菌之變化圖譜；及(6)吸附劑再生試驗及成本效益評估。本計畫第一階段(第一年)工作包括：(1)利用批次試驗進行綠色吸附劑(鎂基改質吸附劑製備)、物化特性測試(包括粒徑、界達電位、比表面積、表面微觀型態、晶相)，並利用吸附動力試驗評估吸附機制及吸附效益；(2)利用批次試驗針對製備之綠色化學吸附劑進行吸附影響因子評估；(3)耐氟化物及生物吸附氟化物菌株之分離篩選、菌種鑑定及生化特性分析，並利用膠體固定技術進行菌株之固定化製備；(4)以固定化菌株進行氟化物生物吸附試驗；及(5)利用次世代定序分析及即時定量聚合酶連鎖反應進行菌量及菌相分析，建立生化代謝及特徵基因和優勢菌之變化圖譜。第二階段工作(第二年)工作包括：(1)選擇一處受氟化物污染場址進行背景調查及資料收集；(2)以整治牆概念設置三口整治井(間距 2-5 m，與地下水流向垂直)及上游一口背景監測井和下游二口監測井；(3)現地模場試驗分兩個階段(化學及生物)進行驗證，主要將吸附材料填裝至可回收的多孔吸附袋中並置入整治井中，以最佳的操作參數進行模場應用；及 (4)進行操作最佳化以及成本效益評估。本計畫成果將使氟化物污染場址整治成為一種更具經濟效益且突破傳統設計框架之綠色整治工法，符合現地、風險管理及生物復育之永續整治設計概念，以達到優化及提升氟化物污染地下水整治效率之目的。 第一年工作之主要成果包括：(1)完成兩種改質氧化鎂材料(GA-MgO及SM-MgO)，並鑑定其特性，包含比表面積為市售氧化鎂的50倍(201.8 m2/g及 215.6 m2/g)，且皆具備中孔結構，能提高對污染物的吸附性能；(2) 以GA-MgO及SM-MgO進行對氟鹽的吸附批次試驗，由吸附模式說明具有化學吸附機制，並由變異數分析說明較佳的投藥劑量(GA-MgO: 1.6 g/L；SM-MgO: 1.2 g/L)；(3)由調整初始酸鹼值結果證明兩種氧化鎂吸附材料在水體pH值範圍為2-10時，能保有良好的吸附效能，另外在共存陰離子試驗中得到結果，說明兩種材料在水中僅受碳酸根離子及磷酸根離子影響，且陰離子濃度需達1.0 mM才會有顯著影響，說明兩種材料在現地使用時有較佳適應性及應用性；(4)由氟鹽污染場址篩出4種耐氟菌株，包含有Bacillus subtilis、Paenibacillus sp.、Terribacillus goriensis、Bacillus aryabhattai。這四株菌株經實驗結果得知可在含50 ppm氟化物的培養基中生長；(5)在耐氟菌株去除氟鹽的試驗中，當水中氟鹽濃度控制於與現地環境相近時(5、10 mg/L)，去除效率最高約可達42%；(6)經材料配比試驗已確認可以使用四乙氧基矽烷取代四甲氧基矽烷來製作固定菌株的矽膠顆粒，能有效降低藥劑製作成本，且顆粒型態可維持約210天，應可用於地下水環境使用；(7) 已於高雄軟體園區完成現地模場的場勘及設置，共設置3口2吋注藥井及2口1吋監測井，後續由實驗室試驗成果，規劃模場試驗方法並實際投入現地試驗場地進行測試。 第二年度之主要成果包括：(1)混合微生物菌株在氟化物濃度在5-10 mg/L時，微生物保有相當高之存活率(5 mg/L: 2.67E+08 CFU/mL；1.80E+08 CFU/mL)，而當氟化物濃度在大於25 mg/L時，微生物總菌數則有降低趨勢；(2)鈣及磷兩種鹽類為重要的控制因素，添加進行微生物菌株培養有最高的氟化物去除率(83%)，水中氟化物濃度可從8.0 mg/L降至1.4 mg/L。(3) 結合改質氧化鈣材料與混合菌群與初始濃度為100 mg/L氟化物透過材料利用化學吸附/沉澱將氟化物降至10.1 mg/L，後續配合微生物誘導沉澱，最終能達到98%(1.4 mg/L)去除成效，遠低於地下水管制標準(8 mg/L)。(4)經由二次現地小型注藥試驗結果得知，利用GA-MgO及SM-MgO進行水中氟鹽去除具有顯著去除成效，其中GA-MgO具長效整治功效可緩衝水體pH值升高(pH可控制於7-8之間)及濁度干擾，而SM-MgO具顆粒小、水體易傳輸特性，可針對污染熱區達到即時氟鹽去除能力；因此，以GA-MgO及SM-MgO進行地下水氟鹽污染整治具有實場應用潛力。(4)本計畫已進行兩次模場試驗，分別以15 kg之GA-MgO及 9 kg之SM-MgO灌注於模場設置的三口注藥井(IW-1、IW-2、IW-3)，並在下游監測井(MW1、MW2)進行監測評估。(5)由現地氟鹽濃度變化結果，在GA-MgO灌注後的3天可有效將下游區域的氟鹽濃度降至地下水監測標準(4.0 mg/L)以下，而SM-MgO灌注後的24小時時可達到同樣的效果。(6)由模場測試結果可知，以GA-MgO作為現地的整治及控制藥劑，其控制效能約可維持14天以上，並可將下游區域氟鹽濃度維持在5 mg/L以下，目前仍持續監測其整治效益。以SM-MgO則可作為緊急應變藥劑，具快速處理及良好傳輸性。模場試驗結果顯示，本計畫所開發之改質氧化鎂材料可有效控制氟鹽污染地下水，降低其對下游造成之風險並有效處理氟化物。
計畫英文摘要	Fluoride pollution in groundwater mainly comes from the interpretation of geological minerals and the leakage of industrial wastewater storage. Ingestion of 0.5-1.5 mg/L of fluoride is beneficial to teeth and bone health, while excessive intake will lead to bone and nerve diseases. The use of adsorption and precipitation mechanisms for remediation of groundwater pollution by fluoride salts has considerable advantages in cost, operation, and removal efficiency. The goals of this study will include: (1) development of innovative and long-lasting chemical and biological adsorption techniques, (2) establishment of the fluoride removal theories and mechanisms using the developed methods, (3) modularization and industrialization of the developed remedial system. The main tasks will contain the followings: (1) design and development of the Mg-based (MgO) adsorbents (granulated magnesium oxide aggregates and surface- modified magnesium oxide powder) and conduction of adsorption experiments under different environmental conditions and performance evaluation (2) isolation of fluoride biosorption bacteria from a fluoride-contaminated site, conduction of bacteria identification processes, and evaluation of the biosorption mechanisms, (3) development and design methods for field application, and development of bacterial solidification/immobilization techniques using colloidal materials to enhance the treatment efficiency, (4) selection of a fluoride-contaminated groundwater site for a pilot-scale study and conduction of a performance evaluation, (5) use molecular biotechnology to analyze the bacterial count and bacterial phase, and establish a map of biochemical metabolism, characteristic genes and dominant bacteria at the fluoride site; and (6) adsorbent regeneration test and cost-benefit evaluation. During the first year of the two-year study, the following tasks will be performed: (1) conduction of a bench- scale study for Mg-based adsorbents development, evaluation of characteristics, adsorption mechanisms, and treatment efficiency of adsorbents, and conduction of the adsorption tests to determine the influence factors; (2) conduction of the column study to evaluate the adsorption efficiency of the adsorbents, and determination of the stability of the adsorbed fluoride; (3) isolation and identification of the fluoride-enduring bacteria for fluoride adsorption, and application of the bacterial solidification/immobilization technique for isolated bacteria immobilization using colloidal materials; (4) conduction of the biosorption tests using the immobilized bacteria, conduction of the column study to evaluate the effectiveness of the fluoride adsorption using immobilized bacteria, and (5) conduction of the bacterial diversity using the next generation sequencing technique. The second-year tasks will include: (1) site investigation of the selected site; (2) design of the barrier system for fluoride removal, and installation of three remediation wells (one background and two downgradient monitor wells); (3) conduction of the pilot-scale study, which will contain two stages: the first stage will be the test of chemical adsorption and adsorbents will be installed into the remediation wells, and the second- stage will be the biosorption stage and immobilized bacteria will be installed into the wells for fluoride removal; (4) molecular biology techniques will be applied to analyze the microbial diversity to obtain the metabolic routes of fluoride reduction; and (5) conduction of adsorbent regeneration experiments and cost and performance evaluation. The proposed treatment scheme would be expected to provide a more cost-effective alternative to remediate fluoride-contaminated aquifers. The results of this research can clarify the mechanism of fluoride chemical and biological precipitation, and develop a green fluoride remediation system to optimize and improve the efficiency of fluoride- contaminated groundwater remediation. The results of this research will make the remediation of fluoride-contaminated sites a green remediation method that is more economical and breaks through the traditional design framework, in line with the sustainable remediation design concepts of on-site, risk management and biological restoration. Results from the first-year study include the following: (1) Completed the synthesis of two modified magnesium oxide materials (GA-MgO and SM-MgO) and characterized their properties, with a surface area 50 times higher than commercial magnesium oxide (201.8 m2/g and 215.6 m2/g). Both materials exhibit a mesoporous structure, enhancing their adsorption capacity for pollutants. (2) Conducted batch adsorption tests using GA-MgO and SM-MgO for fluoride ions, demonstrating a chemical adsorption mechanism through adsorption models. The optimal dosages were determined through variance analysis (GA-MgO: 1.6 g/L; SM-MgO: 1.2 g/L). (3) Adjusted the initial pH values to show that both magnesium oxide adsorbents maintain good adsorption efficiency in the pH range of 2 to 10 in water. Coexistence tests with anions indicated that the materials are only affected by carbonate and phosphate ions at a concentration of 1.0 mM, indicating better adaptability and applicability for field use. (4) Isolated four fluoride-resistant bacterial strains from the fluoride-contaminated site, including Bacillus subtilis, Paenibacillus sp., Terribacillus goriensis, and Bacillus aryabhattai. These strains were found to grow in culture media containing 50 ppm fluoride. (5) In the fluoride removal experiment using the fluoride-resistant bacterial strains, the highest removal efficiency was approximately 42% when the fluoride concentration in the water was controlled to be similar to the local environment (5 and 10 mg/L). (6) Through material ratio experiments, it has been confirmed that tetraethoxysilane can replace tetramethoxysilane in producing silica gel particles to immobilize bacterial strains. This substitution effectively reduces the production cost of the reagents, and the particle morphology can be maintained for about 210 days, making it suitable for use in groundwater environments. (7) Completed on-site investigation and setup of a pilot field at the Kaohsiung Software Park, which includes three 2-inch injection wells and two 1-inch monitoring wells. Subsequently, based on laboratory test results, a pilot test method will be developed and implemented at the field site for further testing. The main achievements of the second year include: (1) Mixed microbial strains demonstrated high survival rates at fluoride concentrations of 5-10 mg/L (5 mg/L: 2.67E+08 CFU/mL; 10 mg/L: 1.80E+08 CFU/mL). However, when fluoride concentrations exceeded 25 mg/L, there was a tendency for the total microbial count to decrease; (2) Calcium and phosphorus salts were identified as crucial control factors, with the highest fluoride removal rate of 83% achieved through their addition during microbial culture, reducing fluoride concentration from 8.0 mg/L to 1.4 mg/L; (3) Combining modified calcium oxide materials with a mixed microbial consortium at an initial fluoride concentration of 100 mg/L, chemical adsorption/precipitation reduced fluoride to 10.1 mg/L, with microbial-induced precipitation achieving a final removal rate of 98% (1.4 mg/L), far below the groundwater control standard of 8 mg/L; (4) Results from two small-scale in-situ injection tests showed significant fluoride removal using GA-MgO and SM-MgO. GA-MgO provided long-term remediation, buffering the rise in water pH (controlled between pH 7-8) and reducing turbidity interference, while SM-MgO, with its small particle size and easy transportability in water, provided rapid fluoride removal in hot spots, showing potential for field applications in groundwater fluoride contamination remediation; (5) Two model field tests were conducted, with 15 kg of GA-MgO and 9 kg of SM-MgO injected into three injection wells (IW-1, IW-2, IW-3) at the model site, and downstream monitoring wells (MW1, MW2) used for evaluation; (6) Field fluoride concentration results showed that three days after GA-MgO injection, fluoride concentrations downstream dropped effectively below the groundwater monitoring standard (4.0 mg/L), and SM-MgO achieved similar results within 24 hours. (7) Model field tests indicated that GA-MgO, used as an on-site remediation and control agent, maintained control effectiveness for over 14 days, keeping downstream fluoride concentrations below 5 mg/L, with monitoring ongoing to assess its remediation benefits. SM-MgO demonstrated fast processing and good transportability, making it suitable as an emergency response agent. Results from the model tests confirmed that the modified magnesium oxide materials developed in this project can effectively control groundwater fluoride contamination, reducing downstream risks and efficiently treating fluoride pollution.