本研究係將滲透性反應牆設置於電動力復育受砷污染土壤系統中，探討滲透性反應牆對於提昇電動力處理效率之影響。電動力試驗主要分為管柱試驗及三維模場試驗兩部分，首先以直徑為4.2 cm，長為12 cm之管柱試驗探討反應牆設置位置與材質、操作流質及電位坡降之影響，再以36 (L) ×18 (W) ×18 (H) cm之三維模場進行處理時間及增加碳棒接觸面積、電位坡降及反應基材用量之影響，以模擬現地污染整治之情形，作為未來現地污染整治之參考；反應牆係由反應基材及渥太華砂以1：2之重量比混合組成，反應基材則為商用性零價鐵(Fe(0)C)、自製零價鐵(Fe(0)M)、商用性氧化氫氧化鐵(FeOOHC)及自製氧化氫氧化鐵(FeOOHM)；操作流質為地下水、EDTA、檸檬酸及界面活性劑等。
實驗結果顯示，滲透性反應牆之設置會降低電動力系統之電滲透係數(Ke)，然可有效提昇去除效率。於管柱試驗中，未設置反應牆之對照組其五價砷去除率僅為26.78-26.91%，當設置滲透性反應牆後，土壤之去除率可提昇至43.89-70.25%。其整體之電滲透係數Ke 為4.30-12.61×10-6 cm2/V-s，電力耗損為105.13-464.87 kWh/m3。以零價鐵作為反應基材時，反應後之土壤pH 有明顯偏中性較一般單獨採用電動力進行時為不同，而陽極端收集到之砷濃度較高顯示砷於系統中受離子遷移之影響較為明顯。
至於三維模場試驗，單獨進行電動力時，去除率僅有27.76%，電滲透係數Ke 為3.30-5.39×10-6 cm2/V-s，電力耗損量為1724.81 kWh/m3，總處理成本為9583 元/m3，然經增加處理時間、碳棒接觸面積、電位坡降及反應基材用量時，的確能有效提昇去除率至45.11-71.22%(約1.63-2.56倍)，而電力耗損量為1312.84-1963.70 kWh/m3(約0.76-1.14倍)，然總處理成本卻增加至24800-57730 元/m3(約2.59-6.02倍)。經研究證實於電動復育技術中設置滲透性反應牆確實能有效提昇去除效率，但於電力耗損及總處理成本亦會隨之增加。
然探討經電動力處理後之土壤鍵結型態發現，反應牆之設置可使反應牆後端土壤中之鐵錳氧化態、有機態及殘留態轉變成較易處理之交換態及碳酸鹽鍵結型態，且隨反應時間之增加其轉換率越高，最高可達72.5%，但於反應牆前端之鍵結型態發現仍為鐵錳氧化態為主，且所佔比率相當穩定約為61.6-81.6%，整體實驗結果顯示，反應牆之設置對於電動力復育技術有相當明顯之貢獻，應用得當即可有效將砷與土壤之主要鍵結型態由較不易去除之鐵錳氧化態轉變成較易去除之交換態及碳酸鹽鍵結態。
由整體結果顯示，單獨使用電動力系統處理時其主要去除機制係為電動力系統所產生之移除作用，然當以電動力-滲透性反應牆系統進行處理砷污染土壤時，其主要處理機制即為反應基材之吸附作用，而零價鐵於反應過程中之氧化還原作用在此系統中並無明顯之影響。

This research was aimed to investigate the enhancement of electrokinetic (EK) remediation arsenate-contaminated soil by permeable reaction barrier (PRB). All experiments, which experimental parameters included the position, materials, and quantity of PRB, processing fluid types, potential gradients, and treatment time, were conducted in two types of EK systems. One was Pyrex glass cylindrical cells with dimension of 4.2 cm (ψ) × 12 cm (L) and the other was a small pilot-scale modulus with dimension of 36cm (L) ×18cm (W) ×18cm cm (H). The PRBs were composed of four kinds of reaction materials, which included commercial zero valent iron (Fe(0)C), manufactured zero valent iron (Fe(0)M), commercial hydrous ferric oxide (FeOOHC), and manufactured hydrous ferric oxide (FeOOHM), mixed with ottawa sand in a ratio of 1:2,respectively, and installed in the anode, middle, and cathode side of the EK systems.

For 5-day EK cylindrical cell tests, the results showed that the PRB installation would result in a lower electroosmosis permeability (Ke) and a higher removal efficiency of arsenate. The arsenate removal efficiency of EK system with PRB was in the range of 43.89-70.25%, which was 1.5~2.6 times greater than that without PRB, and the value of Ke was in the range of 4.30-12.61×10-6 cm2/V-s. The soil pH after EK/PRB treatment was much closer to natural and more arsenate was collected in the anode reservoir. Moreover, the remediation performance of FeOOHC as PRB materials was much better than other materials.

For EK pilot-scale modulus tests, it was shown that the removal efficiency of arsenate was effectively enhanced as improved experimental parameters and, however, led to increase the treatment cost. In EK modulus without PRB, the removal efficiency of arsenate, elctroosmosis permeability, and energy consumption were 27.76%, 3.30-5.39×10-6 cm2/V-s, and 1724.81 kWh/m3, respectively. Furthermore, the treatment cost was NT 9583/m3. As increasing treatment time, graphite electrode, potential gradient, and quantity of PRB materials, the removal efficiency of arsenate increased to as high as 45.11-71.22% and the treatment cost also increased up to NT 24,800-57,730/m3.

As investigated the binding form of arsenate with soil after EK/PRB treatment, it was found that the arsenate –soil binding forms of Fe-Mn oxide bound, organically bound, and residual in the soil section behind the PRB were much easier transformed to the forms of exchangeable and carbonate bound. The transformation rate reached as high as 72.5% and it increased with treatment time. However, the Fe-Mn oxide bound was still the main binding form, 61.6-81.6%, in the soil section prior to the PRB. The removal mechanism of arsenate contaminated soil remediation was dominated by electromigration, electrolysis, and electroosmosis in EK system without PRB. And, in EK/PRB system, the removal of arsenate from soil was mainly resulted from adsorption rather than redox reaction by PRB.

To sum up, the PRB can effectively enhance the electrokinetic remediation of arsenate contaminated soil by choosing the right PRB materials and operation parameters.

第一章 前言
1.1 研究緣起----------------------------------------------1
1.2 研究目的----------------------------------------------3
1.3 研究內容----------------------------------------------3
第二章 文獻回顧
2.1 砷之化學特性------------------------------------------5
2.1.1 砷之來源--------------------------------------------7
2.1.2 砷對人體及環境之危害--------------------------------7
2.1.3 地下環境之砷污染情形--------------------------------9
2.1.4 重金屬與土壤介質之結合型態-------------------------13
2.2 受重金屬污染土壤之復育技術---------------------------16
2.3 砷污染之處理技術-------------------------------------18
2.4 電動力處理技術---------------------------------------21
2.4.1 電動力法之去除機制.--------------------------------25
2.4.2 電動力法之影響因子. -------------------------------26
2.4.3 電動力法之應用.------------------------------------29
2.5 滲透性反應牆處理技術---------------------------------42
2.5.1 滲透性反應牆之處理機制.----------------------------43
2.5.2 現地應用情況.--------------------------------------47
2.5.3 反應牆材質.----------------------------------------54
2.6 電動力法及滲透性反應牆組合技術.----------------------58
第三章 實驗材料與方法
3.1 研究架構---------------------------------------------64
3.2 實驗材料及設備---------------------------------------67
3.2.1 土壤樣品來源及前處理---------------------------67
3.2.2 試藥及材料-------------------------------------67
3.2.3 電動力法-滲透性反應牆處理系統------------------68
3.2.4 分析儀器---------------------------------------74
3.3 反應牆設計參數---------------------------------------74
3.4 實驗方法---------------------------------------------74
3.4.1 人工氧化氫氧化鐵配製---------------------------74
3.4.2 人工污染土樣配製及填裝-------------------------75
3.4.3 地下水水質資料---------------------------------76
3.5 分析方法.--------------------------------------------76
3.5.1 土壤基本性質分析-------------------------------76
3.5.2 土壤中五價砷之分析方法-------------------------81
3.5.3 液相砷與反應基材之反應動力行為-----------------81
3.5.4 土壤之砷鍵結型態分析---------------------------82
3.6 實驗之品保品管(QA/QC) -------------------------------84
3.7 實驗分析及監測---------------------------------------85
3.7.1 分析項目---------------------------------------85
3.7.2 監測項目---------------------------------------86
第四章 結果與討論----------------------------------------87
4.1 土壤基本性質分析-------------------------------------87
4.2 反應基材之特性分析.----------------------------------88
4.3 液相砷與反應材質之反應動力行為..---------------------92
4.4 電動力-滲透性反應牆管柱處理系統.---------------------96
4.4.1 反應牆材質及設置位置之影響..-------------------96
4.4.2 操作流質及電位坡降之影響.---------------------101
4.4.3 最適操作條件評析.-----------------------------104
4.5 電動力-滲透性反應牆三維模場處理系統.----------------107
4.5.1 處理時間之影響..------------------------------107
4.5.2 碳棒接觸面積、電位坡降及鐵粉量之影響.---------127
4.5.3 更換操作流質頻率之影響.-----------------------145
4.6 反應系統處理機制之探討.-----------------------------158
4.7 處理後土壤之砷鍵結型態分析.-------------------------161
4.8 經濟效益分析.---------------------------------------168
第五章 結論與建議..-------------------------------------171
第六章 參考文獻.----------------------------------------176

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