- 期刊
啟電為力，以動致淨－電動力技術及結合氧化電極整治土壤污染之研究
Promotion of Electrical Force to Make a Clean Environment-Studies of the Electrokinetic Process Coupled with Oxidation Electrodes for Soil Remediation
摘要
目前電動力技術應用於低滲透性土壤復育最具有效性，因提供地下環境驅動力，使污染物於土相移除加速移動性，其主要優點為：（1）可產生均勻之電滲透流於異質且低滲透性之土壤介質中 移動、（2）可有效控制電滲透之流向、（3）高移除效率且具安全性、（4）在參數設計下為一種高經濟效益之現地處理技術。該技術可直接應用於地下污染整治，配合電極種類與操作流質可有效將污染物降解或移除；另該技術亦可利用產生之驅動力，控制灌注藥劑等傳輸方向，使其往污染熱區移動，以克服污染物及整治試劑無法準確投藥解決病灶之問題。污染物/整治試劑傳輸行為，亦可於地下環境中將有機污染物降解，本文章整理五個電動力技術應用案例，涵括重金屬、苯系有機物、含氯有機物及藥品與個人保健用品之處理，以及藉由電動力場加速生物製劑傳輸。結果顯示電動力技術不但適用於重金屬污染土壤，藉由使用雙金屬氧化電極亦可處理有機及含氯有機物之污染土壤，並可同時處理有機與重金屬複合污染之土壤，且電動力技術可提升生物製劑傳輸速度4.6倍以上。目前實驗室規模試驗電動力參數之探討已漸趨成熟，未來應用於實場可有效預測整治期程，掌握整治進度。此技術將為一可控制傳輸方向、傳輸快速、節省成本之整治效能提升現地整治技術選擇。
並列摘要
1. Introduction Electrokinetic (EK) remediation is an in-situ technology that has already proven its value in contaminated fine-grain soils. Basically, the EK technique relies on the action of an electric field generated between inserted inert electrodes in a medium by applying a direct current or a constant voltage. The low-level direct current is used as the cleaning agent, and its several advantages include: (1) providing an electroosmosis flow to transport in a low permeable matrix, (2) effective control of transport direction and elecroosmosis flow, (3) safety as well as high removal and degradation efficiency, and (4) economy benefits related to in-situ technology. EK remediation can also be coupled with other technologies, i.e., bioremediation and in-situ chemical oxidation, to facilitate the transportation of chemicals, shorten remediation period, and reduce costs. Five case studies of EK remediation were reviewed in this study. The target pollutants included heavy metals, the benzene group, chlorinated compounds, and pharmaceuticals and personal care products (PPCPs). The experiments were partly conducted in a lab-scale EK system and partly in a pilot-scale EK system. The remediation efficiency and residual profiles of the pollutants were investigated. 2. Materials and Methods The chemicals investigated included cooper, lead, chromium, zinc, nickel, pentachlorobenzene, Ibuprofen (IBP), benzene, and EOS (a type of commercial biological agent). A pilot-scale EK system of 0.5 m × 1.0 m × 0.7 m was investigated for copper-contaminated soil, and lab-scale EK systems were investigated in four other studies. The selection of the processing fluid in the EK system depends on the characteristics of the investigated chemicals because the procession fluid must be soluble with chemicals. The oxidation electrodes applied in the EK system include RuO_2/Ti (RT), Pd/Ti (PT), Pb+Co/Ti (PCT), and Fe/Al. EOS is a common agent applied for biological remediation of chlorinated compounds. This study was focused on the transportation performance of the EK process. The remaining four studies were focused on remediation performance. 3. Results and Discussion For the heavy metal-contaminated soil, the remediation efficiency of Zn, Cu, Pb, Cr, and Zn was as high as 88.6%, 84.4%, 99.5%, 89.0%, and 77.0%, respectively, as found in the pilot-scale EK system. Among the oxidation electrodes, the PT electrode exhibited the best remediation of pentachlorobenzene (57.16% for a 5-day treatment with sodium dodecyl sulfonate [SDS, an anionic surfactant] used as the processing fluid). A significant degradation effect was demonstrated. A cheaper oxidation electrode, Fe/Al, was applied for remediation of IBP-contaminated soil. Treatment efficiency as high as 94.6% was achieved. The processing fluid, treatment time, electrode area, and addition of oxidant were the factors dominating the remediation performance. In the case of the EK system coupled with an Fe/Al electrode, successful remediation was shown in soil co-contaminated with benzene and cooper. It is worth mentioning that contaminant migration from the deeper to shallow layers was found. Using the EK process, the electroosmosis permeability of the EOS in the soil was enhanced 4.6 times, which indicated that the remediation time could be significantly shortened. 4. Conclusions The EK process was confirmed to successfully remediate heavy metals and organic chemicals. Coupled with oxidation electrodes, the EK process was able to further degrade organic chemicals. Other than achieving good remediation performance, the EK process can also be coupled with bio-remediation to enhance transportation of biological agents and shorten remediation time. Making good use of the EK process could result in a cleaner environment.