以近實場規模之現地電動力技術整治鉛汙染農地之研究

本研究以近實場規模之循環式電動力法(circulation-enhanced electrokinetics, CEEK)整治南投市某處鉛污染農地，經過63天污染整治處理後，其污染土壤中的鉛去除率約達64%，平均土壤鉛濃度可從7,246 mg kg^(-1)降至約2,612 mg kg^(-1)。本CEEK系統針對1.0 m^2的鉛污染土壤，每去除1%鉛污染所需要的操作電費約為9.83元。整治期間及整治後，土壤的pH值及導電度皆維持在中性及穩定的狀態，其顯示本系統對土壤環境的低衝擊性。經由本電動力整治方法處理後的土壤肥力略降，需要添加適當肥料方能回復肥力。在63天不同晴雨天氣下，本系統電流及電壓維持在穩定的狀態。同時，本系統溫度接近操作當天的大氣氣溫（介於20~30°C），呈現本系統極佳的穩定性。唯CEEK的木製不透水渠道日益變形，造成操作液體積的變異，且無法重複使用；但此渠道經改良後已為密閉式不透水渠道，同時可降低循環操作液受天氣的影響，亦可於整治後重複再使用，以利未來節省實際工程上的初設成本。

關鍵字

鉛污染土壤；電動力法；實場整治

並列摘要

Soil contamination is one of the major environmental issues in the many developed countries, and contamination with heavy metals poses a direct threat to the effective utilization of agricultural land in Taiwan. There is thus a need to develop fast and effective remediation processes for use with contaminated agricultural land, with in-situ model remediation tests being an important part of this. A number of works have applied electrokinetics to the removal of heavy metal contaminants from the soil, with successful results. However, the test samples of contaminated soil in these studies were all manually prepared and on a laboratory scale. When it comes to practical applications in the field, there are still many problems that need to be noted and overcome. This study applies Circulation-Enhanced Electrokinetics (CEEK) on the near-real scale to clean lead contaminated soil in Nantou City, Taiwan. The operational solution concentration of 0.01 M EDTA-2Na and 0.01 M Na_2CO_3 was used in this experiment. The initial experimental conditions were set according to the previously optimum parameters, including a total current of about 10 A, neutral pH, 20% moisture content in the soil and the use of a certain amount of chelating agent. During this experiment, the variations in the pH value and lead concentration in the both the soil and operational solution were measured, and this data was analyzed to obtain the lead mass balance. Moreover, the sample was also examined to measure the operational solution pH, moisture content and current at certain time intervals. The data obtained in this way were then used to assess the removal efficiency with regard to lend contamination, and the operating cost of the CEEK process. After 63 days of treatment, the following conclusions were obtained. The lead removal efficiency was close to 64%, and the average lead concentration decreased from 7,246 mg kg^(-1) to 2,612 mg kg^(-1). The operational cost of electricity for removal is 9.83 NT dollars per 1% lead in an area of 1.0 m^2. The pH and electrical conductivity of the soil were maintained in a neutral and stable conditions, an indication that the CEEK process has little impact on soils. The fertility of the treated soil was slightly less than that of the untreated soils, and thus additional fertilizer was necessary. If further improvements can be made to the CEEK system, then this could make the electrokinetics technique more attractive to potential users. The results show that the use of a closed and non-infiltrated channel for the CEEK can help reduce the effects of effect and problem of deformation over long-term operations, meaning that the channel can be reused, thus reducing costs. The electrical current and voltage can be maintained in a stable condition, and thus the CEEK process is very stable. In addition, the temperature of the operational solution is close to the atmospheric temperature.

並列關鍵字

lead contaminated soil ； electrokinetics ； in-situ remediation

國際替代計量

以近實場規模之現地電動力技術整治鉛汙染農地之研究

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