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題 名 | Modeling the Rebounding of Contaminant Concentrations in Subsurface Gaseous Phase during Intermittent Soil Vapor Extraction Operation |
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作 者 | Wang, Mei-Sheue; Wu, Shian-Chee; Kuo, Chun-Wei; | 書刊名 | Journal of Environmental Engineering and Management |
卷 期 | 17:1 2007.01[民96.01] |
頁 次 | 頁11-19 |
分類號 | 434.22 |
關鍵詞 | Rebounding; Soil vapor extraction; Volatile organic compound; Mass transfer; Stagnant region; |
語 文 | 英文(English) |
英文摘要 | Soil vapor extraction (SVE) process for contaminated soil remediation often shows a tailing of the breakthrough concentration in the contaminant plume and rebounding of gaseous phase concentration after a pause of the extraction operation. These phenomena are believed to have something to do with the limitation of mass transfer between mobile fluid and some stagnant aggregates or clay lens. An advection-diffusion mass transport model in unsaturated soil with the consideration of diffusive mass transfer between the mobile regions and the immobile regions was adopted to simulate the rebounding of gaseous phase concentrations of some volatile organic compounds (VOCs). Experimental results of apiolot scale SVE showed that after being lowered to one-tenth of the initial concentration levels, concentrations of VOCs in the monitoring well rebounded significantly up to about 20% of the initial concentrations again. Model simulation could explain the rebounding phenomenon and fit the data well by only adjusting the volume fraction of the immobile regions, the average radius of the aggregates and the standard deviation of the logarithmic mass transfer coefficient. The model will be able to assist the designing of the SVE system and operational strategy, and the prediction of the performance of the clean-up action. |
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