EPSCoR: Investigating NAPL Source Removal From Low Permeable Silt Layers

本研究的总体重点是研究非饱和条件下低渗透淤泥层中非水相液体（NAPL）污染的行为和增强去除。淤泥层也将采用低温加热，并确定其对污染物去除的影响。将采用综合方法来调查这一问题，包括实验室实验、现场数据和数学建模。一个独特的大型（10'x14'x 8'）最先进的物理地下水将用于中试规模的实验。柱实验将用于测量热导率作为水分含量的函数。现有的温度数据从我们的博士生的现场将建模和用于规模的电力需求，为大规模的坦克实验。最后，将进行传热传质的数学建模，并将其应用于实验室数据，以便更好地理解所涉及的过程。低渗透多孔介质中的NAPL污染仍然是地下水污染的一个重要的长期来源，目前的修复策略仍然无法解决。在非饱和区，土壤蒸汽提取（SVE）是一种常见的原位修复技术，但对于低渗透层的NAPL污染场地，SVE是一种能源密集型、昂贵且效果较差的修复技术。被动式SVE是一种相对较新的创新修复技术，它利用大气压力的变化从土壤中泵出气体，而不依赖于电力。这种低成本技术适用于传质率低的场所，例如在低渗透介质中，以及健康和环境风险不会迫在眉睫的地方。与其他加热技术相比，使用可再生技术的低温加热提供了低成本、更可持续的地下加热解决方案。这个想法是加热地下，这样从低渗透性层到更渗透性层的质量传递就会增强。结合另一种低成本的方法，如被动SVE，该技术可以大大提高污染物的去除。低温加热还可以大大增强受热层中的生物活性，从而增强污染物的降解。使用可再生能源供暖提供间歇性加热，这可能是有利的，因为它将导致较少的土壤干燥。如果促进生物降解是目的，干燥土壤可能会破坏目的。所提出的实验和模型研究的智力价值在于，它将有助于更好地理解粉土层中NAPL源去除和NAPL传质。此外，还将确定淤泥介质在不同含水饱和度下的传热。将可再生技术应用于场地修复是一种有趣的可能性，需要进一步探索。

0229147 Hayden The overall focus of this research is to investigate the behavior, and enhanced removal of a nonaqueous phase liquid (NAPL) contamination from low permeable silt layers under unsaturated conditions. Low temperature heating will also be employed in the silt layer and the effect of this on contaminant removal will be determined. A comprehensive approach to investigating this problem including laboratory experiments, field data and mathematical modeling will be used. A unique large-scale (10'x14'x 8') state-of-the-art physical groundwater will be used for pilot-scale experiments. Column experiments will be used for measuring thermal conductivity as a function of moisture content. Existing temperature data from our doctoral student's field site will be modeled and used to size the power requirements for the large-scale tank experiments. Finally, mathematical modeling of heat and mass transfer will be performed and applied to the laboratory data in order to better understand the processes involved. NAPL contamination in low permeable porous media is still a significant long-term source of groundwater contamination that continues to defy current remediation strategies. In the unsaturated zone, soil vapor extraction (SVE) is a common in-situ remediation technique, but it is energy intensive, expensive and less effective for sites where the NAPL contamination is residing in low permeable layers. Passive SVE is a relatively new, innovative remediation technology that utilizes changes in barometric pressure to pump gas from the soil and does not rely on electricity. This low cost technique is useful at sites where rates of mass transfer are low, such as in low permeable media, and where health and environmental risk are not imminent. Low temperature heating using renewable technologies offers a low cost, and more sustainable solution to the idea of heating the subsurface than other heating technologies. The idea is to heat the subsurface such that mass transfer from the low permeable layers to more permeable layers is enhanced. In combination with another low cost method, such as passive SVE, this technique could greatly enhance the removal of the contaminants. Low temperature heating could also greatly enhance the biological activity in the heated layer thereby enhancing the degradation of the contaminants. Heating using renewable energy sources provides intermittent heating, which may be advantageous in that it will result in less drying of the soil. Drying the soil may defeat the purpose if enhancing biological degradation is the aim. The intellectual merit of the experimental and modeling research proposed is that it will lead to a better understanding of NAPL source removal and NAPL mass transfer from silt layers. In addition, heat transfer through silt media at different water saturations will also be determined.The application of renewable technologies to site remediation is an intriguing possibility that needs to be explored further.