Quantitative Predictions of Phase Behavior and Mass Transfer for Complex Mixed Wastes

许多受污染的场所涉及非水相液体(NAPL)污染物，这些污染物是有机化合物的复杂混合物。目前描述地下系统中NAPL污染物的方法不能充分考虑污染物成分的空间和时间变化。一个经常被忽视但重要的考虑因素是，NAPL通常含有在环境温度下以纯固体形式存在的化合物，并且可能随着NAPL组成的变化而固化。这一现象可能会对地下环境中某些复杂混合物的长期命运产生重大影响，并对风险评估和清理行动的决定产生相关影响。该项目将多组分相平衡的热力学与孔道尺度的计算模型相结合，以研究地下环境中复杂的、混合废物的NAPL的命运。主要目标是：(1)进行实验室实验，研究孔尺度和柱尺度下的相行为、传质和NAPL固化。(2)建立了多组分污染物在多相多孔介质中的流动、行为和传质的组成孔隙尺度数值模型。(3)利用实验室和计算结果进行风险评估计算，以估计与复杂混合物NAPL相关的长期风险，以及NAPL组件固化的影响。本项目侧重于含有多环芳烃(PAHs)的NAPL，因为它们作为环境污染物很重要，其复杂的多组分性质需要采用成分方法，以及潜在相变的重要性。为了在实验研究中最大限度地提高推理能力，使用了一种新的实验室方法，该方法涉及合成的多环芳烃-NAPLS作为环境污染物的代表性但表征良好的替代物。

9805376CeliaMany contaminated sites involve non-aqueous-phase liquid (NAPL) pollutants that are complex mixtures of organic compounds. Current methods for describing NAPL contaminants in subsurface systems do not adequately account for spatial and temporal variations in contaminant compositions. An often-overlooked but important consideration is that NAPLs often contain compound that is solids in their pure forms at ambient temperatures, and which may solidify as the NAPL composition changes. This phenomenon may have a significant impact on the long-term fate of some complex-mixture NAPLs in the subsurface environment, with associated implications for risk assessment and decisions on clean-up actions. This project couples the thermodynamics of multicomponent phase equilibria with pore-scale computational models to investigate the fate of complex, mixed-waste NAPLs in subsurface environments. The major objectives are: (1) Perform laboratory experiments to investigate phase behavior, mass transfer and NAPL solidification at the pore scale and column scale. (2) Develop a compositional pore-scale numerical model to simulate fluid flow, behavior, and mass transfer for multicomponent contaminants in multi-phase porous media. (3) Perform risk assessment calculations using the laboratory and computational results to estimate long-term risks associated with complex-mixture NAPLs, and the effects of solidification of NAPL components. This projects focuses on NAPLs containing polycyclic aromatic hydrocarbons (PAHs), because of their importance as environmental contaminants, their complex multicomponent nature which necessitates a compositional approach, and the importance of potential phase transformations. To maximize inference ability in experimental investigations, a novel laboratory procedure is used which involves synthetic PAH-NAPLs to serve as representative yet well-characterized surrogates for environments contaminants.