Collaborative Research: Exploration of the Interplay between Contaminant Partitioning and Biotransformation in Multiphase Porous Media

旨在清理被非水相液体污染的含水层的生物技术经常产生多种降解产物，这些降解产物可能代表或可能不代表对人类健康构成的风险的总体减少。 了解这些降解产物在多相地下环境中的命运和运输是至关重要的，因为人们有兴趣应用生物强化溶解来修复受氯化溶剂非水溶性液体污染的场地。 评估生物降解产物在多流体地下环境中的归宿和迁移需要了解物理、化学和生物过程之间的相互作用。 这种相互作用的中心是影响污染物命运的降解产物的生物利用度。 生物利用度受到多相地下环境中活跃的传质过程动力学的影响。 本研究整合了实验室实验和数学模型，探讨相间传质动力学如何影响含氯乙烯的NAPL源区的生物降解和降解产物积累速率。 具体目标是：（1）确定氯乙烯非水相液体可逆地隔离顺式二氯乙烯和氯乙烯的能力，（2）研究这些降解产物在含有氯乙烯非水相液体的非均质多孔介质中的传质速率，（3）了解这些过程在野外规模、生物活性、非水相液体源区的意义。从这项研究中获得的知识将增加对地下环境中母体和子体产品生物利用度的理解。 此外，定量描述之间的复杂的相互作用的传质和生物转化率将补充正在进行的努力，在其他实验室，旨在评估氯乙烯抑制参与代谢还原脱氯的微生物物种的水平。 对含有非均质分布的非水相污染物的地层中的质量转移和生物转化的耦合速率进行描述，最终将能够更准确地评估生物修复技术在地下水净化中的应用。该研究项目促进了多个学术层次的教育，并为在塔夫茨大学和美国空军学院工作的学生提供了一个独特的合作环境。 研究正在通过以下方式融入本科生的经历：（1）与拟议研究目标直接相关的本科生研究项目;（2）发展以研究为基础的模型引出活动（MEA），以便在本科工程课程中实施，以及（3）通过美国空军学院的教育中心，对科罗拉多斯普林斯和波士顿大都市地区的高中生进行宣传卓越和通过塔夫茨中心工程教育推广。

Biological technologies aimed at cleaning up aquifers contaminated by nonaqueous phase liquids (NAPLs) frequently produce multiple degradation products which may or may not represent an overall reduction of the risk posed to human health. Understanding the fate and transport of these degradation products within a multiphase subsurface environment is critical given the interest in applying bioenhanced dissolution for remediation of sites contaminated by chlorinated solvent NAPLs. Assessing the fate and transport of biological degradation products in multifluid subsurface environments requires knowledge of the interplay between physical, chemical, and biological processes. At the center of this interplay is bioavailability of degradation products influencing contaminant fate. Bioavailability is influenced by the kinetics of mass transfer processes active in multiphase subsurface environments. This research project integrates laboratory experiments and mathematical modeling to explore how kinetics of interphase mass transfer influences rates of biodegradation and degradation product accumulation in NAPL source zones containing chloroethenes. Specific objectives are: (1) identify the capacity of chloroethene NAPLs to reversibly sequester cis-dichloroethene and vinyl chloride, (2) investigate the rates of mass transfer of these degradation products within heterogeneous porous media containing chloroethene NAPLs, and (3) understand the significance of these processes in the context of field-scale, bioactive, NAPL source zones.Intellectual Merit: Knowledge gained from this research will increase the understanding of parent and daughter products bioavailability within subsurface environments. In addition, quantitative descriptions of the complex interplay between the rates of mass transfer and biotransformation will complement ongoing efforts in other laboratories that are aimed at assessing the levels at which chloroethenes inhibit the microbial species involved in metabolic reductive dechlorination. Implementation of the developed descriptions for the coupled rates of mass transfer and biotransformation within formations containing heterogeneously distributed NAPL will ultimately enable more accurate assessment of the application of bioremediation technologies for groundwater clean-up.Broader Impacts: The research project fosters education at a number of academic levels, and provides a unique collaborative environment for training of students working at both Tufts and the U.S. Air Force Academy. Research is being integrated into the undergraduate experience through: (1) undergraduate research projects directly related to the goals of the proposed research; (2) the development of research-based model-eliciting activities (MEAs) for implementation within undergraduate engineering curricula, and (3) outreach to high school students in the Colorado Springs and Boston metropolitan areas implemented through the US Air Force Academy's Center for Educational Excellence and through the Tufts Center for Engineering Education Outreach.