Collaborative Research: A Multiscale Analysis of Chemotactic Bacteria Transport in Heterogeneous Porous Media

合作研究：异质多孔介质中趋化细菌传输的多尺度分析

• 批准号: 1141400
• 负责人: Roseanne Ford
• 金额: $ 30.3万
• 依托单位: University of Virginia Main Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-02-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1141400&HistoricalAwards=false
• 关键词: Collaborative; Research; Multiscale; Analysis; Chemotactic

COLLABORATIVE RESEARCH: A MULTISCALE ANALYSIS OF THE TRANSPORT OF CHEMOTACTIC BACTERIA IN HETEROGENEOUS POROUS MEDIARoseanne M. Ford Department of Chemical Engineering, University of VirginiaBrian D. Wood School of Chemical, Biological, and Environmental Engineering, Oregon State UniversityChemotaxis is the ability of motile bacteria to sense chemical concentration gradients in their local surroundings and swim toward higher concentrations of pollutants that they degrade. In the subsurface, bioremediation is often hindered by the inability to achieve good mixing between injected substances and the resident contaminants. In such situations, chemotaxis might be exploited to enhance the mixing of bacterial populations within contaminated zones. The goal of this study is to connect direct experimental measurement of chemotaxis in physically and chemically heterogeneous porous media with appropriate mechanistic descriptive theory. Two main hypotheses will be used to organize the research effort. They will combine both (a) multiscale experimental observations, and (b) a multiscale upscaling analysis to develop a theoretical framework that can describe chemotaxis in chemically and physically heterogenous media at microscopic and macroscopic scales. The first hypotheses is that in porous media with trapped sources of nonaqueous phase liquid (NAPL) pollutants, chemotactic bacteria will have measurably slower transport than non-chemotactic bacteria. In particular, chemotactic bacteria will exhibit greater retardation and tailing than will non-chemotactic mutants because of selective trapping of chemotactic bacteria at the fluid-NAPL interfaces. The second hypothesis is that transport of bacteria under chemotactic versus non-chemotactic conditions are dramatically different in the presence of large-scale heterogeneities. Although chemotaxis is inherently a pore-scale process, the net influence of chemotactic bacteria on transport from high to low conductivity regions of a heterogeneous medium will be experimentally measurable, and will have relevance to bacterial transport in the field. This project will combine innovative experimental designs for data collection and upscaling to develop multiscale models for chemotaxis. The purpose of this research is to develop an understanding of the macroscopic scale (bulk) transport behavior of chemotaxis in porous media. This necessarily involves linking the macroscale transport to the essential microscale features of the system that control chemotaxis. Improvements in the ability to measure phenomena at small scales has lead to experimental data sets that contain detail that was nearly unimaginable even a decade ago. The development of such extraordinary data sets has also frequently promulgated the question ?how does one make sense of these data? Is there a way to search for essential features of behavior in them?? New archetypes for data analysis (e.g., machine learning algorithms, data mining) have been employed as methods to assess such data sets. When applied to the problem of large data sets arising from physical systems, upscaling methods are among these data analysis archetypes. Outcomes from this proposal will result in more robust models for predicting microbial transport in groundwater systems, which will lead to improved design and implementation of bioremediation schemes.

协作研究：对异构多孔的中虫中的趋化细菌运输的多尺度分析。在地下，通常无法在注射物质和居民污染物之间实现良好的混合而妨碍生物修复。在这种情况下，可能会利用趋化性来增强受污染区域中细菌种群的混合。这项研究的目的是通过适当的机械描述理论将趋化性的直接实验测量与物理和化学异质多孔培养基联系起来。将使用两个主要的假设来组织研究工作。他们将结合（a）多尺度实验观察结果，以及（b）多尺度上尺度分析，以开发一个理论框架，该框架可以在显微镜和宏观尺度上描述化学和物理异源培养基中的趋化性。第一个假设是，在具有诱捕的非水相液体（NAPL）污染物来源的多孔培养基中，趋化细菌的传输将比非化学细菌慢。 特别是，由于在流体NAPL界面上选择性诱捕趋化细菌的选择性捕获，趋化细菌将表现出比非化学突变体更大的迟缓和尾巴。第二个假设是，在大规模异质性的情况下，在趋化性和非化学条件下的细菌转运在非化学条件下的运输截然不同。 尽管趋化性本质上是一个孔隙尺度的过程，但趋化细菌对从异质培养基的高电导率区域转运的净影响将在实验上测量，并且与该领域的细菌运输有关。该项目将结合用于数据收集的创新实验设计和开发趋化性多尺度模型的升级模型。这项研究的目的是对多孔培养基中趋化性的宏观量表（BOLK）转运行为有所了解。 这必然涉及将宏观运输与控制趋化性的系统的基本微观特征联系起来。在小尺度上测量现象的能力的提高已导致实验数据集，这些数据集包含几乎无法想象的细节。这样的非凡数据集的开发也经常引发该问题？一个人如何理解这些数据？有没有办法搜索行为的基本特征？用于数据分析的新原型（例如，机器学习算法，数据挖掘）已被用作评估此类数据集的方法。当应用于物理系统引起的大数据集的问题时，这些数据分析原型之一就是进行缩放方法。该提案的结果将导致更强大的模型来预测地下水系统中的微生物运输，这将改善生物修复方案的设计和实施。