Pore-scale investigation of abiotic and biotic mass transfer

项目摘要。微生物在DNAPL污染的多孔介质系统中的存在可以增强或抑制传质过程，这取决于生物质的类型、数量和分布。最近的工作，使用高分辨率同步辐射X射线断层扫描显示的能力，研究人员的图像和量化非生物系统中的孔隙尺度的传质机制。然而，使用这种高分辨率技术还没有证明成像和区分培养基内生物量的能力。由于生物质主要由水组成，因此很难与孔隙水区分开来。本项目的目标是系统地测试几种技术，试图在简化的多相多孔介质系统中对生物质进行成像。待测试的技术包括胶体金掺杂的微生物细胞，相衬同步加速器X射线成像，并使用琼脂作为替代生物膜，以调查通过微生物系统的掺杂剂的扩散。在研究过程中开发和完善的成功成像技术将被应用于更复杂的DNAPL系统，以研究微生物存在下的孔尺度传质过程。这项研究的结果也将有助于孔尺度的研究，旨在确定生物质在其他多孔介质问题中的影响（例如，生物结垢）。

Project Abstract. The presence of microorganisms in DNAPL-contaminated porous media systems can enhance or inhibit mass transfer processes depending on the type, quantity, and distribution of biomass. Recent work using high-resolution synchrotron x-ray tomography has demonstrated the ability of researchers to image and quantify pore-scale mass transfer mechanisms in abiotic systems. However, the ability to image and distinguish biomass within the media has not been demonstrated using this high-resolution technique. Because biomass is composed mostly of water, it is difficult to distinguish from pore water. The objective of this project is to systematically test several techniques in an attempt to image biomass in simplified multi-phase porous media systems. Techniques to be tested include colloidal gold-doping of microbial cells, phase-contrast synchrotron X-ray imaging, and the use of agar as a surrogate biofilm to investigate the diffusion of doping agents through microbial systems. The successful imaging technique(s) developed and refined in the course of the research will then be applied to more complex DNAPL systems to study pore-scale mass transfer processes in the presence of microorganisms. Results from this study will also be useful for pore-scale research directed at determining the impact of biomass in other porous media problems (e.g., biofouling).