Theses and Dissertations at Montana State University (MSU)
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Item Magnetic resonance studies of fluid transport in porous systems and medical devices(Montana State University - Bozeman, College of Engineering, 2017) Nybo, Elmira; Chairperson, Graduate Committee: Sarah L. Codd; Joseph D. Seymour (co-chair)This research describes the application of nuclear magnetic resonance (NMR) techniques for non-invasive investigation of fluid transport and hydrodynamics in porous systems and medical devices. NMR microscopy is used to obtain information about internal structures and transport properties in porous materials and opaque systems. Controlling dispersion within restricted pore spaces is of importance in a variety of applications including soil consolidation and dewatering and electromigration of solutes. NMR pulsed gradient stimulated echo (PGSTE) techniques combined with electroosmotic flow (EOF) are used to study diffusion and dispersion coefficients in model glass bead packs. The results show that significant EOF-induced backflow can cause structural changes and alter the flow. Understanding the transport of liquids in porous materials during the application of electrical field holds promise for solving problems involving the delivery of binding agents to infill the pore space in rigid cement-based structures via electroosmosis. NMR PGSTE techniques and micro-CT scan imaging were used to study fluid transport and structural changes in a hydrating cement paste in a closed cell. It is shown that EOF in closed cement paste samples caused a significant increase in macroscopic void volume compared to closed samples with no flow. Needleless connectors (NCs) are commonly used medical devices with complicated internal design that leads to flow complexity that may cause undesirable bacterial deposition and biofilm formation. Magnetic resonance imaging (MRI) is applied to acquire spatial velocity maps of fluid flow at various positions within the devices. MRI velocimetry is demonstrated as an effective method to quantify flow patterns and fluid dynamic dependence on structural features of NCs. Alginate and alginate-based materials find an increasing interest in environmental engineering as adsorbents for heavy metal recovery from aqueous solutions. A Ca 2+ and Cu 2+ containing fluid flow through calcium-based alginate gel has been visualized using NMR velocimetry. NMR indicated velocity changes in gel capillaries caused by ion exchange processes and followed gel structural changes. NMR microscopy is shown as an effective method to describe fluid transport and internal structural features in opaque porous systems and medical devices.Item Nuclear magnetic resonance studies of biofilm - porous media systems(Montana State University - Bozeman, College of Engineering, 2017) Kirkland, Catherine Mullinnix; Chairperson, Graduate Committee: Sarah L. Codd; Joseph D. Seymour (co-chair); Sarah L. Codd was a co-author of the article, 'Low-field borehole NMR applications in the near subsurface environment' submitted to the journal 'Vadose zone journal' which is contained within this thesis.; Randy Hiebert, Adrienne Phillips, Elliot Grunewald, David O. Walsh, Joseph D. Seymour and Sarah L. Codd were co-authors of the article, 'Biofilm detection in a model well-bore environment using low-field NMR' in the journal 'Groundwater monitoring and remediation' which is contained within this thesis.; Maria P. Herrling, Randy Hiebert, Andrew T. Bender, Elliot Grunewald, David O. Walsh and Sarah L. Codd were co-authors of the article, 'In-situ detection of subsurface biofilm using low-field NMR - a field study' in the journal 'Environmental science and technology' which is contained within this thesis.; Sam Zanetti, Elliot Grunewald, David O. Walsh, Sarah L. Codd and Adrienne J. Phillips were co-authors of the article, 'Detecting microbially-induced calcite precipitation (MICP) in a model well-bore using downhole low-field NMR' in the journal 'Environmental science and technology' which is contained within this thesis.; Jessica Weisbrodt, Catherine M. Kirkland, Nathan H. Williamson, Susanne Lackner, Sarah L. Codd, Joseph D. Seymour, Gisela Guthausen and Harald Horn were co-authors of the article, 'NMR investigation of water diffusion in different biofilm structures' submitted to the journal 'Biotechnology and bioengineering' which is contained within this thesis.Nuclear magnetic resonance (NMR) allows for in-situ non-invasive studies of opaque systems over a wide range of length and time scales, making the method uniquely suited to studies of biofilms and porous media. The research comprising this thesis uses NMR to explore biophysical, chemical, and transport properties within heterogeneous porous media systems at both a macro- and micro-scale. The macro-scale projects validate a low-field borehole NMR instrument to monitor field-scale environmental engineering applications like subsurface biofilms and microbially-induced calcite precipitation (MICP). Subsurface biofilms are central to bioremediation of chemical contaminants in soil and groundwater whereby micro-organisms degrade or sequester environmental pollutants like nitrate, hydrocarbons, chlorinated solvents and heavy metals. When composed of ureolytic microbes, subsurface biofilms can also induce calcite precipitation. MICP has engineering applications that include soil stabilization and subsurface barriers, as well as sealing of cap rocks and well-bore regions for carbon dioxide sequestration. To meet the design goals of these beneficial applications, subsurface biofilms and MICP must be monitored over space and time - a challenging task with traditional methods. The low-field borehole NMR tool recorded changes in the T 2 relaxation distribution where enhanced relaxation indicated biofilm accumulation in a sand bioreactor and in subsurface soil. Additionally, the tool was able to detect MICP in a sand bioreactor. The changed mineral surface of the sand lead to an increase in T 2 relaxation times. The complementary high-field NMR project investigated micro-scale internal structures and mass transport within biofilm granules used for wastewater treatment. Granular sludge, composed of spherical aggregates of biofilm grown without a carrier, is an innovative biological treatment method with the potential to vastly reduce the cost of wastewater treatment without sacrificing efficiency. Large gaps remain, however, in our understanding of the fundamental formation mechanisms and the factors that control granule activity and stability. Magnetic resonance imaging (MRI) identified heterogeneous internal structures within aerobic granular sludge where relaxation rates and diffusion coefficients vary. Ultimately, these results will help improve modeling for optimization of granular sludge wastewater treatment process design.