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Full-Text Articles in Engineering
Experimental Investigation Of Clay Aggregate And Granular Biofilm Behavior, Tao Jiang
Experimental Investigation Of Clay Aggregate And Granular Biofilm Behavior, Tao Jiang
Doctoral Dissertations
Clay minerals are a class of phyllosilicates as the major solid constituents in cohesive fine-grained soils (e.g., clays). Owing to their tiny size (i.e., < 2 μm), high aspect ratio, and active surface properties that inherit from the geological process, clay minerals can extensively interact with other suspended matter (e.g., exoployemers, microorganisms) and dissolved ions via the process of flocculation and aggregation, resulting in the formation of larger, porous cohesive particulate aggregates or flocs. Such a complex mechanism of microscale particle interaction generates significant challenges for understanding the bulk clay behavior as a particulate system. In order to better characterize the flocculation and aggregation of clay minerals under various stimuli and to understand the underlying mechanism of particle interactions, particle/aggregate size kinetics of flocculated suspensions of illite, a representative 2:1 clay mineral abundant in marine soils, are studied with varied ionic strength induced by monovalent salt (NaCl), pH, and hydrodynamic shearing in the first phase of this research. Furthermore, a new statistical data binning method termed “bin size index” (BSI) was employed to determine the probability density function (PDF) distributions of flocculated illite suspensions. The statistical results demonstrate that the size kinetics of flocculated illite suspensions is chiefly controlled by the face-to-face and edge-to-face interparticle interactions under the mutual effects of ionic strength and pH, while the hydrodynamic shearing has minimal effects on the variation of particle size groups. In the second phase of this research, the mechanics of clay aggregates are studied using an innovative measurement technique and analytical approach. Individual clay minerals prepared with different mineralogy and salinities are tested via unconfined compression, which shows that the increasing ionic strength can improve the strength and stiffness of clay aggregates, which are further affected by the mineralogical compositions and dominant microfabric in different water chemistry. In the final phase of this research, a collaborative study with an environmental engineer on an NSF CAREER project was conducted to investigate the mechanical behavior of macroscale, light-induced oxygenic granules (biofilm aggregates) using the same technique and analytics developed for the individual clay aggregates. The findings are expected to provide reference values to subsequent studies and engineering practices associated with the water treatment process.
Spatiotemporal Metabolic Modeling Of Pseudomonas Aeruginosa Biofilm Expansion, Robert Sourk
Spatiotemporal Metabolic Modeling Of Pseudomonas Aeruginosa Biofilm Expansion, Robert Sourk
Masters Theses
Spatiotemporal metabolic modeling of microbial metabolism is a step closer to achieving higher dimensionalities in numerical studies (in silico) of biofilm maturation. Dynamic Flux Balance Analysis (DFBA) is an advanced modeling technique because this method incorporates Genome Scale Metabolic Modeling (GSMM) to compute the biomass growth rate and metabolite fluxes. Biofilm thickness is pertinent because this variable of biofilm maturation can be measured in a laboratory (in vitro). Pseudomonas aeruginosa (P. aeruginosa) is the model bacterium used in this computational model based on previous research conducted by Dr. Michael Henson, available GSMMs, and the societal significance of patients suffering from …
3d Printed Architected Materials For Improving Biofilm Carriers For Wastewater Treatment Applications, Bryan Ovelheiro
3d Printed Architected Materials For Improving Biofilm Carriers For Wastewater Treatment Applications, Bryan Ovelheiro
Environmental & Water Resources Engineering Masters Projects
Wastewater infrastructure in the United States has been in dire need of improvement for quite a while. It was estimated that wastewater treatment systems would need about $57.2 billion to maintain acceptable levels of treatment in the coming years (Christen, 2003). This is just for maintaining the treatment systems in place, without any room for improvement, and it only accounts for about 31.6% of the total waster infrastructure need in this area (Christen, 2003). In fact, without sufficient upgrades, water quality gains achieved through the passing of the Clean Water and Safe Drinking Water acts could be lost (Christen, 2003). …