ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
Displaying 1 - 2 of 2
Filtering by
- All Subjects: Microbiology
- Creators: Kavazanjian, Edward
Characterization and Manipulation of Microbiomes From Arid Landfills for Improved Methane Production
Description
Environmentally harmful byproducts from solid waste’s decomposition, including methane (CH4) emissions, are managed through standardized landfill engineering and gas-capture mechanisms. Yet only a limited number of studies have analyzed the development and composition of Bacteria and Archaea involved in CH4 production from landfills. The objectives of this research were to compare microbiomes and bioactivity from CH4-producing communities in contrasting spatial areas of arid landfills and to tests a new technology to biostimulate CH4 production (methanogenesis) from solid waste under dynamic environmental conditions controlled in the laboratory. My hypothesis was that the diversity and abundance of methanogenic Archaea in municipal solid waste (MSW), or its leachate, play an important role on CH4 production partially attributed to the group’s wide hydrogen (H2) consumption capabilities. I tested this hypothesis by conducting complementary field observations and laboratory experiments. I describe niches of methanogenic Archaea in MSW leachate across defined areas within a single landfill, while demonstrating functional H2-dependent activity. To alleviate limited H2 bioavailability encountered in-situ, I present biostimulant feasibility and proof-of-concepts studies through the amendment of zero valent metals (ZVMs). My results demonstrate that older-aged MSW was minimally biostimulated for greater CH4 production relative to a control when exposed to iron (Fe0) or manganese (Mn0), due to highly discernable traits of soluble carbon, nitrogen, and unidentified fluorophores found in water extracts between young and old aged, starting MSW. Acetate and inhibitory H2 partial pressures accumulated in microcosms containing old-aged MSW. In a final experiment, repeated amendments of ZVMs to MSW in a 600 day mesocosm experiment mediated significantly higher CH4 concentrations and yields during the first of three ZVM injections. Fe0 and Mn0 experimental treatments at mesocosm-scale also highlighted accelerated development of seemingly important, but elusive Archaea including Methanobacteriaceae, a methane-producing family that is found in diverse environments. Also, prokaryotic classes including Candidatus Bathyarchaeota, an uncultured group commonly found in carbon-rich ecosystems, and Clostridia; All three taxa I identified as highly predictive in the time-dependent progression of MSW decomposition. Altogether, my experiments demonstrate the importance of H2 bioavailability on CH4 production and the consistent development of Methanobacteriaceae in productive MSW microbiomes.
ContributorsReynolds, Mark Christian (Author) / Cadillo-Quiroz, Hinsby (Thesis advisor) / Krajmalnik-Brown, Rosa (Thesis advisor) / Wang, Xuan (Committee member) / Kavazanjian, Edward (Committee member) / Arizona State University (Publisher)
Created2022
Description
Earthquake-induced soil liquefaction poses a significant global threat, especially to vulnerable populations. There are no existing cost-effective techniques for mitigation of liquefaction under or around existing infrastructure. Microbially Induced Desaturation and Precipitation (MIDP) via denitrification is a potentially sustainable, non-disruptive bio-based ground improvement technique under existing structures. MIDP has been shown to reduce liquefaction triggering potential under lab conditions in two ways: 1) biogenic gas desaturation in the short-term (treatment within hours to days) and 2) calcium carbonate precipitation and soil strengthening in the long-term (treatment within weeks to months). However, these experiments have not considered MIDP behavior under field stresses and pressures, nor have they considered challenges from process inhibition or microbial competition that may be encountered when upscaled to field applications. This study presents results from centrifuge experiments and simplified modeling to explore scaling effects on biogenic gas formation, distribution, and retention when simulating field pressures and stresses. Experimental results from the centrifuge demonstrated MIDP’s potential to mitigate the potential liquefaction triggering through desaturation. This study also includes the development of a biogeochemical model to explore the impact of water constituents, process inhibition, and alternative biochemical metabolisms on MIDP and the subsequent impact of MIDP on the surrounding environment. The model was used to explore MIDP behavior when varying the source-water used as the substrate recipe solute (i.e., groundwater and seawater) and when varying the electron donor (i.e., acetate, glucose, and molasses) in different substrate recipes. The predicted products and by-products were compared for cases when desaturation was the targeted improvement mechanism and for the case when precipitation was the primary targeted ground improvement mechanism. From these modeling exercises, MIDP can be applied in all tested natural environments and adjusting the substrate recipe may be able to mitigate unwanted long-term environmental impacts. A preliminary techno-economic analysis using information gained from the modeling exercises was performed, which demonstrated MIDP’s potential as a cost-effective technique compared to currently used ground improvement techniques, which can be costly, impractical, and unsustainable. The findings from this study are critical to develop treatment MIDP plans for potential field trials to maximize treatment effectiveness, promote sustainability and cost-effectiveness, and limit unwanted by-products.
ContributorsHall, Caitlyn Anne (Author) / Rittmann, Bruce E. (Thesis advisor) / Kavazanjian, Edward (Thesis advisor) / van Paassen, Leon A. (Committee member) / DeJong, Jason T. (Committee member) / Arizona State University (Publisher)
Created2021