Browsing by Subject "ammonia"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Evaluating on-farm methods for estimating gas emissions and quantifying risk of disease transmission for livestock barns
    (2023-08) Warmka, Anna
    The need for producers to demonstrate the environmental and economical sustainability of their operations is driven by several stakeholder and consumer groups, creating a call for methods to accurately estimate gas emissions and quantify risk of disease transmission. In this work, I first provide background on the mechanisms of gas emissions from deep-pit swine operations and a summary of current emission estimation strategies in the literature. Next, I present one thesis project demonstrating the opportunities and limitations to applying a mass balance approach to estimate methane and ammonia emissions from deep-pit swine barns. Through this project, different mass balance approaches are evaluated against each other and typical emission modeling approaches. Findings from this project show that there are limitations to the application of a mass balance approach in swine barns, particularly related to in-barn sample collection and dataavailability. Then, I present a second thesis project identifying opportunities and limitations to using a fluorescent gel as a proxy for disease transfer in biosecurity research. In this project, I present a method to quantify the luminance of the fluorescent gel and investigate the factors important in measuring the transfer of gel from one surface to another. Findings from these two projects provide a framework for the methods needed to conduct research in gas emissions and biosecurity in livestock operations. Understanding the current state and limitations of these methods is important to consider when applying them to future research, and the current limitations presented provide an outline for future work needed in these fields.
  • Thumbnail Image
    Item
    Optimization of Ammonium and Biohydrogen Production from Mutant Strains of Azotobacter vinelandii Deregulated for Nitrogen Fixation
    (2018-05) Plunkett, Mary
    The increase in demand for food and fuel as a result of an increasing population must be sustainable and renewable in the face of global climate change. Azotobacter vinelandii, an aerobic nitrogen fixing bacterium, has the potential to supplement or replace a major consumer of global energy, which is the production of ammonium (NH4+) for use in fertilizers. A requisite by-product of nitrogen fixation includes the production of hydrogen gas (H2), which can be used for many applications, including renewable hydrogen fuel cells. A. vinelandii produces both of these in a biochemical process which takes place at ambient temperatures and pressures using renewable carbon sources for energy. Within this research, improvement of the conditions needed for higher NH4+ and H2 production from a strain deregulated for the production of nitrogenase was explored and H2 output was characterized as a result of multiple genetic modifications and changes to culture conditions.
  • Thumbnail Image
    Item
    Zeolite MFI Membranes Towards Industrial Applications
    (2020-11) Duan, Xuekui
    Zeolite membranes have been the interest of research for decades due to their potentials in various separation applications including gas separation, water purification, pervaporation, etc. Among the zeolite materials studied, MFI zeolite (Silicalite-1 and ZSM-5) is one of the major subjects of research, mainly because of its suitability for the separation of hydrocarbons, such as n-butane from iso-butane and para-xylene from its isomers. Besides, all-silica Silicalite-1 and high-silica ZSM-5 have been explored for organic/water pervaporation as well by utilizing their high hydrophobicity. Despite years of research efforts on these applications, the industrialization of MFI membranes has not been achieved. One reason is that the cost associated with the fabrication of these membranes is too high to be commercially attractive. The high-cost, specially engineered silica membrane supports account for a major share of the total cost. Alternative supports such as polymeric supports and low-cost and commercially available alumina supports are possible substitutes to explore. Another problem is the lack of demonstration of high membrane separation performance at industrially relevant conditions (high temperature and high pressure). It is thus the goal of this thesis to address these problems and make progress towards the commercialization of MFI membranes. First, the recent advances of MFI zeolite membranes were reviewed. Then, the fabrication of high-performance MFI membranes using aqueous dispersions of open-pore, two-dimensional MFI zeolite nanosheets on low-cost polymeric substrates was demonstrated. Next, progress towards making MFI membranes on alumina supports has been made. Despite these efforts to use other supports, we failed to make high-performance membranes as comparable to the silica-supported ones. Besides these efforts, ultra-thin MFI membranes fabricated using dc-5 nanosheets as seeds were showed to have high xylene isomer separation performance at industrial conditions and high performance for H2/hydrocarbons separation and ammonia/H2/N2 separation. These works demonstrated the potential of high-performance MFI membranes for energy-efficient separation processes in industrial conditions.