Doctor of Philosophy, Miami University, 2023, Microbiology

Ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA) and complete ammonia oxidizers (comammox) comprise aerobic ammonia oxidizers (AO). Here, we present the ammonium concentration as a determinant of the distribution of ammonia-oxidizers. The ecophysiology of comammox enrichment Cmx-BO4 was characterized by growing it in different ammonium concentrations, pH, light and nitrite concentrations. Cmx-BO4 oxidized up to 3 mM ammonium, with the highest growth rate at 10 M ammonium. The comammox enrichment oxidized ammonium through pH 6 to 8 and was inhibited by blue and white light. Cmx-BO4 oxidized nitrite in presence of ammonium but did not oxidize nitrite only. The genomic characterization of comammox strain Nitrospira sp. BO4 in the comammox enrichment Cmx-BO4 was performed through metagenomic sequencing. The metagenome assembled genome (MAG) of Nitrospira sp. BO4 possessed genes for ammonia and nitrite oxidation. The MAG, however, lacked genes for assimilatory nitrite reduction and nitrite transporters, corresponding to the inability of the culture to consume nitrite as the nitrogen source. Comammox Nitrospira sp. BO4 was competed for ammonium against AOA Nitrosoarchaeum sp. BO1 to investigate if the two oligotrophic AO had niche differentiation or if they co-existed in nature. Cmx-BO4 and AOA-BO1 have Nitrosopira sp. BO4 and Nitrosoarchaeum sp. BO1 as the AO respectively. Nitrospira sp. BO4 outcompeted Nitrospira sp. BO1 at all three tested ammonium concentrations (<10-, 50- and 500 M). Comammox may have an advantage over AOA at ammonium limited environments and the AOA may occupy microniches devoid of comammox to be able to coexist in oligotrophic environments. The effect of elevated ammonium availability was investigated to characterize the toxic effects of high ammonium concentration on Nitrosomonas sp. Is79 and N. eutropha. We cultivated both cultures at low, intermediate and high ammonium concentrations to investigate the effect of ammonium c (open full item for complete abstract)

Committee: Annette Bollmann Dr. (Advisor) Subjects: Microbiology

Doctor of Philosophy (PhD), Ohio University, 2011, Chemical Engineering (Engineering and Technology)

Ammonia oxidation is being considered as a viable technology for hydrogen production for use in fuel cells. This study was undertaken to gain insight into current issues related to catalytic inactivity with time. Density Functional Theory was used in modeling the chemical species present during ammonia oxidation: NHx (x = 0 - 3), OHy (y = 1 & 2) and N2Hz (z = 0 - 4) and the adsorption of these molecules on the surface of platinum clusters. Using comparison with experimental measurements where possible, it was found that the strength of adsorption for these molecules followed this trend: N2 < H2O < NH3 < N2H2 < N2H4 < N2H < N2H3 < OH < NH2 < NH < N. This suggests that the species present towards the right of this spectrum were especially relevant to surface blockage and could play a role in catalytic inactivity. In addition, the formation and oxidation of the N2Hz molecules could possibly be tracked by spectrochemical analysis of the position of the N - N bond, which went from single (N2H4) to double (N2H2) to triple (N2) as the oxidation of ammonia progressed. The presence or absence of this peak is an indicator of the orientation of the molecule formed and an indicator of the progress of the reaction. Finally, an exploratory investigation of a mechanism of ammonia oxidation, where ammonia is deprotonated in successive steps, predicted that the conversion of the imide radical to nitrogen, although thermodynamically favorable, exhibits slow kinetics in comparison to deprotonation of ammonia or amidogen

Committee: Gerardine Botte PhD (Advisor); Howard Dewald PhD (Committee Member); Daniel Gulino PhD (Committee Member); Nancy Sandler PhD (Committee Member); Valerie Young PhD (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy, The Ohio State University, 2019, Food, Agricultural and Biological Engineering

The U.S. egg industry is the world's second-largest egg producer with an annual production of 5.6 billion kilograms of eggs and provides 81,515 jobs and $22.77 billion to the economy. Due to the very large-scale and concentrated operations, the egg industry is facing crucial challenges in reducing its significant environmental impacts and solving indoor air quality problems. Egg production is a significant contributor of air emissions to the atmosphere, especially ammonia (NH3) emission, which has caused serious concerns on health and the environment, such as soil and water acidification, visibility impairment, and respiratory diseases. Effective management and mitigation of NH3 emissions from layer operations are urgently needed but are limited because of the lack of effective tools for estimating NH3 emissions. It is also in the egg industry's and the public's interests to understand the health and environmental impacts of NH3 on the neighboring communities. The U.S.EPA regulatory air dispersion model AERMOD needs to be evaluated for its performance in estimating NH3 dispersion after being emission from layer houses. In addition, heat stress is a serious problem in layer houses with annual losses of $61-98 million nationwide due to impaired egg production. Global warming further worsens the heat stress problem due to increasing events of hot weather and heavier precipitation. Exposure to high-concentration NH3 is another risk to layers and workers. It damages layers' immune system and egg production and affects workers' health. The problems of heat stress and NH3 exposure are aggravated in layer houses due to non-uniform airflow resulted from current ventilation systems. The knowledge of the spatial and temporal distribution of heat stress and NH3 concentrations inside layer houses is essential for assessing the associated risks of layers and workers and developing mitigation strategies, but is not yet available. This dissertation aims to fill the gap by de (open full item for complete abstract)

Committee: Lingying Zhao (Advisor); Albert Heber (Committee Member); Jiqin Ni (Committee Member); Heather Allen (Committee Member); Ann Christy (Committee Member); Gil Bohrer (Committee Member) Subjects: Agricultural Engineering; Environmental Engineering

Doctor of Philosophy (PhD), Ohio University, 2017, Chemical Engineering (Engineering and Technology)

Ammonia is a crucial chemical used in many fields such as the fertilizer, textile, and food industries. Nowadays, ammonia is commonly used as a reducing agent to reduce nitrogen oxide (NOx) to non-harmful nitrogen gas and water which is called the selective catalytic reduction (SCR) process. For the on-site production of ammonia, two traditional methods are urea hydrolysis and urea pyrolysis. However both of them require high temperature and pressure which are not accessible in mobile engines. A novel electrochemically induced urea to ammonia (eU2A) process in alkaline media was introduced and investigated in this investigation. Nickel beads are employed as the working catalyst in a two-electrode eU2A reactor using 7.0 M KOH as the supporting electrolyte at 70 °C. The ammonia generation rate per effective volume of catalyst in the eU2A process is ~28 times higher than the thermal hydrolysis of urea (THU). The eU2A operates at low temperature and pressure which is suitable for SCR process in mobile engines and saves energy. The eU2A process is a promising technique that finds applications on the SCR process for the removal of nitride oxide from combustion systems (e.g., diesel vehicles and power plants). In addition, the mechanism of eU2A in the alkaline medium using nickel electrodes was investigated in a classical three-electrode reactor with a mercury/mercury oxide reference electrode. In this investigation, the intermediates and products in the bulk solution were monitored by Fourier Transform Infrared spectroscopy, and the intermediates and products on the catalyst surface in eU2A process were analyzed by in-situ Raman spectroscopy. Urea electrolysis and THU (in the bulk solution) take place in parallel with the eU2A process in the eU2A reactor. It was found that the ammonia production rate depends strongly on the amount of nickel oxyhydroxide and the concentration of OH- ions. In addition, the redox couple of Ni2+ and Ni3+ ions played important roles in ammo (open full item for complete abstract)

Committee: Gerardine Botte (Advisor); Howard Dewald (Committee Member); David Ingram (Committee Member); Kevin Crist (Committee Member); John Staser (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy, The Ohio State University, 2014, Food, Agricultural and Biological Engineering

Ammonia (NH3) is a pungent, colorless gas that is considered an air quality concern. The expansion of AFOs in the United States significantly increases NH3 emission levels that largely affect air quality inside the barns, within the vicinity of animal operations, and of the ambient air. Among the existing technologies, acid wet scrubbers are promising due to its simple design, low pressure drop advantage on fans, and the additional benefit of generating nitrogen fertilizer simultaneously. In this study, a modular spray-type wet scrubber was developed under laboratory conditions by optimizing its design, operating, and environmental parameters. Full-scale scrubbers were developed for long-term field application at a commercial poultry manure composting facility and a deep-pit swine facility. The effluents generated were characterized for its N fertilizer value that would help assess the economic feasibility of the process. The overall scrubber efficiency was then modeled using fundamental understanding of the process to be able to describe the underlying process of gas absorption in an acid spray scrubber. The optimized scrubber module called the Spray Scrubber Module (SSM) was optimized for its nozzle type, scrubber column size and geometry, and number of stages of the spray scrubber module. Effects of operating parameters such as acid concentration, superficial air velocity, retention time, and inlet NH3 concentration were quantified. The SSM was optimized as a hexagonal scrubber column with a diameter of 45.72 cm equipped with 3 stages of PJ40 spray nozzles, spraying 1% (w/v) H2SO4 scrubbing liquid counter-current to an exhaust air stream with superficial gas velocity of 3 to 4 m s-1 equivalent to air retention times of 0.55 to 0.41 s and was able to recover 91% NH3 at an operating liquid pressure of 0.51 MPa and a superficial air velocity of 4 m s-1 for an inlet NH3 concentration of 30 ppmv operated in single stage of spray nozzle. The optimized SSM was scaled u (open full item for complete abstract)

Committee: Lingying Zhao (Advisor) Subjects: Agricultural Engineering; Agriculture; Engineering; Environmental Engineering

Bachelor of Science (BS), Ohio University, 2019, Engineering Physics

Electrochemical ammonia synthesis is being actively studied as a low temperature, low pressure alternative to the Haber-Bosch process. This thesis explores iridium as the catalyst for the electrochemical process, following a previous study of platinum catalysts. Specifically, the adsorption characteristics of intermediates involved in the synthesis reaction were studied on a theoretical 15-atom cluster of iridium. Characteristics studied here include bond energies, bond lengths, spin densities, and free and adsorbed vibrational frequencies for the following set of molecules: N2, N, NH, NH2, NH3, N2H, N2H2, N2H3, N2H4, H2O, and OH radical. Objective one was to generate useful information that will set the basis for a mechanistic study of the synthesis process. Objective two was to use these simulations to explore the use of dispersion-corrected Density Functional Theory methods that can model N2 adsorption – the key reactant for electrochemical ammonia synthesis via transition metal catalysis. Specifically, three methods were tested: hybrid B3LYP, a dispersion-corrected form B3LYP-D3, and semi-empirical B97-D3. The latter semi-empirical method was explored to increase the accuracy obtained in vibrational analysis as well as reduce computational time. Two lattice surfaces, (111) and (100), were compared. The adsorption energies were stronger on (100) and follow the trend EB3LYP > EB3LYP-D3 > EB97-D3 on both surfaces. In the conclusion of this thesis, recommendations are given on how this data may be used to support a future study in pursuit of a mechanism for ammonia synthesis on iridium.

Committee: Gerardine Botte (Advisor); David Tees (Advisor) Subjects: Chemical Engineering; Chemistry; Engineering; Physics

Doctor of Philosophy (PhD), Ohio University, 2018, Chemical Engineering (Engineering and Technology)

Nowadays, the development of energy-efficient processes for the treatment of wastewater is becoming an essential research field; taking into account the projected global population rise, the depletion of fresh water, and the necessity for available and renewable sources of energy. Within this context, the electro-oxidation of ammonia has been received considerable and increasing attention due to its advantageous in deammonification of wastewater and at the same time, production of pure hydrogen as a source of energy. However, the performance of this process should be optimized prior to wide industrial utilization. There are several factors that affect the performance of ammonia electrolysis. These factors can be divided into macro scale (like flowrate, concentration) and micro scale (like electrodes material and morphology). The effects of these factors can be evaluated in a mathematical model which would be able to optimize the process. Optimization of the process results in widely and commercially usage of ammonia electrolyzers. In this electrolyzer, water reduces at the cathode, while ammonia oxidizes at the anode. Hydrogen evolution reaction (HER) at the cathode can proceed on transition metals like nickel. However, ammonia oxidation needs noble metals like platinum to proceed; one of the other hindrances of widely commercialization of this process. This problem can be solved if the knowledge of the process kinetics and mechanism of the reaction on the surface of the catalyst clarified. The first part of this research focused on developing a mathematical model using flow regime, transport equations, the ammonia oxidation kinetics on platinum at the anode and the hydrogen evolution kinetics on nickel at the cathode. All of the non-linear differential equations were solved by finite difference methods in a comprehensive FORTRAN code. The model showed both qualitative and quantitative agreement with experimental measurements which were carried on in a bench s (open full item for complete abstract)

Committee: Gerardine Botte (Advisor); Valerie Young (Committee Member); Howard Dewald (Committee Member); Nancy Sandler (Committee Member); Kevin Crist (Committee Member) Subjects: Chemical Engineering; Environmental Engineering; Experiments

Master of Science (MS), Bowling Green State University, 2016, Physics

Heterogeneous catalysis is of a great importance in the energy and environmental industries. One of the most challenging and energetically expensive chemical reactions is the ammonia cracking. We perform first principles calculations to determine the activation energy of ammonia cracking on the surfaces of various compositions of Heusler alloys, like NiMnGa and CoCrGe. Our hypothesis is that a higher number of density of states of electrons at the Fermi level can act as a sign of a better catalyst. The surfaces of stoichiometric compositions, Ni2MnGa and Co2CrGe, have demonstrated a significant lowering of the dissociation barrier of ammonia. In these calculations, we have used a software package called VASP and adopted a powerful computational technique called “Nudged Elastic Band Method”, which allows us to find the optimum energy path for the dissociation reaction. As the next step, we calculated the density of states at the Fermi level and formation energies of all possible compositions of NiMnGa, in order to pick the most promising candidates and examine our selection hypothesis with respect to the activation energy of ammonia, when it is on the surface of these compositions. By investigating 105 compositions of NiMnGa, Ni4Mn11Ga1 was picked as our candidate and we continued the study. The Ni4Mn11Ga1 surface significantly lowered the activation energy of ammonia by showing that there is a mutual relationship between the density of states near the Fermi level and catalytic activities of a surface.

Committee: Alexey Zayak Dr. (Advisor); Lewis Fulcher Dr. (Committee Member); Zamkov Mikhail Dr (Committee Member) Subjects: Chemistry; Physics; Solid State Physics

Master of Science, Miami University, 2014, Microbiology

Ammonia oxidation within nitrification is performed by ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA). AOB and AOA have been detected in the same freshwater environments, and lake characteristics associated with specific trophic states have been suggested as mechanisms for niche differentiation. To investigate the influence of lake trophic state on niche differentiation between AOB and AOA, culture-dependent methods and culture-independent methods were utilized. Regardless of lake trophic state, the AOB grew faster than the AOA when grown in lake water and were also more abundant than the AOA. The AOA growth rates and abundances suggest that they may be more successful in mesotrophic/meso-oligotrophic lakes. It is possible that lake parameters characteristic of certain trophic states contribute towards niche differentiation, however future work in understanding the effects of these lake parameters is necessary to determine what influence trophic state has on AOB and AOA niche differentiation.

Committee: Annette Bollmann PhD (Advisor); Rachael Morgan-Kiss PhD (Committee Member); Mitchell Balish PhD (Committee Member); Michael Vanni PhD (Committee Member) Subjects: Microbiology

Master of Science, The Ohio State University, 2013, Environment and Natural Resources

Hypoxia is a common phenomenon in aquatic environments which most frequently occurring during late summer or late winter. Hypoxic events are increasing in intensity as water temperatures increase, and it is important to understand how hypoxia affects aquatic ecosystems, particularly fish. Additionally, increases in ammonia concentrations have been shown to occur during periods of hypoxia. Ammonia is converted to nitrate in aquatic environments through nitrification, via the nitrogen cycle. However, this process is carried out by aerobic bacteria and is depressed by hypoxia. Ammonia has been shown to be more toxic to fish during hypoxia than during normoxia, indicating that it could have large implications on fish foraging activity in hypoxic waters. While fish have reduced growth in hypoxic water, the simultaneous accumulation of ammonia may result in death. Therefore, evaluation of how hypoxia affects fish simultaneously exposed to ammonia is essential to understand how fish are affected during natural hypoxic events, such as those that occur in the hypolimnion of Lake Erie. Juvenile yellow perch were reared under varied oxygen conditions to examine how hypoxia affects growth and survival of fish. Yellow perch are a physoclistous fish which can result in irreversible failure to inflate the swim bladder. Therefore, fish with both inflated and uninflated swim bladders were tested at different concentrations of oxygen for survival, growth, and oxygen consumption to gain a better understanding of how hypoxia affects yellow perch. Fish were stocked into 12 tanks with three levels of oxygen: 3, 4, and >7 mg O2/L (33, 45, & >78% saturation at 21 degrees Celsius). Fish were fed ad libitum with live brine shrimp nauplii over a 14-day period. Oxygen consumption was measured at the end of the experimental trial. Survival was not affected by lowered dissolved oxygen, but growth was reduced significantly in fish with both inflated (at 32% oxygen saturation) and uninflated swim (open full item for complete abstract)

Committee: Konrad Dabrowski (Advisor); Robert Gates (Committee Member); Roman Lanno (Committee Member) Subjects: Natural Resource Management

Master of Science, The Ohio State University, 2013, Animal Sciences

Excess ammonia emissions are a major concern for the dairy industry due to the detrimental impact ammonia emissions have on the environment and wastage of dietary nitrogen. Hyper-ammonia-producing bacteria (HAB) and protozoa in the rumen are the major contributors of excessive ammonia excretions from cattle. Besides Clostridium aminophilum, C. sticklandii, and Peptostreptococcus anaerobius, little is known about the HAB present in the rumen. In addition, rumen protozoa prey on bacteria and other microbes, excreting considerable amounts of amino acids and/or peptides that could promote the growth of HAB. In addition, inhibition of HAB by plant secondary metabolites may ultimately reduce ammonia production by HAB, thereby lowering excess nitrogen emissions. The studies presented in this thesis investigate HAB characterizations and interactions. In the first study, mixed microbes were obtained from the rumen of three fistulated dairy cows and further enriched and isolated for amino acid-fermenting bacteria. As a result, new isolates displayed high rates of ammonia production, ranging from 0.87 to 2.45 mg N/dL, and identified through 16S rRNA gene sequencing as a Bacillus sp. and Proteus mirabilis. In the second study, HAB enrichment cultures were co-cultured with an Entodinium caudatum culture. The co-culturing experiment was conducted with or without a feed substrate for E. caudatum and Micrococcus luteus to assess the impact of feeding the protozoan. Ammonia concentrations were higher in the E. caudatum alone treatments, both with and without the addition of the feed substrate compared with HAB alone or co-culture of HAB and E. caudatum, with 20.5 ± 0.8, 18.5 ± 0.2, 23.9 ± 0.3, and 23.2 ± 1.1 mg ammonia N/dL in treatment groups E. caudatum with feed substrate, E. caudatum without feed substrate, E. caudatum with feed substrate and with M. luteus, and E. caudatum without feed substrate but with M. luteus, respectively. Ammonia concentration was al (open full item for complete abstract)

Committee: Zhongtang Yu Dr. (Advisor); Jeffrey Firkins Dr. (Committee Member); Macdonald Wick Dr. (Committee Member) Subjects: Animal Sciences

Master of Science (MS), Bowling Green State University, 2012, Biological Sciences

In the past 100 years the nitrate levels in Lake Superior have increased more than five times (Sterner et al. 2007). Based on stable isotope assays, previous research has shown that most of this nitrate is coming from in-lake nitrification process in the lake (Finlay et al. 2007), reflecting an imbalanced nitrogen cycle. By contrast, in Lake Erie the nitrate levels are declining. Lake Erie is the shallowest of the Great Lakes. The shallowness of the lake, the warmer temperature of the water, and nutrient inputs from urban and agricultural sources make it most biologically productive of the Great lakes. Nitrification is a major process in the nitrogen cycle mainly carried out by the nitrifying microbial community (both Archaea and Bacteria), during which ammonia (NH3) is converted to Nitrite (NO2-) and then to nitrate (NO3-) by ammonia oxidizers (both Bacteria and Archaea) and Nitrite oxidizers (Bacteria only) respectively. Ammonia is oxidized by the enzyme ammonia monooxygenase, and hydroxylamine oxidoreductase (HAO). Nitrite (NO2-) converted to nitrate (NO3–) by Nitrite oxidizers (Bacteria) and enzyme nitrite oxidoreductase, carries this reaction. In this thesis, I investigated the microbial nitrifier community structure by identifying and enumerating the ammonia-oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) present in these two lakes using the technique of fluorescence in-situ hybridization (FISH). This is the first study on Lake Superior and Lake Erie proving the overview of the abundance and diversity of these organisms. This study is focusing on understanding the nitrifying microbial community structure, contribution to other studies dealing with how these organisms function in the nitrogen cycling in these lakes. Therefore, the goal of this study is to provide measure of abundance of AOB and NOB in Lake Superior and Lake Erie as well as the diversity of AOB in these lakes.

Committee: George Bullerjahn PhD (Advisor); Robert McKay PhD (Committee Member); Zhaohui Xu PhD (Committee Member) Subjects: Biology; Ecology; Environmental Science; Limnology; Microbiology; Molecular Biology

Master of Science, Miami University, 2024, Microbiology

Complete ammonia oxidizers (Comammox) are a novel group of nitrifiers which have received little ecophysiological characterization in freshwater ecosystems. Here, the response of two freshwater comammox, enriched from Lake Superior (Sup3) and Lake Erie (E28) sediment, to temperature, ammonium concentration, pH, and salinity were characterized using cultivation-dependent methods. Resulting responses shared similarities with previous characterized ammonia oxidizers, however, Sup3 and E28 were more susceptible to changes in environmental factors. Response to salinity is consistent with the absence of comammox in marine ecosystems. The ability of comammox to both produce and oxidize nitrite has called into question the competition between them and canonical nitrite oxidizing bacteria (NOB) for nitrite. The capacity of comammox and NOB to compete for nitrite was assessed through cultivation-dependent and molecular methods. Results indicated that comammox outcompete NOB for nitrite following oxidation from ammonia. amoA (Ammonia-monooxygenase subunit A) and nxrB (Nitrite-oxidoreductase subunit B) abundance in a combined comammox and NOB enrichment culture were similar to that of comammox alone while nxrB copies were highest in an NOB enrichment. This indicated a very small to nonexistent population of NOB. Though, oxidation trends of nitrite assert the presence of NOB within the combined enrichment.

Committee: Annette Bollmann (Advisor); D.J. Ferguson (Committee Member); Rachael Morgan-Kiss (Committee Member) Subjects: Microbiology

Master of Science, The Ohio State University, 1980, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1922, Graduate School

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Master of Science, The Ohio State University, 1969, Graduate School

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Master of Science, The Ohio State University, 1960, Graduate School

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Master of Science, The Ohio State University, 2007, Graduate School

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Master of Science, The Ohio State University, 2005, Graduate School

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Master of Science, The Ohio State University, 1962, Graduate School

Committee: Not Provided (Other) Subjects: