京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第20009号 / 農博第2193号 / 新制||農||1045(附属図書館) / 学位論文||H28||N5018(農学部図書室) / 33105 / 京都大学大学院農学研究科応用生命科学専攻 / (主査)教授 小川 順, 教授 阪井 康能, 教授 栗原 達夫 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Due to the adverse effects of ammonia on the environment, many governments, including Canada, have imposed new regulations to reduce the discharge of ammonia wastewater effluent into natural receiving waters, which has resulted in the upgrade of ammonia removal at water resource recovery facilities (WRRFs) across the world. There is therefore a need to investigate present urban/peri-urban and rural challenges associated with municipal total ammonia (TAN) removal. In particular, there is a need to further advance and optimize technologies such as the moving bed biofilm reactor (MBBR) to meet these critical challenges. The first objective of this thesis is to validate an elevated loaded strategy for partial nitritation (PN) MBBR as an application for mainstream urban and peri-urban municipal wastewater treatment and to elucidate the mechanism of nitrite-oxidation suppression of this system. The second objective is to identify practical storage strategies for nitrifying MBBR units as rural municipal wastewater upgrade systems (lagoon systems), optimizing the TAN removal performance during seasonal discharge periods. In the context of the present climate change crisis and sustainable development requirements, there is an increased need for efficient TAN removal from urban and peri-urban municipal wastewaters. The application of the energy and cost-efficient partial nitritation/anammox (PN/A) technology to mainstream urban and peri-urban municipal wastewater can prove challenging because of limited ability to achieve the stable PN. Hence, there is a need for the validation of the present strategies for achieving effective and stable PN in the mainstream portion of conventional urban and peri urban WRRFs. The 45 days operation of a laboratory-scale, elevated loaded PN MBBR with average surface area loading rate (SALR) of 5.2 ± 0.1 g TAN/m²·d and a hydraulic retention time of 2h showed a successful and stable nitrite accumulation. The average surface area removal rate (SARR) of 2.3 ± 0.2 g TAN/m²·d (theoretical performance objective of 2.7 g TAN/m²·d), TAN removal efficiency of 43.1 ± 3.4% (theoretical performance objective of 53%) and NO₂- / (NO₂- + NO₃-) ratio of 82.4 ± 4.8% (theoretical performance objective of 100%) meets the necessary requirement to support subsequent cost-efficient anammox process. Biofilm analyses of the laboratory-scale, elevated loaded PN MBBR indicated that the attached biofilm was thick and dense, stable biofilm that did not show and biofilm loss or washout. Biofilm cell viability analyses was indicative of an active biofilm. The ratio of AmoA gene targets of the ammonia oxidizing bacteria (AOB) in the MBBR biofilm to the targeted gene region of the Nitrospira nitrite oxidizing bacteria (NOB) population demonstrates that NOB activity suppression of this technology was the dominant mechanism of nitrite-oxidation in the elevated loaded PN MBBR system. In North America, the TAN removal performance of waste stabilization ponds (also termed wastewater treatment lagoon systems), which are widely applied as rural WRRFs, is often not stable due to seasonal temperature variations. Nitrifying MBBR as an upgrade TAN removal unit has been successfully applied to improve TAN removal during winter. However, re-seeding the nitrifying MBBR biofilm during each seasonal operation period is not sustainable. There is therefore an urgent need for optimizing storage strategies of nitrifying MBBR carriers when used as TAN removal upgrade systems of rural WRRFs. The study of storage strategies for nitrifying MBBR as lagoon upgrading systems indicated the batch storage of the nitrifying MBBR biofilms with intermittent aeration could be an effective storage strategy for short-term (12 weeks) storage. Carriers stored in continuous flow aerated condition was shown to be the second most suitable storage method for nitrifying MBBR carriers for systems exposed to less than 12 weeks of storage. Carriers stored in dry condition, batch aerated conditions without flow, and continuous flow aerated condition for long-term (over 18 weeks) failed to achieve full nitrification following 18 days of operation conditions. Carriers stored in dry condition did not successfully achieve full nitrification for short-term and long-term storage and may not be applied to store full nitrification MBBR carriers. The study suggested that, compared to re-seeding start up strategy of the lagoon upgrading nitrifying MBBR biofilm, the use of the appropriate storage strategies, such as batch aerated conditions without flow, has the potential to shorten the start-up time and save energy during the non-discharge periods.

No description available.

Understanding how nitrifiers react when exposed to low DO conditions could provide a greater understanding of low DO operations in full-scale biological wastewater treatment. Previous methods to observe nitrifier oxygen kinetics do exist in literature, however they are inefficient and labor intensive. Other more efficient methods require the use of selective inhibitors, which alter the characteristics of the biomass. This study developed a time and labor efficient respirometric method to distinctly measure oxygen half-saturation coefficients for both ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) without the use of selective inhibitors. By eliminating the use of inhibitory substances, representative biomass characteristics were maintained throughout the tests. The developed method, called the declining DO method, consisted of using a high-speed dissolved oxygen (DO) probe to measure relative oxygen uptake rates (OUR) within a batch reactor when varying substrates (ammonia and nitrite) were present in excess within the system. A forward model was developed based on Monod kinetics to simultaneously fit Monod curves to the experimental OUR data. These curves were fit by solving for optimum oxygen kinetic parameters representing endogenous respiration, NOB, and AOB. An inverse model using Markov chain Monte Carlo analysis was applied to the results found in the forward model to provide statistical validation of the proposed respirometric method. A separate method, called the substrate utilization rate test, was conducted in parallel with the declining DO tests to compare and verify oxygen half-saturation coefficient results. Parallel tests were conducted using biomass samples from three different Hampton Roads Sanitation District (HRSD) full-scale facilities. Operating conditions between the three HRSD facilities were considered when performing parallel testing, including averages for DO, solids retention time (SRT), and floc size. Average floc size was found to have a significant effect on the observed oxygen half-saturation values. Observed trends for the KO values estimated using the two methods remained consistent throughout all tests, where KO,NOB was always lower than KO,AOB. The comparison of the two methods highlighted some faults associated with the substrate utilization rate test, which is commonly used in literature to observe nitrifier oxygen kinetics. The declining DO method appeared to be more resistant to potential experimental error and required less than half the time compared to the substrate utilization rate test. The development of the declining DO method without the use of selective inhibitors provided a more time and labor efficient technique for estimating apparent KO values for NOB and AOB without sacrificing biomass characteristics representative of the full-scale treatment process. Biomass samples collected from variable treatment process conditions yielded consistent parallel test results, providing further evidence that the proposed declining DO method can be a robust and reliable technique for distinctly measuring apparent oxygen half-saturation values for NOB and AOB. / Master of Science / Wastewater treatment operations utilizing biological nitrogen removal (BNR) require a continuous supply of oxygen for aerobic processes. Energy costs associated with aeration generally accounts for at least 50% of the total energy consumption at conventional activated sludge wastewater treatment facilities. Operating aerobic zones at low average dissolved oxygen (DO) concentrations could be an effective way to significantly reduce aeration costs as well as material costs associated with BNR treatment processes. This study developed a method to measure oxygen kinetics for the two groups of autotrophic bacteria responsible for performing nitrogen removal. The method consisted of measuring relative oxygen uptake rates (OUR) within a batch reactor when varying substrates were available. This method is unique from previously developed techniques in that the use of selective inhibitors was not included, meaning the characteristics of the wastewater were largely unchanged and therefore better represent biomass conditions within the full-scale process. The results of the proposed method were verified using an alternate method for estimating oxygen kinetics. These two methods were conducted in parallel using biomass samples from several full-scale Hampton Roads Sanitation District wastewater treatment facilities utilizing a variety of process designs and operating conditions. Consistent results obtained between the two methods suggested the proposed method is an effective technique for distinctly measuring nitrifier oxygen kinetics.

Aquarium biofilters are designed to promote the growth and activity of nitrifying microorganisms, which are primarily responsible for the removal of toxic nitrogen-cycle intermediates. Ammonia is a natural waste product excreted by fish that is lethal to aquatic life at relatively low concentrations. Ammonia-oxidizing archaea (AOA) outnumber ammonia-oxidizing bacteria (AOB) in biofilters of mature freshwater aquaria with low-ammonia conditions. However, no study has investigated the early establishment of AOA and AOB within biofilter communities, especially when aquarium ammonia concentrations are elevated. My thesis research investigated the relative abundance of AOA and AOB in freshwater aquarium biofilters through early aquarium establishment. AOA and AOB genes were detected in DNA extracts from the biofilters of 14 start-up freshwater aquaria with increasing fish biomass loads (Experiment 1), as well as from 12 biofilters of start-up aquaria treated with AOA and AOB supplements (Experiment 2). In start-up aquaria, early ammonia concentrations increased with fish biomass, and AOB amoA genes were strongly detected over AOA marker genes in all filters without initial AOA inoculation. Inoculation of AOA-dominated supplements into newly established biofilters improved early ammonia oxidation rates in comparison to filters supplemented with AOB or those lacking supplements. Inoculated AOA thrived in filter biofilm during and beyond stabilization of low-ammonia conditions in aquaria. Microbial activity experiments demonstrated that AOA were present and active in the biofilters eight months after inoculation, when aquaria were fully established. In addition, AOB and AOA populations were monitored in new aquaria in three unregulated home environments. Thaumarchaeal 16S rRNA genes were detected in all aquarium filters within one month of aquarium development. In one filter, AOA were the only ammonia-oxidizers detected in the biofilm during aquarium development, suggesting that AOA were the sole contributors to nitrification in this aquarium. The results from these experiments suggest that AOA may be key players in early aquarium nitrification once introduced into the aquarium environment. Further, this research provides insight into the ecology of AOB and AOA in engineered freshwater environments

Thesis (Ph.D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 19, 2009) Vita. Includes bibliographical references.

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Chemistry and Chemical Biology." Includes bibliographical references (p. 23-24).

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 165-181). Also available via the Internet.

Este trabalho apresenta uma interpretação química quantitativa do atrito nas camadas mais externas do aço AISI 1045 nitretado e pós-oxidado com diferentes tempos de oxidação (0, 1, 5, 10, 20 e 30 min). A caracterização da morfologia, microestrutura, espessura e composição química qualitativa das camadas nitretadas e pós-oxidadas foi realizada por microscopia eletrônica de varredura (MEV) e espectroscopia de emissão óptica por descarga luminescente (GD-OES). A estrutura cristalina presente nas camadas mais superficiais das amostras foi identificada por difração de raios X (DRX), empregando ângulo rasante. Na camada nitretada, as amostras apresentam as fases de nitretos g’-Fe4N e e-Fe2-3N, enquanto que na camada oxidada há uma combinação das fases µ-Fe2O3 e Fe3O4 ou somente a fase Fe3O4 (amostra pós-oxidada por 1 min). A nanodureza foi obtida através de indentações de baixa penetração (até 200 nm). O módulo de elasticidade reduzido, a rugosidade superficial e o coeficiente de atrito (CoF) foram obtidos por ensaios de deslizamento unidirecional, utilizando o equipamento nanoindentador Nanotest-600 da MicroMaterials. O regime de deformação provocado por esses ensaios foi identificado através do cálculo do índice de plasticidade (Y). As amostras apenas nitretada e a pósoxidada durante 1 min apresentaram resultados constantes, dentro do erro experimental e da faixa de profundidade analisada (entre 100 e 200 nm), das propriedades tais como dureza, módulo elástico reduzido, rugosidade e índice de plasticidade, porém com coeficientes de atrito (CoF) diferentes. Desta forma, a evolução do CoF em função da química da superfície pode ser avaliada sem a influência de mudanças nas propriedades mecânicas mais importantes, que determinam o CoF. Esses resultados experimentais podem ser explicados usando um modelo baseado na origem fonônica do atrito, que depende da frequência vibracional característica das camadas mais externas do material. O modelo apresenta boa concordância com os resultados experimentais, com uma diferença de 3% entre teoria e prática. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-06-23T11:22:55Z No. of bitstreams: 1 Dissertacao Márcia Freislebem.pdf: 7918824 bytes, checksum: d6e46c5d7b5a22f4ff1607cb915fa302 (MD5) / Made available in DSpace on 2014-06-23T11:22:55Z (GMT). No. of bitstreams: 1 Dissertacao Márcia Freislebem.pdf: 7918824 bytes, checksum: d6e46c5d7b5a22f4ff1607cb915fa302 (MD5) / This work presents a quantitative chemical interpretation of friction for the most external layers of AISI 1045 steel previously nitrided and post-oxidized during 0, 1, 5, 10, 20 and 30 min. The characterization of morphology, microstructure, thickness and qualitative chemical composition of nitrided and post-oxidized layers was performed by scanning electronic microscopy (SEM) and glow discharge optical emission spectroscopy (GD-OES) analysis. The superficial crystalline structure was identified by grazing incident X-ray diffraction. The nitrided layer presented g’-Fe4N and e-Fe2-3N phases, while the postoxidized layer presented µ-Fe2O3 and Fe3O4 phases or just Fe3O4 phase (1 min postoxidized sample). The nanohardness was determined by low depth indentations (until 200 nm). The reduced elastic modulus, the surface roughness and the coefficient of friction (CoF) were determined by unidirectional sliding tests, using a MicroMaterials Nanotest- 600 nanoindenter. The deformation regime was identified through the plasticity index (Y). Nitrided only and 1 min post-oxidized samples showed constant results, considering the experimental error and the analyzed depth range (from 100 to 200 nm), for hardness, reduced elastic modulus, surface roughness and plasticity index, but different CoF. Therefore, the evolution of CoF as a function of the surface chemistry can be assessed without any influence from the change of the most important mechanical properties that determine the CoF. These experimental results can be explained using a phononic model relying on the characteristic vibrational frequency of the most external layers of the material. The model shows a reasonable agreement with the experimental results, with a difference of 3% between theoretical and practical results.

Este trabalho apresenta uma interpretação química quantitativa do atrito nas camadas mais externas do aço AISI 1045 nitretado e pós-oxidado com diferentes tempos de oxidação (0, 1, 5, 10, 20 e 30 min). A caracterização da morfologia, microestrutura, espessura e composição química qualitativa das camadas nitretadas e pós-oxidadas foi realizada por microscopia eletrônica de varredura (MEV) e espectroscopia de emissão óptica por descarga luminescente (GD-OES). A estrutura cristalina presente nas camadas mais superficiais das amostras foi identificada por difração de raios X (DRX), empregando ângulo rasante. Na camada nitretada, as amostras apresentam as fases de nitretos g’-Fe4N e e-Fe2-3N, enquanto que na camada oxidada há uma combinação das fases µ-Fe2O3 e Fe3O4 ou somente a fase Fe3O4 (amostra pós-oxidada por 1 min). A nanodureza foi obtida através de indentações de baixa penetração (até 200 nm). O módulo de elasticidade reduzido, a rugosidade superficial e o coeficiente de atrito (CoF) foram obtidos por ensaios de deslizamento unidirecional, utilizando o equipamento nanoindentador Nanotest-600 da MicroMaterials. O regime de deformação provocado por esses ensaios foi identificado através do cálculo do índice de plasticidade (Y). As amostras apenas nitretada e a pósoxidada durante 1 min apresentaram resultados constantes, dentro do erro experimental e da faixa de profundidade analisada (entre 100 e 200 nm), das propriedades tais como dureza, módulo elástico reduzido, rugosidade e índice de plasticidade, porém com coeficientes de atrito (CoF) diferentes. Desta forma, a evolução do CoF em função da química da superfície pode ser avaliada sem a influência de mudanças nas propriedades mecânicas mais importantes, que determinam o CoF. Esses resultados experimentais podem ser explicados usando um modelo baseado na origem fonônica do atrito, que depende da frequência vibracional característica das camadas mais externas do material. O modelo apresenta boa concordância com os resultados experimentais, com uma diferença de 3% entre teoria e prática. / This work presents a quantitative chemical interpretation of friction for the most external layers of AISI 1045 steel previously nitrided and post-oxidized during 0, 1, 5, 10, 20 and 30 min. The characterization of morphology, microstructure, thickness and qualitative chemical composition of nitrided and post-oxidized layers was performed by scanning electronic microscopy (SEM) and glow discharge optical emission spectroscopy (GD-OES) analysis. The superficial crystalline structure was identified by grazing incident X-ray diffraction. The nitrided layer presented g’-Fe4N and e-Fe2-3N phases, while the postoxidized layer presented µ-Fe2O3 and Fe3O4 phases or just Fe3O4 phase (1 min postoxidized sample). The nanohardness was determined by low depth indentations (until 200 nm). The reduced elastic modulus, the surface roughness and the coefficient of friction (CoF) were determined by unidirectional sliding tests, using a MicroMaterials Nanotest- 600 nanoindenter. The deformation regime was identified through the plasticity index (Y). Nitrided only and 1 min post-oxidized samples showed constant results, considering the experimental error and the analyzed depth range (from 100 to 200 nm), for hardness, reduced elastic modulus, surface roughness and plasticity index, but different CoF. Therefore, the evolution of CoF as a function of the surface chemistry can be assessed without any influence from the change of the most important mechanical properties that determine the CoF. These experimental results can be explained using a phononic model relying on the characteristic vibrational frequency of the most external layers of the material. The model shows a reasonable agreement with the experimental results, with a difference of 3% between theoretical and practical results.