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Dissertations / Theses on the topic 'Nitrifying'

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Published: 4 June 2021

Last updated: 28 January 2023

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Encarnacion, Gem Deangkinay. "Microbial ecology of nitrifying simulated premises plumbing." Diss., Montana State University, 2012. http://etd.lib.montana.edu/etd/2012/encarnacion/EncarnacionG0512.pdf.

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Because of the Stage 2 Disinfectants and Disinfection Rule limiting then concentration of disinfection by products in drinking water, the use of chloramine as an alternative to chlorine has been increasing. However, the ammonia introduced by chloramination can lead to nitrification which results in the production of nitrite and nitrate, leading to regulatory violations. Nitrification in reactors with copper and polyvinyl chloride (PVC) surfaces was established by indigenous organisms from Bozeman tap water and has been stably maintained for more than 6 years. Statistical analyses of polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) profiles determined that the active bacterial populations were different in the two systems. The assemblage of the organisms was also different from the starting population (BAC influent) suggesting both material and ammonia/carbon source affect the population. No known ammonia oxidizing bacteria were detected suggesting the role of different group for ammonia oxidation. Fluorescence in situ hybridization (FISH) detected archaea in the biofilm from both reactors. Archaeal 16S rRNA gene sequences were found to be phylogenetically affiliated with known archaeal ammonia oxidizers. Two archaeal amoA sequences were amplified from the system as determined by DGGE. We propose to provisionally classify a detected archaeon as Candidatus Nitrosotenuis bozemanii, based on its affinity to Nitrosotenuis uzonensis (Hatzenpichler et al., in preparation). Bacterial abundances were comparable in the two systems but archaeal abundances were higher in the PVC reactor suggesting material effect on the overall microbial population composition and density. Enrichment in modified synthetic Crenarchaeota medium yielded a culture of archaea and bacteria that consistently oxidizes ammonia to nitrate. Attempts to isolate the archaeal component using antibiotics failed, suggesting the disruption of a possible beneficial relationship between the archaea and bacteria. Genes involved in the transformation of nitrogen within the system were also investigated and hao distantly related to that of ammonia oxidizing bacteria was detected but its potential role remains unknown. This study provides evidence of archaea associated with biofilms in drinking water and while further analysis is needed to definitively elucidate their role, results of this study prompts the reevaluation of the current concept of nitrification in drinking water. 'Co-authored by Mark D. Burr, Anne K. Camper and Mohammad Shahedur Rahman.'

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McKinlay, Sarah M. "The interactions between ammonifying and nitrifying bacteria." Thesis, University of Aberdeen, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338396.

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The effects of adhesion to surfaces on the specific growth rates of Nitrosomonas europaea and Nitrobacter sp. were determined in batch culture systems both in monoculture and co-culture. It was found that the presence of a glass slide in co-cultures of these bacteria significantly reduced the specific growth rates of both species of bacteria. In monoculture, the specific growth rate of N. europaea was significantly lower in a mature biofilm system. The specific rates of production of ammonia by these four species of Pseudomonas were investigated in minimal medium. All four species converted approximately 60 - 80% of the provided L-alanine to ammonia, and this production of ammonia raised the pH of the medium. All four strains were capable of this when the initial pH of the medium was 5.5 or 7.5, however, lowering the initial pH of the medium reduced the specific rate of production of ammonia for P. cepacia, P. fluorescens and P. syringae, and reduced the final concentration of ammonia produced by P. cepacia. Ammonia produced by P. fluorescens could support the growth of N. europaea in liquid batch culture. The growth of the pseudomonad increased the pH of the medium from 5.5 to 6.8 and this increase in pH allowed growth of the nitrifier in the medium with the lower initial pH. The growth of N. europaea and P. fluorescens in continuous flow biofilm reactors was examined, and the addition of P. fluorescens to a nitrifying biofilm raised the pH of the bulk medium, thus removing the effects of pH inhibition on the ammonia oxidiser. Further investigations were carried out in continuous flow sand column systems and it was found that the rapid growth of the pseudomonad caused obstruction of the column.

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Schopf, Alexander Gerald. "Advancement of Nitrifying Wastewater Treatment Design and Operation." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/41961.

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There is an urgent need to develop ammonia removal treatment systems for municipal and industrial wastewater treatment due to the increasingly stringent ammonia effluent discharge regulations implemented by Canada, the United States, and the European Union. The objective of this dissertation is to develop new understanding and advance the current design and operation of total ammonia nitrogen (TAN) removal via the moving bed biofilm reactor technology (MBBR) for municipal and industrial wastewaters. The first specific objective is to develop a passive, low operationally intensive, efficient and robust design strategy for municipal wastewater treatment to achieve partial nitritation (PN) as a pre-treatment to anammox treatment without using control strategies such as operating at low dissolved oxygen, or the use of inhibitors. This first objective includes developing new knowledge of the biofilm, biomass and microbiome of attached growth PN systems. The second specific objective is to investigate the impact of defining a maximum biofilm thickness, via bio-carrier design, to enhance the effects of free nitrous acid inhibition for PN of municipal wastewaters. The third objective is to investigate the effect of influent copper concentration on nitrifying MBBR systems over long-term operations, to demonstrate the feasibility of the nitrifying MBBR as a solution for TAN removal from gold mining wastewaters. The results pertaining to the first objective, achieved via a study investigating the operation of a nitrifying moving bed biofilm reactor at elevated TAN surface area loading rates (SALRs) of 3, 4, 5, and 6.5 g TAN/m²∙d with the aim of achieving passive PN, demonstrates that operating at a TAN SALR value of 6.5 g TAN/m²∙d can achieve PN without restricting dissolved oxygen or using inhibitors. Operating at a TAN SALR value of 6.5 g TAN/m²∙d achieves a TAN surface area removal rate (SARR) of 3.5 g TAN/m²∙d, and a nitrite accumulation of 99.8% of the oxidized TAN, demonstrating the suppression of nitrite oxidizing bacteria (NOB) activity, while achieving elevated TAN SARR values. At the molecular-scale, there is a statistically significant change in the ammonia oxidizing bacteria (AOB) to NOB ratio from 1:2.6 to 8.7:1 as the TAN SALR increases from 3 to 6.5 g TAN/m²∙d; however, even at a TAN SALR value of 6.5 g TAN/m²∙d there is an NOB abundance of approximately 2%; thus demonstrating that NOB remain present in the biofilm, while their activity is suppressed by operation at elevated TAN SALR values. Furthermore, this system was shown to achieve stable PN consistently for over a period of 10 months of operation, demonstrating a robust, passive, low operational strategy for attached growth PN. The second objective of this dissertation is addressed through a study that compared the carrier design of defined maximal biofilm thickness (z-prototype carrier) to undefined maximal biofilm thickness (chip-prototype carrier) for PN via free nitrous acid inhibition of tertiary, low carbon, municipal wastewaters. The study demonstrates that defined maximal biofilm thickness is a preferred design choice to achieve attached growth PN. The chip-prototype carrier shows biofilm thicknesses and biofilm mass values that are ten-fold higher than the z-prototype carrier, which is shown to contribute to the impact of free nitrous acid on AOB and NOB activities. The z-prototype carrier shows PN is achieved after 3 hours of exposure to free nitrous acid while the chip-prototype carrier does not achieve PN within this same time of exposure. Therefore, the defined maximal biofilm thickness carrier is identified in this research as the preferred design option to achieve attached growth PN for municipal, low carbon, tertiary wastewater treatment. The results of the third objective, achieved via a study investigating the effects of influent copper concentrations on nitrifying MBBR during long term operations to gold mining wastewaters, demonstrates that there is no AOB inhibition in attached growth systems exposed to 0.1, 0.3, 0.45, and 0.6 mg Cu/L for long exposure times. A trend of increasing nitrite accumulation with increasing influent copper concentrations is shown, indicating that NOB inhibition occurs at influent copper concentrations of 0.3 mg Cu/L and greater, with the greatest NOB inhibition observed with an influent copper concentration of 0.6 mg/L. There is no statistically significant difference in biofilm characteristics at the copper concentrations tested; however, there is a trend of increasing biofilm thickness and biofilm roughness with increasing copper concentrations. This study demonstrates the resilience of the nitrifying biofilm to copper inhibition and demonstrates that the nitrifying MBBR is a promising system for removing TAN in mining wastewater in the presence of copper.

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Cheatham, Amy Kathleen. "Responses of Nitrifying Bacteria to Aquaculture Chemotherapeutic Agents." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26879.

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As in any animal production industry, disease is inevitable; therefore, it is imperative that aquaculturists are able to effectively manage the disease and maintain their high production levels in an effort to bridge the gap between supply and demand in the seafood industry that has been caused in part by global over-fishing. This management responsibility lies not only in understanding the impact of the treatment on the cultured species, but also in understanding the impact of the treatment to the aquaculture system as an ecosystem. Currently, there is a narrow variety of chemicals approved by either the Food and Drug Administration (FDA) or the Environmental Protection Agency (EPA) for the treatment of disease outbreaks and water quality issues in aquaculture. Approved chemotherapeutants include oxytetracycline, Romet-30®, copper, and formalin. Additionally, a number of chemicals, such as Chloramine-T and potassium permanganate, are used off-label for the treatment of aquaculture systems. In this research, these six more commonly used chemotherapeutants were analyzed for their impacts to the nitrifying bacteria in aquaculture systems. It was found that three of the chemotherapeutants: oxytetracycline, Romet-30®, and chelated copper caused inhibition to the nitrifying bacteria at the whole cell level as demonstrated in the results from water quality and specific oxygen uptake rate analyses. The nitrification process resumed once the chemotherapeutant was removed from the system, either by a mandatory water change or by natural degradation. The other three chemicals: formalin, Chloramine-T, and potassium permanganate did not result in any significant inhibition to the nitrification process. Experiments on laboratory-cultured nitrifying bacteria confirmed these findings. These experiments also resulted in the observation that the expression of amoA was upregulated by the copper exposure and inhibited by oxytetracycline and Romet-30®, but began to resume as the antibiotics degraded. Comprehensively, the findings of these analyses demonstrated that, although nitrifiers are well-known to be sensitive to their environment, the ability of nitrifying bacteria to continue their oxidative processes following exposure to chemical stress is inherent to the bacteria themselves rather than simply occurring under the protection of a biofilm community as has been suggested. Ph. D.

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Forrest, Daina. "Tertiary Nitrifying Moving Bed-Biofilm Reactor: A Study of Carrier and Loading Effects on Nitrifying Kinetics, Biologically Produced Solids and Microbial Community." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31425.

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There is an increasing need for tertiary level wastewater treatment in Canada, driven in some cases by both provincial and federal regulation (Canada Gazette, 2012). Tertiary nitrification is the biologically mediated oxidation of nitrogen in the form of ammonia to nitrate following secondary treatment of carbonaceous material (Barnes & Bliss, 1983). The application of tertiary nitrification can prove challenging in the Canadian climate because of the temperature sensitive nature of nitrifiers (Hwang & Oleszkiewicz, 2007). Hence the greater than 1000 lagoon treatment plants currently in operation throughout country are susceptible to the full onslaught of weather effects and as such their nitrification processes become non-existent during the winter months (Delatolla et al., 2011,Hoang et al., 2014). The moving bed biofilm reactor (MBBR) system has been studied and shows promise for continuous nitrification with prolonged exposure to cold temperatures (Hoang et al., 2014). They are marketed as cost effective and low operation intensive upgrade options for existing treatment plants as well as effective stand-alone systems and are currently in operation in many countries worldwide (WEF, 2011). Despite the MBBRs initial development as a nitrification technology, recent research has been focused on COD removal systems. Studies showing that MBBR performance is directly related to surface area loading rates (SALRs) and not carrier type or shape have been performed exclusively on COD removal systems. The influence of MBBR carrier type on system solids production has also been solely studied for COD removal and the principles learnt have been transferred to tertiary nitrification systems without confirmation that they hold true. There is an absence of research on tertiary nitrifying kinetics; the effect of loading and carrier type, the nature of the solids produced and the carrier biofilm characteristics. This study investigated three MBBR carrier types, the K3, M and P Anoxkaldnes carriers in an effort to quantify the effects of carrier type on nitrifying kinetics, biologically – produced solids and the bacterial community at normal and high loading conditions. Four tertiary nitrifying laboratory scale MBBRs were fed with synthetic wastewater and operated at a high loading condition (HLC) with a SALR of 1.89 ± 0.10 g-N/m2•d and a normal loading condition (NLC) with SALR of 0.91 ± 0.1 g-N/m2•d. At both HLC and NLC, results show no difference in the ammonia removal rates obtained by the different carrier types. It was however noticed that stressed operational conditions developed for the P and M carrier at the HLC due to the clogging of carrier pore spaces with biofilm and subsequent reductions in removal efficiency were observed. Despite the fact that larger surface area to volume carriers (such as the M and P) may lead to MBBR designs with smaller footprints and lower operational cost, the study revealed their greater propensity to become clogged under high loading conditions than the smaller surface area carriers (such as the K3 ). In addition the larger surface area carriers demonstrated longer transitional periods from high loading conditions to lower loading conditions. A reduction in effluent total suspended solids (TSS) concentrations and improved solids settleability was observed with the shift from HLC to NLC. These results suggest the avoidance of high loading conditions in tertiary nitrifying MBBR operation. If low loading rates are not achievable then system design may have to consider the incorporation of coagulant use or an advanced solids separation technique to meet effluent solids regulation. Variable pressure scanning electron microscope (VPSEM) images at HLC showed the presence of water mites on the K3 carrier and nematodes and ciliates on the M and P carriers. While NLC images do not show these organisms. VPSEM also measured thicker biofilms during the HLC than the NLC for all carriers. The results demonstrate a difference in the meso-environments and suggest a difference in the micro-environments of the biofilm attached to each carrier. Microbial analysis showed no shifts in the dominant nitrifying species between the loading conditions, as well as no differences in the percent live /dead cell coverage. Nitrosomonas and Nitrospira were identified as the dominant AOB and NOB genera respectively at both the HLC and the NLC. Clear shifts in the microbial populations were observed for specific bacteria; with filamentous bacteria being observed at greater relative abundance at HLC than HLC. The increased relative abundance of filamentous organisms are also associated with the significantly poorer effluent settling characteristics observed at HLC.

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Song, Weining. "Some aspects of the utilization of inorganic nitrogen compounds and carbon compounds by "Nitrobacter hamburgensis" /." Title page, contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09A/09as724.pdf.

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Ren, Baisha. "Understanding Extracellular Polymeric Substances in Nitrifying Moving Bed Biofilm Reactor." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32879.

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Water and wastewater treatment solutions incorporating biofilm systems are becoming increasingly popular due to more stringent regulations pertaining to drinking water and wastewater effluent discharge in Canada and in other parts of the world. As a major component of biofilm, extracellular polymeric substances (EPS) have been considered as an important factor affecting the physical and chemical properties of biofilm. Further, the selected method of EPS extraction and the methods of detecting the composition of the EPS have shown to affect the results of EPS measurements. In this research, protocols for EPS extraction and EPS composition analysis were investigated and optimized for nitrifying moving bed biofilm reactor (MBBR) biofilm. In addition, the confocal Raman microscopy (CRM) spectra of EPS in nitrifying MBBR biofilm and the protein, polysaccharide and extracellular DNA (eDNA) percent concentrations of the EPS were investigated at various operating temperatures. Further, the CRM spectra and the protein, polysaccharide and eDNA percent concentration of EPS in nitrifying MBBR biofilm along with the biofilm morphology and thickness and the viability of the embedded cells were investigated at various hydraulic retention times (HRTs). The EPS was characterized at various temperatures and HRTs in order to investigate potential correlation between the EPS components of the nitrifying biofilm and the ammonia removal kinetics. The biofilm morphology and thickness along with the bacterial viability of the biofilm were also investigated at various HRTs. Biofilm morphology images and thickness measurements were acquired using a variable pressure scanning electron microscope (VPSEM). The percentages of viable embedded cells in the biofilm were quantified using live/dead staining in combination with confocal laser microscopy (CLSM) imaging. The research demonstrates that an increase in protein content and subsequently a decrease in polysaccharides and eDNA contents in the EPS of nitrifying MBBR biofilm were observed at the lowest operational HRT and the highest temperature in this work. In particular, the EPS protein to polysaccharide (PN/PS) ratio of nitrifying MBBR systems was shown to significantly decrease below a value of 3 when the system was underloaded (observed at the highest operational temperature in this study) or hydraulically overloaded (observed at the lowest HRT in this study). As such, data obtained at lower operational temperatures, with the system no longer underloaded, and at longer HRTs, with the system no longer hydraulically overloaded, all demonstrate an EPS PN/PS ratio of approximately 3. Correlations were observed between the chemically measured EPS PN/PS ratios and the measured Raman spectra intensity ratios; supporting the concept of higher PN/PS ratios of EPS in more optimal nitrifying MBBR operations. Further, the ammonia removal kinetics and EPS response at HRT values of 0.75 and 1.0 h indicate that nitrifying MBBR systems may be optimized to operate at HRTs as low as 0.75 to 1.0 hour as opposed to conventional HRTs of 2.0 to 6.0 h.

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Delatolla, Robert. "Nitrifying biofilms at cold temperatures: kinetics and in-situ characterization." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32550.

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The biological process of nitrification is currently the most economical and commonly employed means of removing ammonia from wastewater. Although nitrification is cost-effective and has been used in many treatment facilities in North America, the temperature sensitivity of suspended growth nitrifying bacteria is of considerable concern when designing wastewater treatment facilities in many North American cities. Notwithstanding the limited ability of suspended growth treatment systems to achieve nitrification at low temperature, there is evidence that attached growth nitrification processes have the potential to consistently achieve ammonia removal at low temperatures. The objective of this dissertation is to investigate the effect of prolonged exposure to cold temperatures on the kinetics of attached growth nitrification in wastewater treatment facilities as well as the subsequent consequences on the nitrifying bacterial community. Methodological techniques to characterize the weight, nitrogen content and volume of the biofilm along with the volume of nitrifying biomass were developed that minimize loss of mass and manipulation of the biofilm samples. Subsequently, laboratory experiments were performed on attached growth nitrifiers at 4°C. In addition, field experiments were conducted on attached growth laboratory-scale and pilot-scale treatment systems at 4°C. The laboratory experiments demonstrated significant rates of attached growth nitrification at 4°C for the approximate span of a cold climate, North American winter. Specifically, significant nitrification rates were confirmed after 115 days at 4°C. A pronounced kinetic reduction of the rate of nitrificati À présent, le processus biologique de nitrification est le moyen le plus économique d'enlever l'ammoniaque des eaux usées. Bien que cette méthode soit utilisée dans des installations de traitement à travers l'Amérique du Nord, la sensibilité des bactéries à la température est problématique pour la conception de certaines nouvelles installations. Même si les bactéries ont une plus faible capacité de nitrification à basse température, la recherche suggère que cette méthode pourrait enlever l'ammoniaque systématiquement même à basse température. L'objectif de cette thèse était d'investiguer l'effet d'une exposition prolongée à de basses températures sur la cinétique de nitrification de bactéries fixées dans une installation de traitement, ainsi que les effets subséquents sur la communauté de bactéries. Des techniques méthodologiques pour caractériser le poids, la teneur en azote, le volume de biofilm ainsi que le volume de bactéries nitrifiantes ont été développées qui minimisent la perte de masse et la manipulation des prélèvements de biofilm. Ensuite, des expériences ont été effectuées avec une biomasse nitrifiante fixée à 4°C. De plus, des expériences de terrain ont été accomplies avec des bactéries fixées à 4°C avec des unités pilote et de laboratoire. Les expériences ont démontré des taux significatifs de croissance des bactéries fixées et de nitrification à 4°C pendant une durée correspondant à un hiver froid nord-américain. En particulier, des taux significatifs de nitrification ont été confirmés après 115 jours à 4°C. Le taux a baissé immédiatement après la période d'acclimatation et après

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Song, June S. "Effect of copper on nitrifying and heterotrophic populations in activated sludge." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file., 142 p, 2005. http://proquest.umi.com/pqdweb?did=954050351&sid=7&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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Smith, Timothy R. "Evaluating the effectiveness of commercial nitrifying bacteria in a constructed wetland." Virtual Press, 1996. http://liblink.bsu.edu/uhtbin/catkey/1020149.

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This research was conducted to determine the effects of commercially available nitrifying bacteria in a constructed wetland. The study was conducted at Paws, Inc., near Desoto, Indiana during the summer of 1995. The wetland, called Solar Aquatics Treatment System (SAS), was developed by Ecological Engineering Associates and constructed in a, greenhouse. The commercial nitrifying bacteria (Bacta-Pur), contained Nitrosomonas and Nitrobacter Spp. and have been added to the wetland for the past five years to aid in the removal of nitrogen.Water samples were taken from the wetland and analyzed for ammonia, nitrite, nitrate, dissolved oxygen, hydrogen ion concentrations and water temperature from Monday through Friday for three weeks. A baseline was established from these samples. After three weeks of testing the addition of Bacta-Pur to the wetland was discontinued.To determine whether these additional bacteria were needed, testing without the Bacta-Pur was conducted for three weeks. These samples were collected and analyzed for the same parameters as those used to establish baseline information.Ammonia concentrations were significantly lower without the addition of Bacta-Pur bacteria. There were no significant differences for concentrations of nitrite and nitrate. The water temperature was higher in the three weeks when no Bacta-Pur was added. This was due to the increase in ambient temperature which caused the water temperature in the SAS to increase. Since the nitrogen compounds either remained the same or decreased in concentration at the effluent without the addition of bacteria, the addition of Bacta-Pur is not needed in order to remain in compliance with EPA regulations for effluent standards.A container experiment was conducted to provide an' environment that had no introduced bacteria before the addition of Bacta-Pur. There were no significant differences for the nitrogen compounds between wastewater samples with addition and without addition of Bacta-Pur bacteria. Department of Natural Resources and Environmental Management

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Song, June Sup. "Effect of copper on nitrifying and heterotrophic populations in activated sludge." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 142 p, 2005. http://proquest.umi.com/pqdweb?did=954050351&sid=7&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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Lako, Joseph. "Analysis of ammonia-oxidizing bacteria associated with the roots of Proteaceae plant species in soils of Fynbos ecosystem." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&amp.

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The major objective of this study was to investigate soil ammonia-oxidizing bacterial diversity and composition associated with plant roots of Proteaceae plants and to compare it with non-plant associated soil.

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Montràs, Boet Anna. "Mathematical modelling and molecular analysis of a nitrifying packed bed biofilm reactor." Doctoral thesis, Universitat Autònoma de Barcelona, 2009. http://hdl.handle.net/10803/5327.

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MELiSSA (Micro Ecological Life Support System Alternative) és el sistema desenvolupat per l'Agència Espacial Europea (ESA) i el consorci MELiSSA en el camp del suport de vida durant missions de llarga durada a l'espai. Basat en un ecosistema aquàtic, MELiSSA va ser concebut com una eina per desenvolupar la tecnologia necessària per a un sistema de suport de vida biològic que en un futur ha de permetre la producció d'aliment, aigua i oxigen a partir dels residus orgànics generats per una tripulació. Per assolir aquest objectiu, el concepte MELiSSA compta amb l'activitat combinada de cinc compartiments colonitzats per diferents microorganismes i plantes superiors, interconnectats entre ells. Aquesta tesi es centra en el tercer compartiment del bucle MELiSSA, en el qual l'amoni és convertit a nitrat, que és la font de nitrogen més adequada per al creixement dels cianobacteris i plantes superiors que colonitzen els compartiments fotosintètics. L'oxidació biològica d'amoni a nitrat té lloc en dues etapes successives que porten a terme dos tipus de soques bacterianes. En el projecte MELiSSA aquest procés es porta a terme en una columna de llit fix mitjançant Nitrosomonas europaea i Nitrobacter winogradkyi immobilitzats sobre un suport polimèric, i amb aportació d'aire en el mateix sentit de circulació que el medi líquid. El reactor pilot del tercer compartiment ha estat operant a la planta pilot del projecte MELiSSA durant períodes prolongats de temps abans de l'inici del treball realitzat en aquesta tesi. La principal aportació d'aquesta tesi es troba en l'obtenció de nova informació sobre el funcionament del reactor a través d'un estudi detallat de la biopel·lícula i també mitjançant el desenvolupament d'un model matemàtic que ens permetrà estudiar els efectes de diferents paràmetres d'operació sobre el procés i l'estructura de la biopel·lícula. S'implementaran també els aparells de mesura necessaris per millorar la qualitat de la monitorització de les diferents espècies de nitrogen a la fase líquida. Els coneixements adquirits en la realització d'aquest treball seran utilitzats per portar a terme el re-disseny del reactor per tal de millorar-ne el funcionament dins de la planta pilot del projecte MELiSSA. MELiSSA (Micro Ecological Life Support System Alternative) is the system developed by the European Space Agency (ESA) and the MELiSSA consortium in the field of life support for long term manned missions in Space. Based on the principle of an aquatic ecosystem, MELiSSA was conceived as a tool to develop the required technology for a future biological life support system. Its final aim is the production of food, fresh water and oxygen from the organic wastes of a crew. To achieve this goal, the MELiSSA concept is based on the use of five interconnected compartments colonised by several microorganisms and higher plants. This thesis is focused on the third compartment of the MELiSSA loop, in which ammonium is converted to nitrate, the most suitable nitrogen source for the growth of the bacteria and higher plants colonising the photosynthetic compartment. The biological oxidation of ammonium to nitrate, which consists of two successive reactions carried out by two different bacterial strains, takes place in a packed bed biofilm reactor. Nitrosomonas europaea and Nitrobacter winogradskyi are immobilised on a polymeric support, with air flowing cocurrently with the feed medium. The pilot-scale reactor of compartment III (CIII) had been in operation in the MELiSSA pilot plant for several years before the start of the present work. The main contributions of this thesis are in increasing the understanding of the reactor performance by studying the nitrifying biofilm in depth, and by developing a mathematical model that allows the effects of different operational parameters on the process and on the biofilm structure, to be studied. Moreover, continuous monitoring of the nitrifying efficiency will be improved by installing the necessary on-line equipment to experimentally measure the concentrations of all the nitrogen species in the liquid phase. The additional knowledge achieved on the reactor performance via this work will finally lead to re-design the reactor hardware for optimal performance in the MELiSSA pilot plant. The knowledge acquired in this thesis was finally used to define the main features of the re-design of the pilot reactor of the MELiSSA compartment III.

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Fouratt, Melissa Amanda. "Application of Molecular Techniques to the Characterization of a Nitrifying Bioaugmentation Culture." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/33171.

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Nitrification is the biological process whereby ammonia is converted first to nitrite by ammonia-oxidizing bacteria, and then the nitrite is subsequently converted to nitrate by nitrite-oxidizing bacteria. Ammonia and nitrite levels are closely monitored during treatment of wastewater due to their toxicity to other biological processes. Sybron Chemicals, Inc., is a company that manufactures a nitrifying bioaugmentation culture (1010N) that is used to enhance the naturally occurring levels of biological nitrification. The microbial population of the 1010N product has been examined using a combination of conventional bacteriological methods and modern molecular techniques, with the goal of developing nucleic acid probes that can be used to detect the product in an environmental sample. Small regions of the 16S rRNA genes of the bacteria in 1010N (and two new nitrifying enrichment cultures) were amplified via the polymerase chain reaction (PCR) and analyzed via temperature gradient gel electrophoresis (TGGE). TGGE is a procedure that allows for separation and visualization of individual PCR products that are the same size, based on differences in their sequence. Two of the predominant PCR products in 1010N were purified from the TGGE gel matrix, reamplified via PCR, and sequenced to allow for phylogenetic analysis and nucleic acid probe design. Coincidentally, two strains (NS500-9 and MPN2) that had been isolated from the 1010N mixed consortium and grown in pure culture were found, via TGGE, to have identical 16S rRNA sequences to the PCR products under investigation. Nearly the full-length 16S rRNA genes from these two organisms were PCR amplified, cloned, and sequenced in order to provide a basis for more accurate phylogenetic analysis. The two dominant organisms in the 1010N product, NS500-9 and MPN2, were thereby found to be most closely related to Nitrosomonas and Nitrobacter, respectively, in the existing database. Using the nucleic acid sequences of the cloned DNA, organism-specific DNA probes were designed for both NS500-9 and MPN2. Unfortunately, difficulties were encountered in using the probes to monitor 1010N activity levels via quantitative dot blot hybridizations (rRNA-DNA). Therefore, efforts were redirected to using the TGGE semi-quantitatively with an internal PCR standard (BrÃ¼ggeman, et al., 2000) to estimate original cell numbers of 1010N within a mixed consortium. This method was not applicable to our system due to substantial preferential binding of the primers to template other than the standard. Samples from a laboratory-scale bioreactor, bioaugmented with 1010N, were used in an attempt to correlate an increase in activity with a detectable shift in population via TGGE. No detectable shift in population was detected in these samples even though the system exhibited increased levels of nitrification. Therefore, the sensitivity of the TGGE system was also examined by determining the limits of detection when 1010N was present in activated sludge. In both whole cell spiking experiments and genomic DNA spiking experiments, it was found that 1010N must be present at a level of at least 5% of the total population in order to be detected. While this provides some information about microbial populations, in order to evaluate the biological activity of a system, nucleic acid probes should be used in a rRNA based study. Master of Science

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Ray, Anirban. "Identification, Enumeration and Diversity of Nitrifying Bacteria in the Laurentian Great Lakes." Bowling Green State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1351276518.

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Mofokeng, Teboho. "Full-scale trials of external nitrification on plastic media nitrifying trickling filter." Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/5024.

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Includes abstract. Includes bibliographical references. In South Africa, many wastewater treatment plants (WWTP) still make us of their rock filled trickling filters. Instead of using them for organics removal and nitrification, there is growing interest in integrating them with biological excess P removal activated sludge (BEPRAS) systems in an external nitrification flow scheme (Hu et al., 2000). In such a scheme, the full influent flow (after primary settling) is discharged to the anaerobic reactor of the BEPRAS system, after which the activated sludge is separated from the water by internal settling tanks. The clarified supernatant is pumped to the trickling filter for nitrification and the activated sludge to the anoxic reactor of the BEPRAS system, where the nitrified water rejoins the main BEPRAS system. This external nitrification BEPRAS system has several advantages over continuing to use the trickling filters for organics removal and nitrification, such as significantly reduced oxygen demand (~50%) and biological N and P removal on the full wastewater flow. To date full-scale studies in South Africa have been performed only with rock media trickling filters, for example that at Daspoort WWTP (Muller et al., 2004, 2006a, b). This report describes an investigation on the full-scale operation of a plastic media nitrifying trickling filter (NTF) at the 1 Ml/d Citrusdal WWTP.

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Jones, Nicole Jean. "NITRIFYING BACTERIAL ABUNDANCE IN RELATION TO NITROGEN AND PHOSPHORUS COMPOUNDS IN WETLANDS." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/theses/829.

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Floodplain lakes are wetlands which receive flood waters from nearby rivers or other sources. Water samples were taken from floodplain lakes near the Illinois River, the Mississippi River, and the Cache River in Southern Illinois. Fluorescence in situ hybridization (FISH), spectrophotometry, and gene probes were used to investigate the effect of nutrient and chemical concentrations on the abundance of nitrifying bacteria; specifically ammonia-oxidizing Nitrosococcus and Nitrosomonadales and nitrite-oxidizing Nitrospira and Nitrobacter. Nitrosococcus was the dominant ammonia-oxidizing bacteria at each river system. Nitrospira and Nitrobacter had similar average abundances. Nitrosococcus abundances showed a significant positive correlation with nitrate (NO3-) (R2= 0.247, P=0.05, 95% confidence R2≥0.199) and a positive trend with nitrite (NO2-) (R2= 0.194, P=0.10, 90% confidence R2≥0.125). Nitrosomonadales abundance positively correlated with temperature (R2= 0.530, P=0.05, 95% confidence R2≥0.510). Nitrospira abundances positively correlated with ammonium (NH4+) (R2= 0.265, P=0.05, 95% confidence R2≥0.199), NO2- (R2= 0.372, P=0.05, 95% confidence R2≥0.199), and NO3- (R2= 0.482, P=0.05, 95% confidence R2≥0.199). None of the target bacterial abundances significantly correlated with pH or dissolved inorganic phosphate.

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Young, Bradley. "Nitrifying MBBR Performance Optimization in Temperate Climates Through Understanding Biofilm Morphology and Microbiome." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36001.

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Nitrification is currently the most common means of ammonia removal from wastewaters in temperate climates. In conventional suspended growth systems operating in northern climate regions, nitrification completely ceases at temperatures below 8°C. This is a considerable concern in passive treatment systems where wastewater temperatures can reach as low as 1°C for extended periods in the winter months. There is evidence biofilm technologies have the ability to nitrify at low temperatures, however, the literature is missing an understanding of low temperature nitrification and the subsequent impacts during seasonal changes. Additionally, there is an urgent need to gain a fundamental knowledge of the interplay between nitrifying performance optimization, biofilm morphology and the microbiome. This research aims to fill these needs using nitrifying moving bed biofilm reactors (MBBRs) at the lab and pilot scale. This research concluded the most important factor determining MBBR carrier selection is a combination of surface area and pore space size. Although high surface area to volume carriers are attractive, the propensity to clog at high loading rates significantly decreases the removal rates. The viability of the biomass and ammonia oxidizing bacterial communities were not significantly changed, indicating the ammonia removal rates were reduced due to loss of surface area in the clogged carriers. Operation at 1°C demonstrated significant rates of nitrification can be attained and stable for extended periods of operation. This study developed the first kinetic curve at 1°C with a maximum removal rate of 0.35 gN/m2·d. The performance of the post carbon removal nitrifying MBBR systems were shown to be enhanced at 1°C by an increase in the viable embedded biomass as well as thicker biofilm. This effectively increased the number of viable cells present during low temperature operation, which partially compensated for the significant decrease in rate of ammonia removal per nitrifying cell. At all studied loading rates at 1°C, the ammonia oxidizing bacteria were primarily in the family Nitrosomonadaceae (greater than 95 percent abundance of AOB population) and the nitrite oxidizing bacteria were primarily the genus Nitrospira (greater than 99 percent abundance of NOB population). Operation at 20°C demonstrated high rates of removal in high loaded condition and robustness in extreme low loaded conditions. In both high loaded and extreme low loaded conditions the viability of the nitrifying biomass was sustained, with the family Nitrosomonadaceae as the primary ammonia oxidizing bacteria and the genus Nitrospira as the primary nitrite oxidizing bacteria. In extreme low loaded conditions and as well during start-up phases there are high prevalence of bacteria not directly related to the nitrification process. Their presence however indicates a dynamic process with changes in microbial composition within the biofilm matrix in response to varying conditions. Change in microbial composition likely helps stabilize and maintain the biofilm matrix enhancing process robustness in the temperate climates. The new knowledge gained in this research optimizes the operation of nitrifying MBBR systems and elucidates the impacts of operational conditions on the biofilm and microbial community of nitrifying MBBR systems to further our understanding of nitrifying attached growth treatment technologies. The results of this study are anticipated to be used to design the first MBBR treatment system for year round ammonia removal in passive treatment systems located in northern climate regions.

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Meng, Yiyu. "Nitrite oxidising bacteria in soil : examination of the interactions with ammonia oxidisers and the influence of pH on their diversity and distribution." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=231853.

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Nitrification is a central part of the nitrogen cycle, whereby the most reduced form, ammonia, is converted to the most oxidised form, nitrate via nitrite. The first step is performed by ammonia oxidising bacteria (AOB) and archaea (AOA), with the second step performed by nitrite oxidising bacteria (NOB). Although both groups are closely associated in nature, ammonia oxidisers have received more attention compared to NOB as ammonia oxidation is considered the rate-limiting step. Nitrobacter and Nitrospira are two important groups of soil NOB. To determine whether there are specific associations of AOA or AOB with certain NOB, the effect of organic and inorganic ammonia sources was tested by adding glutamate or ammonium sulphate to soil together with either 5% 12CO2 or 13CO2 to determined autotrophic growth by DNA-SIP. The results demonstrated that while the various ammonia and nitrite oxidisers responded differently, there was no direct evidence of specific coupled interactions. The effects of soil pH on Nitrobacter and Nitrospira was then investigated in a long-term pH gradient in an agricultural field. The results demonstrated that Nitrospira abundance was lower in acidic soils, whereas Nitrobacter abundance remained equally or more abundant. pH also influenced the relative distribution of Nitrobacter and Nitrospira populations, with distinct community structures at both high and low pH. The interaction of AOA and NOB was further investigated in a co-culture experiment, and demonstrated that the removal of nitrite and free nitrous acid NOB enhanced both rates and amounts of ammonia oxidised, indicating that in acidic environments these relationships may be particularly critical. Finally, the use of the compound PTIO was investigated for potential use in elucidating specific relationships between AOA and NOB. Results demonstrated a lack of specificity for the target group, and was unstable in soil, and therefore its use in soil should proceed with caution.

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Zaklikowski, Anna Emilia. "The Effect of Chlorine and Chloramines on the Viability and Activity of Nitrifying Bacteria." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/33758.

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Nitrification is a significant concern for drinking water systems employing chloramines for secondary disinfection. Utilities have implemented a range of disinfection strategies that have varying levels of effectiveness in the prevention and control of nitrification events, including optimizing the chlorine-to-ammonia ratio, maintaining chloramine residual throughout the distribution system, controlling pH, and temporal switching to free chlorination. Annual or semi-annual application of free chlorination is practiced by 23% of chloraminating systems on a temporary basis as a preventative measure, even though it has the undesirable consequences of temporarily increasing disinfection byproducts, facilitating coliform detachment, and altering water taste and odor. Although temporal free chlorination and other nitrification control methods have been widely studied in the field and in pilot-scale systems, very little is known about the stress responses of nitrifying bacteria to different disinfection strategies and the role physiological state plays in the resistance to disinfection. It is well known that many commonly studied bacteria, such as Escherichia coli, are able to better resist disinfection by free chlorine and chloramines under nutrient limitation through regulation of stress response genes that encode for DNA protection and enzymes that mediate reactive oxygen species. We compared the genomes of E. coli and the ammonia-oxidizing bacterium Nitrosomonas europaea, and found that many of the known stress response mechanisms and genes present in E. coli are absent in N. europaea or not controlled by the same mechanisms specific to bacterial growth state. These genetic differences present a general susceptibility of N. europaea to disinfection by chlorine compounds. Using an experimental approach, we tested the hypothesis that N. europaea does not develop increased resistance to free chlorine and monochloramine during starvation to the same degree as E. coli. In addition, N. europaea cells were challenged with sequential treatments of monochloramine and hypochlorous acid to mimic the disinfectant switch employed by drinking water utilities. Indicators of activity (specific nitrite generation rate) and viability (LIVE/DEADÂ® BacLightâ ¢ membrane-integrity based assay) were measured to determine short-term effectiveness of disinfection and recovery of cells over a twelve day monitoring period. The results of disinfectant challenge experiments reinforce the hypothesis, indicating that the response of N. europaea to either disinfectant does not significantly change during the transition from exponential phase to stationary phase. Exponentially growing N. europaea cells showed greater susceptibility to hypochlorous acid and monochloramine than stationary phase E. coli cells, but had increased resistance compared with exponential phase E. coli cells. Following incubation with monochloramine, N. europaea showed increased sensitivity to subsequent treatment with hypochlorous acid. Complete loss of ammonia-oxidation activity was observed in cells immediately following treatment with hypochlorous acid, monochloramine, or a combination of both disinfectants. Replenishing ammonia and nutrients did not invoke recovery of cells, as detected in activity measurements during the twelve day monitoring period. The results provide evidence for the effectiveness of both free chlorine and chloramines in the inhibition of growth and ammonia-oxidation activity in N. europaea. Furthermore, comparison of viability and activity measurements suggest that the membrane integrity-based stain does not serve as a good indicator of activity. These insights into the responses of pure culture nitrifying bacteria to free chlorine and monochloramine could prove useful in designing disinfection strategies effective in the control of nitrification. Master of Science

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Morris, Michael. "Studies in the behaviour of a nitrifying verical flow constructed wetland wastewater treatment system." Thesis, University of Worcester, 1999. http://eprints.worc.ac.uk/750/.

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A novel configuration of vertical downflow constructed wetland was used to treat up to 75 m3 per day of sugar beet processing wastewaters. The 403 m2, two-stage pilot system included planted and unplanted cells of a variety of sand depths (0.15 - 0.4 m) and sand particle size distributions (d10 = 0.07 - 1.2 mm). The hydraulic regime of each bed was also manipulated. Typical beet processing wastewaters contained 235 mg BOD l-1, 45 mg NH4-N l-1, 0.03 mg PO4-P l-1, 16 mg TSS l-1, at pH 8.2 and 29 °C. Overall performance of the pilot system, with respect to BOD, NH4-N, and TSS removal, was similar to, or better than, comparable two-stage vertical flow wetland systems. In vertical flow systems, influent BOD concentrations >600 mg l-1 were coincident with reduced rates of nitrification. Mean BOD removal rate in the pilot system was 38.8 g BOD m-2 d-1, with a mean loading rate of 40.4 g BOD m-2 d-1. The first-order reaction rate for BOD removal was calculated to be 0.369 m d-1 over the whole system. High rates of oxygen transfer and efficient removal of organic solids were seen as the most important factors enhancing BOD removal. Mean NH4-N removal rate in the pilot system was 5.6 g NH4-N m-2 d-1, with a mean loading rate of 7.3 g NH4-N m-2 d-1. The temperature corrected first-order reaction rate for NH4-N removal was calculated to be 0.23 m d-1 over the whole system. Nitrification accounted for between 85% and 99% of TKN removal. Evidence is presented which supports the hypothesis that cycles of assimilation/adsorption and release of NH4-N may play an important role in nitrification mechanisms in vertical flow constructed wetlands. In bed 1, removal of BOD and NH4-N were at their most efficient in the vegetated cell with the deepest (0.21 m), coarsest (d10 = 1.2 mm) sand layer. TSS removal was highest in an unvegetated cell with shallower (0.15 m), finer (d10 = 0.56 mm) sand. In bed 2, removal of BOD, NH4-N, and TSS were all at there most efficient in the vegetated cell with the deepest (0.4 m), coarsest (d10 = 0.1 mm) sand layer. Low influent phosphate concentrations may have limited nitrification rates in the pilot system. The surface area available for biofilm attachment, and media depth, both provided good models of NH4-N removal, whilst cell surface area was more important in solids removal. Media hydraulic conductivity at the beginning of the dosing cycle was five times higher in vegetated cells than in unvegetated cells. After 12 hours of dosing, media particle size distribution became the dominant factor determining media hydraulic conductivity. High influent BOD concentration was more closely associated with cell logging than hydraulic loading, TSS concentration, or BOD or TSS loading. Growth of one provenance of Phragmites australis was limited by phosphate availability. However, populations of nitrifying bacteria were highest in samples of media and roots taken from plots containing this provenance. No correlation was demonstrated between nitrifying bacteria population and root biomass. Water stress caused by high media hydraulic conductivity and inadequate influent distribution resulted in sub-optimal conditions for reed growth in bed 1. The study concludes with details of the proposed design of a full scale system designed to treat up to 1000 m3 d-1 of beet processing effluents.

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Li, Chunju. "Dynamic variations of carbonaceous and nitrifying activities in hybrid reactors with different operating conditions /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20LI.

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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004. Includes bibliographical references (leaves 178-188). Also available in electronic version. Access restricted to campus users.

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Hughes, Leonie. "Multistage and multiple biomass approaches to efficient biological nitrogen removal using biofilm cultures." Thesis, Hughes, Leonie ORCID: 0000-0001-6496-988X (2008) Multistage and multiple biomass approaches to efficient biological nitrogen removal using biofilm cultures. PhD thesis, Murdoch University, 2008. https://researchrepository.murdoch.edu.au/id/eprint/674/.

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Nitrogen removal from wastewater is important for the revention of significant health and environmental impacts such as eutrophication. Nitrogen removal is achieved by the combined action of nitrification and denitrification. Nitrification is performed by autotrophic, slow growing microorganisms that require oxygen and are inhibited in the presence of denitrifiers when oxygen and COD are available due to competition for oxygen. Denitrification however, performed by relatively fast growing heterotrophic bacteria, is inhibited by oxygen and requires COD. This implies that nitrification and denitrification are mutually exclusive. The supply of oxygen to a fresh wastewater, high in ammonia and COD, causes waste of both oxygen and COD. Conservation of COD is therefore critical to efficient wastewater treatment. The approach investigated in this study to achieve complete nitrogen removal was to physically separate the nitrification and denitrification biomasses into separate bioreactors, supplying each with appropriate conditions for growth and activity. A storage driven denitrification sequencing batch biofilm reactor (SDDR) was established which exhibited a high level of COD storage (up to 80% of influent COD) as poly-B-hydroxybutyrate capable of removing >99% of nitrogen from wastewaters with a C/N ratio of 4.7 kg COD/kg N–NO3 –. The SDDR was combined in sequential operation with a nitrification reactor to achieve complete nitrogen removal. The multiple stage, multiple biomass reactor was operated in sequence, with Phase 1 - COD storage in the storage driven denitrification biofilm; Phase 2 - ammonia oxidation in the nitrification reactor; and Phase 3 - nitrate reduction using the stored COD in the storage driven denitrification reactor. The overall rate of nitrogen removal observed was up to 1.1 mmole NH3 L–1 h–1 and >99% of nitrogen could be removed from wastewaters with a low C/N ratio of 3.9 kg COD/kg N–NH3. The multiple stage, multiple biomass system was limited in overall nitrogen removal the reduction in pH caused by nitrification. A parallel nitrification-denitrificatio (PND) reactor was developed in response to the pH control issue. The PND reactor was operated with Phase 1 – COD storage in the storage driven denitrification biofilm and Phase 2 – simultaneous circulation of reactor liquor between the denitrification and nitrification biofilms to achieve complete nitrogen removal and transfer of protons. The PND reactor performed competitively with the multistage reactor (removal of >99% nitrogen from wastewaters with feed ratios of 3.4 kg COD/kg N–NH3) without the need for addition of buffering material to oderate the pH.

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Hughes, Leonie. "Multistage and multiple biomass approaches to efficient biological nitrogen removal using biofilm cultures." Hughes, Leonie (2008) Multistage and multiple biomass approaches to efficient biological nitrogen removal using biofilm cultures. PhD thesis, Murdoch University, 2008. http://researchrepository.murdoch.edu.au/674/.

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Hjorth, Ingrid. "Molecular genetic analysis of the microbial community structure in nitrifying biofilms adapted to different salinities." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bioteknologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14053.

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Nitrification, the microbial oxidation of ammonia to nitrate, is a key step inthe biological cycling of nitrogen, and is often used in wastewater treatmentfor removal of ammonium. Fish-farming in flow-through systems such asopen net pens is the largest contributor to human discharge of inorganicnutrients along the Norwegian coast. It is important to limit these emissionsby converting to recirculating systems for nitrogen removal. However, thenitrification process is known to be sensitive to high concentrations of salts,a factor of importance when establishing technology for treatment of salinewastewaters.The aim of this thesis was to investigate and compare the microbialcommunities of nitrifying biofilms adapted to different salinities. Two con-tinuous biofilm reactor systems were operated, one supplied with seawater-based cultivation medium, while the other was supplied with tapwater-basedcultivation medium. The microbial communities in the two reactors wereinvestigated by denaturing gradient gel electrophoresis (DGGE) and fluo-rescence in situ hybridization (FISH). A batch culture salinity response testwas carried out to investigate the acute effect of different salinities on thenitrification activity in the seawater-adapted culture.DGGE analysis based on 16S rRNA and amoA sequences showed thatthe seawater-based reactor had lower microbial diversity than the tapwater-based reactor, and that different nitrifiers seemed to dominate in the tworeactors. Ammonia- and nitrite-oxidizers affiliated with the nitrosomonadsand with Nitrospira were identified in both reactors. Ammonia-oxidizersrelated to Nitrosomonas oligotropha seemed to dominate in the tapwater-based reactor, while Nitrosomonas halophila seemed to dominate in theseawater-based reactor. The batch culture salinity respons test, comparedto a similar experiment by (Kristoffersen 2004), indicated that the nitrify-ing culture adapted to high salinity was more halotolerant than a cultureadapted to low salinity. Nitrifikasjon er en mikrobiell prosess der ammonium oksideres til nitrat.Nitrifikasjon er en viktig prosess i den biologiske nitrogensyklus, og er oftebrukt innen vannrensing for ̊ fjerne ammonium. Fiskeoppdrett i ̊aapnemerder er den største bidragsyteren til menneskaskapte utslipp av uorgan-iske næringssalter langs norskekysten, og det er viktig begrense disse ut-slippene ved ̊ g ̊ over til resirkulerte systemer for nitrogenfjerning. Nitri-a afikasjonsprosessen er kjent for ̊ være følsom for høye saltkonsentrasjoner,aog det er viktig ̊ ta hensyn til dette n ̊ teknologi for rensing av avløpsvannaarmed høyt saltinnhold etableres.M ̊ med denne oppgaven var ̊ undersøke og sammenlikne mikro-aletabielle samfunn i nitrifiserende biofilmer adaptert til ulike saliniteter. Tokontinuerlige reaktorsystemer ble drevet, ́n ble forsynt med sjøvannsbasertekultiveringsmedium, den andre ble forsynt med springvannsbasert kultiver-ingsmedium. De mikrobielle samfunnene i de to reaktorene ble undersøktved hjelp av denaturerende gradient gelelektroforese (DGGE) og fluorescensin situ hybridisering (FISH). En salinitetsresponstest ble utført for ̊ un-adersøke den akutte effekten av ulike saliniteter p ̊ nitrifikasjonsaktiviteten iaden sjøvanns-adapterte kulturen.DGGE-analyse basert p ̊ sekvenser av 16S rRNA og amoA indikerteaat den sjøvannsbaserte reaktoren hadde lavere mikrobiell diversitet enn denspringvannsbaserte reaktoren, og at ulike nitrifiserende bakterier dominerte ide to reaktorene. Ammonium- og nitrittoksiderende bakterier beslektet medNitrosomonas og Nitrospira ble funnet i begge reaktorene. Ammonium-oksiderende bakterier beslektet med Nitrosomonas oligotropha s ̊ ut til ̊aadominere i den springvannsbaserte reaktoren, mens Nitrosomonas halophilavar mer dominerende i den sjøvannsbaserte reaktoren. Salinitetsrespons-testen, sammenliknet med et liknende eksperiment utført av Kristoffersen(2004), indikerte at den nitrifiserende kulturen adaptert til høy salinitet varmer halotolerant enn en kultur adaptert til lav salinitet.

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Bäckman, Jenny. "Nitrification and nitrifying bacterial communities in coniferous forest soils : effects of liming and clear-cutting /." Linköping : Univ, 2003. http://www.bibl.liu.se/liupubl/disp/disp2002/tek809s.pdf.

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Yang, Jeongwoo. "Fate and effect of alkyl benzyl dimethyl ammonium chloride in mixed aerobic and nitrifying cultures." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19871.

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Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008. Committee Chair: Spyros G. Pavlostathis; Committee Member: Ching-Hua Huang; Committee Member: John A. Pierson.

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Azimi, A. A. "The effects of reactor configuration on the performance of nitrifying activated sludges under transient loadings." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233194.

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Daims, Holger. "Population structure and functional analyses by in situ techniques of nitrifying bacteria in wastewater treatment plants." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963771582.

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Morris, Raymond Anthony. "Investigation of the Optimal Dissolved CO2 Concentration and pH Combination for the Growth of Nitrifying Bacteria." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3256.

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Ammonium (NH4+) is a biological nutrient that is transformed in a wastewater treatment plant (WWTP) in a process called activated sludge. This is accomplished in an aerobic environment using microorganisms and inorganic carbon that convert the ammonium to nitrate (NO3-). This process is termed nitrification. Removal of ammonium is necessary due to its oxygen demand and toxicity to the environment. Nitrification is considered a slow process due to the slow growth rate of the nitrifying bacteria. Ammonia oxidizing bacteria (AOB) first covert the ammonium (NH4+) to nitrite (NO2-) followed by conversion to nitrate (NO3-) by nitrite oxidizing bacteria (NOB). These slow rates limit the treatment capacity of the WWTP. The initial hypothesis suggested that these slow rates were due to limited carbon in the aeration basin of a WWTP. A series of designed experiments and observational studies revealed substantial dissolved CO2 exists throughout a WWTP. Based on these findings, the central research focused on determining if an optimum dissolved CO2 concentration/ pH combination exists that maximizes nitrification. Experimentation conducted at a pH of 7.0 and varying concentrations of dissolved CO2 concentration revealed inhibition at low (<5 mg/l) and high (>30 mg/l) dissolved CO2 concentration levels. Further research found that optimum nitrification can be attained in a dissolved CO2 concentration range of 10 - 15 mg/l and a pH range of 7.5 - 8.0. A maximum specific growth rate of 1.05 - 1.15 days-1 was achieved. A partitioning of the sums of squares from these designed experiments found that pH accounts for approximately 83 percent of the sums of squares due to treatment with the dissolved CO2 concentration accounting for 17 percent. This suggests that pH is the dominant factor affecting nitrification when dissolved CO2 concentration is optimized. Analysis of the growth kinetics for two of the designed experiments was conducted. However, a set of parameters could not be found that described growth conditions for all operating conditions. Evaluating the results from these two experiments may suggest that a microbial population shift occurred between 16 and 19 mg/l of dissolved CO2 concentration. These dissolved CO2 concentrations represent pH values of 7.1 and 7.0, respectively, and were compared to experimentation conducted at a pH of 7.0. Though the pH difference is minor, in combination with the elevated dissolved CO2 concentration, a microbial shift was hypothesized. Microbial samples were collected from the designed experiment that optimized dissolved CO2 concentration (5, 10 and 15 mg/l) and pH (6.5, 7.0, 7.5 and 8.0). These samples were evaluated using Fluorescence in situ hybridizations (FISH) to determine the population density of common ammonium oxidizing bacteria (AOB) (Nitrosomonas and Nitrosospira) and nitrite oxidizing bacteria (NOB) Nitrobacter and Nitrospirae). The dominant AOB and NOB microbes were found to be Nitrosomonas and Nitrospirae. These results suggest that increased nitrification rates can be achieved by incorporating appropriate controls in a wastewater treatment plant (WWTP). With higher nitrification rates, lower nitrogen values can be obtained which will reduce the WWTP effluent nitrogen concentration. Conversely, these increased nitrification rates can also reduce the volume of an aeration basin given similar effluent nitrogen concentrations.

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Repke, Rodrigo Alberto 1988. "Efeito de diferentes concentrações e estirpes da bactéria Azospirillum brasilense nos componentes de produção em plantas de trigo /." Botucatu, 2016. http://hdl.handle.net/11449/144493.

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Orientador: Silvio José Bicudo Coorientador: Rogério Peres Soratto Banca: Marcio Christian S. Domingues Banca: Priscila Gonzales Figueiredo Banca: Carlos Jorge da Silva Banca: Luciano Soares de Souza Resumo: O triticum aestivum é uma espécie de ciclo anual, pertencente à família Poaceae. Cultivado em regiões de climas subtropical e temperado, ocupa a segunda maior área plantada no mundo. Para obtenção de altas produtividade dentre outros cuidados, é essencial o fornecimento de nutrientes na quantidade demandada pelas cultivares de alto potencial produtivo, com destaque para o nitrogênio (N). A fixação biológica de nitrogênio é realizada por microrganismos simbióticos associados com raízes das plantas. Entre os microrganismos simbióticos que fixam nitrogênio associados com raízes de plantas, destacam-se os do gênero Azospirillum brasilense. O objetivo no presente trabalho foi avaliar a eficiência do uso da inoculação Azospirillum brasilense no desenvolvimento e componentes produtivos da cultura do trigo. O estudo foi dividido em dois experimentos sendo o primeiro em ambiente protegido e o segundo em ambiente não protegido, ambos na Faculdade de Ciências Agronômicas - Universidade Estadual Paulista "Júlio de Mesquita Filho", Campus de Botucatu, SP, no ano agrícola 2013. O delineamento utilizado foi o de blocos inteiramente casualizados para ambiente protegido e blocos casualizados para ambiente não protegido, com 10 tratamentos em esquema fatorial 3x3+1. Sendo os tratamentos compostos pelo uso de duas estirpes (Ab-V5 e Ab-V6) isoladamente e em combinação das mesmas (Ab-V5+Ab-V6), todos aplicados em três concentrações 65, 130 e 195 milhões de unidades formadoras de colônia (UFC) de... Abstract: Triticum aestivum is a yearly crop species belonging to the Poaceae family. It is cultivated in regions with subtropical and temperate climate, and takes up the second largest planted area in the world. Nutrient provision in the demanded amount by high productive potential cultivars, mainly nitrogen (N), is essential to obtain high productivity. The biological fixation of nitrogen is done by symbiotic microorganisms associated with plan roots. Azospirillum brasilense is one of the genera in which the symbiotic microorganisms fixate nitrogen associated with plant roots. This study aimed to evaluate the agronomical efficiency of Azospirillum brasilense inoculation on the growth and productive components of wheat cultivation. The study was divided into two experiments: the fist protected environment, and the second non-protected environment conditions, both in the School of Agriculture - Universidade Estadual Paulista "Júlio de Mesquita Filho", Campus of Botucatu, SP, Brazil, during 2013 crop year. The experiment had completely randomized block design for the fist experiment in protected environment, and random blocks for the second experiment in non-protected environment, with 10 treatments in 3x3+1 factorial scheme. The treatments consisted of two separate (V5 and V6) and combined (V5+V6) stocks and three concentrations (65, 130 and 195 million UFC of bacteria) were applied. The control treatment had no bacterial inoculation. For the protected environment, each experimental plot consisted of plants cultivated in an asbestos recipient with the following dimensions: 0.50 m of height, 0.88 m of width and 1.05 m of length, and 0.462 m3 of soil. Seven 0.88-m rows with 0.15 m spacing and 40 seeds per meter were utilized. In the field experiment, the experimental plot consisted of ten 2.0-m rows with 0.17 m spacing and 45 seeds per meter. For both experiments, the seeding density was 266 seeds m2, aiming ... Doutor

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Moore, J. Michael. "Nitrification inhibition by metalaxyl as influenced by pH, temperature, and moisture content in three soils." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54249.

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Metalaxyl, [N—(2,6-Dimethylphenyl)-N-(Methoxyacetyl)-alanine methyl ester], is used extensively in tobacco (Nicotiana tabacum L.) production for prevention of black shank (Phytophthora parasitica Dast. var. nicotianae), blue mold (Peronospora tabacina Adam), and damping-off (Pythigm spp.). Metalaxyl is also patented as a nitrification inhibitor, although not marketed for that purpose. Proper maturity and ripening of flue-cured tobacco depends on an adequate supply of N through the time of removal of the inflorescence, with a declining supply of N from that point. Use of a chemical which might prolong the availability of N in tobacco could delay maturity and reduce the quality of the cured leaf. These studies were conducted to determine whether metalaxyl might inhibit nitrification under a broad range of soil physical and environmental conditions prevalent in the tobacco producing areas of Virginia. The influence of soil type, soil pH, soil temperature, and soil moisture on inhibition of nitrification by metalaxyl (1 mg kg⁻¹) were investigated in three soils used extensively for tobacco production. Soils used in the study were Cecil sandy loam (clayey, kaolinitic, thermic Typic Hapludult), Appomattox fine sandy loam (clayey, mixed, thermic Typic Kandhapludult), and Mattoponi sandy loam (clayey, mixed, thermic Typic Hapludult). Metalaxyl did not inhibit nitrification under any of the conditions studied. However, NO₂⁻ accumulation with metalaxyl was sometimes greater than the control, especially at high pH (7.0) in the Cecil and Appomattox soils, and at 10 and 20°C. Nitrite and NO₃⁻ accumulations from four rates of metalaxyl (1, 5, 25, and 125 mg kg⁻¹) were compared with those of an untreated control and a nitrapyrin standard over a seven week soil incubation period in further studies using the same soils and adjusted pH levels. Significant NO₂⁻ accumulation occurred during the first week after treatment at high pH in all soil types, with 5, 25, and 125 mg kg⁻¹ metalaxyl. Only the 125 mg kg⁻¹ metalaxyl treatment caused NO₂⁻ accumulation at the high pH in all soils beyond the second week after treatment, with the peak occurring in most cases between weeks three and four. Nitrate accumulation proceeded normally in all soil types and pH levels except with treatments of 25 and 125 mg kg". Nitrate accumulations with 25 mg kg⁻¹ were similar to those for nitrapyrin. The 125 mg kg⁻¹ rate was consistent in causing near total inhibition of NO₃⁻ accumulation at all pH levels in all soils. Nitrate accumulation tended to be lower at lower soil pH levels compared to the highest pH for all soils. Little difference in nitrification due to soil appears to be evident. Use of metalaxyl at recommended rates of 0.25 to 1.5 mg kg⁻¹ would not be expected to inhibit nitrification. Ph. D.

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Ruiz, Rueda Olaya. "Nitrifying and denitrifying bacterial communities in the sediment and rhizosphere of a free water surface constructed wetland." Doctoral thesis, Universitat de Girona, 2008. http://hdl.handle.net/10803/7871.

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La contínua descàrrega de nutrients, sobretot fosfats i nitrogen, és la major causa d'eutrofització dels ecosistemes aquàtics. Els sistemes de tractament basats en aiguamolls construïts s'han emprat per reduir ells nivells de nitrogen a l'aigua com a alternativa de baix cost als mètodes de depuració convencionals. L'eliminació del nitrogen a aquests sistemes depèn en bona part de la vegetació, i l'alternança de condicions aeròbiques i anaeròbiques per promoure els processos de nitrificació i desnitrificació. En aquest treball hem volgut investigar les activitats microbianes de nitrificació i desnitrificació en relació a dues espècies de plantes macròfites en un sistema d'aiguamolls de tractament de flux superficial (FS-SAC), dissenyat per minimitzar l'impacte de l'alliberament d'aigua carregada de nutrients a la reserva natural dels Aiguamolls de l'Empordà (Girona, Espanya). The continuous delivery of nutrients, mainly phosphate and nitrogen, is the major cause of eutrophication of aquatic environments. Treatment technologies based on constructed wetlands have been applied to reduce the levels of nitrogen as a cost-effective alternative compared to conventional treatment methods. The nitrogen removal efficiency in wetlands relies on the presence of plants and the alternation of aerobic and anaerobic conditions to promote both nitrification and denitrification. Although the role of emergent macrophytes in such systems is largely recognized, their contribution to the overall treatment process has not been quantified very frequently. We have investigated the microbial nitrification and denitrification activities in relation to two plant species in a free water surface constructed wetland (FWS-CW), designed to minimize the impact of nutrient release into the Natural Reserve of Els Aiguamolls de l'Empordà (Girona, Spain).

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Hoang, Phuong Ha, Hong Thu Nguyen, Trung Thanh Trung, Thanh Tung Tran, Lan Phuong Do, and Thi Nhi Cong Le. "Isolation and selection of nitrifying bacteria with high biofilm formation for treatment of ammonium polluted aquaculture water." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-227866.

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A biofilm is any group of microorganisms in which cells stick to each other and adhere to a surface by excreting a matrix of extracellular polymeric substances (EPS). The chemoautotrophic nitrifying bacteria hardly form biofilms due to their extremely low growth rate; however, biofilm formation of nitrifying bacteria trends to attach in carrier by extracellular polysaccharides that facilitate mutual adhesion, the forming biofilm is also beneficial in nitrogen removal in biological filter systems, especially in aquaculture water treatment systems. The microbial activity within bio-carrier is a key factor in the performance of biofilm reactor. Selection the nitrifier bacteria that biofilm formation and immobilization on the carrier for application in ammonium polluted water treatment technologies, especially in aquaculture is our research objective. Therefore, in this study, ten and six strains of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) respectively were isolated from six different aquaculture water samples collected from Quang Ninh and Soc Trang. Basing on their high nitrification activity and biofilm forming capacity, six bacterial strains have been selected to take photo by scanning electron microscope (SEM) and carry out in 2 – liter tanks with and without carriers. As the results, the system with carriers (30% of total volume) increased nitrogen compounds elimination efficiency from 1.2 times to 2 times in comparison with the system without carrier. Two representatives of ammonia oxidizing bacterial group (B1.1; G2-1.2) were classification based on characteristics and they were classified as Nitrosomonas sp. and Nitrosococcus sp Màng sinh học được hình thành từ vi sinh vật nhờ các tế bào tiết ra các chất cao phân tử ngoại bào (EPS) và dính vào nhau đồng thời được gắn lên một bề mặt vật thể lỏng hoặc rắn. Vi khuẩn nitrate hóa tự dưỡng có thể tạo ra màng sinh học nhưng khá khó khăn do tỷ lệ sinh trưởng rất chậm của chúng. Tuy nhiên vi khuẩn nitrate hóa tạo màng sinh học thường có xu thế bám lên giá thể nhờ sự gắn kết của các polisaccarit ngoại bào. Sự hình thành màng sinh học cũng là lợi thế để loại bỏ các hợp chất nitơ trong các hệ thống lọc sinh học, đặc biệt là trong các hệ thống xử lý nước nuôi trồng thủy sản. Hoạt tính vi sinh vật cùng với giá thể sinh học là một yếu tố quan trọng để thực hiện trong các bể phản ứng màng sinh học. Trong nghiên cứu này, mục tiêu của chúng tôi là lựa chọn được các vi khuẩn nitrate hóa có khả năng tạo màng sinh học và cố định chúng lên giá thể để ứng dụng trong các công nghệ xử lý nước bị ô nhiễm ammonia đặc biệt là trong nuôi trồng thủy sản. Kết quả cho thấy, từ sáu mẫu nước nuôi trồng thủy sản khác nhau từ Quảng Ninh và Sóc Trăng, 10 chủng vi khuẩn oxy hóa ammonia (AOB) và 6 chủng vi khuẩn oxy hóa nitrite (NOB) đã được phân lập. Dựa vào hoạt tính nitrate hóa và khả năng tạo màng sinh học của các chủng vi khuẩn phân lập được 6 chủng điển hình đã được lựa chọn để chụp ảnh kính hiển vi điện tử quét và được ứng dụng trong hai bể sinh học với dung tích 2 lít có chứa và không chứa chất mang (giá thể). Sau 7 ngày, hệ thống sinh học chứa giá thể (chiếm 30% thể tích) có hiệu suất loại bỏ các hợp chất nitơ tăng hơn từ 1,2 đến 2 lần so với bể sinh học không chứa chất mang. Hai đại diện của nhóm vi khuẩn oxy hóa ammonia (B-1.1 và G2-1.2) đã được phân loại sơ bộ dựa vào một số đặc điểm sinh học và chúng đã được xác định thuộc chi Nitrosomonas và chi Nitrosococcus

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Shishido, Masahiro 1960. "Effectiveness of dominant Rhizobium meliloti indigenous to Arizona soil." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276929.

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A total of 200 Rhizobium meliloti isolates were sampled from alfalfa (Medicago sativa L.) nodules in five uninoculated fields throughout Arizona. Dominant strains (≥ 20% nodule occupancy at each site) were identified using plasmid profile analysis and intrinsic antibiotic resistance patterns. The major dominant strains and a commercial strain (102F77b) were evaluated for their N fixing effectiveness in a Leonard jar study. All strains were highly effective, and no significant differences were found (p ≥ 0.05) in shoot weight, root weight, nodule weight, acetylene reduction and total N content among the strain treatments. These effective dominant R. meliloti strains indigenous to Arizona soil probably contribute to the state's high alfalfa yield. Furthermore, indigenous strains AZTCYJ, AZSC, and AZY have potential as inoculants for arid lands due to their high effectiveness and unique resistances to extreme abiotic stresses present in arid land soils.

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Ahmed, Warsama. "Nitrifying Moving Bed Biofilm Reactors at Low Temperatures and Cold Shock Conditions: A Kinetic, Biofilm and Microbiome Study." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41196.

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The nitrification process, the biologically mediated process of ammonia treatment in water resources recovery facilities (WRRF), remains the most common treatment process to mitigate the adverse effects of effluent ammonia discharges in surface water. However, it is well established that the temperature-sensitive process of nitrification remains hindered at low temperatures in conventional suspended growth technologies; specifically, passive treatment systems such as the lagoons, representing over 50% of Canadian treatment facilities in operation. As such, nitrification in lagoon facilities remains unreliable during the cold seasons with no nitrification occurring at 1°C. In contrast to suspended growth systems, attached growth technologies such as the moving bed biofilm reactors (MBBR) have recently been proven capable of achieving significant nitrification rates at temperatures as low as 1°C and are proposed as suitable upgrade systems to the common lagoon facility to reach year-long ammonia treatment targets. As such, the main objective of this research is to investigate and expand the current knowledge by investigating the key research questions lacking in the current literature on post-carbon, low temperature nitrifying MBBR systems. With this aim, a temperature-controlled study of attached growth nitrification kinetics was conducted to isolate the effects of low temperatures on nitrifying MBBR system performance down to 1°C. A removal rate of 98.44 ± 4.69 gN/m³d is identified as the 1°C intrinsic removal rate and the design removal rate for nitrifying MBBR systems at low temperatures. Considering this intrinsic rate at 1°C, an assessment of reactor efficiency at elevated TAN concentrations typical of non-combined sewer systems indicates that a two reactor in-series MBBR system configuration is recommended for retrofitting lagoon facilities connected to sanitary sewers. The study of the reactor performance to temperatures as low as 1°C demonstrates a non-linear decline in removal efficiency between 10°C and 1°C, with the existence of a kinetic threshold temperature delineated between 4°C and 2°C. As such, this delineated temperature range accounts for a significant decline in the performance of low carbon nitrifying MBBR systems during the onset of the cold seasons. This research identifies new recommended Arrhenius correction coefficient values taking into account this kinetic threshold temperature, with a coefficient of 1.049 being recommended above the kinetic threshold (≥4°C) and 1.149 below the threshold temperature at 1°C. Moreover, since the elapsed time to low temperature was identified as a key factor of attached growth nitrification kinetics, a modified theta model accounting for temperature and time is proposed in this research to accurately model the rate of nitrifying MBBR systems between 4°C and 1°C. Finally, with the severe adverse effects of sudden decreases in temperature, or cold shocks, on nitrification kinetics being previously demonstrated but not well understood, this research compares acclimatized and cold shocked MBBR reactors down to 1°C. The findings indicate 21% lower kinetics in the cold shocked reactor with reactor efficiencies never reaching those of the acclimatized reactor despite extended operation at 1°C. Thus, the research delineates the potentially lasting effects of extreme weather events such as cold air outbreaks and snowmelt periods on nitrifying MBBR system performance. On the other hand, these same findings demonstrate the resiliency of nitrifying MBBR reactors as nitrification was maintained within these systems despite being cold-shocked down from 10°C and 1°C. This study of attached growth kinetics was coupled with an investigation of the nitrifying biofilms, biomass, and microbiome responses to low temperatures and cold shock down to 1°C to provide an understanding of the changes occurring in these systems down to the cellular level. Comparisons of acclimatized and cold shocked nitrifying biofilms responses down to 1°C were characterized by increases in biofilm thickness, increases in biomass viability; and, greater shifts in microbiome communities occurring above 4°C in the acclimatized biofilm. Considering these observations, results also indicated a significant increase in nitrifiers per carrier above 4°C. As such, these findings suggested that the bulk of nitrifying biofilm adaptation to cold temperatures occurs above 4°C, a crucial adaptation phase in acclimatized systems. This adaptation phase is shown to be lacking in cold-shocked systems, with the cold shocked biofilm and microbiome demonstrating significant differences with the acclimatized systems’ biofilm and microbiome. This research was performed to answer the critical research questions relating to the design and operation of the post-carbon, low temperature nitrifying MBBR systems, with the first low temperature MBBR systems being scheduled to begin operation in the fall of 2020. This research expands the current knowledge on low temperature attached growth nitrification kinetics as well as cold shocked attached growth nitrification kinetics in MBBR systems down to 1°C. In addition, this research delineates the effects of low temperatures and cold shocks on the nitrifying MBBR system’s biofilms and their embedded cells.

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Correa, Camila Zoe. "Reator de leito estruturado com recirculação submetido à aeração intermitente no tratamento de esgoto sanitário." Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1680.

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O lançamento de compostos nitrogenados em corpos d’água pode resultar em problemas ambientais, sendo assim tratar águas residuárias, como o esgoto sanitário com o objetivo de remover não apenas matéria orgânica, mas tambémnitrogênio tem sido objeto de estudo há algumas décadas. O objetivo deste trabalho foi avaliar o desempenho de um reator de leito estruturado e fluxo contínuo, com recirculação, na remoção de matéria orgânica e nitrogênio presente em esgoto sanitário, sob diferentes ciclos de Aeração intermitente (AI) e avaliar a influência destes ciclos no desenvolvimento de bactérias nitrificantes (Bactérias Oxidadoras de Amônia – BOA e Bactérias Oxidadoras de Nitrito – BON) e desnitrificantes (DESN) aderidas (Material Suporte - MS) e em suspensão (Efluente – EF e Lodo – LD). O reator utilizado possuía volume útil de 9,4 L. Como material suporte (MS) foi utilizado espuma de poliuretano, cortada e fixada em hastes de PVC. Foram trabalhadas 3 fases de aeração (AE) e não aeração (AN) com diferentes tempos: Fase 1 (4 h AE/ 2 h AN); Fase 2 (2 h AE/ 1 h AN) e Fase 3 (2 h AE/ 2 h AN). Durante todas as fases o tempo de detenção hidráulico foi mantido em 16 h e o efluente recirculado a uma vazão de 3 vezes a vazão afluente. Foram analisados: pH, alcalinidade total, temperatura, Demanda Química de Oxigênio (DQO), Demanda Bioquímica de Oxigênio (DBO), Nitrogênio Kjeldhl Total (NKT), N-amoniacal – N-NH4+, nitrito- N-NO2 e nitrato- N-NO3. A concentração das BOA, BON e DESN foi determinada utilizando o Número Mais Provável.gSSV-1 (NMP.gSSVmL-1). Na Fase 1 o percentual de remoção de NKT, N-NH4+ e NT foi de 76±10%, 70±21% e 67±10% respectivamente. Na Fase 2 de 80±15% de remoção de NKT, 86±15% de N-NH4+ e 68±9% de remoção de NT e na Fase 3 de 58±20%, 72±28% e 41±6% de NKT, N-NH4+ e NT, respectivamente. A eficiência de desnitrificação nas 3 fases foi acima de 70%, indicando que no reator ocorreu o processo de Nitrificação e desnitrificação Simultânea (NDS). Os percentuais de remoção de DQOT foram de 88%±4 na Fase 1, 94%±7 na Fase 2 e 90%±11 na Fase 3. A ANOVA multivariada aplicada ao NMP.gSSV-1, indicou que houve diferença significativa (F: 20,2; p-valor <0,01) entre a concentração dos organismos analisados nos diferentes ciclos de AI. Porém as diferenças entre os NMP.gSSV-1 não depende apenas de fatores isolados e sim de quais meios, fases e grupos estão sendo analisados. Dos resultados conclui-se que o sistema foi eficiente em termos de remoção de nitrogênio e matéria orgânica, e que a fase que apresentou a maior disponibilidade de Oxigênio Dissolvido (OD) e relação C/N (Fase 2), foi a que obteve as menores concentrações efluentes de matéria orgânica e N-NH4+. Apontasse que houve diferença significativa entre a concentração (NMP.gSSV-1) dos organismos analisados (BOA, BON e DESN), porém esta diferença não depende de fatores isolados e sim de quais meios (MS, EF ou LD, fases (1, 2 ou 3) e grupos (BOA, BON e DESN) está sendo considerado. The release of nitrogen compounds in water bodies can result in many environmental problems, so treat wastewater, such as sewage in order to remove not only organic matter but also nitrogen has been studied a few decades. From the above, the objective of this study was to evaluate the performance of a structured bed reactor, continuous flow, with recirculation, in removing organic matter and nitrogen present in wastewater under different cycles of intermittent aeration (AI) and to evaluate the influence of these cycles in the development of nitrifying bacteria (Oxidizing Bacteria Ammonia - BOA and Bacteria Oxidizing Nitrite - BON) and denitrifying (DESN) adhered (Support Material - MS) and suspension (Effluent - EF and sludge - LD). The reactor used has usable volume of 9.4 L. As support materials (MS) polyurethane foam was used, cut and fixed in PVC rods. 3 were worked aeration phases (AE) and non-aeration (AN) at different stage: Stage 1 (4 h EA / AN 2H); Stage 2 (2H EA / AN 1 h) and Phase 3 (2H EA / AN 2 h). During all hydraulic detention time phases was kept at 16 h and the effluent recirculated at a rate of 3 times the inflow. Were analyzed: pH, total alkalinity, temperature, chemical oxygen demand (COD), Biochemical Oxygen Demand (BOD), nitrogen Kjeldhl Total (NKT), ammonia-N-N-NH4+, nitrito-N-NO2+andnitrato-NO3-. The concentration of BOA, BON and DESN was determined using the number More Provável.gSSV-1 (NMP.gSSV-1). In phase 1 the percentage removal NTK N-NH4+ and NT was 76±10%, 70±21% and 67±10% respectively. In Phase 2 80±15% of removel NKT, 86±15% of N-NH4+ e 68±9% of removel NT e na Fase 3 de 58±20%, 72±28% and 41±6% of NKT, N-NH4+ of NT, respectively. The denitrification efficiency in stage 3 was over 70%, indicating that occurred in the reactor the process of simultaneous nitrification and denitrification (NDS). DQOT the removal percentages were 88 ± 4% in Phase 1, 94 ± 7 in Phase 2 and 90± 11% in Phase 3. The multivariate ANOVA applied to NMP.gSSV-1, it indicated that there was significant (F: 20,2, p <0,01) between the analyzed concentration of organisms AI in different cycles, but the differences between NMP.gSSV-1 depends not only isolated factors but of which means, and phase groups being analysis. From the results it is concluded that the working system is efficient in terms of nitrogen removal and organic matter, and that the stage with the highest availability of Dissolved Oxygen (DO) and C/N ratio (Step 2), was the one obtained the lower concentrations of organic matter effluents and N-NH4+. Hinted that there was a significant difference between the concentration (NMP.100mL-1) of the analyzed organizations (BOA, BON and DESN), but this difference does not depend on factors alone but of which means (MS, EF or LD), stages (1, 2 or 3) and groups (BOA, BON and DESN) is being considered.

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Keuter, Sabine [Verfasser], and Eva [Akademischer Betreuer] Spieck. "Characterization of nitrifying bacteria in marine recirculation aquaculture systems with regard to process optimization / Sabine Keuter. Betreuer: Eva Spieck." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2012. http://d-nb.info/1022196472/34.

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Smith, Robert C. "Ecological Factors in Design of a Two-Sludge Nitrifying Activated Sludge System Incorporating Side-Stream Treatment of Anaerobic Digester Supernatant." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1291307830.

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Hüpeden, Jennifer [Verfasser], and Eva [Akademischer Betreuer] Spieck. "Taxonomic and functional diversity of nitrifying biofilm communities in biofilters of different recirculating aquaculture systems / Jennifer Hüpeden ; Betreuer: Eva Spieck." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2020. http://d-nb.info/1209676087/34.

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Posso-Blandon, Lina. "Stimulation of nitrification by carbon dioxide in lab-scale activated sludge reactors." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001285.

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Cao, Huiluo, and 曹慧荦. "Molecular ecology of ammonia oxidizing archaea and bacteria." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47155358.

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The newly recognized ammonia-oxidizing archaea (AOA) makes re-evaluation of the contribution to ammonia oxidization by both AOA and ammonia-oxidizing bacteria (AOB) necessary and meaningful. The growing population and increasing anthropogenic activities around coastlines have affected wetland and coastal marine ecosystems through discharging polluted water containing large amounts of reactive inorganic nitrogen. The objectives of this study were to detect the phylogenetic diversity and abundance of ammonia oxidizers including AOA and AOB on different scales and to elucidate the distribution patterns along an anthropogenic pollution gradient from the coastal wetland of the Mai Po Nature Reserve in Hong Kong to the South China Sea (SCS). Generally, besides lineages shared by similar environments, various endemic lineages were also observed in the polluted mangrove sediments of Hong Kong, and in the coastal, and deep-sea surface and subsurface sediments from the SCS indicating their geographical distance should be responsible for these phylogenetic distinctions. The community structures of AOA and AOB observed were proposed to be associated with environmental parameters including metals and total phosphorus (TP) separately in the sediments while their abundance was correlated with the pH value and temperature. On the other hand, along a profile of surface sediments with stable salinity from the coastal margin to the slope in the SCS, a clear community structure transition was detected for both AOA and AOB, showing major differences in each of their responses. Although the abundance of AOA was lower than that of AOB in the subsurface sediment samples from the SCS, the statistical support for relationships between AOA and nitrite concentration shed new light on the active contributor to the subsurface nitrogen cycle in the oxygen minimum zone from the deep-sea sediments. On a large scale, along the anthropogenic pollution gradient from the Pearl River Delta to the coastal margin and then the SCS, the dominant genus transition from Nitrosomonas to Nitrosospira was detected in response to the salinity and anthropogenic influences. Among a wide spectrum of environmental conditions in the western Pacific, a suite of statistical analyses clearly delineated the shallow and deep-sea sediments clusters suggesting that the depth and other contributing environmental factors involved shape the current distribution pattern of AOA. On a global scale, our understanding about the systematics and evolution of AOA was advanced through phylogenetic analyses. Salinity, lifestyle and temperature were proposed to be responsible for the global distribution patterns of AOA. On the basis of studies in the anthropogenic influence areas, the methods to detect specific responses of ammonia oxidizers to known anthropogenic pollution were concluded. Highlights of this study advance not only our understandings about phylogenetic diversity of ammonia oxidizers and the driving forces shaping their community structure and distribution patterns, but also a revised comprehensive view about them on the larger scale. published_or_final_version Biological Sciences Doctoral Doctor of Philosophy

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Zhan, Weixi. "The fate of dosed copper to inhibit nitrification in chloraminated water distribution system." Thesis, Curtin University, 2007. http://hdl.handle.net/20.500.11937/1359.

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Chloramine as a secondary disinfectant has been widely used by many water utilities around the world especially in a distribution system requiring a longer retention time such as the 600km long Goldfield water distribution system of Western Australia. Chloramine is selected mainly due to its better stability and low by-products over other disinfectants. However, it is reported that under nitrifying conditions, chloramine residual could drop dramatically. Consequently the required disinfectant concentration can not be maintained. Nitrification, microbial process, is known to be causing rapid depletion of the chloramine residual and enhancing the growth of heterotrophic bacteria. In preliminary studies conducted in Water Corporation, copper at concentrations of 0.25mg/L has been found to be effective against nitrifiers. A concentration of 0.25mg/L as copper is achieved by directly dosing into the main pipeline at the outlet of the Cunderdin reservoir. Nonetheless, the preferred copper concentration can not be maintained as gradual decrease of dissolved copper in bulk water has been encountered along the pipeline.This research aimed to investigate fate of copper in bulk water and distribution system. Three fundamental mechanisms leading to copper loss had been investigated: gravitational sedimentation, adsorption onto wall or biofilm and mineral ions induced aggregation. During investigation of these mechanisms, potential controlling factors (pH, alkalinity, DOC, mineral ions…etc) were brought into a series of experiments as variables. Hardly can free cupric ions or copper hydroxide particles exist in bulk water samples. It was found that major Cu-containing forms are inorganic and organic copper compounds. Solubility of inorganic copper compounds is in equilibrium with calcium carbonate buffered system while organic copper compounds are controlled by organic matters and dissolved organic carbon in drinking water. Minerals such as ferric/ferrous ions and calcium ions contained in the distribution system can aggregate various copper species in bulk water to form particles.Consequently, it can lead to sedimentation or deposition onto walls or sediments. Wall adsorption had been simulated using glass fibre (GF) filters in the laboratory. GF filters were found able to absorb various forms of dissolved copper and copper compounds, though further work needs to be done to investigate the real pipe surface adsorption and complete the adsorption model. Historical data from the field had been analysed. Combined with laboratory results, it shows that both adsorption and mineral ions induced aggregation are contributing to the loss of copper in the distribution system. However, to further quantify these two mechanisms respectively and build up a comprehensive model, more field data are needed and more laboratory work needs to be done. Copper with different forms will be brought into inhibition experiments in the next stage of research in order to find effective form(s) against nitrifying bacteria. Based on the current achievement on the fate of copper, an inhibition strategy is suggested at the end of this thesis.

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Huang, Ying-Sheng. "Evidence for Multiple Functions of a Medicago Truncatula Transporter." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699903/.

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Legumes play an important role in agriculture as major food sources for humans and as feed for animals. Bioavailable nitrogen is a limiting nutrient for crop growth. Legumes are important because they can form a symbiotic relationship with soil bacteria called rhizobia that results in nitrogen-fixing root nodules. In this symbiosis, rhizobia provide nitrogen to the legumes and the legumes provide carbon sources to the rhizobia. The Medicago truncatula NPF1.7/NIP/LATD gene is essential for root nodule development and also for proper development of root architecture. Work in our lab on the MtNPF1.7/MtNIP/LATD gene has established that it encodes a nitrate transporter and strongly suggests it has another function. Mtnip-1/latd mutants have pleiotropic defects, which are only partially explained by defects in nitrate transport. MtNPF1.7/NIP/LATD is a member of the large and diverse NPF/NRT1(PTR) transporter family. NPF/NRT1(PTR) members have been shown to transport other compounds in addition to nitrate: nitrite, amino acids, di- and tri-peptides, dicarboxylates, auxin, abscisic acid and glucosinolates. In Arabidopsis thaliana, the AtNPF6.3/NRT1.1( CHL1) transporter was shown to transport auxin as well as nitrate. Atchl1 mutants have defects in root architecture, which may be explained by defects in auxin transport and/or nitrate sensing. Considering the pleiotropic phenotypes observed in Mtnip-1/latd mutant plants, it is possible that MtNPF1.7/NIP/LATD could have similar activity as AtNPF6.3/NRT1.1(CHL1). Experimental evidence shows that the MtNPF1.7/NIP/LATD gene is able to restore nitrate-absent responsiveness defects of the Atchl1-5 mutant. The constitutive expression of MtNPF1.7/NIP/LATD gene was able to partially, but not fully restore the wild-type phenotype in the Atchl1-5 mutant line in response to auxin and cytokinin. The constitutive expression of MtNPF1.7/NIP/LATD gene affects the lateral root density of wild-type Col-0 plants differently in response to IAA in the presence of high (1mM) or low (0.1 mM) nitrate. MtNPF1.7/NIP/LATD gene expression is not regulated by nitrate at the concentrations tested and MtNPF1.7/NIP/LATD does not regulate the nitrate-responsive MtNRT2.1 gene. Mtnip-1 plants have an abnormal gravitropic root response implicating an auxin defect. Together with these results, MtNPF1.7/NIP/LATD is associated with nitrate and auxin; however, it does not act in a homologous fashion as AtNPF6.3/NRT1.1(CHL1) does in A. thaliana.

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Pelivanoski, Bojan [Verfasser], and Martin [Akademischer Betreuer] Denecke. "Elucidating the potential of anaerobic wastewater treatment for nitrogen removal with nitrifying airlift reactor and lithotrophically denitrifying FeS granules / Bojan Pelivanoski ; Betreuer: Martin Denecke." Duisburg, 2021. http://d-nb.info/1232175870/34.

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Scudeletti, Daniele 1990. "Modos de inoculação de azospirillum brasilense em cana-de-açúcar /." Botucatu, 2016. http://hdl.handle.net/11449/146731.

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Orientador: Carlos Alexandre Costa Crusciol Coorientador: Marcelo de Almeida Silva Banca: Gabriela Ferraz Siqueira Banca: Eduardo Negrisoli Resumo: A cana-de-açúcar (Saccharum spp.) é uma cultura de grande importância econômica para o Brasil, pois além de gerar empregos em setores como agrícola, industriais e terceiros, a cultura também proporciona a produção de biomassa energética. Há muitas evidências de que esta cultura seja beneficiada pela interação com bactérias diazotróficas, principalmente as do gênero Azospirillum que, além da fixação de N atmosférico podem produzir fitormônios que promovem, na maioria dos casos, efeitos positivos no crescimento vegetal, no rendimento e nas alterações fisiológicas da planta. A principal barreira à utilização do Azospirillumn a cultura da cana-de-açúcar tem sido a incon¬sistência dos resultados de pesquisa, que podem variar de acordo com a cultivar, as condições eda¬foclimáticas e a metodologia de condução da pes¬quisa. Objetivou-se, mediante o presente estudo, avaliar a eficácia dos modos de inoculação de Azospirillum brasilense, nos parâmetros biométricos, fisiológicos e tecnológicos, e as possíveis melhorias na absorção de nutrientes do solo e na produtividade. O trabalho foi desenvolvido em área experimental pertencente à Usina da Barra, localizada no município de Santa Maria da Serra - SP, na safra 2015/2016. O delineamento experimental foi em blocos ao acaso, em esquema fatorial 2 x 2, com 4 repetições. Os tratamentos foram constituídos por inoculação do Azospirillum brasilense (sem e com) e pelos modos de aplicação (tolete e foliar). Foi considerada como área útil as 4 ... Abstract: The sugarcane (Saccharum spp.) is a crop of great economic importance to Brazil, as well as create jobs in several sectors such as agricultural, industrial and third culture also provides the production of energy biomass. There are many evidences that this crop culture is benefited by interaction with diazotrophs, especially the Azospirillum genus that in addition to atmospheric N fixation can produce phytohormones that promote, in most cases, positive effects on plant growth, yield and amendments physiological plant. The main barrier to the use of Azospirillum in sugarcane has been the inconsistency of search results, which may vary according to the cultivar, the climatic conditions and methodology of research. The aim, through this study, was to evaluate the effectiveness of Azospirillum brasilense inoculation modes, the biometric, physiological and technological parameters, and possible improvements in the uptake of soil nutrients and yield. The study was conducted in the experimental area of Sugar mill Barra, localized in Santa Maria da Serra - SP, in 2015/2016. The experimental design was a randomized block in factorial 2 x 2, with four repetitions. The treatments consisted of inoculation of Azospirillum brasilense (with and without) and the application modes (stem and leaf). It was considered useble area of the center lines 4 of 8 lines planted. The inoculation was performed by applying 2 L-1 ha of the commercial product. The inoculation of the stems was performed before covering the plating furrows and in plots that received foliar it occurred at tillering stage. It was concluded that inoculation with Azospirillum brasilense did not affect the macronutrient content, leaf chlorophyll content, stalk number, internode number and the technological quality of sugarcane and there was an increase in stalk height due to the increase in average length internode, resulting in higher yield in ... Mestre

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Chauret, Christian. "Effect of tungsten on nitrate and nitrite reductases in Azospirillum brasilense SP 7." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59635.

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Azospirillum brasilense reduced nitrate in W-containing Mo-limited medium, but at lower rates than in W-free medium. However nitrate reduction by Paracoccus denitrificans was completely suppressed under the same conditions. Nitrite reductase activity of growing A. brasilense was negatively affected by tungstate. Nitrite accumulation was shown to be the result of an inhibitory effect of nitrate on nitrite reductase activity. Both resting whole cell and cell-free extract preformed nitrite reductase activities were equally affected by increasing levels of tungstate. Preformed nitrate reductase activity of the cell-free extract was shown to be more sensitive to increasing concentrations of tungstate than whole cell activity, suggesting that the cytoplasmic membrane served as a protective barrier against tungsten inactivation of nitrate reductase.

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Lee, Woo Hyoung. "Development and Use of Microelectrodes to Evaluate Nitrification within Chloraminated Drinking Water System Biofilms, and the Effects of Phosphate as a Corrosion Inhibitor on Nitrifying Biofilm." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1258489526.

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Oliveira, Karina Vogel Vidal de. "Caracterização de comunidade microbiana em biofilme associada a filtro biológico para o tratamento de efluente de aquacultura." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/26913.

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Na aquacultura de recirculação são utilizados filtros biológicos para o tratamento do efluente antes que este retorne aos tanques. Estas unidades de tratamento têm como finalidade a transformação de nitrogênio amoniacal em nitrato, pois a amônia e o nitrito são tóxicos para os peixes. O nitrogênio amoniacal tende a se acumular na água de cultivo, pois é um importante produto de excreção dos organismos aquáticos e degradação da ração não consumida. Nestes filtros biológicos, os microorganismos responsáveis pelo tratamento da água residuária se encontram aderidos no meio de preenchimento, formando um biofilme. O presente trabalho teve como objetivo caracterizar as comunidades microbianas presentes no biofilme associado ao filtro biológico de uma unidade experimental de tratamento de efluente de aquacultura. Durante o experimento, realizado em dois sistemas paralelos representando unidades de aquacultura com e sem recirculação de água, também foram monitorados parâmetros de qualidade da água. Os tanques experimentais foram povoados com juvenis de tilápias-do-Nilo (Oreochromis niloticus), que foram submetidos a pesagens a cada quinze dias para avaliar seu ganho de biomassa. As bactérias foram identificadas através da técnica de análise microbiológica da hibridização fluorescente in situ (FISH). A estrutura do biofilme foi avaliada através de microscopia eletrônica de varredura. Os resultados indicam que a nitrificação teve um papel mais importante no controle da qualidade da água no sistema com recirculação em relação ao tanque sem recirculação. A análise microbiológica do meio de preenchimento do filtro revelou uma presença marcante (com proporções de Cy3/DAPI variando entre 0,5% e 7,6%) de células ativas de organismos nitrificantes (oxidadores de amônia e de nitrito), pertencendo a gêneros distintos como Nitrobacter, Nitrococcus e Nitrosomonas, além de outros grupos de presença expressiva, como bactérias filamentosas (com proporções de 11,2% a 17,3% da contagem de células marcadas com DAPI). As imagens de Microscopia Eletrônica de Varredura revelaram a natureza do arranjo destas bactérias no meio filtrante, caracterizando um biofilme bem desenvolvido, composto por diversos morfotipos microbianos. O conhecimento das bactérias que compõe este biofilme pode tornar possível a geração de melhorias que podem ser implementadas para aumentar a eficiência do sistema. In recirculating aquaculture, biological filters are used for treating the effluent before it returns to tanks. These treatment units are intended for transforming ammoniacal nitrogen into nitrate, since ammonia and nitrite are toxic to fish. Ammoniacal nitrogen tends to accumulate in culture water, because it is an important excretion product from aquatic organisms and also due to degradation of non consumed feed. In these biological filters, microorganisms responsible for the treatment of waste water adhere to the filler, forming a biofilm. The present work intended to characterize the microbial community present in the biofilm associated to the biological filter at an experimental aquaculture effluent treatment unit. During the experiment, conducted in two parallel systems representing aquaculture units with and without water recirculation, water quality parameters were also monitored. Experimental tanks were populated with juvenile Nile Tilapias (Oreochromis niloticus), which were subjected to weighing every 15 days in order to assess their biomass gain. Bacteria were identified through the microbiological analysis technique of Fluorescent In Situ Hybridization (FISH). The biofilm structure was assessed using scanning electron microscopy. The results indicate that nitrification had a more important role in the control of water quality in the system with recirculation compared with the tank without recirculation. The microbiological analysis of the filter media revealed a significant presence (with Cy3/DAPI range between 0.5% e 7.6%) of active cells from nitrifying organisms (ammonia and nitrite oxidizers), which belonged to different genera such as Nitrobacter, Nitrococcus and Nitrosomonas, in addition to groups that had an expressive presence, such as filamentous bacteria (representing 11.2% to 17.3% of the total DAPI stained cells). Scanning Electron Microscopy images revealed the nature of the arrangement of these bacteria in the filtering media, characterizing a well developed biofilm made up of diverse microbial morphotypes. The knowledge about the bacteria making up the biofilm may enable improvements that can be implemented to increase system effectiveness.

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Miller, Jerry Lee 1960. "Desorption and biodegradation experiments: 1) Effect of application solvents on nitrifying bacteria, 2) Effect of surfactants on release and biodegradation of strongly bound soil residues of atrazine and naphthalene." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/565576.

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