Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 23 for “"nitrifier"”.
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The biogeochemistry of marine nitrous oxide
… isotopic signatures of N2O produced by marine nitrifiers. This thesis shows that in addition to chemical controls on N2O production rates such as oxygen (O2) and nitrite (NO-2) concentrations, there are also biological controls such as nitrifier cell abundances and coastal phytoplankton blooms …
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The biogeochemistry of marine nitrous oxide
… isotopic signatures of N₂O produced by marine nitrifiers. This thesis shows that in addition to chemical controls on N₂O production rates such as oxygen (O₂) and nitrite (NO₂- ) concentrations, there are also biological controls such as nitrifier cell abundances and coastal phytoplankton blooms …
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Air stripping and biological treatment of ammonium sulfate wastewater from the caprolactam manufacturing process
… was conducted using conditions to promote nitrifier growth, nitrification was not observed using either conventional or PAC treatment. Air stripping removed fifty per cent of the ammonia-nitrogen at gas-to-liquid ratios greater than 500. However, it had no apparent effect on nitrifier …
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Design of an integrated fixed-film activated sludge (IFAS) system for possible application at the Borcherds Quarry WWTW
… biological nutrient removal (BNR). Suspended nitrifiers only grow in the aerobic zone of the biological reactor but are subjected to anaerobic and anoxic conditions where no nitrifier growth takes place. To establish a nitrifier population that consistently produces low effluent ammonia …
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Stream microbial communities along an agricultural gradient
… nitrifying gene ammonia monooxygenase, measured nitrifier abundance. A geographic information system (ArcGIS) was used to determine the percentage of agricultural land within each of the ten sampled tributary drainages; these percentages ranged from 0% at the headwaters to 96% along the Palouse. …
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Characterizing Kinetic Shifts in Nitrifying, Denitrifying, and Phosphorus Removing Biomass Adapting to Low DO
… it is critical to fully understand how nitrifier, denitrifier, and polyphosphate accumulating organism (PAO) oxygen kinetics adapt in a shift from traditional DO operation (2 mg O2/L or more) to low DO operation. Research characterizing how oxygen kinetics shift over time in activated …
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Development of Kinetic Parameterization Methods for Nitrifying Bacteria using Respirometry
Understanding how nitrifiers react when exposed to low DO conditions could provide a greater understanding of low DO operations in full-scale biological wastewater treatment. Previous methods to observe nitrifier oxygen kinetics do exist in literature, however they are inefficient and labor …
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Fate and Impacts of Contaminants of Emerging Concern during Wastewater Treatment
… nanomaterials or analogs. However, decrease of nitrifier gene abundances and distinct microbial communities were observed in SBRs receiving nanoAg, Ag+, nanoCeO2, and bulkCeO2. There was no apparent effect of nanoTiO2 or NZVI on nitrification, nitrifier gene abundances, or microbial community …
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Concentration and isotopic composition of marine nitrous oxide, in particular the oxygen-17 isotope excess
… of the Southern Ocean suggest nitrification and nitrifier-denitrification as the main N2O production pathway in the oxic, deep ocean. High δ(15N) values in the south Atlantic Gyre are presumably associated with a denitrification source. A novel off-the-shelf N2O analyser was tested in combination …
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Controls on terrestrial carbon and nutrient cycling in Arctic permafrost environments
… conditions favouring nitrous oxide release via nitrifier denitrification, the strong carbon dioxide uptake offset the methane and nitrous oxide release, allowing the wetland to be a net greenhouse gas sink. The experimentally warmed mesic tundra site demonstrated a sustained warming effect on …
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Using Oligonucleotide Probes to Characterize Nitrification in a Two-Stage Pilot Scale Biological Aerated Filter System
… suggest that this shift in the location of the nitrifier population is due to higher BOD loads to the second stage, which supported higher levels of heterotrophic growth in the second stage of the system. It was concluded that the strongest influence on nitrification performance in this type of …
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Chemical Inhibition of Nitrification: Evaluating Methods to Detect and Characterize Inhibition and the Role of Selected Stress Responses Upon Exposure to Oxidative and Hydrophobic Toxins
… isomerase. Therefore, investigating these nitrifier stress responses showed that nitrifiers lack short-term stress responses that may be used to rapidly detect inhibition, indicating that conventional methods of detecting nitrification inhibition, like differential respirometry and nitrate …
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Effects of temperature and mean cell residence time on the performance of high-rate biological nutrient removal processes
… However, the BNR system was more susceptible to nitrifier washout at 5 d MCRT and temperatures of 10 and 15 °C. Although less volume was needed for complete nitrification in the BNR system, specific nitrification rates and the degree of nitrification were equal in the two systems when compared on …
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Coupled cycling of metals with nitrogen and carbon in marine sediments
… “leakage” of intermediate hydroxylamine from nitrifier cells could potentially react with manganese(III) in a mixed biotic-abiotic process without previously being noticed. Finally, I performed experiments using carbon-13 labelling to measure rates of anaerobic oxidation of methane (AOM) in …
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Coupled cycling of metals with nitrogen and carbon in marine sediments
… “leakage” of intermediate hydroxylamine from nitrifier cells could potentially react with manganese(III) in a mixed biotic-abiotic process without previously being noticed. Finally, I performed experiments using carbon-13 labelling to measure rates of anaerobic oxidation of methane (AOM) in …
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Comparing the responses of nitrifiers to differing ammonia loadings
Return active sludge from the Danville Sanitary plant (Danville, IL) was fed 10 mg NH3-N/L per cycle of separated swine manure to allow the biomass to adapt to a new influent in a sequencing batch reactor. The biomass was then separated into three reactors. A control reactor was exposed to 10 mg …
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Nitrification Investigation And Modeling In The Chloraminated Drinking Water Distribution System
… denitrification began. Dissolved oxygen limited nitrifier growth and nitrification. No significant alkalinity variation was observed during nitrification. Residual and nitrites are key parameters for monitoring nitrification in drinking water distribution systems. (2) Using Monod kinetics, a …
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Nitrification in premise plumbing and its effect on corrosion and water quality degradation
… concrete and iron materials encouraged growth of nitrifiers in certain oligotrophic waters, materials such as lead, PVC/plastic pipe, glass and surfaces of other materials were readily colonized by nitrifiers, and materials such as copper and brass were very toxic and relatively resistant to …
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Ammonia-monooxygenase-mediated cometabolic biotransformation and abiotic transformation of micropollutants
Biotransformation of a number of micropollutants (MPs) has been found to positively correlate with nitrification activities in inhibition studies of nitrifying activated sludge communities. To further elucidate roles played by ammonia-oxidizing bacteria (AOB), and nitrite-oxidizing bacteria (NOB) …
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Mixed layer nitrogen cycling in the Southern Ocean: seasonality, kinetics, and biogeochemical implications
… annually. To better understand the controls on nitrifier ecology in the surface Southern Ocean, a series of nitrite oxidation kinetics experiments were conducted across the Indian sector (37- 62ºS) in winter. All experiments yielded a Michaelis-Menten relationship with substrate concentration, …
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