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 380 for “"anoxic"”.
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Measurement of ordinary heterotroph organism anoxic yield in anoxic-aerobic activated sludge systems
… heterotrophic organism (OHO) cell yield under anoxic conditions relative to its value under aerobic conditions for municipal sewage. In this regard, three primary objectives were identified: 1. Determine the ratio Y H,No: Y H,AE for real sewage in terms of electron acceptor (i.e. nitrate and …
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Oxidative stress in anoxic habitats
… oxic life, it can also affect the organisms in anoxic environments and at oxic- anoxic interfaces. The present body of work looks into the latter condition by investigation the effects of oxidative stress endured by a facultative anaerobe (Escherichia coli) and an obligate anaerobe (Bacteroides …
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Muddy affairs: Microbial methane cycling in anoxic coastal sediments
Contains fulltext : 326268.pdf (Publisher’s version ) (Closed access)
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The Late Cenomanian Anoxic Event; implications for foraminiferal evolution
… the effect of the late Cenomanian Oceanic Anoxic Event (OAE) on the planktonic and benthonic foraminifera. On the former, the OAE was the cause of major extinctions within the population, the return to pre-OAE oxygen levels permitting recolonization of the vacated niches. On the latter, the …
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Characterizing the Drivers of Carbon Use in Post-Anoxic Denitrification
… Facilities (WRRFs) add methanol for post-anoxic denitrification: the Virginia Initiative Plant (VIP), Nansemond Plant (NP), and Army Base (AB). From 2017-2020, VIP averaged 0.49 ± 0.03 lb COD/lb N removed, while NP and AB averaged 1.48 ± 0.06 and 2.11 ± 0.15 lb COD/lb N, respectively. …
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The effect of fully anoxic conditions and frequency of exposure to anoxic and aerobic conditions on the growth of low F/M filaments in nitrogen remova
… 3 phases investigating (1) the effect of fully anoxic conditions and low nitrate concentrations during the anoxic phase of an intermittent aeration cycle on low F/M filament growth in continuously fed completely mixed single reactor systems receiving a synthetic sewage feed; (2) the effect of …
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ORGANIC MATTER IN ANOXIC PORE WATER FROM GREAT BAY, NEW HAMPSHIRE
… It was shown that failure to exclude oxygen from anoxic sediment samples results in changes in both the amounts and nature of the organic matter in the pore water. In addition, the loss of iron, phosphate and titration alkalinity from the pore water of oxygen exposed samples was …
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Microbial Oxidation of Arsenite in Anoxic Environments: Impacts on Arsenic Mobility
… of this study is to evaluate the importance of anoxic oxidation of As(III) to As(V) by anaerobic microorganisms such as chemolithotrophic denitrifying bacteria and chlorate respiring bacteria in the biogeochemical cycle of arsenic. This study also investigated a arsenic potential bioremediation …
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Normoxic and anoxic metabolism of Nicotiana tabacum transformants lacking root nitrate reductase
… roots would facilitate survival of hypoxic and anoxic (flooding)-phases. For that purpose, we compared the response of roots of hydroponically grown tobacco wildtype (Nicotiana tabacum cv. Gatersleben) and of a transformant (LNR-H) with no nitrate reductase (NR) in the roots but almost normal NR …
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The effect of a large anoxic mass fraction and concentrations of nitrate and nitrite in the primary anoxic zone on low f/m filament bulking in nutrient removal activated sludge systems
Filamentous bulking occurs when filamentous organisms are present in excessive numbers and extend from floes into the bulk solution. They interfere with the compaction and settling of the activated sludge either by producing a very diffuse floe structure or by causing bridging between floes. This …
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Foraminiferal and stable isotope investigation of the Cenomanian-Turonian extinction and oceanic anoxic event
… Particularly well researched is the oceanic anoxic event (OAE 2) and the organic-rich black shales deposited during this interval. Associated with these organic-rich sediments is a positive carbon isotope anomaly. This excursion has a distinct profile and has hence been used for global …
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Towards an understanding of the carbon isotopic changes across the Toarcian oceanic anoxic event
… of the Toarcian (early Jurassic, 183 Ma) ocean anoxic event (OAE). In this study, we reveal that apparent negative isotopic excursions in bulk organic and carbonate carbon were the result of compositional changes of organic matter and diagenesis, respectively. Organic petrology and Rock-Eval …
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The effect of anoxic selectors on the control of activated sludge bulking and foaming
… municipal wastewater to evaluate the effects of anoxic selectors on controlling activated sludge bulking and foaming. These experiments were conducted with two pilot plants; a three stage anoxic selector preceding a complete mix system (experimental unit) and a complete mix system (control unit). …
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The biodegradation of valeric, butyric, propionic and acetic acids in anoxic, subsurface, soil environments
The biodegradation potential of two subsurface soils was characterized by monitoring the biodegradation of short-chain fatty acids in anaerobic soil microcosms. Valerate, butyrate, propionate, and acetate concentrations were monitored independently using separate microcosms. The effect of sulfate …
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Biogeochemical Cycling and Paleoenvironmental Reconstructions of the Toarcian Oceanic Anoxic Event from Western North America
The Toarcian Oceanic Anoxic Event (T-OAE; ~183 million years ago) represents an interval during the Mesozoic when the emplacement of the Karoo-Ferrar Large Igneous Province (LIP) is thought to have resulted in significant environmental change. Associated with this interval was the widespread …
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A New Phase Speciation Leaching Procedure for the Determination of Metals in Oxic and Anoxic Sediments
… with the purpose of being used on either oxic or anoxic sediments. However, natural sediments often contain prominent redox boundaries; therefore, it is useful to develop a single phase speciation leaching scheme which can be used on both oxic and anoxic sediments.</p> <p>A six step leaching …
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Development of a Borehole Log Signature for Oceanic Anoxic Events and Its Application to the Gulf of Mexico
Oceanic anoxic events (OAEs) are periods in Earth's history when oceans were depleted in dissolved oxygen and characterized by deposition of organic-rich sediments. The Oceanic Drilling Program (ODP) has drilled through OAEs in a number of areas worldwide, collecting core and borehole log data. …
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