Thesis (Ph. D.)--Drexel University, 2007. / Includes abstract and vita. Includes bibliographical references (leaves 160-174).

abstract: Cities can be sources of nitrate to downstream ecosystems resulting in eutrophication, harmful algal blooms, and hypoxia that can have negative impacts on economies and human health. One potential solution to this problem is to increase nitrate removal in cities by providing locations where denitrification¬— a microbial process in which nitrate is reduced to N2 gas permanently removing nitrate from systems— can occur. Accidental urban wetlands– wetlands that results from human activities, but are not designed or managed for any specific outcome¬– are one such feature in the urban landscape that could help mitigate nitrate pollution through denitrification. The overarching question of this dissertation is: how do hydrology, soil conditions, and plant patches affect patterns of denitrification in accidental urban wetlands? To answer this question, I took a three-pronged approach using a combination of field and greenhouse studies. First, I examined drivers of broad patterns of denitrification in accidental urban wetlands. Second, I used a field study to test if plant traits influence denitrification indirectly by modifying soil resources. Finally, I examined how species richness and interactions between species influence nitrate retention and patterns of denitrification using both a field study and greenhouse experiment. Hydroperiod of accidental urban wetlands mediated patterns of denitrification in response to monsoon floods and plant patches. Specifically, ephemeral wetlands had patterns of denitrification that were largely unexplained by monsoon floods or plant patches, which are common drivers of patterns of denitrification in non-urban wetlands. Several plant traits including belowground biomass, above- and belowground tissue chemistry and rooting depth influenced denitrification indirectly by changing soil organic matter or soil nitrate. However, several other plant traits also had significant direct relationships with denitrification, (i.e. not through the hypothesized indirect relationships through soil organic matter or soil nitrate). This means these plant traits were affecting another aspect of soil conditions not included in the analysis, highlighting the need to improve our understanding of how plant traits influence denitrification. Finally, increasing species richness did not increase nitrate retention or denitrification, but rather individual species had the greatest effects on nitrate retention and denitrification. / Dissertation/Thesis / Doctoral Dissertation Biology 2016

Efluentes com grandes concentrações de fenol e nitrogênio amoniacal apresentam grande potencial poluidor ao meio ambiente. Exemplo deste tipo de despejo é o da unidade de coqueria da indústria siderúrgica que apresenta em termos quantitativos os fenóis como os principais constituintes orgânicos. Constituintes inorgânicos também estão presentes neste tipo de despejo e são principalmente cianeto, tiocianato, sulfato e nitrogênio amoniacal, sendo que a concentração deste último pode atingir níveis de centenas de miligramas por litro. No Estado de São Paulo, para atendimento às legislações em vigor - Decreto Estadual 8468/76 e Resolução CONAMA 357/05 - em termos de nitrogênio amoniacal e fenóis, as fontes poluidoras devem atender aos limites de emissão de 20 mg N/L para nitrogênio amoniacal total e 0,5 mg C6H5OH/L para índice de fenóis, e além disso, devem atender a classificação do corpo d\'água. Após resultados bem sucedidos de pesquisas realizadas anteriormente no Departamento de Engenharia Hidráulica e Sanitária da EPUSP objetivando remoção de compostos fenólicos e nitrogênio amoniacal, presentes em uma água residuária sintética de coqueria, através de nitrificação/desnitrificação do afluente em sistemas de lodo ativado, idealizou-se a presente pesquisa objetivando promover a nitrificação/desnitrificação de um despejo similar contendo altas concentrações de fenol (1000 mg/L) e nitrogênio amoniacal (500 a 1000 mgN/L) em sistema piloto de lodo ativado de lodo único, com duas concepções distintas: parcial (\"P\") a nitrito (ou \"nitritação/desnitritação\") em um primeiro caso, somente com fonte interna de carbono para a desnitrificação, e total (\"T\") num segundo caso, com fontes interna e externa de carbono. Além disso, também foi objetivo comparar os resultados obtidos do sistema piloto \"P\" com um sistema em bateladas seqüenciais operado paralelamente para remoção de nitrogênio via nitrito. A pesquisa permitiu concluir que o sistema contínuo, em virtude de seu regime operacional, não foi eficiente para remoção de nitrogênio via nitrito por não favorecer a manutenção de amônia livre na fase aeróbia em concentrações inibitórias aos microrganismos oxidadores de nitrito, já que segundo os resultados satisfatórios do sistema em bateladas seqüenciais, a existência de amônia livre e o pH se mostraram os principais parâmetros que regem o acúmulo de nitrito no reator. Apesar disso, o sistema apresentou resultados satisfatórios quanto à desnitrificação com fenol como fonte de carbono sendo que, durante toda a operação do sistema, o efluente final apresentou concentrações de fenol desprezíveis. Resumindo, o sistema contínuo só se mostrou adequado para remoção de nitrogênio via nitrato, ao passo que o sistema em batelada favoreceu a remoção via nitrito. Quanto ao sistema \"T\", que visava nitrificação/desnitrificação completa com fontes interna e externa de carbono, os resultados permitiram concluir que, apesar do etanol ser utilizado com eficiência pelas bactérias heterotróficas para promover a desnitrificação, seu uso como fonte externa de carbono não foi adequado em sistema de lodo único. Isto porque os microrganismos deixaram de utilizar o fenol na desnitrificação passando a utilizar somente o etanol, provocando acúmulo de fenol e desequilíbrio do sistema. Sendo assim, concluiu-se que o uso de etanol como fonte externa de carbono para a desnitrificação só seria recomendável em reator anóxico em separado, ou seja, em sistema de dois lodos e não de lodo único, como o da presente pesquisa. / Wastewaters containing high phenol and ammonium concentrations present a great pollutant potential to the environment. An example of this kind of effluent is the discharge of coke-plants, which presents, quantitatively, the phenols as the main organic compound. Inorganic compounds are also present in these wastewaters and are mainly cyanide, thiocyanate, sulphate and ammonium, the last one being able to achieve hundreds of milligrammes per litre. In Sao Paulo State, there are two legislations to be accomplished, State Decree 8468/76 and CONAMA Resolution 357/05 that stand that the polluters must accomplish the discharge limits of 20 mg N/L to total ammonium nitrogen and 0,5 mg C6H5OH/L to phenols, as well as accomplish the waterbody classification. The present research was planned after well succeded results of former researches in EPUSP\'s Hydraulic and Sanitation Engineering Department aiming to remove phenolic compounds and ammonium from a synthetic coke-plant wastewater, by nitrification/denitrification of the influent in activated sludge plants. The main purpose of this work was to remove nitrogen of a similar wastewater containing high phenol (1000 mg/L) and ammonium (500 a 1000 mgN/L) concentrations in two activated sludge pilot plants (single sludge): a partial one (\"P\") to remove nitrite (or \"nitritation/denitritation\") in the first case, only with internal carbon source for the denitrification, and a total one (\"T\") in a second case, with internal and external carbon sources. It was also aim of this work to compare the results obtained by the Partial (\"P\") pilot system with a parallel batch sequence reactor operated to remove nitrogen via nitrite. The research concluded that the continuos system, due to its operational characteristic, was not efficient to remove nitrogen via nitrite that does not favor the maintenance of free ammonia in the oxic phase in inhibitory concentrations to the nitrite oxidizers, as according to the wellsucceeded batch system, the existance of free ammonia and the pH have been the main parameters to raise the nitrite accumulation in the reactor. Nevertheless, the system presented satisfactory results to the denitrification with phenol as carbon source and, during the whole experimental work, the final effluent just showed despicable phenol concentrations. Summing up, continuos system was just adequate to remove nitrogen via nitrate, while the batch system favored its removal via nitrite. Due to the Total (\"T\") system which aims to complete nitrification/denitrification with internal and external carbon sources, the results showed that, despite ethanol having been successfully used by the heterotrophic bacteria to denitrification, its use as external carbon source was not adequate in single sludge system, because the microorganisms do not use phenol in denitrification, just using ethanol, causing phenol accumulation and unbalance of the system. Therefore, it was concluded that the use of ethanol as external carbon source to denitrification would be recommended only in anoxic separated reactor, i.e., in a double sludge system and not in a single sludge one, as this research.

Diploma thesis Effect of emergent micropolutants on the denitrification process through activated sludge is focused on three specific substances. The substances under investigation are atrazine, terbutylazine and sulfametaxazole. Atrazine and terbutylazine are pesticides, particularly herbicides. Sulfametaxazole was chosen as a common antibiotic. The thesis is summarized into 10 chapters and conclusion. The work consists essentially of theoretical and practical part. Part of the theoretical part of the thesis is legislation that deals with the matters of the problem with micropolutants. The next chapter is an introduction to the issue, where we want to familiarize the reader with the current situation. There are also chapters on emergent micropolutants, denitrification and investigated substances. If we look at the practical part, there are chapters on sampling, evaluation of BATCH tests and evaluation of inhibition tests. There are also chapters on BATCH tests and respiratory inhibition test, which describe procedures of how we performed this test. Laboratory test reports are included in the Annex.

Since the industrial revolution human activities have more than doubled the amount of bioavailable nitrogen (N) on earth leading to far-reaching ecological consequences for coastal marine ecosystems. Salt marsh systems, including their intertidal creek and mudflat sediments, serve as nutrient filters transforming nitrogen and removing it through denitrification. However, as hotspots of nitrogen transformation, these ecosystems are also thought to be sources of nitrous oxide, a powerful greenhouse gas, to the atmosphere. We investigated the influence of various scales of anthropogenic fertilization on the nitrogen cycling in intertidal creek and mudflat sediments in the salt marsh ecosystem of Plum Island Ecosystem Long Term Ecological Research site in northern Massachusetts, USA. Benthic fluxes from whole core incubations showed that long-term fertilization of tidal creek sediment stimulated net denitrification with significantly higher rates in the fertilized creek compared to the reference (162.7 ± 32 and 0.74 ± 39 μmol N m^-2 hr^-1, respectively). However, fertilization also appeared to stimulate dissimilatory nitrate reduction to ammonium (DNRA) with calculated rates also significantly higher in the fertilized compared to reference creek and representing 45 and 11% of total nitrate uptake, respectively. These results indicate that DNRA may outcompete denitrification at higher nitrate concentrations, thus anthropogenic fertilization may be driving tidal creek sediments toward this N regeneration process and thus inhibiting the overall nitrogen removal capacity of the ecosystem. Conversely, a smaller scale, short-term nitrogen addition experiment had no significant impact on nearby tidal flat sediments likely because the fertilization exposure time on the tidal sediments was too short. Overall benthic flux rates were lower in the tidal flat compared to the tidal creeks. However, the tidal flat was also a net N filter with an average net N2 flux of 5.7 ± 2.6 μmol N N m^-2 hr^-1. Rates of nitrification and therefore coupled nitrification-denitrification appeared to be affected by the active microphytobenthos (MPB) community within the tidal flat sediments with oxygen production from photosynthesis fueling coupled denitrification in the light while N fixation dominated under dark conditions. As in the tidal creeks, we found evidence that DNRA is also an important N transformation process within tidal flat sediments. Finally, sediment microprofiling measurements showed these tidal mudflat sediments to be a net sink of N2O (average -6.9 ± 1.7 μmol N2O N m^-2 hr^-1) with significantly higher rates of uptake the longer sediments were exposed to the atmosphere at low tide. Fluxes were shown to be driven by nutrient supply and nitrate limitation of denitrifiers with tidal pulsing. Additionally, smaller, core scale nutrient additions revealed an increase in N2O flux with dissolved inorganic nitrogen (DIN) addition. Importantly, N2O uptake was found to be phosphorus limited. Again, nutrient enrichment appeared to stimulate DNRA over denitrification indicating that fertilization may not only hamper nitrogen removal capacity, but also increase N2O flux to the atmosphere.

Of the many changes humans have caused in coastal systems, excess nutrient loading is perhaps the most dramatic. Specifically, excess nitrogen (N) can lead to a series of negative consequences such as eutrophication, low oxygen conditions, and decreased biodiversity. Concurrent with changes in nutrient loading, coastal shellfish populations have been devastated through overharvesting, disease, and pollution. For example, oyster reefs – once a dominant feature along many coastlines – have been reduced by 85% of their historic range globally. Today, oysters are returning to coastal systems through restoration projects and a boom in aquaculture. Yet the impact of returning oysters to coastal systems is unknown. My dissertation helps to fill this major knowledge gap. Specifically, this dissertation focuses on the role oysters play in regulating coastal nutrient cycling and greenhouse gas (GHG) emissions. In chapter one, I estimated the GHG cost of protein production using oyster aquaculture. Using a combined field and laboratory approach, I quantified rates of N2O, CH4, and CO2 release from cultured oysters, and changes in sediment fluxes of these GHGs. On a kg CO2-equivalent kg-1 protein produced, oyster aquaculture has less than 0.5% of the GHG cost of terrestrial livestock production. In chapter two, I took advantage of an oyster aquaculture chronosequence to examine how organic matter loading from oysters altered sediment N cycling processes over time. I found that sediment fluxes under oyster aquaculture oscillated over time, shifting between N removal (N2) and recycling (NH4+) processes, demonstrating non-linear dynamics. In chapter three, I demonstrate that sediment N cycling processes in oyster habitats follow seasonal patterns of water column productivity, recording net denitrification in the spring following a phytoplankton bloom and net nitrogen-fixation in the fall. In chapter four, I use a meta-analysis approach to describe the role of oysters in regulating coastal nutrient recycling, removal of excess N, and GHG footprint. I show that in a biogeochemical context oyster reefs and aquaculture are interchangeable habitat that stimulate both N removal and recycling, with only a small GHG footprint.

Supplemental carbon has been successfully added and implemented at biological nutrient removal treatment plants all around the world in order to reach low nitrogen discharge limits. Although, methanol has been the most prevalent external electron donor used due to its low cost and effectiveness, many utilities are moving away from it due to cost volatility, safety issues, and hindered performance in cold weather conditions. Many sustainable and alternative sources are being researched, such as glycerin-based products (Rohrbacher et al., 2009), sugar-based waste products (Pretorius et al., 2007), and effluents from food and beverage industries (Swinarski et al., 2009). Four 22-L sequencing batch reactors (SBRs) were utilized to investigate four different supplemental carbon sources: 100% reagent grade methanol, 100% reagent grade glycerol, bio-diesel glycerol waste, and an industrial waste alcohol. These reactors were operated at 20�"C with a 15 day solids retention time. Intensive profiles were carried out three times a week to monitor performance and collect data to calculate COD consumption: nitrate-nitrogen denitrified (C: N) ratios. The glycerol and bio-diesel glycerol waste reactors performed similarly as they both exhibited significant and consistent nitrite accumulation during the entire experiment. Based on reactor restart, nitrite accumulation was evident and significant within two days after startup and consistent for all further operation. Rapid nitrate to nitrite reduction coincident with COD uptake was also observed. The two glycerol reactors demonstrated an increased carbon demand over time. The commonly reported hypothesis that activated sludge transitions from a generalist population of ordinary heterotrophic organisms (OHO) that use substrate, glycerol in this case, less efficiently, producing low yields and slow growth rates, to a specialist population that use glycerol more efficiently, with higher yields and slightly faster growth rates, was verified. This is known as the generalist-specialist theory. While this hypothesis appears to be supported from an overall analysis of the data, the actual mechanism seems to be intracellular glycerol storage coincident with rapid nitrate to nitrite denitrification, followed by slow nitrite reduction to nitrogen gas. This can possibly lead to degradation of the internally stored glycerol in the aerobic zones of the following cycle, implying a significant economic impact with glycerin addition. Although this has not been investigated further, it is believed that the presence of glycogen-accumulating organisms (GAOs) could be responsible for this intracellular storage of glycerol resulting in partial denitrification and accumulation of nitrite. The methanol and waste alcohol reactors also performed similarly to each other and neither of these reactors exhibited any nitrite accumulation upon carbon addition. The specific denitrification rate (SDNR) of the waste alcohol was slightly higher and increased more rapidly than for the methanol reactor. The C: N for these two reactors was comparable, and methanol was close to the expected value of 4.8 g COD utilized/ g nitrate-N denitrified. The C: N for the waste alcohol during steady state operation was somewhat higher than expected. The waste alcohol exhibited an �"alcoholic�" odor upon addition to the reactors during startup, but this issue diminished as the biomass became acclimated to the waste alcohol. Both industrial waste alcohol and glycerol can be considered viable alternatives to methanol; however, glycerol supplementation for denitrification can be problematic. If the glycerol dose is not optimized, then partial denitrification is observed and will lead to nitrite in the effluent, causing an increased chlorine demand for plants applying chlorine for disinfection. This is thought to occur due to energy limitations resulting from carbon storage and thus, using glycerol at treatment plants performing biological phosphorus removal (BPR) or enhanced biological phosphorus removal (EBPR) might see inefficient removal due to selective carbon utilization by polyphosphate-accumulating organisms (PAOs), or due to competition between PAOs and GAOs. Although denitrification of nitrate to nitrite occurs more quickly with prolonged glycerol addition, it also results in an increased carbon demand which causes a significant impact economically. / Master of Science

No description available.

Methanol (MeOH) is a common external carbon source for wastewater denitrification, because of its low cost and low sludge yield. Ethanol (EtOH), on the other hand, is more expensive, but yields higher denitrification rates. This study introduces gasoline-denatured ethanol (dEtOH), which is now being produced in large quantities for the production of E10 gasoline, as an alternative carbon source. The gasoline added, as the denaturant, is known as "straight-run" gasoline; a lower grade material that contains mostly aliphatic compounds, but lacks the components that normally boost the octane rating, such as benzene, toluene, ethylbenzene and xylenes (BTEX). Herein are presented the results of using dEtOH, EtOH (95.5% ethanol-4.5% water) and MeOH for denitrification in lab-scale, sequencing batch reactors (SBRs). We also focused on the quantification of BTEX present in dEtOH solution and the inhibition potential of these compounds on both nitrification and denitrification. BTEX content in the dEtOH solution had low and consistent concentration. Ethylbenzene and o-xylene were not detected in the reactor. The removal rates of benzene, toluene and m-xylene were 3.1°1.4, 3.4°1.9 and 0.6°0.4 ?g/L·h, respectively. BTEX were not detected in the effluent and did not inhibit nitrification and denitrification. The denaturant did not affect biomass production or the settling properties of the sludge. The yield (COD/NOx-N) and denitrification rates of dEtOH were similar to those of EtOH and higher than those of MeOH. The cost of dEtOH ($0.91//lb NO??-N removed) is slightly higher than that of methanol ($0.74/lb NO??-N removed). Using dEtOH as an external carbon source is, therefore, very promising and utilities will have to decide if it is worth paying a little extra to take advantage of dEtOH's benefits. / Master of Science

<p> This dissertation examines the influence of the process variables, organic carbon concentration, nitrate concentration, pH, organism concentration, and temperature, on the rate of denitrification of dominant batch cultures of Pseudomonas denitrificans. The aim of the work was to determine which of the first four variables were important in controlling rate, and whether significant interactions existed between variables. As well, the ability of these typical bacterial denitrifiers to operate at low temperature conditions was to be ascertained. </p> <p> The experimental procedure indicated that pH and carbon concentration are the major influences on the unit denitrification rate a well as the overriding factor temperature which profoundly influences any bacterial process. Organic carbon concentration controls the rate up to the point where the stoichiometric requirements for nitrate reduction and the carbon needs for new cell growth are satisfied. A broad pH optimum within the normal range experienced in most wastewater treatment conditions was demonstrated. The temperature dependancy of the unit denitrification rate was shown to follow an Arrhenius relationship between 3ºC and 27ºC. As well, for the simplified system investigated the unit rate was independent of nitrate concentration. </p> <p> The dominant culture was related to mixed cultures of activated sludge to provide an estimate of the denitrifying rate of activated sludge on a similar simple batch system. </p> / Thesis / Doctor of Philosophy (PhD)