La formation des sous-produits de chloration dans les piscines couvertes dépend de nombreux paramètres cinétiques et hydrauliques. Cette étude propose le développement d’un modèle de prédiction de la formation de certains sous-produits de chloration et de leur transfert dans l’air. La construction du modèle est basée sur le couplage de constantes cinétiques déterminées à l’échelle laboratoire avec des modèles hydrauliques caractérisant les écoulements dans le bassin. Afin de calibrer et de valider les modèles, un bassin expérimental à l’échelle 1/10ème a été mis en place. Par ailleurs, une méthode de mesure des concentrations des sous-produits de chloration dans l’eau et dans l’air par Membrane Inlet Mass Spectrometry a été évaluée. La représentativité et la reproductivité des expériences réalisées sur le bassin ont été étudiées. À l’échelle laboratoire, les constantes cinétiques de consommation du chlore, de formation du chloroforme et de formation du dichloroacétonitrile par chloration du Body Fluid Analogue utilisé pour mimer les apports organiques des baigneurs ont été déterminées. Le comportement hydraulique du bassin a été modélisé par une série de réacteurs idéaux. Cette modélisation a été validée par la réalisation d’expériences de traçage sur le bassin expérimental. Enfin, les constantes de transfert eau-air des sous-produits de chloration volatils ont été déterminées et comparées avec plusieurs modèles de la littérature. Les résultats obtenus montrent que les modèles permettent de prévoir de façon satisfaisante l’évolution des paramètres modélisés. Le bassin expérimental constitue également un outil prometteur pour la calibration de modèles et l’évaluation de solutions de traitement. / The formation of chlorination by-products in swimming pools depends on many kinetic and hydraulic parameters. This study presents the development of a predictive model for the formation of chlorination by-products as well as their water-to-air transfer. The model is based on the coupling of kinetic rates determined in batch with hydraulic models which describe the flows in the basin. A pilot pool unit has been built in order to collect experimental data for the calibration and validation of the models. Moreover an analytical method by Membrane Inlet Mass Spectrometry has been assessed. The representativeness and the reproducibility of experiments performed on the pilot pool unit have been described. Kinetic rates for chlorine consumption, chloroform formation and dichloroacetonitrile formation have been studied at lab scale, based on chlorination experiments of a Body Fluid Analogue, a mix of chemicals which reproduces human intakes in swimming pools. The hydraulic behavior of the basin has been modeled by a series of ideal reactors. The model has been validated by comparison with tracer-based experiments. Finally, water-to-air transfer rates have been determined and compared with models from the literature. The modeled parameters were satisfactorily modeled. Moreover the pilot pool unit has been demonstrated to be useful in calibrating models or in assessing treatment solutions.

Photosynthesis is the unique biological process that converts carbon dioxide into organic compounds, for example sugars, using the energy of sunlight. Thereby solar energy is converted into chemical energy. Nearly all life depends on this reaction, either directly, or indirectly as the ultimate source of their food. Oxygenic photosynthesis occurs in plants, algae and cyanobacteria. This process created the present level of oxygen in the atmosphere, which allowed the formation of higher life, since respiration allows extracting up to 15-times more energy from organic matter than anaerobic fermentation. Oxygenic photosynthesis uses as substrate for the ubiquitous water. The light-induced oxidation of water to molecular oxygen (O2), catalyzed by the Mn4CaO5 cluster associated with the photosystem II (PS II) complex, is thus one of the most important and wide spread chemical processes occurring in the biosphere. Understanding the mechanism of water-oxidation by the Mn4CaO5 cluster is one of today’s great challenges in science. It is believed that one can extract basic principles of catalyst design from the natural system that than can be applied to artificial systems. Such systems can be used in the future for the generation of fuel from sunlight. In this thesis the light-induced production of molecular oxygen and carbon dioxide (CO2) by PSII was observed by membrane-inlet mass spectrometry. By analyzing this observation is shown that CO2 not only is the substrate in photosynthesis for the production of sugars, but that it also regulates the efficiency of the initial steps of the electron transport chain of oxygenic photosynthesis by acting, in form of HCO3-, as acceptor for protons produced during water-splitting. This finding concludes the 50-years old search for the function of CO2/HCO3− in photosynthetic water oxidation. For understanding the mechanism of water oxidation it is crucial to resolve the structures of all oxidation states, including transient once, of the Mn4CaO5 cluster. With this application in mind a new illumination setup was developed and characterized that allowed to bring the Mn4CaO5 cluster of PSII microcrystals into known oxidation states while they flow through a narrow capillary. The optimized illumination conditions were employed at the X-ray free electron laser at the Linac Coherent Light Source (LCLS) to obtain simultaneous x-ray diffraction (XRD) and x-ray emission spectroscopy (XES) at room temperature. This two methods probe the overall protein structure and the electronic structure of the Mn4CaO5 cluster, respectively. Data are presented from both the dark state (S1) and the first illuminated state (S2) of PS II. This approach opens new directions for studying structural changes during the catalytic cycle of the Mn4CaO5 cluster, and for resolving the mechanism of O-O bond formation. In two other projects the mechanism of molecular oxygen formation by artificial water oxidation catalysts containing inexpensive and abundant elements were studied. Oxygen evolution catalyzed by calcium manganese and manganese only oxides was studied in 18O-enriched water. It was concluded that molecular oxygen is formed by entirely different pathways depending on what chemical oxidant was used.  Only strong non-oxygen donating oxidants were found to support ‘true’ water-oxidation. For cobalt oxides a study was designed to understand the mechanistic details of how the O-O bond forms. The data demonstrate that O-O bond formation occurs by direct coupling between two terminal water-derived ligands. Moreover, by detailed theoretical modelling of the data the number of cobalt atoms per catalytic site was derived.

The typical strategy for atmospheric analysis of volatile organic compounds (VOCs), is to collect discrete samples which are then transported to a laboratory for analysis. This method has limited spatial and temporal resolution, and can be both costly and time consuming. To overcome these limitations, a mobile monitoring platform was developed for real-time quantitative chemical analysis. This work describes the development of membrane introduction mass spectrometer and identi es the necessary requirements to make a reliable and e ective instrument for in-situ chemical analysis. These include, the integration of a membrane interface with a miniaturized mass spectrometer, development of a data management strategy, reducing the e ects of isobaric interferences and employing an internal standard for quantitative measurements. Furthermore, the negative e ects of environmental variables, such as the Earth's magnetic eld, were examined and e ectively eliminated. In addition, this work demonstrates quantitative mapping of atmospheric VOCs in real-time, which allows rapid identi cation of chemical plumes and therefore, areas of potential concern. Both lab and eld-based comparisons of iv membrane introduction mass spectrometer data and traditional whole air sampling canister data were undertaken. The primary eld site was near Ft. McMurray, AB where baseline data was collected around a steam assisted gravity drainage (SAGD) facility and surrounding public roads. Monitoring for fugitive emissions at this facility and surrounding bitumen mining and processing operations is demonstrated. Field data were also obtained, near an industrial site in Ft.Saskatchewan, AB, that demonstrate the e cacy of an adaptive sampling strategy. Finally, chemical ionization was investigated as a soft ionization strategy to improve chemical selectivity for the analysis of complex hydrocarbon mixtures. The development of an in-line liquid chemical ionization reagent delivery system is presented and proposed as an e ective strategy for eliminating interferences arising from biogenic terpenes and alkyl aromatics. In all, this thesis presents the design and implementation of a mobile membrane introduction mass spectrometer for atmospheric chemical analysis. Results that improve performance and demonstrate the novelty of the data-type are provided, along with avenues for future development. / Graduate / 0486 / 0799 / 0608

Ce travail de thèse a eu pour objectif principal l'étude thermodynamique des changements métaboliques dans l'acidogénèse. L'acidogénèse est un procédé anaérobie à double intérêt qui en traitant des résidus organiques, permet de produire des composés chimiques comme l'hydrogène, l'éthanol et les acides organiques. Par conséquent, l'acidogénèse se place comme un procédé biotechnologique dans le concept de bioraffinerie. En outre, ce processus n'a pas besoin de conditions stériles d'opération et fonctionne sur une large gamme de pH. Ces changements métaboliques sont dépendants des modifications dans les conditions opératoires. Afin d'étudier ces changements métaboliques, des expériences basées sur des modifications du ciel gazeux du réacteur par introduction d'azote et sur des changements du pH, ont été menées. Un des résultats les plus intéressants a été l'augmentation du rendement de production d'hydrogène de 1 à 3,2 molH2/molglucose à pH 4,5 et débit de N2 de 58,4 L/d. Ce rendement est proche de la valeur théorique (4 molH2/molglucose). L'étude thermodynamique a permis d'expliquer les mécanismes métaboliques concernant l'hydrogène, dont la production importante, représentée par le rendement de 3,2 molH2/molglucose, est due à la réaction inverse H2/NAD+, qui est thermodynamiquement faisable à faibles pressions partielles d'hydrogène (par exemple 0,02 bar). En outre, les bas rendements en hydrogène ont été expliqués par l'action consommatrice d'hydrogène par la réaction d'homoacetogénèse. Cependant, le modèle n'a pas été capable d'expliquer les changements métaboliques de l'acétate, du butyrate et de l'éthanol lors de la fermentation acidogénique du glucose. / This thesis deals with thermodynamic based modelling of metabolic shifts during acidogenic fermentation. Acidogenic fermentation is an anaerobic process of double purpose: while treating organic residues, it produces chemical compounds, such as hydrogen, ethanol and organic acids. Therefore, acidogenic fermentation arises as an attractive biotechnology process towards the biorefinery concept. Moreover, this process does not need sterile operating conditions and works under a wide range of pH.Changes of operating conditions produce metabolic shifts, inducing variability on acidogenic product yields. In order to study these metabolic shifts, an experiment design was based on reactor headspace N2-flushing (gas phase) and pH step changes (liquid phase). A major result was the hydrogen yield increase from 1 to 3.2 (molH2/molglucose) at pH 4.5 and N2-flushing of 58.4 L/d. This yield is close to the theoretical acidogenic value (4 molH2/molglucose).The thermodynamic model, based on the assumption that acidogenic fermentation is characterised by limited energy available for biological process, allowed to explain the mechanisms that govern hydrogen metabolic shifts, showing that the synthesis of extra hydrogen, i.e. yield of 3.2 (molH2/molglucose), was due to reverse H2/NAD+ redox reaction, which is thermodynamically feasible at low hydrogen partial pressures (e.g. 0.02 bar). Moreover, low hydrogen yields were explained by the action of homoacetogenesis hydrogen consuming reaction. However, the model was not capable to explain the metabolic shifts of acetate, butyrate and ethanol on acidogenic glucose fermentation.