1,721,063 research outputs found
Analyse et modélisation du traitement de l’azote dans un procédé de granulation aérobie Hybride
Get PDFDans ce travail, le traitement des nutriments et plus particulièrement celui de l’azote en procédé de granulation aérobie a été étudié. \ud
L’approche expérimentale a dans un premier temps eu pour objet de comparer la stabilité des caractéristiques physiques et microbiologiques d’agrégats développés dans deux réacteurs fonctionnant en alternances de phases anaérobie / aérobie ou anoxie / aérobie. L’opération d’un procédé de granulation aérobie en alternance de phases anoxie / aérobie a favorisé la stabilisation des performances de traitement de l’azote et notamment celle de la nitrification. Le développement d’une boue hybride comprenant une fraction de flocs et de granules a été observé. \ud
Dans le but d’évaluer comment le caractère hybride de la boue obtenue en conditions anoxie/aérobie oriente les performances et vitesses de transformation de l’azote, une caractérisation ex-situ des limitations au transfert d’oxygène au sein des flocs, granules et boue hybride a été réalisée par respirométrie. En complément, la localisation des espèces nitrifiantes par la technique d’hybridation fluorescente in situ (FISH) a été réalisée. Les résultats obtenus indiquent que la présence de flocs au sein d’une boue granulaire permet d’augmenter la vitesse de la nitrification, en particulier pour de faibles concentrations en oxygène dissous. D’autre part, il est ici mis en évidence la nécessité de contrôler simultanément le ratio floc/granules et la taille des granules en vue de l’optimisation du traitement de l’azote.\ud
Enfin un outil mathématique permettant de décrire les phénomènes réactionnels ayant lieu au sein d’une biomasse hybride a été développé. Celui-ci a été employé dans le but d’optimiser le fonctionnement du procédé hybride par l’évaluation de l’effet des propriétés physiques de la biomasse, et plus particulièrement de la proportion de granules en présence, pouvant conduire à une élimination efficace de l’azote et à l’augmentation de la robustesse du procédé vis-à-vis de diminutions ponctuelles de l’oxygène dissous.--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------In this work, the treatment of nutrients, especially that of nitrogen in aerobic granulation process was studied.\ud
The experimental approach has initially been intended to compare the stability and the physical and microbiological characteristics of aggregates developed in two reactors operating in alternating anaerobic / aerobic or anoxic / aerobic conditions. The presence of a pre-anoxic phase promoted the stabilization of nitrogen removal performances and especially those of nitrification. The development of a hybrid sludge process containing a fraction of flocs and granules was observed.\ud
In order to evaluate and quantify the influence of the simultaneous presence of flocs and granules in the nitrifying activity of the hybrid sludge developed in the alternating anoxic / aerobic conditions, the nitrification rate and oxygen limitation of flocs, granules and hybrid sludge was assessed using respirometric assays at different dissolved oxygen concentrations. The spatial distribution of nitrifying bacteria was investigated using fluorescence in situ hybridization (FISH). Results indicated that the presence of flocs with granules could increase the rate of nitrification to transitory reductions of aeration. On the other hand, the optimization of nitrogen removal requires the simultaneous control of the floc to granule ratio and granule size.\ud
Finally, a mathematical model to describe the reaction phenomena taking place in the hybrid biomass was developed. It was used in order to optimize the operation of the hybrid process through the evaluation of the effect of physical properties of biomass, specifically the ratio of granules and flocs in the reactor that can lead to efficient removal of nitrogen and increase the robustness of the process.\ud
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Analyse et modélisation du traitement de l'azote dans un procédé de granulation aérobie hydride
No full textIn this work, the treatment of nutrients, especially that of nitrogen in aerobic granulation process was studied. The experimental approach has initially been intended to compare the stability and the physical and microbiological characteristics of aggregates developed in two reactors operating in alternating anaerobic / aerobic or anoxic / aerobic conditions. The presence of a pre-anoxic phase promoted the stabilization of nitrogen removal performances and especially those of nitrification. The development of a hybrid sludge process containing a fraction of flocs and granules was observed. In order to evaluate and quantify the influence of the simultaneous presence of flocs and granules in the nitrifying activity of the hybrid sludge developed in the alternating anoxic / aerobic conditions, the nitrification rate and oxygen limitation of flocs, granules and hybrid sludge was assessed using respirometric assays at different dissolved oxygen concentrations. The spatial distribution of nitrifying bacteria was investigated using fluorescence in situ hybridization (FISH). Results indicated that the presence of flocs with granules could increase the rate of nitrification to transitory reductions of aeration. On the other hand, the optimization of nitrogen removal requires the simultaneous control of the floc to granule ratio and granule size. Finally, a mathematical model to describe the reaction phenomena taking place in the hybrid biomass was developed. It was used in order to optimize the operation of the hybrid process through the evaluation of the effect of physical properties of biomass, specifically the ratio of granules and flocs in the reactor that can lead to efficient removal of nitrogen and increase the robustness of the process.Dans ce travail, le traitement des nutriments et plus particulièrement celui de l’azote en procédé de granulation aérobie a été étudié. L’approche expérimentale a dans un premier temps eu pour objet de comparer la stabilité des caractéristiques physiques et microbiologiques d’agrégats développés dans deux réacteurs fonctionnant en alternances de phases anaérobie / aérobie ou anoxie / aérobie. L’opération d’un procédé de granulation aérobie en alternance de phases anoxie / aérobie a favorisé la stabilisation des performances de traitement de l’azote et notamment celle de la nitrification. Le développement d’une boue hybride comprenant une fraction de flocs et de granules a été observé. Dans le but d’évaluer comment le caractère hybride de la boue obtenue en conditions anoxie/aérobie oriente les performances et vitesses de transformation de l’azote, une caractérisation ex-situ des limitations au transfert d’oxygène au sein des flocs, granules et boue hybride a été réalisée par respirométrie. En complément, la localisation des espèces nitrifiantes par la technique d’hybridation fluorescente in situ (FISH) a été réalisée. Les résultats obtenus indiquent que la présence de flocs au sein d’une boue granulaire permet d’augmenter la vitesse de la nitrification, en particulier pour de faibles concentrations en oxygène dissous. D’autre part, il est ici mis en évidence la nécessité de contrôler simultanément le ratio floc/granules et la taille des granules en vue de l’optimisation du traitement de l’azote.Enfin un outil mathématique permettant de décrire les phénomènes réactionnels ayant lieu au sein d’une biomasse hybride a été développé. Celui-ci a été employé dans le but d’optimiser le fonctionnement du procédé hybride par l’évaluation de l’effet des propriétés physiques de la biomasse, et plus particulièrement de la proportion de granules en présence, pouvant conduire à une élimination efficace de l’azote et à l’augmentation de la robustesse du procédé vis-à-vis de diminutions ponctuelles de l’oxygène dissous
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Sidestream characteristics in water resource recovery facilities: A critical review
No full textInternational audienceThis review compiles information on sidestream characteristics that result from anaerobic digestion dewatering(conventional and preceded by a thermal hydrolysis process), biological and primary sludge thickening. Theobjective is to define a range of concentrations for the different characteristics found in literature and to confrontthem with the optimal operating conditions of sidestream processes for nutrient treatment or recovery. Eachcharacteristic of sidestream (TSS, VSS, COD, N, P, Al3+, Ca2+, Cl , Fe2+/3+, Mg2+, K+, Na+, SO42 , heavy metals,micro-pollutants and pathogens) is discussed according to the water resource recovery facility configuration,wastewater characteristics and implications for the recovery of nitrogen and phosphorus based on currentpublished knowledge on the processes implemented at full-scale. The thorough analysis of sidestream charac-teristics shows that anaerobic digestion sidestreams have the highest ammonium content compared to biologicaland primary sludge sidestreams. Phosphate content in anaerobic digestion sidestreams depends on the type ofapplied phosphorus treatment but is also highly dependent on precipitation reactions within the digester.Thermal Hydrolysis Process (THP) mainly impacts COD, N and alkalinity content in anaerobic digestion side-streams. Surprisingly, the concentration of phosphate is not higher compared to conventional anaerobic diges-tion, thus offering more attractive recovery possibilities upstream of the digester rather than in sidestreams. Allsidestream processes investigated in the present study (struvite, partial nitrification/anammox, ammonia strip-ping, membranes, bioelectrochemical system, electrodialysis, ion exchange system and algae production) sufferfrom residual TSS in sidestreams. Above a certain threshold, residual COD and ions can also deteriorate theperformance of the process or the purity of the final nutrient-based product. This article also provides a list ofcharacteristics to measure to help in the choice of a specific process
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Production de protoxyde d’azote en post-dénitrification: Rapport annuel du programme de recherche Mocopée 2019
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