Utilisation d'un respiromètre RODTOX dans une station de récupération des ressources de l'eau - installation, amélioration et modélisation

La respirométrie est une discipline consistant en la mesure et l’interprétation du taux de respiration de microorganismes. Avec les années, cette technique est devenue un outil indispensable pour la caractérisation des boues activées et d’échantillons d’eau usée. En 2016, l’usine pilEAUte de l’Université Laval s’est doté d’un respiromètre en ligne du type RODTOX afin de caractériser l’effluent de son traitement primaire. Or, bien que les expériences réalisées automatiquement par le RODTOX soient riches en information, les données rendues accessibles aux utilisateurs du RODTOX par l’appareil sont plutôt pauvres. Des outils ont donc été développés dans le cadre de ce projet de maîtrise afin d’extraire du RODTOX les données brutes provenant de sa sonde d’oxygène dissous et analyser son signal. Cela a permis d’extraire des données de la sonde des estimations de la demande biochimique en oxygène à court terme (DBOct) de l’eau usée, ainsi que du taux de respiration exogène (OURex) de la boue activée et du coefficient de transfert de masse d’oxygène (KLa) du réacteur dans lequel le RODTOX réalise ses expériences. De plus, un modèle mathématique du RODTOX a été conçu, ce qui a permis l’estimation des certains coefficients biocinétiques de la boue activée du RODTOX. En retour, ces coefficients ont permis l’estimation de la part de la DBOct attribuable soit à la biodégradation des composés carbonés ou à celle des composés azotés. Ce document décrit le processus de développement de ces outils d’analyse du signal du RODTOX. S’ensuit une démonstration de leur efficacité et une discussion des aspects pouvant être améliorés dans l’avenir. Enfin, des usages potentiels pour les informations produites par le RODTOX et des outils employés pour décoder son signal sont suggérés.Respirometry is the measurement and interpretation of the respiration of microorganisms. Over the years, this discipline has proven itself to be an invaluable tool for the characterization of activated sludge and wastewater samples. In 2016, Université Laval’s pilEAUte plant purchased a RODTOX on-line respirometer to characterize its primary effluent. Though the respirometric experiments performed by this machine are information-rich, the default output available to its users is very sparse. Thus, to take advantage of the experiments performed automatically within the RODTOX, tools were developed in the context of this M. Sc. study to extract the raw data produced by the RODTOX’s built-in dissolved oxygen sensor and process its signal. This allowed for the extraction of estimates of the wastewater’s short-term biochemical oxygen demand (stBOD), the activated sludge’s exogenous oxygen uptake rate OURex and the oxygen mass transfer coefficient (KLa) of the RODTOX’s built-in bioreactor. Additionally, a mathematical model of the RODTOX sensor was developed which enabled the estimation of some of the sludge’s biokinetic characteristics. This, in turn, has led to the estimation of the portions of stBOD attributable to carbonaceous and nitrogenous compounds, respectively. This document relates the development of these processing tools, the demonstration of their adequate performance and suggestions for future improvements. Then, prospective uses for the measurements produced by the RODTOX and its new processing tools are suggested

Territorial Behavior of Short-eared Owls, Asio flammeus, at more than 1000 km North of their Current Breeding Range in Northeastern Canada: Evidence of Range Expansion?

A pair of Short-eared Owls was observed throughout the summer of 2008 showing territorial behavior more than 1000 km north of their known breeding range in north-eastern Canada. These observations might be related to high lemming densities and/or climate change occurring in the Arctic

Sensitivity and vulnerability to groundwater overexploitation by a ‘pressure state impact’ and process based approach

A methodology is developed for proposing a groundwater vulnerability assessment in a Pressure-State-Impact causal chain that is familiar to decision makers. The ‘Driver Pressure State Impact Response’ (DPSIR) framework, for describing interactions between society and the environment, defines a chain of Drivers that exert Pressures on the State of a given resource, such as groundwater, which then generates an Impact that will require an appropriate Response (Kristensen, 2004). The method is here based on the calculation of sensitivity coefficients for a user-defined groundwater state for which several physically-based indicators are proposed. These sensitivity coefficients reflect the easiness with which the groundwater state transmits pressures into impacts. They are grouped into a vulnerability matrix of pressures and impacts that quantify vulnerability for every combination of causal links identified in the DPSIR chain. For that reason, the sensitivity coefficients are converted to vulnerability, using the concept of ‘transgressing a given threshold’, which is commonly used in socioeconomic sciences (Luers et al. 2003). The concept of ‘rising above a given concentration threshold’ can be used for groundwater quality issues. The concept of ‘falling below a given piezometric head threshold’ can be used for groundwater quantity issues as aquifer overexploitation problems. Outside the careful selection of the sensitivity analysis method that can significantly influence the computational effort (Beaujean et al., 2013), emphasis is given to the illustration of the general methodology on a simple groundwater quantity case (of an alluvial aquifer with concerns related to water supply) demonstrating the potential use of this general and physically based vulnerability assessment method. While the methodology is general, the choice of causal chains has to be made prior to the calculation. The vulnerability is also related to a damaged state and is related to the ‘distance’ between the current state and a given threshold. This choice is arbitrary such that the vulnerability is sensitive to the choice of the threshold

Developping a physically based groundwater vulnerability concept in a DPSIR framework

A general physically based method is presented to assess vulnerability of groundwater to external pressures with respect to quality and/or quantity issues. In the vulnerability assessments, many scientific authors agree nowadays that ‘physically based’ methods must be preferred to traditional approaches based on empirical overlay and index methods where physical attributes are often mixed with implicitly embedded conventional priorities. Results from one or another of these last methods can consequently be very dissimilar for a given case study and decision makers are losing confidence in these tools. A methodology is proposed to reframe the groundwater vulnerability assessment in a Pressure-State-Impact causal chain that is familiar to decision makers. The DPSIR framework, for describing interactions between society and the environment, defines a chain of Drivers that exert Pressures on the State of a given resource, such as water, which then generates an Impact that will require an appropriate Response (Kristensen, 2004). The concept of groundwater vulnerability assessment considered here is based on the calculation of sensitivity coefficients for a user-defined groundwater state for which several physically-based indicators are proposed. These sensitivity coefficients reflect the easiness with which the groundwater state transmits pressures into impacts. They are grouped into a vulnerability matrix of pressures and impacts that quantify vulnerability for every combination of causal links identified in the DPSIR chain. For that reason, the sensitivity coefficients are converted to vulnerability, using the concept of ‘falling below a given threshold’, which is commonly used in socioeconomic sciences (Luers et al. 2003). Outside the careful selection of the sensitivity analysis method that can significantly influence the computational effort (Beaujean et al., 2013), emphasis will be given to the illustration of the general methodology on a simple case (of an alluvial aquifer with concerns related to water supply) demonstrating the potential use of this general and physically based vulnerability assessment method. While the methodology is general, the choice of causal chains has to be made prior to the calculation. The vulnerability is also related to a damaged state and is related to the ‘distance’ between the current state and a given threshold. This choice is arbitrary such that the vulnerability is sensitive to the choice of the threshold. The framework is general and, when applied to water, can include states that are not limited to quality such as, for example, water quantity and availability

Comparison of scales for faecal sludge gravimetric characterization in low-resource settings

Physical and chemical properties of faecal sludge (FS) samples must be routinely measured for FS characterization as well as for design treatment and monitoring purposes. Many of the parameters of interest for FS rely on gravimetric methods of measurement (e.g. total solids, total volatile solids, etc.). As such, they require the use of weighing scales of sufficient reliability, accuracy and precision. Laboratory-grade analytical scales can be difficult to use in remote areas because of their bulk and price point. This study aims to compare two relatively low-cost, off-the-shelf electronic scales to a laboratory-grade analytical (reference) scale. Three scales were compared using their bias, load eccentricity errors and sensitivity errors. The comparison showed that the low-cost scales exhibit a positive bias and are more prone to eccentricity errors than the reference scale. However, they perform well enough to warrant further investigation into whether they can be an acceptable alternative to laboratory scales in field or low-resource settings for faecal sludge characterization

Are feeding preferences of white-tailed deer related to plant constituents?

Controlled feeding experiments can provide valuable insights into food selection of herbivores. We conducted cafeteria trials on captive yearling white-tailed deer (Odocoileus virginianus) during 2 years to determine feeding preferences in relation to plant chemical constituents, i.e., nitrogen and fibers. We simultaneously offered 8 species of cultivated and wild plants in monthly foraging trials conducted from June to October. We predicted that species preferences would be positively related to protein content from June to August and to digestible energy in September and October. As predicted, crude protein (CP) was positively related to feeding preferences, particularly as summer progressed. Feeding preferences were also negatively related to fiber content, especially in early summer. Our results indicate high protein needs over the complete growing season for yearling deer but a decrease in overall plant selectivity as summer progresses. Our results also suggest that deer browsing on cultivated plants might be due to higher CP content of cultivated plants than wild plants. To prevent deer impact on crops, managers should favor regeneration of plants rich in CP content in forests

Entre l'homme et son coeur de Tariq Ramadan : un homme, un contexte, un discours spirituel et persuasif

Tariq Ramadan a un projet d’envergure : convaincre, persuader et expliquer à tous les occidentaux, musulmans ou non, les fondements de la spiritualité musulmane afin de (re)sacraliser notre monde. Pour ce faire, il a acquis, approfondi et mis en pratique son savoir religieux en contexte occidental. Une fois qu’il maîtrise cette réalité, il propose à son auditoire d’adhérer, de s’identifier et de vivre cette identité musulmane. Notre recherche - qui se fonde sur !’argumentation de la persuasion rationnelle - procède à l’analyse du discours que le prédicateur a construit dans son livre Entre l’homme et son cœur pour convaincre les interlocuteurs de la justesse de sa cause et de les inciter à agir. L’étude prend en considération la crédibilité de l’auteur, le contexte global de création, puis met en relief les techniques spirituelles et persuasives ainsi que les valeurs qui les sous-tendent