Traitement Expérimental Par Coagulation Floculation Des Effluents Brutes D’une Industrie Aéronautique À Casablanca (Maroc)

Les effluents de l’industrie de traitement de surface présentent souvent une forte charge en produits chimiques très toxiques qui doivent être traités conformément à une réglementation de plus en plus stricte. Dans ce travail, nous avons effectué une caractérisation des effluents liquides d’une unité de traitement de surface au Maroc qui a révélé une forte pollution colloïdale (Turbidité=131 NTU), une charge en matière oxydable élevée (DCO = 960 mg/l) et en éléments métalliques (Fer, cuivre, zinc, nickel, aluminium, chrome et cyanure). L’objectif de cette étude expérimentale consiste à appliquer un traitement physico-chique par coagulation-floculation à ces eaux uses industrielles toxiques en vue de les conformer aux normes de rejet dans le réseau d’assainissement local. En effet, ce traitement, précédé d’un ajustement du pH, une oxydation des cyanures et d’une réduction du chrome hexavalent, a abouti à une réduction très satisfaisante de la toxicité de ces effluents avec des taux d’abattement de 94% pour la DCO et jusqu'à 99 % pour la turbidité et charge métallique. Effluents from the surface treatment industry often have a high load o f highly toxic chemicals that need to be treated in accordance with increasing ly stringent regulations. In this work, we performed a characterization of liqu id effluents from a surface treatment unit in Morocco that revealed high collo idal pollution (Turbidity=131 NTU), high stainless material (COD=960 mg/l ) and metal elements (Iron, copper, zinc, nickel, aluminum, chromium and cy anide). The objective of this experimental study is to apply a physico-chemical treatment by coagulation-flocculation to these toxic industrial wastewater in order to comply with the discharge standards in the local sewage system. This treatment, preceded by pH adjustment, cyanide oxidation and reduction of hexavalent chromium, resulted in a very satisfactory reduction in toxicity of these effluents with abatement rates of 94% for COD and up to 99% for turbidity and metal load

EuroDia: a beta-cell gene expression resource

Type 2 diabetes mellitus (T2DM) is a major disease affecting nearly 280 million people worldwide. Whilst the pathophysiological mechanisms leading to disease are poorly understood, dysfunction of the insulin-producing pancreatic beta-cells is key event for disease development. Monitoring the gene expression profiles of pancreatic beta-cells under several genetic or chemical perturbations has shed light on genes and pathways involved in T2DM. The EuroDia database has been established to build a unique collection of gene expression measurements performed on beta-cells of three organisms, namely human, mouse and rat. The Gene Expression Data Analysis Interface (GEDAI) has been developed to support this database. The quality of each dataset is assessed by a series of quality control procedures to detect putative hybridization outliers. The system integrates a web interface to several standard analysis functions from R/Bioconductor to identify differentially expressed genes and pathways. It also allows the combination of multiple experiments performed on different array platforms of the same technology. The design of this system enables each user to rapidly design a custom analysis pipeline and thus produce their own list of genes and pathways. Raw and normalized data can be downloaded for each experiment. The flexible engine of this database (GEDAI) is currently used to handle gene expression data from several laboratory-run projects dealing with different organisms and platforms

Evaluation of the behaviour of different solar mirrors against soiling phenomenon

To assess their performance and behavior against soiling phenomenon, two different types of mirrors were tested in this study, namely glass and polymer mirrors used in Concentrated Solar Power plants, CSP. Samples were exposed in a natural desert site in Morocco to evaluate their performances. Obtained results show that polymer mirrors present more soiling deposition than glass solar mirrors at same exposure conditions. In addition, it was shown that both tested types present a variation of soiling rate with the climatic season on the site. It was also relieved that the soiling rate is function of the variation of the wind speed and the relative humidity during the exposure

Low temperature deformation in iron studied with dislocation dynamics simulations

a b s t r a c t Tensile tests of iron single crystals reported in the literature were analyzed to deduce the effective stress associated to the double-kinks mechanism in order to establish a mobility law for screw dislocations. This mobility law is used to carry out the first dislocation dynamics simulations of low temperature deformation in iron. The sensitivity of the flow stress on temperature and strain rate is investigated and compared to experiment. First simulation results give an insight into the effect of temperature on the microstructure evolution and on the dislocation-dislocation interactions

Low temperature deformation in iron studied with dislocation dynamics simulations

International audienc

Orowan strengthening at low temperatures in bcc materials studied by dislocation dynamics simulations

International audienc

Influence de l’ajout de la boue obtenue après épuration des eaux usées sur les caractéristiques physico-chimiques des ciments

Le traitement des eaux usées par boue activée entraîne une production croissante d’un déchet appelé « boue ». La valorisation de ces boues dans la fabrication de ciment a pour objectif de réduire la consommation de clinker et de la matière première de carrière, en contribuant de manière simple et économique à résoudre les problèmes liés à l’environnement. Ce travail étudie la possibilité de substituer partiellement le clinker ou le calcaire par ces boues dans le mortier à divers pourcentages (5, 10 et 20 %). Les boues ont été séchées à 40 °C à l’état brut ou après lavage à l’eau de robinet. La caractérisation des matériaux utilisés a été assurée par la fluorescence X, la Diffraction des Rayons X, la Microscopie Électronique à Balayage (MEB) et par Spectroscopie d’émission atomique Plasma à Couplage Inductif (ICP-MS). Il ressort de cette étude que la boue contient une quantité importante d’oxydes de tailles différentes, deux minéraux : la Calcite, le Quartz et plusieurs métaux. L’introduction de la boue brute ou lavée dans le ciment a augmenté d’une part, le taux de la chaux libre du ciment, amélioré le rendement des broyeurs et augmenté la Surface Spécifique de Blaine. D’autre part, elle a influencé de façon néfaste sur le temps de prise et les résistances mécaniques. Les meilleurs résultats sont obtenus pour la substitution du calcaire par 20 % de boue lavée à 28 jours

Laboratory simulation of the surface erosion of solar glass mirrors

During their functioning in concentrated solar power plant – CSP, Glass mirrors are exposed to several climate conditions that cause their degradation. Surface erosion is among mechanical degradation phenomena that can alter mirrors surface and cause a decrease of the overall performance of the CSP plant. Several parameters are influencing this degradation phenomenon, namely the impact speed, the impact angle and the erosive sand particles properties. In this study, we proceed by simulation tests to investigate the effect of surface erosion phenomenon on thin glass mirrors. In order to be representative of the natural degradation phenomenon, the inputs parameters are chosen according to collected data from two different sites in Morocco. Results of simulation tests analysis indicate that the loss in specular reflectance increases with the impact speed. By analyzing the effect of the impact angle, it was discovered that the maximum surface erosion is observed at normal impact angle of 90°. Concerning the effect of sand particles properties on optical degradation, it was found that this latter increases by increasing the sand particle’s size which increase the erosion surface rate. In addition, it was shown that the sand particle’s sharpness presents a precursor for surface erosion phenomenon

Study of the Surface Damage of Glass Reflectors Used in Concentrated Solar Power Plants

AbstractSolar mirrors are exposed, during their operation in Concentrated Solar Power plants –CSP-, to climatic stress factors that cause their degradation and therefore a decrease in the global efficiency of the plant. Sandstorms are among parameters that cause a decrease of mirrors optical performances by generating surface erosion. The intensity and the gravity of this erosion phenomenon is function of climatic, geological parameters and mirrors surface nature.To evaluate the effect of these parameters on the optical performance degradation, two approaches were adopted, namely the natural aging tests in two different sites in Morocco, and the aging tests in controlled environment in a sandblasting chamber. The objectives are, by monitoring the stress factors in natural aging sites, to define aging tests under controlled environment that reproduce similar degradation phenomenon that those observed on mirrors exposed in natural aging sites. Degradations observed in both natural and controlled aging tests are compared and correlated to validate the methodologies and the hypotheses on the analysis of the degradation phenomenon. The aging tests in controlled environment permits the evaluation of the effect of each influencing parameter separately from the others on the mirrors surface erosion, and eventually accelerate the apparition of surface erosion on mirrors.Under controlled environment, tests show that glass mirrors present maximum surface erosion at normal impact angle and that the loss in specular reflectivity is directly related to the wind speed. Exposed mirrors in natural aging sites present low loss in reflectivity which doesn’t exceed 0.4% after 240 days of outdoor exposure. Concerning the effect of sand properties on erosion phenomenon, it was found that the sand hardness affect the roughness parameters, whilethe sharp forms influence on the impactsproperties(roughness parameters, impacts number, impacted area, impacts size diameter). By increasing the sand particle's size, the impacted area increase and the losses in relative specular reflectivity increase