Aeration and hydrodynamics in submerged membrane bioreactors

Membrane bioreactor (MBR) is already a well-developed wastewater treatment process for both municipal and industrial applications. Nonetheless, membrane fouling remains a significant problem for its wider development. In the case of submerged membrane bioreactors (SMBRs), one of the most efficient strategies to limit fouling is the use of a gas/liquid two-phase flow to enhance the mass transfer. However, the effect of aeration still remains incompletely understood. The complexity of flows and of the nature of activated sludge makes a theoretical approach difficult. Aeration is the source of a large part of the operating costs in most industrial scale plants and its optimization is a necessity to make the process really efficient. This paper first deals with hydrodynamics in MBRs, then it reviews the parameters of aeration and their impact on filtration performance. Finally, the effects of aeration mechanisms on biological media are described

Place a la litterature dans le cours de conversation!

Au niveau universitaire, la plupart des programmes de francais offrent un cours que l\u27on peut classer sous l\u27appellation generique de cours de conversation ( Conversational Skills , French for Oral Communication, etc.). Si le but de ce cours est clair: ameliorer les competences communicatives orales des apprenants, son contenu est par contre tres ouvert. Dans ce type de cours, la conversation prend souvent appui sur l\u27exploitation de documents authentiques et permet ainsi aux apprenants d\u27approfondir leurs connaissances culturelles. Cette bipolarite: developpement des competences de communication orale et decouverte de la culture nous semble tout a fait appropriee. On peut cependant regretter l\u27absence de la litterature dans un tel type de cours. Il est rare en effet de trouver des textes litteraires parmi les documents qui servent de tremplins aux activites communicatives et a la decouverte de la culture. Ceuxci sont reserves aux cours dits de litterature qui, par ailleurs, survivent encore trop souvent sous une forme traditionnelle, se limitant a la lecture et a l\u27explication de textes

Peripapillary choroidal neovascularization associated with melanocytoma of the optic disc: a clinicopathologic case report

Background: Melanocytoma of the optic disc is a benign melanocytic tumor that rarely causes visual impairment. We report a case of a melanocytoma of the optic disc with a decreased vision related to a peripapillary choroidal neovascular membrane (PCNVM) that was successfully treated by submacular surgery. Methods: A 45-year-old southern European patient had a melanocytoma of the optic disc in his left eye with vision of 20/100. Fluorescein angiography demonstrated a PCNVM impeding the fovea associated with a subretinal hemorrhage. Results: The patient underwent a complete vitrectomy and removal of the PCNVM. Subsequently, the subretinal hemorrhage disappeared and visual acuity improved to 20/25. Visual acuity remained good for a period of 14months' follow-up without any recurrence of neovascular membrane. Conclusions: Submacular surgery is a potentially effective treatment for large PCNVM associated with a melanocytoma of the optic dis

Concepts actuels de l'hyperaldostéronisme primaire

peer reviewe

Aeration for fouling control in Submerged Membrane Bioreactors for wastewater treatment: shear simulation and experimental validations

Aeration for fouling prevention in SMBRs represents a great part of energy consumption of the process. To decrease it a better understanding of the impact of aeration on filtration performances is required. In spite of its beneficial effect (shear stress on membrane surface, turbulences...), the aeration has an impact on a potential destructuration of mixed liquor that could be detrimental to filtration. Our study aims at estimating this impact for SADm and SADp close to those used in full scale plants. To do so work was separated in two main parts: 1) Hydrodynamics characterisation to quantify shear stresses imposed to mixed liquor through Computational Fluid Dynamics (CFD) simulations 2) A pilot campaign to assess experimentally the impact of aeration on mixed liquor parameters. The aim is to link air flowrate (operational parameter) to fouling through local mechanism induced by aeration: shear stresses imposed to mixed liquor and the induced variations of floc size and Extracellular Polymeric Substances (EPS) concentrations

Microgeographic adaptation and the effect of pollen flow on the adaptive potential of a temperate tree species

Recent interest for microgeographic adaptation, i.e. adaptation at spatial scales compatible with substantial amount of gene dispersal, offers to reconsider the scale at which evolution occurs (Richardson et al. 2014). Whether gene flow is constraining or facilitating local adaptation at this fine spatial scale remains an unresolved question. Too important gene flow would overwhelm the effects of natural selection and decrease local adaptation along environmental gradients. Conversely, gene flow, and particularly long-distance dispersal events, could play a major role in resupplying the genetic variation of populations and favouring the spread of beneficial alleles (Kremer et al. 2012). Hence, the high dispersal capacities of trees are often assumed to be the main process maintaining the large levels of genetic variation measured in their natural populations. However, evidences for microgeographic adaptation and the quantitative assessment of the impact of gene flow on adaptive genetic variation are still limited in most temperate trees. Here, we sampled 60 open-pollinated families of European beech (Fagus sylvatica L.) from three natural plots, spreading along a short elevation gradient (∼1.5 km) at the warm margin of this species distribution. We analysed the phenotypic and genotypic data of ∼2,300 seedlings grown in a common garden. We focused on 11 potentially adaptive traits with significant heritabilities (Gauzere et al. 2016) and tested for signature of local selection on quantitative trait differentiation. We then identified the offspring likely originating from local or distant pollen immigration events and quantified the role of gene flow in increasing locally the additive variance of traits under selection. We found a significant signal of adaptive differentiation among plots separated by less than one kilometre, with local selection acting on growth and phenological traits. We found that trees in the plots at high elevation, experiencing the lowest temperature conditions, flushed earlier and had a higher height and diameter growth in our common garden than trees from the plot at low elevation. Beech populations originating from higher longitude or elevation have also been shown to be genetically earlier in provenance tests, suggesting that these populations evolved phenological traits promoting a longer vegetation period. At this southern margin of the species, the reduced allocation to stem growth at the low elevation plot is likely an adaptive response to drought, which has previously been described by comparing marginal vs central beech populations. Consistently with theoretical expectations, our results suggest a beneficial effect of pollen dispersal by increasing the genetic diversity for these locally differentiated traits. These effects were quantitatively high, with more than twice higher genetic variance for immigrant than local offspring, although with large standard errors around estimates. Our results highlight that local selection is an important evolutionary force in natural tree populations, and provide a strong evidence that adaptive genetic differentiation can occur despite high gene flow. For the two genetically differentiated traits, our analyses suggested a beneficial effect of pollen dispersal by increasing genetic diversity after one episode of reproduction. The findings suggest that conservation and management interventions to facilitate movement of gametes along short ecological gradients would boost genetic diversity of individual tree populations, and thereby enhance their adaptive potential

Efficacy of a new carvacrol-based product on Campylobacter jejuni in challenge test in vivo and impact on the whole caecal microbiota

Efficacy of a new carvacrol-based product on Campylobacter jejuni in challenge test in vivo and impact on the whole caecal microbiota. 6. International Conference on Poultry Intestinal Healt

Rapport final du projet VERT. Le vélo évalué en rabattement dans les territoires. Volume 1

This report is the final report of project VERT (evaluation of the bicycle as a feeder mode to rail outside urban areas). The VERT project aims at studying bicycle use as a feeder mode to railway stations, for regular use, in exurban areas. It focuses first on a state of the art fostered by international and French experience, providing quantitative and qualitative elements for research (T2), second on economic analysis (T3) implemented in several modeled scenarios (T4), making it possible to compare bike and ride solutions with park and ride solutions, and to draw a cost-benefit analysis for users and the community. Third, project includes qualitative analyses (T5) backed by interviews with stakeholders, and is applied in a case study in Amboise (T6), comparing scenarios for developing the bicycle as a feeder mode to train, built from observations of present situation, software development to map catchment areas of bicycles and pedelecs,analysing feeder routes and computing the cost-benefit balance of bike and ride. This very positive balance as well as other results show that the Amboise site possesses characteristics enabling this intermodal development, that are supported by some local stakeholders' projects. This confirms that this intermodal potential must be backed by local policies, as shown by experience in other regions or in other countries.Ce rapport est le rapport final du projet VERT (le vélo évalué en rabattement dans les territoires). Le projet VERT vise à étudier l'utilisation du vélo comme mode d'accès aux gares, pour un usage régulier, dans le milieu périurbain. Il se concentre sur un état de l'art nourri d'expériences étrangères et françaises, fournissant des éléments quantitatifs et qualitatifs pour la recherche (T2), sur un bilan économique (T3) mis en oeuvre dans plusieurs scénarios modélisés (T4) permettant de comparer les solutions de vélo+train à des solutions de voiture+train, et d'en établir un bilan économique pour l'usager et pour la collectivité. Le projet inclut aussi des analyses qualitatives (T5) appuyées par des entretiens avec les acteurs, et comporte une étude de cas sur le terrain d'Amboise (T6), comparant plusieurs scénarios de développement du vélo en rabattement sur la gare, construits à partir d'observations de la situation actuelle, du développement de logiciel cartographiant les zones atteintes par le vélo et le VAE (vélo à assistance électrique), analysant des itinéraires de rabattement et établissant un bilan économique de l'intermodalité vélo-TC. Ce bilan très positif et les autres résultats montrent que le site d'Amboise possède des caractéristiques permettant de développer cette intermodalité, confortées par les projets de certains acteurs locaux. Cela confirme que le potentiel de cette intermodalité doit être appuyé par les politiques locales, comme l'ont montré les expériences d'autres régions ou d'autres pays

Two-photon luminescence of single colloidal gold nanorods: revealing the origin of plasmon relaxation in small nanocrystals

The two-photon luminescence (TPL) of small 10 nm x 40 nm colloidal gold nanorods (GNR) is investigated at the single object level, combining polarization resolved TPL and simultaneously acquired topography. A very high dependence of the TPL signal with both the nanorods longitudinal axis and the incident wavelength is observed confirming the plasmonic origin of the signal and pointing the limit of the analogy between GNRs and molecules. The spectral analysis of the TPL evidences two emission bands peaks: in the visible (in direct connection with the gold band structure), and in the infrared. Both bands are observed to vary quadradically with the incident excitation beam but exhibit different polarization properties. The maximum two-photon brightness of a single GNR is measured to be a few millions higher than the two-photon brightness of fluorescein molecules. We show that the important TPL observed in these small gold nanorods results from resonance effects both at the excitation and emission level : local field enhancement at the longitudinal surface plasmon resonances (LSPR) first results in an increase of the electron-hole generation. Further relaxation of electron-hole pairs then mostly leads to the excitation of the GNR transverse plasmon mode and its subsequent radiative relaxation