Caractérisation et optimisation d'une pile à combustible microbienne

Dans le cadre de ce projet initiant la nouvelle thématique de recherche sur les piles à combustible microbiennes (PCM) au LOCIE, nous tentons de répondre aux problématiques suivantes : Quelles stratégies d'intensification des transferts peuvent être mises en œuvre pour optimiser les efficacités de conversion chimiques et énergétiques des PCM ? Quels sont les moyens de caractérisation et de contrôle des phénomènes mécanistiques inhérents aux réactions bio-électro-chimiques à chaque électrodes ? Dans un premier temps, nous abordons le sujet à travers deux stratégies concrètes d'optimisation en terme d'architecture : l'utilisation d'électrodes poreuses en carbone vitreux réticulé (CVR) pour maximiser l'aire d'électrode active au sein d'un volume donné d'une part, et d'autre part, l'intégration multi-échelle via l'approche constructale, dont l'objectif est de minimiser la résistance à l'écoulement au sein du réacteur. Dans un second temps, nous conduisons une démarche fondamentale qui s'est attaché à identifier et caractériser les mécanismes électrochimiques, via l'évaluation de l'effet de facteurs d'ordre physico-chimiques (température, conductivité, pouvoir tampon et charge organique) et matériels (oxydation du CVR, catalyseur en platine sur la cathode, épaisseur de membrane, aire de cathode) sur le fonctionnement d'une PCM. Cette approche multifactorielle utilise la méthodologie des plans d'expérience via les tables de Tagushi. Des analyses par spectroscopie d'impédance électrochimique visent à apporter une vision complémentaire de notre système. L'analyse des spectres d'impédance des électrodes et du réacteur nous a permis de modéliser les mécanismes électrochimiques en jeu à travers des analogies électriques.In this project we addressed the two following issues : what transfer intensification strategies can be set up to optimize the chemical and energetic yields in microbial fuel cells ? What are the most relevant methods to characterize and control the bio-electrochemical phenomenon that are taking place ? We first report two strategies regarding the reactor engineering that are (i) the use of reticulated vitreous carbon as high-surface area porous electrodes and (ii) the use of constructal approach as a multi-scale optimization for fluid distribution. Advantages and limits are discussed. In a second part, we address some basic research which aims at identifying and characterizing the electrochemical phenomenon occurring in our reactor and quantifying the effect of various physicochemical (temperature, conductivity, buffer and substrate concentration) and material factors (oxydized RVC, platinized air-cathode, membrane thickness, cathode surface area). This multifactorial analysis was performed using Tagushi experimental plans and electrochemical impedance spectroscopy (IES). IES was successfully used to simulate our electrodes and cell phenomenon based on electrical analogies using resistive and capacitive elements.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Seasonal and Spatial Changes of Microorganism Communities in Constructed Wetlands: A Community Level Physiological Profiling Analysis

In constructed wetlands, microorganisms associated with plants are assumed to play a major role. A one-year survey was conducted in five vertical flow constructed wetland systems that had been operating from 2 months to 8 years in small French villages (100–500 People Equivalent) to provide a better understanding of microbiological activity. The objective of our study was to highlight the most important factor generating variability between microorganisms communities compared to treatment performances. Results of community level physiological profiling using Biolog Ecoplates were analyzed using principal component analysis. The greatest microbial activity was observed in the oldest wetland during summer. Profiles of fed and rest bed were differentiated by the nature of the main carbon source metabolized. Whereas carbohydrates and carboxylic acids appeared to be better assimilated with fed beds, it seemed that phosphate compounds as well as amines allowed better growth in the plates inoculated with samples of rest beds. In all fed beds, the most important parameters affecting the diversity were the season and the age of the wetlands. There were only slight profile differences between surface and subsurface samples and between the first and second stage samples

Circulating microRNAs in sera correlate with soluble biomarkers of immune activation but do not predict mortality in ART treated individuals with HIV-1 infection: A case control study

Introduction: The use of anti-retroviral therapy (ART) has dramatically reduced HIV-1 associated morbidity and mortality. However, HIV-1 infected individuals have increased rates of morbidity and mortality compared to the non-HIV-1 infected population and this appears to be related to end-organ diseases collectively referred to as Serious Non-AIDS Events (SNAEs). Circulating miRNAs are reported as promising biomarkers for a number of human disease conditions including those that constitute SNAEs. Our study sought to investigate the potential of selected miRNAs in predicting mortality in HIV-1 infected ART treated individuals. Materials and Methods: A set of miRNAs was chosen based on published associations with human disease conditions that constitute SNAEs. This case: control study compared 126 cases (individuals who died whilst on therapy), and 247 matched controls (individuals who remained alive). Cases and controls were ART treated participants of two pivotal HIV-1 trials. The relative abundance of each miRNA in serum was measured, by RTqPCR. Associations with mortality (all-cause, cardiovascular and malignancy) were assessed by logistic regression analysis. Correlations between miRNAs and CD4+ T cell count, hs-CRP, IL-6 and D-dimer were also assessed. Results: None of the selected miRNAs was associated with all-cause, cardiovascular or malignancy mortality. The levels of three miRNAs (miRs -21, -122 and -200a) correlated with IL-6 while miR-21 also correlated with D-dimer. Additionally, the abundance of miRs -31, -150 and -223, correlated with baseline CD4+ T cell count while the same three miRNAs plus miR- 145 correlated with nadir CD4+ T cell count. Discussion: No associations with mortality were found with any circulating miRNA studied. These results cast doubt onto the effectiveness of circulating miRNA as early predictors of mortality or the major underlying diseases that contribute to mortality in participants treated for HIV-1 infection

Development and Validation of a Risk Score for Chronic Kidney Disease in HIV Infection Using Prospective Cohort Data from the D:A:D Study

Ristola M. on työryhmien DAD Study Grp ; Royal Free Hosp Clin Cohort ; INSIGHT Study Grp ; SMART Study Grp ; ESPRIT Study Grp jäsen.Background Chronic kidney disease (CKD) is a major health issue for HIV-positive individuals, associated with increased morbidity and mortality. Development and implementation of a risk score model for CKD would allow comparison of the risks and benefits of adding potentially nephrotoxic antiretrovirals to a treatment regimen and would identify those at greatest risk of CKD. The aims of this study were to develop a simple, externally validated, and widely applicable long-term risk score model for CKD in HIV-positive individuals that can guide decision making in clinical practice. Methods and Findings A total of 17,954 HIV-positive individuals from the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) study with >= 3 estimated glomerular filtration rate (eGFR) values after 1 January 2004 were included. Baseline was defined as the first eGFR > 60 ml/min/1.73 m2 after 1 January 2004; individuals with exposure to tenofovir, atazanavir, atazanavir/ritonavir, lopinavir/ritonavir, other boosted protease inhibitors before baseline were excluded. CKD was defined as confirmed (>3 mo apart) eGFR In the D:A:D study, 641 individuals developed CKD during 103,185 person-years of follow-up (PYFU; incidence 6.2/1,000 PYFU, 95% CI 5.7-6.7; median follow-up 6.1 y, range 0.3-9.1 y). Older age, intravenous drug use, hepatitis C coinfection, lower baseline eGFR, female gender, lower CD4 count nadir, hypertension, diabetes, and cardiovascular disease (CVD) predicted CKD. The adjusted incidence rate ratios of these nine categorical variables were scaled and summed to create the risk score. The median risk score at baseline was -2 (interquartile range -4 to 2). There was a 1: 393 chance of developing CKD in the next 5 y in the low risk group (risk score = 5, 505 events), respectively. Number needed to harm (NNTH) at 5 y when starting unboosted atazanavir or lopinavir/ritonavir among those with a low risk score was 1,702 (95% CI 1,166-3,367); NNTH was 202 (95% CI 159-278) and 21 (95% CI 19-23), respectively, for those with a medium and high risk score. NNTH was 739 (95% CI 506-1462), 88 (95% CI 69-121), and 9 (95% CI 8-10) for those with a low, medium, and high risk score, respectively, starting tenofovir, atazanavir/ritonavir, or another boosted protease inhibitor. The Royal Free Hospital Clinic Cohort included 2,548 individuals, of whom 94 individuals developed CKD (3.7%) during 18,376 PYFU (median follow-up 7.4 y, range 0.3-12.7 y). Of 2,013 individuals included from the SMART/ESPRIT control arms, 32 individuals developed CKD (1.6%) during 8,452 PYFU (median follow-up 4.1 y, range 0.6-8.1 y). External validation showed that the risk score predicted well in these cohorts. Limitations of this study included limited data on race and no information on proteinuria. Conclusions Both traditional and HIV-related risk factors were predictive of CKD. These factors were used to develop a risk score for CKD in HIV infection, externally validated, that has direct clinical relevance for patients and clinicians to weigh the benefits of certain antiretrovirals against the risk of CKD and to identify those at greatest risk of CKD.Peer reviewe

Traitement par biofiltres d'organochlorés et d'hydrocarbures aromatiques polycycliques (application aux eaux de nappes et de ruissellements)

Des technologies de traitement des eaux ont été développées afin de répondre aux exigences réglementaires face à la problématique de la contamination des eaux par des polluants organiques. A ce titre, les procédés biologiques sont une alternative intéressante aux traitements physico-chimiques classiques, onéreux et gourmands en énergie. La biofiltration, reposant sur le principe de concentrer les polluants sur un support afin qu'ils puissent être utilisés comme source de carbone et d'énergie par les micro-organismes peut alors être considérée comme un procédé particulièrement intéressant. C'est dans ce contexte, que les performances de traitement d'hydrocarbures Aromatiques Polycycliques (HAP) et d'organochlorés aromatiques d'eau contaminée ont été étudiées à l'échelle du laboratoire par biofiltration sur support naturel (tourbe, compost, pouzzolane ou matière organique issue de marais artificiels), en lien avec des pilotes installés sur un site industriel. L'influence de la bioaugmentation et la présence de végétaux ont également été étudiées, de même que la toxicité des effluents pour un rejet en milieu naturel. Des bilans de masse ont pu être réalisés, permettant d'évaluer le devenir des polluants au sein de ces systèmes avec la connaissance de l'absorption, de la volatilisation, du transport par lessivage ou de la dégradation. Ce travail dresse un premier bilan du comportement global des polluants au sein de ces systèmes. Plusieurs éléments d'optimisation ont été proposés afin de mieux comprendre le procédé dans son intégralité pour son utilisation in situ.Technologies for decontamination of water have been developed. In this respect, biological processes are an attractive alternative to conventional physico-chemical treatments, expansive and power consuming. The biofilter based on the principle of concentrating the pollutants on a support so that they can be used as a source of carbon and energy by the microorganisms can be considered as a process particularly interesting. It this context, the treatment performance of Polycyclic Aromatic Hydrocarbons (HAP) and chlorinated benzene contaminated water were studied in laboratory by natural biofiltration media (peat, compost, organic matter or pozzolana), in relation with constructed wetlands installed on an industrial site. The influence of bioaugmentation and the presence of plants (Phragmites australis) were also investigated, as well as the toxicity of effluent. Mass balance has been realized to assess the fate of pollutants in these systems with the knowledge of adsorption, volatilisation, lixiviation and degradation. This work provides a first assessment of the behaviour of pollutants in these systems. Several elements of optimization have been proposed to better understand this process for a use on industrial site.CHAMBERY -BU Bourget (730512101) / SudocSudocFranceF

Optimisation des systèmes de traitement des eaux usées domestiques par filtres plantés de macrophytes

Idéal pour l'assainissement des petites communes (<= 1000 habitants), les filtres plantés de roseaux (FPR), offrent une alternative socio-économique au traitement classique des eaux usées. En 2003, en France, il éxiste plus de 200 stations de ce type. Elles ont été créées en réponse à une situation récente, générée à la fois par l'évolution du contexte législatif et par la répartition de la densité démographique. Bien que les installations françaises offrent de bonnes performances, les mécanismes de dégradation sont peu connus et certaines améliorations semblent encore possibles. Cette thèse a eu pour but d'apporter des éléments sur le fonctionnement des FPR. Les résultats ont été présentés en deux chapitres. Le premier a été focalisé sur les performances du flux horizontal, l'incidence de la charge organique et hydraulique sur l'éfficacité d'écoulement. La finalité a été de proposer de éléments de modélisation. Le second chapitre a reposé sur l'analyse du comportement biologique des flux verticaux. Les variations de la composition et de l'activité biologique ont été suivies dans le temps et dans l'espace. Les résultats obtenus ont permis de mettre en évidence, pour le flux horizontal, les limites pour le traitement des eaux usées primaires, qui entraîne des défaillances hydrauliques et biologiques, et le rôle important de l'évapotranspiration, qui augmente l'efficacité hydraulique et le temps de séjour des effluents. Pour le flux vertical, les résultats ont montré l'importance de la couche qui se développe avec l'âge en surface des filtres, aussi bien au niveau hydraulique que biologique, et l'influence de la saison et de la nature du garnissage sur les principaux catabolismes en présence. Ce travail dresse un premier bilan du comportement global et des limites d'utilisation des deux types de flux des FPR. Plusieurs éléments d'optimisation ainsi que des orientations pour mieux comprendre le procédé ont été proposés.Ideal for small communities of up 1000 residents, constructed wetlands (CWs) provide an environmentally sound alternative to traditional methods of wastewater treatment. In France, in response to a recent situation, there are 200 functioning CWs in 2003. Even though FrenchCWs are satisfactorily efficient, degradation mechanisms are still misunderstood. It is still possible to improve the french specific design of CWs. This thesis work has been conducted in this context. The aim was to determine some conceptual and optimisation parameters of the global filter behaviour. Several samples were collected between 2001 and 2003 in both pilot scale ans full scale CWs. Results were presented ans discussed in two chapters. The first focused on hydraulic and organic loading influence on hydraulic residence time distribution (HRT) occuring in horizontal flow. The objectives were to propose models and to quantify the potential dysfunctions. The second chapter presented vertical flow CW microbiology and its relationship with time and space. Results showed taht in horizontal flow constructed wetlands, there were treatment limitations for raw wastewater, causing hydraulic and biological deficiences and the effect of evapotranspiration was significant, increasing the HRT and the hydraulic efficiency. In vertical flow constructed wetlands, results showed that the development of a surface layer with time had an important role for hydraulic repartition, retention and biological diversity and that season and media size had a strong effect on biological catabolism. In winter and with small size media the conditions were more anaerobic that in summer with larger filtration material. To conclude, this thesis draws a first summary of the global behaviour and design limits of both horizontal and vertical CWs. Several optimisation suppositions for future research were recommended.CHAMBERY -BU Bourget (730512101) / SudocSudocFranceF

Lab-Scale Performance Evaluation of Vertical Flow Reed Beds for the Treatment of Chlorobenzene Contaminated Groundwater

International audienc

Performance of a compost biofilter containing earthworms to treat cheese whey

International audienc

Premiers pas vers une pile à combustible microbienne constructale

International audienc