Influence of Uranium on Bacterial Communities: A Comparison of Natural Uranium-Rich Soils with Controls

This study investigated the influence of uranium on the indigenous bacterial community structure in natural soils with high uranium content. Radioactive soil samples exhibiting 0.26% - 25.5% U in mass were analyzed and compared with nearby control soils containing trace uranium. EXAFS and XRD analyses of soils revealed the presence of U(VI) and uranium-phosphate mineral phases, identified as sabugalite and meta-autunite. A comparative analysis of bacterial community fingerprints using denaturing gradient gel electrophoresis (DGGE) revealed the presence of a complex population in both control and uranium-rich samples. However, bacterial communities inhabiting uraniferous soils exhibited specific fingerprints that were remarkably stable over time, in contrast to populations from nearby control samples. Representatives of Acidobacteria, Proteobacteria, and seven others phyla were detected in DGGE bands specific to uraniferous samples. In particular, sequences related to iron-reducing bacteria such as Geobacter and Geothrix were identified concomitantly with iron-oxidizing species such as Gallionella and Sideroxydans. All together, our results demonstrate that uranium exerts a permanent high pressure on soil bacterial communities and suggest the existence of a uranium redox cycle mediated by bacteria in the soil

Rétention d'éléments trace sur une bentonite (étude expérimentale et modélisation)

Le stockage des déchets radioactifs en formation géologique est envisagé en France. L altération des déchets peut mobiliser le polluant, qui pourrait alors migrer vers la géosphère. Des argiles sont envisageables comme barrière anti-pollution étant donnée leur faible perméabilité et leur forte capacité de rétention. Un modèle thermodynamique de complexation de surface basé sur le principe d additivité est proposé pour prédire le comportement des polluants au contact des argiles. Ce principe permet une détermination indépendante de chaque paramètre du modèle, et limite l ajustement de données corrélées entre elles. Il permet alors l établissement d une base de données d adsorption associée au solide. Les prédictions obtenues sont en bon accord avec les données expérimentales, ce qui offre des perspectives encourageantes quant à l utilisation de ce modèle en performance assessment.Radioactive waste storage in deep underground is studied in France. The alteration of the radioactive waste can mobilise the elements which can migrate to the geosphere. Clays (bentonite) are investigated as major materials constituting the barriers because of their low permeability and high retention capacity. A thermodynamic surface complexation model, based on the site additivity principle was investigated, in order to predict the adsorption behaviour of pollutants in contact with clay. The principle allows an independent determination of each parameter of the model, limiting the fitting procedure of correlated data, and it allows the use of an adsorption thermodynamic database for a solid. The predictions obtained were un good accordance with experimental data. The model could then be applied successfully in performance assessment.NICE-BU Sciences (060882101) / SudocSudocFranceF

Mécanismes et transferts de l'arsenic dans une confluence du Var et étude d'une méthode de remédiation dans les eaux potables

Ce travail s inscrit dans une problématique locale de teneur élevée en arsenic naturel dans le but d améliorer la surveillance et la gestion de la qualité de la ressource en eau dans l arrière-pays niçois. L existence de grandes disparités géographiques des teneurs en arsenic font de la géologie la cause principale de cette contamination. L intérêt de ce travail est d appréhender les interactions solide/solution entre l arsenic total dissous et les particules solides (matières en suspensions, sédiment de lit de rivière, solides naturels). Pour décrypter le comportement géochimique de l arsenic, les trois objectifs principaux sont : de déterminer son état de conservativité dans le milieu naturel ; puis d étudier les phénomènes d adsorption en laboratoire sur des solides naturels (illite, oxydes de fer) ou de référence (kaolinite) ; puis enfin d apporter une application directe au piégeage de l arsenic par la création d un pilote de traitement destiné à dépolluer une source d eau destiné à la consommation humaine. La concentration en particule est le facteur influençant la conservativité de l arsenic dans le système de confluence Tinée/Var selon les données des compartiments dissous et particulaire. La fraction colloïdale semble avoir une implication de premier ordre lors de la période de crue étudiée. Le piégeage de l arsenic est favorisé par les oxyhydroxydes de fer, les argiles puis en moindre quantité par les solides acido-solubles.This work aimed to solve a local problem of high water contamination with natural arsenic. In order to monitor and manage the water resource quality in French Riviera region. The different geographical repartition of arsenic content makes the consequences of this contamination to the geology. The interest of this work is to understand the interaction at solid/liquid interfaces between total dissolved arsenic and the solid particles (suspended particles matter, bed sediments and natural solids). To elucidate the geochemical behavior of arsenic, the three main objectives are: to determine the conservative states in the natural environment, then to study the adsorption phenomena under laboratory conditions onto the natural solids (illite and iron oxides) or reference materials (kaolinite); thirdly to apply the outcome of this work to establish a processing pilot for arsenic removal to decontaminate drinking water. The particle content is the main factor which influences the conservativity of arsenic in the confluence Tinée/Var. Colloids seems to have the main role in the arsenic removal in the studied flood period. Arsenic removal is favored by iron oxides, and clays, but less efficiently by acid-soluble compounds. The study of sorption mechanisms onto clays showed that adsorption of arsenic is strongly dependent on pH, quantity of aluminol reactive sites, influence of competitive anions such as carbonates and phosphates. Finally, the association of zeolites (high specific surface area) with coating of amorphous iron oxides (high affinity for arsenic) makes this adsorbent the most efficient, hence was studied and used in this work for arsenic adsorption.NICE-Bibliotheque electronique (060889901) / SudocSudocFranceF

Mise au point d'un nouvel échantillonneur intégratif à base de solide naturel poreux

L échantillonnage passif est une alternative prometteuse à l échantillonnage ponctuel. Cette technique permet d accumuler les contaminants présents dans l eau directement in-situ, intégrant ainsi les variations de concentrations temporelles qui ne sont pas détectables avec l échantillonnage ponctuel. Cependant la plupart des échantillonneurs commercialisés actuellement utilisent des phases complexes et coûteuses. Ces travaux de thèse ont pour objectif de mettre au point un nouvel échantillonneur intégratif plus robuste et moins coûteux, capable d échantillonner autant les contaminants métalliques que les composés organiques. Pour cela, l idée était d utiliser comme phase adsorbante un minéral naturel poreux doté de fortes capacités d adsorption ; des zéolithes et une sépiolite naturelle ont été envisagées. Le développement d un tel dispositif est un processus complexe qui passe tout d abord par l étude des capacités d adsorption des différents solides pour les contaminants métalliques ainsi que pour les composés organiques. La comparaison des capacités d adsorption des différents solides démontre que la sépiolite est la plus efficace pour la rétention de la majorité des contaminants étudiés. Sur la base de ces résultats la sépiolite est sélectionnée comme phase réceptrice du nouvel échantillonneur. Le déploiement de ces nouveaux dispositifs dans un milieu semi-contrôlé soumis à différents scénarios de contamination met en lumière une importante capacité d échantillonnage tant pour les métaux que pour les contaminants organiques hydrophiles. Enfin, dans une dernière étape.Passive sampling is a promising alternative to grab sampling. This approach consists in accumulating contaminants from water directly in-situ. Contrary to conventional grab sampling, this method allows integrating the temporal variations of the concentration. However most commercial samplers use complex and expensive adsorbent phases. In this work, we aimed to develop a new integrative sampler, more robust and less expensive than the commercial ones, able to sample both metals and organic compounds. For this the use of porous natural minerals with high adsorption capacities was investigated. Zeolites and natural sepiolite were considered. The development of this kind of device is a complex process involving a double approach laboratory/field. The first step consists in studying the adsorption capacity of different solids towards metals and organic compounds. The comparison of adsorption efficiency of different solids shows that sepiolite is the most efficient for the retention of most of the studied contaminants. Based on these results, it was selected as receiving phase of the new sampler. Deployment of these new devices in a semi-controlled environment with various scenarios of contamination was tested. This experiment highlighted that sepiolite has an important sampling ability both for metals and for hydrophilic organic contaminants. Finally, the last step of this process consisted in a validation of these samplers in a natural environment and in industrial effluent.NICE-Bibliotheque electronique (060889901) / SudocSudocFranceF

Traitement de sédiments portuaires méditerranéens contaminés en arsenic et en métaux (géochimie et écotoxicologie)

Ce travail de thèse étudie la faisabilité d un traitement des sédiments marins multi-contaminés par stabilisation géochimique à l aide d additifs minéraux. L efficacité du traitement a été évaluée en déterminant la qualité chimique et écotoxicologique des extraits aqueux de sédiments. Dans le cas de la stabilisation de l arsenic, des expériences préliminaires de sorption sur des additifs à base de fer ont révélé que l hématite adsorbe efficacement l arsenic sur une large gamme de pH et de concentration. Les tests de stabilisation en batch et en colonne montrent que les concentrations en arsenic diminuent de 30 à 40 % en présence de 5 % d hématite. L application du procédé de stabilisation à plus grande échelle en milieu extérieur confirme l efficacité du traitement pour la rétention de l arsenic mais aussi des métaux en présence d hématite et de fer métallique. Les bio-essais ont permis (i) de déterminer la toxicité potentielle de sédiments portuaires et (ii) d évaluer l effet des additifs minéraux en terme de toxicité. Les résultats montrent que le gradient de toxicité peut varier en fonction du test de toxicité utilisé. Après traitement par additifs minéraux, l hématite s est révélée être l additif le plus efficace pour améliorer la qualité écotoxicologique des élutriats les plus contaminés. Dans le cas de la mise en dépôt de sédiments contaminés, ce type de traitement permettrait d améliorer la qualité chimique et écotoxicologique des eaux de lixiviationThis thesis work studies the feasibility of treatment by geochemical stabilization mixing mineral additives with contaminated marine sediments. Treatment efficiency was evaluated by determining chemical and toxicity parameters on elutriates from sediment samples. In the case of arsenic stabilization, preliminary sorption experiments on iron based minerals revealed that hematite efficiently adsorbs arsenic on a large range of pH and concentrations. Stabilization tests in batch and column experiments showed that, in sediments mixed with 5% of hematite, arsenic concentrations decreased by 30 to 40 %. The use of this stabilization process in a small scale experiment performed outdoors confirmed the treatment is efficient not only for arsenic but also for metals especially when hematite and zero valent iron were used. Bioassays allowed (i) to determine potential toxicity of port sediments and (ii) to assess the effect of mineral additives on toxicity. Results show that the toxicity gradient can vary as a function of the toxicity test. After treatment by mineral additives, hematite was the most efficient additive to improve the ecotoxicological quality of the most contaminated elutriates. For storage of contaminated sediments, this type of treatment would allow to improve the chemical and toxicological quality of leachatesNICE-BU Sciences (060882101) / SudocSudocFranceF

Batch and column studies of the stabilization of toxic heavy metals in dredged marine sediments by hematite after bioremediation

International audienc

A Review of the Treatment Process of Perfluorooctane Compounds in the Waters: Adsorption, Flocculation, and Advanced Oxidative Process

Perfluorinated compounds (PFCs) are recognized as a new type of refractory organic pollutants. Due to the persistent environmental pollution, bioaccumulation, and biotoxicity of PFCs, they have received extensive attention in recent years. To deal with the environmental risks caused by PFCs, the pollution and distribution of PFCs in the aquatic environment are discussed in detail, mainly for the most widely used PFCs—perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS). The latest progress in the current processing technology of PFOA and PFOS is comprehensively introduced. It includes a variety of physical techniques to remove PFCs such as adsorption and flocculation. It has been confirmed that various adsorbents can play a key role in the enrichment and removal of PFCs through high specific surface area and hydrophobic interaction. In addition, traditional degradation processes are often unsatisfactory for PFCs, prompting the search for more efficient and cost-effective methods, with great progress having been made in advanced oxidation processes (AOPs) based on radical decomposition of pollutants. This review also integrates multiple advanced oxidation processes (AOPs) such as photocatalysis, electrochemical processes, ozone, the Fenton process, and ultrasound. This paper provides an overview of the various PFCs removal techniques and discusses their efficacy. It also explores future possible developments for PFCs elimination technologies for water treatment

A Review of the Treatment Process of Perfluorooctane Compounds in the Waters: Adsorption, Flocculation, and Advanced Oxidative Process

Perfluorinated compounds (PFCs) are recognized as a new type of refractory organic pollutants. Due to the persistent environmental pollution, bioaccumulation, and biotoxicity of PFCs, they have received extensive attention in recent years. To deal with the environmental risks caused by PFCs, the pollution and distribution of PFCs in the aquatic environment are discussed in detail, mainly for the most widely used PFCs—perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS). The latest progress in the current processing technology of PFOA and PFOS is comprehensively introduced. It includes a variety of physical techniques to remove PFCs such as adsorption and flocculation. It has been confirmed that various adsorbents can play a key role in the enrichment and removal of PFCs through high specific surface area and hydrophobic interaction. In addition, traditional degradation processes are often unsatisfactory for PFCs, prompting the search for more efficient and cost-effective methods, with great progress having been made in advanced oxidation processes (AOPs) based on radical decomposition of pollutants. This review also integrates multiple advanced oxidation processes (AOPs) such as photocatalysis, electrochemical processes, ozone, the Fenton process, and ultrasound. This paper provides an overview of the various PFCs removal techniques and discusses their efficacy. It also explores future possible developments for PFCs elimination technologies for water treatment

Stabilisation des métaux et dégradation biologique des polluants organiques dans un sédiment portuaire contaminé

The management of dredged sediments is problematic in some French regions due to their significant contamination by organic and/or mineral pollutants. In this study, dredged sediment from a seaport was treated by composting and chemical stabilization. Sediment contamination (organic and mineral pollutants) was characterized, and samples (control and stabilized samples) weighing 6 kg were treated with different mineral additives in a small scale pilot. Results show that (i) total flux of pollutants is reduced by half in samples treated with hematite and zero-valent iron, (ii) fine zeolite (clinoptilolite) is unsuitable to stabilize pollutants in the sediment, (iii) composting reduces organotin concentrations between 38 and 91%, and total PAH level at 15%.Le devenir des sédiments est problématique dans certaines régions françaises en raison d’une contamination significative en polluants organiques et/ou minéraux. Dans cette étude, un sédiment de dragage portuaire a été traité par compostage et stabilisation chimique. Après caractérisation de la contamination (teneurs totales en polluants organiques et minéraux), des andains de 6 kg de sédiment ont été traités par différents additifs minéraux en présence d’un sédiment témoin en milieu extérieur. Les résultats montrent que (i) les flux de polluants sont réduits de moitié dans les sédiments traités à l’hématite et au fer zéro, (ii) la zéolithe fine (clinoptilolite) est peu efficace pour la rétention des polluants dans le sédiment, (iii) le compostage permet de réduire entre 38 et 91 % des teneurs en organoétains et 15% des HAPs