Traitement électrocinétique appliqué aux composés organiques et inorganiques dans les sédiments de dragage

Les quantités de sédiments de dragage portuaires produites chaque année se chiffrent à 50 millions m-3 en France. Par le passé, le devenir des sédiments dragués contaminés était le relargage en mer, mais ces activités sont désormais strictement réglementées; la mise en dépôt de ces matériaux dans des aires spécialement aménagées, qui arrivent à saturation, est de plus en plus couteuse. Dans cette logique, la valorisation des sédiments de dragage s'avère capitale pour un développement durable. Du fait de l’état ces sédiment qui contient des éléments trace métalliques et organiques, un traitement est nécessaire pour préparer le matériau à l’éventuelle valorisation. Le traitement par la technique électrocinétique consiste à appliquer un faible champ électrique à travers le sédiment de l’ordre de 1V/cm, qui induit la migration des espèces ionisées par électromigration et les espèces non-ionisées par électro-osmose. Les travaux présentés concernent des essais, effectués à l'échelle du laboratoire, en premier lieu sur des échantillons de sédiments modèles reconstitué est dopé par cinq métaux (cadmium, chrome, cuivre, plomb et zinc) et cinq autre type de HAP (Phénanthrène, Fluoranthène, Pyrène, Chrysène, Benzo (b) fluoranthène). En deuxième lieu on a utilisé un sédiment naturel. Nous avons évalué sous différentes conditions les performances de l’atténuation des teneurs éléments trace métallique et organique (HAP). Cette étude a mis en évidence qu’un procédé électrocinétique a permis une atténuation significative des éléments traces métalliques et organiques, que l'extraction des métaux lourds dépend frottements du pH, plus le pH est faible plus le procédé est meilleurs. L’acide nitrique et l'acide citrique ont montré les meilleurs taux d'extraction de métaux lourds. Dans toutes les expériences, le Zinc est l’élément le plus mobile. L’extraction des HAP avec un tensioactif non anionique (Tween 20) est meilleure qu’un un tensioactif anionique (SDS). Le traitement utilisant la combinaison Tween 20 et Acide citrique améliore l'extraction des HAP lourds car l’acidification du milieu améliore le flux électroosmotique donc la mobilité des polluants non-ionisés

Caractérisation d'un milieu poreux colmaté par la méthode du potentiel spontané

Laboratory experiments are performed on the physical clogging of a porous medium by injecting polydispersive suspended particles ranged from 1.7 to 40 μm in a column filled with sand (d50=715 µm). Three suspensions have been injected (2g/l, 3g/l and 5g/l) at constant flow velocity in a saturated porous medium. Hydrodynamic effects on particles deposition and porous medium damage were investigated. Particles retentions are significant at the inlet and decreases with depth which induces the drop of permeability and porosity. The coupling between electric and hydraulic flows is electrokinetic in nature, the second objective of this work is to test the sensitivity of the method of self-potential (SP) and to show the usefulness of this method to understand the controlling parameters of the electrical field associated with the filtration of suspended particles through a porous medium. Electrodes have been used to record the SP signal which detect and quantify the clay particles in the porous medium during injection tests. The variations of the SP signals are linearly correlated to the piezometric level changes. SP signals are directly sensitive to deposition particles distribution, and it is high at the inlet of the column where the deposit is large and decreases with depth. For the test injection with 2g/l the SP signal varies between +16 mv and +13 mv for the test with 3g/l it varies between +12 mv and +8mv and that with 5g/l it varies between - 22mv to-19mv. When the concentration of clay injected in the porous medium increases, the SP signal decreases and changes from a positive sign to a negative sign. SP method confirmed the behavior of the porous medium clogging obtained by the hydraulic measurements. The obtained results show that SP signal is sensitive to clay particles, their immediate passage to the inlet of the column and the amount deposited particles in each section of the porous medium

A Randomized, Placebo Controlled, Double Masked Phase IB Study Evaluating the Safety and Antiviral Activity of Aprepitant, a Neurokinin-1 Receptor Antagonist in HIV-1 Infected Adults

Neurokinin-1 receptor (NK1R) antagonists have anti-HIV activity in monocyte-derived macrophages, decrease CCR5 expression and improve natural killer cell function ex vivo. Aprepitant is a NK1R antagonist approved by FDA as an antiemetic.We conducted a phase IB randomized, placebo controlled, double masked study to evaluate the safety, antiviral activity, pharmacokinetics and immune-modulatory effects of aprepitant in HIV-infected adults not receiving antiretroviral therapy, with CD4+ cell count ≥350 cells/mm(3) and plasma viral load ≥2,000 copies/ml. Subjects were stratified by viral load (< vs. ≥20,000 copies/ml) and randomized within each stratum to receive aprepitant at 125 mg QD(Low), or 250 mg QD(High), or placebo(PL) for 14 days, and followed for 42 days.Thirty subjects were randomized and 27 completed treatment (9, 8, 10 subjects in 125 (Low), 250 (High), and PL groups). 63% were male; 37% white; mean (SD) age 43 (9.3) years. Geometric mean baseline viral load (copies/ml) for Low, High, and PL was 15,709, 33,013, and 19,450, respectively. Mean (95%CI) change in log10 viral load at day 14 for Low, High, and PL was -0.02(-0.24,+0.20), -0.05(-0.21,+0.10), and +0.04(-0.08,+0.16), respectively. The number of subjects with AEs was 4(44.4%), 5(62.5%), and 1(10%) for Low, High, and PL. No Grade 4 AEs occurred.Adverse events of aprepitant were more common in the treated groups. At the dose used in this two-week phase IB study, aprepitant showed biological activity, but no significant antiviral activity.ClinicalTrials.gov NCT00428519

Heavy metals removal from dredged sediments using electrokinetics process

International audienceDredging practices constitute a challenge for developing and maintaining harbor and fluvial activities. They also present a contamination risk of coastal waters which can affect the ecosystems. The unsuitability and restriction to marine disposal of dredged sediments leads ultimately the managers to provide a treatment ashore because of the great volume of material to be treated.So, Heavy metals fate and transport in contaminated sediments involve difficult risk assessment and remediation challenges.Laboratory electromigration experiments show the efficiency of such process on heavy metals removal from fine sediments. Analysis of solid fractions after test allows to highlight the mobility of heavy metals inside the sediment sample. Among all the additives tested for metal removal, nitric acid showed the best removal efficiency, but citric acid, which is environmentally friendly, was also very interesting due to its buffering and chelating capacities. Results revealed that adding a strong inorganic acid (Nitric Acid) into the aqueous fluid was more effective than a weak acid (Citric Acid), but the complexing citric acid was promising for longer treatment. The Citric Acid as enhancing-process fluid provides significant heavy metals removal. Zn and Cd are easy-removed from natural sediment which presents more metals-affinity than model sediment for which removal was more significant. Further results showed that combining an acid and a surfactant allowed simultaneous removal of heavy metals and PAHs

Influence de la taille des particules en suspension sur leur transfert dans un milieu poreux

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Evolution des sédiments de dragage en chambre de dépot

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