Efficiency of Modified Granular Activated Carbon Coupled with Membrane Bioreactor for Trace Organic Contaminants Removal

The aim of the study is to improve removal of trace organic contaminants dissolved in activated sludge by the process of filtration with membrane bioreactor combined with modified activated carbon, for a maximum removal of organic compounds characterized by low molecular weight. Special treatment was conducted in laboratory on activated carbon. Tow reaction parameters: The pH of aqueous middle and the type of granular activated carbon were very important to improve the removal and to motivate the electrostatic Interactions of organic compounds with modified activated carbon in addition to physical adsorption, ligand exchange or complexation on the surface activated carbon. The results indicate that modified activated carbon has a strong impact in removal 21 of organic contaminants and in percentage of 100% of the process

Radiation Hardening of Digital Color CMOS Camera-on-a-Chip Building Blocks for Multi-MGy Total Ionizing Dose Environments

The Total Ionizing Dose (TID) hardness of digital color Camera-on-a-Chip (CoC) building blocks is explored in the Multi-MGy range using 60Co gamma-ray irradiations. The performances of the following CoC subcomponents are studied: radiation hardened (RH) pixel and photodiode designs, RH readout chain, Color Filter Arrays (CFA) and column RH Analog-to-Digital Converters (ADC). Several radiation hardness improvements are reported (on the readout chain and on dark current). CFAs and ADCs degradations appear to be very weak at the maximum TID of 6 MGy(SiO2), 600 Mrad. In the end, this study demonstrates the feasibility of a MGy rad-hard CMOS color digital camera-on-a-chip, illustrated by a color image captured after 6 MGy(SiO2) with no obvious degradation. An original dark current reduction mechanism in irradiated CMOS Image Sensors is also reported and discussed

Alterations in Gut Microbiome in Cirrhosis as Assessed by Quantitative Metagenomics: Relationship With Acute-on-Chronic Liver Failure and Prognosis

Background and Aims: Cirrhosis is associated with changes in gut microbiome composition. Although acute-on-chronic liver failure (ACLF) is the most severe clinical stage of cirrhosis, there is lack of information about gut microbiome alterations in ACLF using quantitative metagenomics. We investigated the gut microbiome in patients with cirrhosis encompassing the whole spectrum of disease (compensated, acutely decompensated without ACLF, and ACLF). A group of healthy subjects was used as control subjects. Methods: Stool samples were collected prospectively in 182 patients with cirrhosis. DNA library construction and sequencing were performed using the Ion Proton Sequencer (ThermoFisher Scientific, Waltham, MA). Microbial genes were grouped into clusters, denoted as metagenomic species. Results: Cirrhosis was associated with a remarkable reduction in gene and metagenomic species richness compared with healthy subjects. This loss of richness correlated with disease stages and was particularly marked in patients with ACLF and persisted after adjustment for antibiotic therapy. ACLF was associated with a significant increase of Enterococcus and Peptostreptococcus sp and a reduction of some autochthonous bacteria. Gut microbiome alterations correlated with model for end-stage liver disease and Child-Pugh scores and organ failure and was associated with some complications, particularly hepatic encephalopathy and infections. Interestingly, gut microbiome predicted 3-month survival with good stable predictors. Functional analysis showed that patients with cirrhosis had enriched pathways related to ethanol production, γ-aminobutyric acid metabolism, and endotoxin biosynthesis, among others. Conclusions: Cirrhosis is characterized by marked alterations in gut microbiome that parallel disease stages with maximal changes in ACLF. Altered gut microbiome was associated with complications of cirrhosis and survival. Gut microbiome may contribute to disease progression and poor prognosis. These results should be confirmed in future studies

Radiation Hardening of Digital Color CMOS Camera-on-a-Chip Building Blocks for Grad Total Ionizing Dose Environments

Radiation Hardening of Digital Color CMOS Camera-on-a-Chip Building Blocks for Grad Total Ionizing Dose Environments

Modifications de la répartition d'espèces métalliques (Cd, Cu) induites par des prétraitements physique (ultrasons), chimique (ozone) et thermique au sein des procédés à boues activées

La rétention du cadmium et du cuivre par les boues activées a été étudiée suite aux effets respectifs de trois traitements de désintégration (ultrasons, thermique, ozone), utilisés pour réduire la production de boues dans les stations d'épuration. Des études pilotes ont montré que la sonication et le traitement thermique provoquent une suraccumulation de cadmium dans les boues et une fuite de cuivre via l'eau de sortie. Durant la sonication. l'augmentation de surface spécifique des particules et la disponibilité accrue de sites négativement chargés accroissent la sorption du cadmium à la surface des flocs. La précipitation est également favorisée suite à l'augmentation de la concentration en phosphates solubles. Ces phénomènes sont également observés suite au traitement thermique et à l'ozonation mais sont contrebalancés par une diminution de la quantités de sites de fixation. Suite aux trois traitements, la rétention du cuivre par les boues est limitée suite à la complexation de ce dernier en solution avec la matière solubilisée lors des traitements. Le développement d'un modèle de sorption a permis de décrire l'affinité entre ces composés et le cuivre.The effect of three disintegration treatments (ultrasound, heat, ozone) used to reduce sludge production in sewage treatment plants on the uptake of cadmium and copper by activated sludge was studied. Pilot studies showed that sonication and heat treatment caused over-accumulation of cadmium in excess sludge and copper leaking through treated effluent. During sonication, the increase of particles specific surface area and the increased availability of negatively charged sites induced an increase of cadmium sorption at floc surface. Precipitation was also favored due to the increased concentration of soluble phosphates. These phenomena were also observed after heat treatment and ozonation but were offset by a decrease of the amount of binding sites. Following the three treatments, copper uptake by sludge was limited due to complexation with the organic matter solubilized during treatment. The development of a sorption model successfully described the affinity between these compounds and copper.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

Heavy metals uptake by sonicated activated sludge: Relation with floc surface properties

International audienceThe effects of sonication of activated sludge on heavy metal uptake were in a first time investigated in respect with potential modifications of floc surface properties. The treatment led to the simultaneous increase of specific surface area and of the availability of negative and/or hydrophilic sites. In parallel, organic matter was released in the soluble fraction. Sorption isotherms of cadmium and copper showed that uptake characteristics and mechanisms were highly dependent on both heavy metal species and specific energy supplied. The increase of both specific surface area and fixation sites availability led to the increase of Cd(II) uptake. For Cu(II), organic matter released in soluble phase during the treatment seemed to act as a ligand and to limit adsorption on flocs surface. Three different heavy metals uptake mechanisms have been identified: proton exchange, ion exchange and (co)precipitation. © 2008 Elsevier B.V. All rights reserved

Mise en oeuvre, modélisation, optimisation et contrôle d'un procédé discontinu séquentiel (SBR) (application au traitement du carbone, de l'azote, du phosphore et des matières en suspension d'eaux résiduaires urbaines)

L optimisation du traitement des eaux urbaines nécessite la mise en place de procédés fiables et un contrôle rigoureux du fonctionnement. Dans ce cadre, le procédé discontinu séquentiel SBR (sequencing Batch reactor) consistant en la succession de phases de réaction, de décantation et de purge au cours du temps est étudié. A cette fin, une méthodologie de développement fondée sur l exploitation de résultats de simulations mathématiques, d expérimentations en laboratoire, d extrapolation à pleine échelle, et de protocoles de contrôle simples mais robustes est présentée. Le simulateur de procédé de traitement de l eau ( Benchmark ) associe un modèle de traitement des eaux (ASM n1 de HENZE et coll., 1986) et un modèle de décantation (TACKACS et coll., 1991). L association de ces deux modèles permet de simuler le fonctionnement d un système d épuration à boues activées. Une étude bibliographique exhaustive a permis de dégager des scénarios de fonctionnement d un SBR susceptibles d aboutir au traitement du carbone, de l azote, du phosphore et des MES contenus dans une eau usée urbaine. Les différents cycles sont testés afin de dégager deux procédures : un cycles long et un cycle court. L utilisation du Benchmark, suite à une mise en place critique de procédures d identification des variables d entrée des modèles, est étendue à l élaboration de différentes stratégies d amélioration de l élimination de l azote. Cette étude, couplée à une étude expérimentale de la déphosphatation, a abouti à la définition d un cycle de 24 heures, améliorant les cinétiques de dénitrification et mettant en exergue les problèmes liés à la variation temporelle de la charge d entrée. Afin d y remédier, une méthode de contrôle et de fiabilisation du fonctionnement, fondée sur l utilisation conjointe de trois capteurs : pH, potentiel rédox, oxygène dissous, est présentée et mise en oeuvre à l échelle semi-industrielle.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

Impact of activated sludge flocs properties after sonication in relation with heavy metal uptake

International audienceThe effects of activated sludge sonication on floes surface properties and heavy metal uptake was investigated. Negative surface charge and specific surface area were estimated by correlation with dye adsorption whereas relative hydrophobicity was measured by adhesion to hexadecane. Experimental results show that ultrasound treatment leads to a simultaneous increase of specific surface area and availability of negatives and/or hydrophilic sites. Thus, fixation sites for heavy metal uptake are made free by sonication. Both increase of specific surface area and fixation sites availability leads to an increase of uptake of Cd(II). For Cu(II), organic matter released in soluble phase during the treatment acts as a ligand and limits adsorption on floes surface. ©Copyright by Institute of Environmental Engineering of the Polish Academy of Science, Zabrze, Poland 2008

Heavy metals biosorption on disintegrated activated sludge: Description of a new equilibrium model

International audienceDue to a high solubilization of organic matter, classical sorption models were not able to correctly describe the equilibrium of heavy metals uptake by activated sludge after disintegration processes (e.g. ultrasonic irradiation). A new semi-mechanistic model deriving from the simple Freundlich equation is developed in this study to describe metal interactions within activated sludge previously subjected to ultrasonic treatment: the equilibrium between both aqueous (complexation with soluble/colloidal organic matter released during the treatment) and particulate (sorption on sludge flocs, precipitation) metal fractions is modeled. The results of biosorption and precipitation tests were described by the new model. This allowed a better understanding of the influence of activated sludge properties (surface functional groups, structure, chemical composition) on the fate of both copper and cadmium in sonicated activated sludge

Etude comparative des digestions aérobie et anaérobie de boues biologiques urbaines traitées par procédés physique, chimique et thermique (application pour la réduction de la production de boues)

Une étude comparative de la digestion aérobie et anaérobie de boue d épuration ayant subi trois techniques de prétraitements est présentée dans le cadre de la réduction de la production de boue. Les trois techniques sont les ultrasons, des traitements thermiques et l ozonation. L efficacité globale des différents traitements et les coûts engendrés sont évalués pour démontrer leur efficacité. Les meilleurs résultats en terme de Solubilization ont été obtenus avec traitement aux ultrasons pour une énergie spécifique de 200000 kJ.kg-TSS-1 et 50W, avec oxydation à l ozone avec une dose of 0.101gO3.g-TSS-1, avec un traitement thermique à 90C pendant 60 minutes. Ce dernier permet une meilleure Solubilization de la DCO et de la DBO comparé aux traitements aux ultrasons et à l ozone. Une étude comparative de la digestion aérobie et anaérobie des boues prétraitées par les trois techniques montre que le traitement aux ultrasons amène à la réduction de boue la plus importante, avec le coût le plus faible (33% de réduction, comparé à l échantillon non traité en aérobie). De plus, le traitement aux ultrasons suivi de la digestion, qu elle soit aérobie ou anaérobie, correspond en terme de biodégradation, au plus fort taux DCO soluble, de valeurs de qCOD, d efficacité de réduction des MES et MV et de taux de biodégradabilité. Cependant, la digestion anaérobie, en raison de la récupération possible du biogaz, est économiquement et environnementalement plus intéressante que la digestion aérobie.A comparative study of aerobic and anaerobic digestion of sludge after three pretreatment techniques in the aim of enhancing sludge reduction has been proposed. The disintegration and solubilization techniques are based on mechanical (US), thermal (Bain-Marie and autoclave), and oxidative (ozonation) treatments. An evaluation of the efficiency of the global treatment and the economic aspects was performed to demonstrate their efficiency. The best solubilization results were obtained with ultrasound treatment with specific energy of 200000 kJ.kg-TSS-1 and 50W, ozonation treatment with an ozone dose of 0.101gO3.g-TSS-1 and thermal treatment at 90C duration 60 minutes. In the solubilization step, thermal treatment is more successful in solubilization of COD and BOD when compared to ultrasonic and ozonation treatments. In contrast, ultrasonic pre-treatment is more successful in solubilization of TSS, VSS and DDCOD compared to ozonation and thermal pre-treatments. A comparative study of the aerobic and anaerobic biological digestion of sludge samples pretreated by US, thermal, and ozonation pretreatments revealed that sonication led to the highest sludge production reduction and the lowest elimination expenses (33% cost reduction compared to non pretreated sample digested in aerobic digester). Moreover, in terms of biodegradation, the highest rate of soluble COD, qCOD values, TSS and VSS removal efficiency, and biodegradability (BOD5/CODS) for both conditions (aerobic and anaerobic) correspond to the digestion of sludge pretreated by ultrasonic. Anaerobic digestion, because of a potential biogas recovery, is economically and environmentally more effective than its aerobic counterpart.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF