Corrosion behavior of carbon steel in presence of sulfate-reducing bacteria in seawater environment

The influence of sulfate-reducing bacteria (SRB)on the corrosion behavior of carbon steel was studiedin a laboratory test-loop, continuously fed with nutrient supplemented North Sea seawater. The mainparts of the test-loop, represented by two separated flow cells, were fitted with steel specimens. The test-loop was operating anoxically for 2200 h and each flow cell was three times inoculated with Desulfovibrioalaskensis or Desulfovibrio desulfuricans species. Additionally, each flow cell was two times perturbed with antimicrobial treatments. Steel specimens exposed in flow cells exhibited comparable appearance andsystems responding similarly to inoculations and antimicrobial treatments. The effect of the inoculations in both flow cells on the steel coupons electrochemical behavior was materialized as lower resistanceto corrosion and higher surface activity or occurrence of localized pitting events. The localized surfaceattacks recognized in both flow cells after inoculations continued to progress with the time, althoughbacterial activity was temporarily suppressed by antimicrobial treatment. Post-exposure sample evalu-ations might suggest that, some particular steel surface areas have been subjected to a dramatic change in the corrosion mechanism from initial localized attack to general corrosion. The long-term exposureof the carbon steel specimens resulted in identifiable formation of biofilms and corrosion products. Cor-rosion deposits were characterized by a specific structure built of iron sulfides (FeS), sulfated green rust(GR(SO42−)), magnetite (Fe3O4), Fe(III) oxyhydroxides (FeOOH), chukanovite (Fe2(OH)2CO3), carbonatedgreen rust (GR(CO32−)) and some calcareous deposits. Presented factual evidence reinforced the idea thatsulfidogenic species in natural seawater environment may cause localized damage with a specific surfacepattern; however, this does not necessarily lead towards significantly elevated corrosion rates

Corrosion of carbon steel by bacteria from North Sea offshore seawater injection systems: Laboratory investigation

Influence of sulfidogenic bacteria, from a North Sea seawater injection system, on the corrosion of S235JR carbon steel was studied in a flow bioreactor; operating anaerobically for 100 days with either inoculated or filtrated seawater. Deposits formed on steel placed in reactors contained magnesium and calcium minerals plus iron sulfide. The dominant biofilm-forming organism was an anaerobic bacterium, genus Caminicella, known to produce hydrogen sulfide and carbon dioxide. Open Circuit Potentials (OCP) of steel in the reactors was, for nearly the entire test duration, in the range − 800 45), suggested pitting on steel samples within the inoculated environment. However, the actual degree of corrosion could neither be directly correlated with the electrochemical data and nor with the steel corrosion in the filtrated seawater environment. Further laboratory tests are thought to clarify the noticed apparent discrepancies

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Geomicrobiological reactivity of iron materials : impact on geological disposal of radioactive wastes

Cette thèse s'est attachée à décrire le concept dynamique d'une activité microbiologique viable et durable en conditions de stockage géologique profond et à évaluer son impact sur les propriétés de confinement et les composants du stockage. Ainsi, dans cette étude, un modèle bactérien basé sur la ferriréduction a été choisi pour ses critères de viabilité dans le système et sa capacité à altérer les matériaux dans les conditions du stockage. Les principaux résultats de ce travail de thèse ont permis de démontrer la capacité du milieu à supporter l'activité bactérienne ferriréductrice et les conditions de son développement dans les environnements argileux profonds. Il a été clairement montré la biodisponibilité du Fe(III) structural des matériaux argileux et des oxydes de fer produits lors des processus de corrosion métallique. Dans ce système, la corrosion paraît être un facteur positif pour les activités bactériennes notamment en produisant une source énergétique, l'hydrogène. Les activités bactériennes ferriréductrices peuvent entraîner une reprise de la corrosion métallique via la consommation des oxydes de fer de la couche passivante. La conséquence directe pourrait être une diminution de la durée de vie des enveloppes métalliques de colisage. Dans le cas des matériaux argileux ferrifères, les conséquences d'une telle activité sont telles qu'elles peuvent avoir un impact sur l'ensemble de l'édifice poreux que ce soit en termes de réactivité chimique des matériaux ou de comportement physique de la barrière argileuse. Un des résultats les plus marquants est la cristallisation de nouvelles phases argileuses à des températures très basses, inférieures à 40°C, témoignant de l'influence considérable de l'activité microbienne anaérobie dans les transformations minéralogiques des minéraux argileux. De plus, il faut noter que ces expériences ont permis de visualiser pour la première fois un mécanisme de respiration bactérienne à distance via une extension de la disponibilité d'éléments essentiels, ici le Fe3+. En conclusion, ces résultats ont clairement démontré l'impact du facteur microbiologique sur la réactivité des matériaux argileux et métalliques tout en s'appuyant sur des paramètres de contrôle de l'activité bactérienne. La pertinence de la prise en compte de ces activités microbiologiques dans le cas des évaluations de sûreté d'un stockage est ainsi établie.This thesis sought to describe the dynamic concept of a viable and sustainable microbiological activity under deep geological disposal conditions and to assess its impact on containment properties and storage components. Thus, in this study, a model based on the bacterial ferric reduction was chosen for its sustainability criteria in the system and its ability to alter the materials in storage conditions. The main results of this work demonstrated the capability of the environment to stand the iron-reducing bacterial activity and the conditions of its development in the deep clay environments. The bio-availability of structural Fe (III) in clay minerals and iron oxides produced during the process of metal corrosion was clearly demonstrated. In this system, the corrosion appears to be a positive factor on bacterial activities by producing an energy source, hydrogen. The iron-reducing bacterial activities can lead to a resumption of metallic corrosion through the consumption of iron oxides in the passive film. The direct consequence would be a reduction of the lifetime of metal containers. In the case of ferric clay minerals, the consequences of such an activity are such that they can have an impact on the overall porous structure both in terms of chemical reactivity of the materials or physical behavior of the clayey barrier. One of the most significant results is the crystallization of new clay phases at very low temperatures, below 40°C, highlighting the influence of the anaerobic microbial activity in the mineralogical transformations of clay minerals. Furthermore, these experiments also allowed to visualize, for the first time, a mechanism of bacterial respiration at distance, this increases the field of the availability of essential elements as Fe3+ for bacterial growth in extreme environment. In conclusion, these results clearly showed the impact of the microbiological factor on the reactivity of clay and metal minerals, while relying on control parameters on bacterial activity. The relevance of taking into account these microbiological activities in the case of safety assessments of a repository is then established

Réactivité géomicrobiologique des matériaux et minéraux ferrifères : impact sur la sureté d'un stockage de déchets radioactifs en milieux argileux

This thesis sought to describe the dynamic concept of a viable and sustainable microbiological activity under deep geological disposal conditions and to assess its impact on containment properties and storage components. Thus, in this study, a model based on the bacterial ferric reduction was chosen for its sustainability criteria in the system and its ability to alter the materials in storage conditions. The main results of this work demonstrated the capability of the environment to stand the iron-reducing bacterial activity and the conditions of its development in the deep clay environments. The bio-availability of structural Fe (III) in clay minerals and iron oxides produced during the process of metal corrosion was clearly demonstrated. In this system, the corrosion appears to be a positive factor on bacterial activities by producing an energy source, hydrogen. The iron-reducing bacterial activities can lead to a resumption of metallic corrosion through the consumption of iron oxides in the passive film. The direct consequence would be a reduction of the lifetime of metal containers. In the case of ferric clay minerals, the consequences of such an activity are such that they can have an impact on the overall porous structure both in terms of chemical reactivity of the materials or physical behavior of the clayey barrier. One of the most significant results is the crystallization of new clay phases at very low temperatures, below 40°C, highlighting the influence of the anaerobic microbial activity in the mineralogical transformations of clay minerals. Furthermore, these experiments also allowed to visualize, for the first time, a mechanism of bacterial respiration at distance, this increases the field of the availability of essential elements as Fe3+ for bacterial growth in extreme environment. In conclusion, these results clearly showed the impact of the microbiological factor on the reactivity of clay and metal minerals, while relying on control parameters on bacterial activity. The relevance of taking into account these microbiological activities in the case of safety assessments of a repository is then established.Cette thèse s'est attachée à décrire le concept dynamique d'une activité microbiologique viable et durable en conditions de stockage géologique profond et à évaluer son impact sur les propriétés de confinement et les composants du stockage. Ainsi, dans cette étude, un modèle bactérien basé sur la ferriréduction a été choisi pour ses critères de viabilité dans le système et sa capacité à altérer les matériaux dans les conditions du stockage. Les principaux résultats de ce travail de thèse ont permis de démontrer la capacité du milieu à supporter l'activité bactérienne ferriréductrice et les conditions de son développement dans les environnements argileux profonds. Il a été clairement montré la biodisponibilité du Fe(III) structural des matériaux argileux et des oxydes de fer produits lors des processus de corrosion métallique. Dans ce système, la corrosion paraît être un facteur positif pour les activités bactériennes notamment en produisant une source énergétique, l'hydrogène. Les activités bactériennes ferriréductrices peuvent entraîner une reprise de la corrosion métallique via la consommation des oxydes de fer de la couche passivante. La conséquence directe pourrait être une diminution de la durée de vie des enveloppes métalliques de colisage. Dans le cas des matériaux argileux ferrifères, les conséquences d'une telle activité sont telles qu'elles peuvent avoir un impact sur l'ensemble de l'édifice poreux que ce soit en termes de réactivité chimique des matériaux ou de comportement physique de la barrière argileuse. Un des résultats les plus marquants est la cristallisation de nouvelles phases argileuses à des températures très basses, inférieures à 40°C, témoignant de l'influence considérable de l'activité microbienne anaérobie dans les transformations minéralogiques des minéraux argileux. De plus, il faut noter que ces expériences ont permis de visualiser pour la première fois un mécanisme de respiration bactérienne à distance via une extension de la disponibilité d'éléments essentiels, ici le Fe3+. En conclusion, ces résultats ont clairement démontré l'impact du facteur microbiologique sur la réactivité des matériaux argileux et métalliques tout en s'appuyant sur des paramètres de contrôle de l'activité bactérienne. La pertinence de la prise en compte de ces activités microbiologiques dans le cas des évaluations de sûreté d'un stockage est ainsi établie

Assessment of microbiological development in nuclear waste geological disposal: a geochemical modeling approach peer-review under responsibility of Organizing and Scientific Committee of WRI 14 -2013

International audienceDeep geological environments are very often poor or devoid of biodegradable organic molecules, but hydrogen could be an efficient energetic source to replace organic matter and promote redox processes such as reduction of O 2 , NO 3-, Fe 3+ , SO 4 2-and CO 2. Moreover, the accessibility and availability of H 2 and nutrients depend on gas/liquid permeability and their migration in the claystone porosity through the excavation damaged zone (EDZ). This study evaluates the spatial and temporal evolution of the geochemical conditions with regard to microbial development. The corrosion process in the argillite is investigated using numerical modeling over a period of 100,000 years. The development of bacterial biomass is estimated using potential redox reactions catalyzed by microorganisms and available nutrients. The simulations show that after the thermal peak (ca. 100-1000 years), physico-chemical conditions are favourable to support bacterial life. Relevant amounts of H 2 and nutrients are released and migrate over the first 2 m of the argillite. Most of the biological redox process are localised close to the container where a high amount of magnetite is produced, providing Fe(III) (electron acceptor) that favours the development of iron-reducing bacteria (IRB)

Impact of microbial activity on the radioactive waste disposal: long term prediction of biocorrosion processes

International audienceThis study emphasizes different experimental approaches and provides perspectives to apprehend biocorrosionphenomena in the specific disposal environment by investigating microbial activity with regard to themodification of corrosion rate, which in turn can have an impact on the safety of radioactive waste geologicaldisposal.It is found that iron-reducing bacteria are able to use corrosion products such as iron oxides and “dihydrogen” asnew energy sources, especially in the disposal environment which contains low amounts of organic matter.Moreover, in the case of sulphate-reducing bacteria, the results show that mixed aerobic and anaerobicconditions are the most hazardous for stainless steel materials, a situation which is likely to occur in the earlystage of a geological disposal. Finally, an integrated methodological approach is applied to validate theunderstanding of the complex processes and to design experiments aiming at the acquisition of kinetic dataused in long term predictive modelling of biocorrosion processes

Challenges for quality and utilization of real-world data for diffuse large B-cell lymphoma in REALYSA, a LYSA cohort

International audienceReal-world data (RWD) are essential to complement clinical trial (CT) data, but major challenges remain, such as data quality. REal world dAta in LYmphoma and Survival in Adults (REALYSA) is a prospective noninterventional multicentric cohort started in 2018 that included patients newly diagnosed with lymphoma in France. Herein is a proof-of-concept analysis on patients with first-line diffuse large B-cell lymphoma (DLBCL) to (1) evaluate the capacity of the cohort to provide robust data through a multistep validation process; (2) assess the consistency of the results; and (3) conduct an exploratory transportability assessment of 2 recent phase 3 CTs (POLARIX and SENIOR). The analysis population comprised 645 patients with DLBCL included before 31 March 2021 who received immunochemotherapy and for whom 3589 queries were generated, resulting in high data completeness (<4% missing data). Median age was 66 years, with mostly advanced-stage disease and high international prognostic index (IPI) score. Treatments were mostly rituximab, cyclophosphamide, doxorubicin hydrochloride, vincristine, and prednisone (R-CHOP 75%) and reduced dose R-CHOP (13%). Estimated 1-year event-free survival (EFS) and overall survival rates were 77.9% and 90.0%, respectively (median follow-up, 9.9 months). Regarding transportability, when applying the CT's main inclusion criteria (age, performance status, and IPI), outcomes seemed comparable between patients in REALYSA and standard arms of POLARIX (1-year progression-free survival 79.8% vs 79.8%) and SENIOR (1-year EFS, 64.5% vs 60.0%). With its rigorous data validation process, REALYSA provides high-quality RWD, thus constituting a platform for numerous scientific purposes. The REALYSA study was registered at www.clinicaltrials.gov as #NCT03869619