19 research outputs found
Modélisation du procédé bioréacteur à membranes immergées : calage et validation du modÚle ASM1 sur un site réel : étude des interactions boues activées, conditions opératoires et membrane
Les biorĂ©acteurs Ă membranes (BAM) sont de plus en plus utilisĂ©s dans le domaine du traitement des eaux rĂ©siduaires urbaines notamment lorsque le terrain est limitĂ© ou quâun traitement Ă©puratoire poussĂ© est requis. NĂ©anmoins, la gestion de ces installations et plus particuliĂšrement du colmatage des membranes reste difficile et constitue toujours une source de problĂšmes pour les exploitants. La modĂ©lisation est un outil efficace et dĂ©jĂ Ă©prouvĂ© sur les procĂ©dĂ©s conventionnels Ă boues activĂ©es pour lâaide Ă la conduite et Ă la comprĂ©hension de procĂ©dĂ© avec les modĂšles de boues activĂ©es de type ASM. Le traitement biologique donc, et aussi les capacitĂ©s de filtration des membranes (colmatage) sont deux aspects qui peuvent ĂȘtre modĂ©lisĂ©s sur les BAM. Au cours de ce travail, trois installations rĂ©elles ont Ă©tĂ© Ă©tudiĂ©es et lâune dâentre elles a Ă©tĂ© choisie pour le calage du modĂšle ASM1. La mĂ©thodologie a Ă©tĂ© adaptĂ©e aux spĂ©cificitĂ©s des biorĂ©acteurs Ă membranes et de lâinstallation modĂ©lisĂ©e en particulier (fractionnement des eaux usĂ©es, calage de lâaĂ©ration) et un nouveau jeu de paramĂštres de lâASM1 a pu ĂȘtre constituĂ©. Lâinfluence des propriĂ©tĂ©s des boues activĂ©es et des conditions dâopĂ©ration sur les capacitĂ©s de filtration des membranes reste encore lâobjet de nombreuses recherches, gĂ©nĂ©ralement sur installations pilotes, et la modĂ©lisation dans ce domaine nâen est quâĂ ses dĂ©buts. Lâobjectif de ce travail concernant la filtration membranaire a Ă©tĂ© de caractĂ©riser le systĂšme « membrane/boues » Ă travers lâĂ©tude des interactions entre les propriĂ©tĂ©s des boues, les conditions dâopĂ©ration et les paramĂštres de la filtration (permĂ©abilitĂ© membranaire et vitesse de colmatage) Ă comparer avec les rĂ©sultats de la littĂ©rature scientifique. Les deux BAM Ă©tudiĂ©s ont montrĂ© des comportements et relations entre paramĂštres assez diffĂ©rents confirmant la complexitĂ© des interactions entre membrane, boues et conditions opĂ©ratoires.Membrane bioreactors (MBRs) are becoming increasingly popular for the treatment of municipal wastewater especially when land is limited or when the treatment requirements are high. Nevertheless, the operation of these plants and in particular the fouling of the membrane are still difficult to manage for the operators. Modelling is an efficient tool, which has already been successfully used on conventional activated sludge processes, for the operation and the understanding of the process using Activated Sludge Models (ASM). Biological treatment and membranes filtration capacity (fouling) are two aspects that can be modeled on MBRs. In this work, three full-scale plants were investigated and one of them was chosen for the ASM1 calibration. The usual methodology was adapted to the MBR specificities and to the modeled wastewater treatment plant in particular (wastewater fractionation, oxygen calibration) and a new set of ASM1 parameters was estimated. The influence of the sludge properties and the operating conditions on the membrane filtration capacity is still the subject of numerous studies, generally on pilot-scale MBRs, and modelling is in its early stages. The objective of this work regarding membrane filtration was to characterize the âmembrane/sludgeâ system by studying the interactions between the sludge properties, the operating conditions and the filtration parameters (membrane permeability and fouling rate) and to compare them with the results from the literature. The two studied MBRs showed quite different behaviors and correlations between parameters, validating the statement that the interactions between membranes, sludge and operating conditions are very complex
Algal Biomass: From Bioproducts to Biofuels
Microalgae covers an extremely diverse type of unicellular microorganisms that use light and efficiently fix CO2 through the process of photosynthesis [...
Modélisation du procédé bioréacteur à membranes immergées (calage et validation du modÚle ASM1 sur un site réel)
Les biorĂ©acteurs Ă membranes (BAM) sont de plus en plus utilisĂ©s dans le domaine du traitement des eaux rĂ©siduaires urbaines notamment lorsque le terrain est limitĂ© ou qu un traitement Ă©puratoire poussĂ© est requis. NĂ©anmoins, la gestion de ces installations et plus particuliĂšrement du colmatage des membranes reste difficile et constitue toujours une source de problĂšmes pour les exploitants. La modĂ©lisation est un outil efficace et dĂ©jĂ Ă©prouvĂ© sur les procĂ©dĂ©s conventionnels Ă boues activĂ©es pour l aide Ă la conduite et Ă la comprĂ©hension de procĂ©dĂ© avec les modĂšles de boues activĂ©es de type ASM. Le traitement biologique donc, et aussi les capacitĂ©s de filtration des membranes (colmatage) sont deux aspects qui peuvent ĂȘtre modĂ©lisĂ©s sur les BAM. Au cours de ce travail, trois installations rĂ©elles ont Ă©tĂ© Ă©tudiĂ©es et l une d entre elles a Ă©tĂ© choisie pour le calage du modĂšle ASM1. La mĂ©thodologie a Ă©tĂ© adaptĂ©e aux spĂ©cificitĂ©s des biorĂ©acteurs Ă membranes et de l installation modĂ©lisĂ©e en particulier (fractionnement des eaux usĂ©es, calage de l aĂ©ration) et un nouveau jeu de paramĂštres de l ASM1 a pu ĂȘtre constituĂ©. L influence des propriĂ©tĂ©s des boues activĂ©es et des conditions d opĂ©ration sur les capacitĂ©s de filtration des membranes reste encore l objet de nombreuses recherches, gĂ©nĂ©ralement sur installations pilotes, et la modĂ©lisation dans ce domaine n en est qu Ă ses dĂ©buts. L objectif de ce travail concernant la filtration membranaire a Ă©tĂ© de caractĂ©riser le systĂšme membrane/boues Ă travers l Ă©tude des interactions entre les propriĂ©tĂ©s des boues, les conditions d opĂ©ration et les paramĂštres de la filtration (permĂ©abilitĂ© membranaire et vitesse de colmatage) Ă comparer avec les rĂ©sultats de la littĂ©rature scientifique. Les deux BAM Ă©tudiĂ©s ont montrĂ© des comportements et relations entre paramĂštres assez diffĂ©rents confirmant la complexitĂ© des interactions entre membrane, boues et conditions opĂ©ratoires.Membrane bioreactors (MBRs) are becoming increasingly popular for the treatment of municipal wastewater especially when land is limited or when the treatment requirements are high. Nevertheless, the operation of these plants and in particular the fouling of the membrane are still difficult to manage for the operators. Modelling is an efficient tool, which has already been successfully used on conventional activated sludge processes, for the operation and the understanding of the process using Activated Sludge Models (ASM). Biological treatment and membranes filtration capacity (fouling) are two aspects that can be modeled on MBRs. In this work, three full-scale plants were investigated and one of them was chosen for the ASM1 calibration. The usual methodology was adapted to the MBR specificities and to the modeled wastewater treatment plant in particular (wastewater fractionation, oxygen calibration) and a new set of ASM1 parameters was estimated. The influence of the sludge properties and the operating conditions on the membrane filtration capacity is still the subject of numerous studies, generally on pilot-scale MBRs, and modelling is in its early stages. The objective of this work regarding membrane filtration was to characterize the membrane/sludge system by studying the interactions between the sludge properties, the operating conditions and the filtration parameters (membrane permeability and fouling rate) and to compare them with the results from the literature. The two studied MBRs showed quite different behaviors and correlations between parameters, validating the statement that the interactions between membranes, sludge and operating conditions are very complex.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF
Liquefaction, cracking and hydrogenation of microalgae biomass resources to â«â« negative advanced biofuels
Deoxygenation of triglycerides is one of the crucial pathways for the production of oxygen-free hydrocarbons and biofuels that are fully compatible with conventional internal combustion engines. The one-step liquefaction and hydrotreatment of Chlorella sorokiniana microalgae was investigated in a three-phase slurry reactor. The production of diesel-like hydrocarbons was successfully accomplished over sulfide form of NiMo/Al2O3 catalyst under hydrogen atmosphere. The present work contains a comprehensive investigation of the temperature and hydrogen pressure influence on the final product composition. The highest yield of C18 and C16 (26.1% and 10.7%, respectively) was reached by increasing the reaction temperature to 350 °C and hydrogen pressure to 50 bar, while at milder conditions (200 °C and 20 bar) the products appeared only in trace concentrations. In order to obtain an accurate kinetic model, reaction mechanism was first needed to be determined based on experimentally obtained products and intermediates. A simplified reaction pathway contains liquefaction, hydrogenolysis, hydrodeoxygenation, decarboxylation and decarbonylation. The model comprises mass transfer phenomena involved in the liquefaction process, the mass transfer of hydrogen from gas to liquid phase, adsorption, desorption and surface reaction kinetics. The lowest rate constant was calculated for the microalgae conversion to triglycerides (k0 = 1.93 Ă 10â6 minâ1), indicating slow liquefaction
DĂ©veloppement dâune mĂ©thode LC x SFC MS/MS hors ligne pour lâanalyse de phytostĂ©rols issus des microalgues
National audienc
Développement d'une méthode LC x SFC -MS/MS hors ligne pour l'analyse de phytostérols issus des microalgues
National audienceLes microalgues sont des organismes unicellulaires qui possĂšdent une croissance rapide. De ce fait, ces organismes photosynthĂ©tiques sont une source durable de biocarburants. Les microalgues ont aussi la particularitĂ© de pouvoir produire des substances industriellement intĂ©ressantes utilisĂ©es en mĂ©decine, en cosmĂ©tique ou comme complĂ©ments alimentaires pour lutter contre la malnutrition.Lâutilisation de microalgues cultivĂ©es par lâindustrie neutraceutique permet lâaccĂšs Ă de nouvelles sources de lipides bioactifs notamment Ă des phytostĂ©rols peu prĂ©sents dans les plantes terrestres. Chez lâHomme, les aliments riches en phytostĂ©rols participent Ă la rĂ©gulation du taux de cholestĂ©rol grĂące Ă une structure biochimique trĂšs proche, ainsi quâĂ la fabrication de nombreuses hormones comme les hormones stĂ©roĂŻdes et la vitamine D.Les phytostĂ©rols sont des composĂ©s analogues qui se diffĂ©rencient uniquement par le nombre et la position dâinsaturations dans le cycle ou sur la chaine latĂ©rale. Cette grande similitude structurelle avec un certain nombre dâisomĂšres de position rend la sĂ©paration et lâidentification relativement difficile. La chromatographie bidimensionnelle LC x SFC prĂ©sente un grand degrĂ© dâorthogonalitĂ© adaptĂ©e aux molĂ©cules neutres, et une sĂ©lectivitĂ© suffisante pour sĂ©parer des isomĂšres de position. Le couplage en mode hors ligne de ces deux dimensions chromatographiques permet la mise en Ćuvre de la spectromĂ©trie de masse haute rĂ©solution avec fragmentation (MS/MS). Le dĂ©veloppement chromatographique a Ă©tĂ© rĂ©alisĂ© sur un mĂ©lange de 7 phytosterols reprĂ©sentatifs du monde algal (campestĂ©rol, fucostĂ©rol, α-spinastĂ©rol, stigmastĂ©rol, cholestĂ©rol, sitostĂ©rol et ergostĂ©rol) ainsi que 2 de leurs prĂ©curseurs (farnĂ©sol et phytol). Puis la mĂ©thode bidimensionnelle LC x SFC - MS/MS a Ă©tĂ© appliquĂ©e sur des extraits dâalgues prĂ©alablement saponifiĂ©s. Les rĂ©sultats, prĂ©sentĂ©s sous forme de cartographies 2D-contour plot, permettent la comparaison des compositions en phytostĂ©rols recherchĂ©s dans diffĂ©rentes espĂšces de microalgues. La LC x SFC dĂ©montre sa capacitĂ© Ă sĂ©parer des isomĂšres de position, notamment dans le cas oĂč ceux-ci fragmentent de maniĂšre similaire en MS/MS. La combinaison de 4 informations par molĂ©cule (2 temps de rĂ©tention, masse et spectre de fragmentation) permet de confirmer la prĂ©sence de molĂ©cules cibles, tout en facilitant la recherche de structures de phytostĂ©rols algaux encore inconnus
The challenge of measuring biofuel sustainability: A stakeholder-driven approach applied to the French case
International audienceMeasuring biofuel sustainability requires dealing with a wide variety of complex and conflicting values at stake. Consequently, the biofuel capacity to contribute to one specific value cannot lead to any absolute conclusion about the overall sustainability of biofuel. The scope of the sustainability concept may vary depending on individuals' preferences, the time scale and the geographical region. Based on the 5 pillars sustainability concept that includes social, economic, environmental, legal and cultural considerations, the present study proposes to assess several biofuel sustainability options for France by 2030 through a stakeholder-driven approach. Rather than seeking to reach a consensus, our approach allows us to capture the wide diversity of stakeholders' perspectives and preferences. French stakeholders perceive 22 different sustainability criteria for biofuels with a very low level of agreement between the different segments of professions (feedstock producers, biofuel producers, refining industry, fuel distributors, car manufacturers, end-users, government and NGOs). In order to operationalize the sustainability assessment, a set of indicators has been identified with stakeholders that allows us to measure the capacity of biofuels to fulfill each of their criteria. Seventeen biofuel options were assessed with regards to economic, social, environmental, cultural and legal considerations, allowing the identification of the strengths and weaknesses of each biofuel
The Environmental Biorefinery: Using Microalgae to Remediate Wastewater, a Win-Win Paradigm
Microalgae have been shown to be a source of multiple bio-based products ranging from high value molecules to commodities. Along with their potential to produce a large variety of products, microalgae can also be used for the depollution of wastewaters of different origins (urban, industrial, and agricultural). This paper is focused on the importance of harnessing the bioremediation capacity of microalgae to treat wastewaters in order to develop the microalgae industry (especially the microalgae biofuel industry) and to find other alternatives to the classic wastewater treatment processes. The current research on the potential of microalgae to treat a specific wastewater or a targeted pollutant is reviewed and discussed. Then, both strategies of selecting the best microalgae strain to treat a specific wastewater or pollutant and using a natural or an artificial consortium to perform the treatment will be detailed. The process options for treating wastewaters using microalgae will be discussed up to the final valorization of the biomass. The last part is dedicated to the challenges which research need to address in order to develop the potential of microalgae to treat wastewaters
Photosynthetic Carbon Uptake Correlates with Cell Protein Content during Lipid Accumulation in the Microalga Chlorella vulgaris NIES 227
Large-scale microalgae cultivation for biofuel production is currently limited by the possibility of maintaining high microalgae yield and high lipid content, concomitantly. In this study, the physiological changes of Chlorella vulgaris NIES 227 during lipid accumulation under nutrient limitation was monitored in parallel with the photosynthetic capacity of the microalgae to fix carbon from the proxy of oxygen productivity. In the exponential growth phase, as the biomass composition did not vary significantly (approx. 53.6 ± 7.8% protein, 6.64 ± 3.73% total lipids, and 26.0 ± 9.2% total carbohydrates of the total biomass dry-weight), the growth capacity of the microalgae was preserved (with net O2 productivity remaining above (4.44 ± 0.93) × 10−7 g O2·µmol PAR−1). Under nutrient limitation, protein content decreased (minimum of approx. 18.6 ± 6.0%), and lipid content increased (lipid content up to 56.0 ± 0.8%). The physiological change of the microalgae was associated with a loss of photosynthetic activity, down to a minimum (1.27 ± 0.26) × 10−7 g O2·µmol PAR−1. The decrease in photosynthetic O2 productivity was evidenced to correlate to the cell internal-protein content (R2 = 0.632, p = 2.04 × 10−6, N = 25). This approach could serve to develop productivity models, with the aim of optimizing industrial processes
Microalgae starch-based bioplastics: Screening of ten strains and plasticization of unfractionated microalgae by extrusion
International audienceMicroalgae were considered in this work as a new resource for developing starch-based bioplastics. Ten green microalgae strains were screened at lab-scale for their ability to produce starch. A long run (800 h) two-stage accumulation strategy was designed with successive cultivation in sulfur-replete, then sulfur-depleted medium in autotrophic conditions. Starch content was assessed on cell lysate by enzymatic digestion of extracted starch into glucose. Chlamydomonas reinhardtii 11-32A strain was selected as it displayed a maximum starch-to-biomass ratio of 49% w/w, 460 h after being switched to a sulfur-deprived medium. Small-scale pilot production (30 L tubular photobioreactor) with C. reinhardtii 11-32A yielded sufficient biomass quantity to investigate its direct plasticization with glycerol in a twin-screw extruder. Microstructural characterization confirmed the ability for starch-enriched microalgae to be homogeneously plasticized, and hence the possibility to use microalgae as a new platform for the development of bioplastics