70 research outputs found
Intensification de la brique « fermentation alcoolique » de substrats betteraviers pour la production d’éthanol
L’éthanol est un composé à usages très variés allant de la chimie à l’agroalimentaire. Cependant, la croissance actuelle du marché se fait essentiellement autour de l’utilisation de l’éthanol en tant que carburant. L’objectif de ce projet est d’intensifier la production d’éthanol à partir du sirop basse pureté, produit de la seconde cristallisation des jus d’extraction de betterave, afin de diminuer les consommations en énergie et en eau pour la production d’éthanol. Pour ce faire, en partenariat avec l’UNGDA et l’ADEME, nous avons mené des travaux de recherche sur les fermentations à haute densité afin d’obtenir des vins à teneur plus élevée en éthanol. A l’issu d’un état de l’art et de quatre visites dans des ateliers de production, une stratégie de recherche en trois points a été établie. Le premier point a consisté en la recherche d’une composition de milieu de fermentation permettant d’augmenter la concentration finale en éthanol. Le second point a eu pour but de déterminer si les besoins en nutriments se limitaient uniquement à la phase de croissance ou au contraire si l’apport de ces nutriments était bénéfique tout au long de la fermentation. Le dernier point a quant à lui utilisé l’ensemble des résultats obtenus pour définir une conduite de procédé, permettant d’obtenir la concentration finale en éthanol la plus élevée possible. Ces résultats montrent qu’il est possible de réaliser des fermentations haute densité à partir de sirop basse pureté et d’obtenir 15,2 % (v/v) d’éthanol en fin de fermentation. L’application de ces travaux dans les ateliers de production permettrait d’économiser par litre d’éthanol pur, entre 20 et 30 % d’énergie pour la distillation, entre 35 et 49 % d’eau pour la réalisation des milieux de fermentation à partir de SBP et de diminuer de 23 à 38 % le volume de déchet produit après distillation. Ethanol is a compound with a wide usage range from chemistry to food. However, the current market growth mainly concerns the use of ethanol as fuel. The objective of this project was to intensify ethanol production from low purity syrup 2, which is a substrate from sugar beet, in order to reduce the consumptions of energy and water for its production. To do this, in partnership with UNGDA and ADEME, we have conducted research on high-gravity fermentations in order to increase the ethanol concentration at the end of the fermentation. With the coming of a state of the art and four visits in production facilities, a three points research strategy has been established. The first point consisted of fermentation medium composition finding in order to increase the final ethanol concentration at the end of the fermentation. The second point was to determine if the nutrients requirements were limited only during the growth phase or, on the contrary, if nutriments were beneficial throughout the fermentation. The latter point was to use the overall results to define a fermentation process, to obtain a final ethanol concentration as high as possible. These results show that it is possible to achieve high gravity fermentation from low purity syrup and reach a final ethanol concentration of 15.2 % (v/v). The application of this work in production facilities could save per liter of pure ethanol between 20 and 30% energy for distillation, between 35 and 49 % water for the production of fermentation media from SBP and decrease from 23 to 38 % of the volume of waste produced after distillation
Intensification de la brique « fermentation alcoolique » de substrats betteraviers (et autres substrats) pour la production d’éthanol
L'éthanol est un composé à usages très variés allant de la chimie à l'agroalimentaire. Cependant, la croissance actuelle du marché se fait essentiellement autour de l'utilisation de l'éthanol en tant que carburant. L'objectif de ce projet est d'intensifier la production d'éthanol à partir du sirop basse pureté, produit de la seconde cristallisation des jus d'extraction de betterave, afin de diminuer les consommations en énergie et en eau pour la production d'éthanol. Pour ce faire, en partenariat avec l'UNGDA et l'ADEME, nous avons mené des travaux de recherche sur les fermentations à haute densité afin d'obtenir des vins à teneur plus élevée en éthanol. A l'issu d'un état de l'art et de quatre visites dans des ateliers de production, une stratégie de recherche en trois points a été établie. Le premier point a consisté en la recherche d'une composition de milieu de fermentation permettant d'augmenter la concentration finale en éthanol. Le second point a eu pour but de déterminer si les besoins en nutriments se limitaient uniquement à la phase de croissance ou au contraire si l'apport de ces nutriments était bénéfique tout au long de la fermentation. Le dernier point a quant à lui utilisé l'ensemble des résultats obtenus pour définir une conduite de procédé, permettant d'obtenir la concentration finale en éthanol la plus élevée possible. Ces résultats montrent qu'il est possible de réaliser des fermentations haute densité à partir de sirop basse pureté et d'obtenir 15,2 % (v/v) d'éthanol en fin de fermentation. L'application de ces travaux dans les ateliers de production permettrait d'économiser par litre d'éthanol pur, entre 20 et 30 % d'énergie pour la distillation, entre 35 et 49 % d'eau pour la réalisation des milieux de fermentation à partir de SBP et de diminuer de 23 à 38 % le volume de déchet produit après distillation. ABSTRACT : Ethanol is a compound with a wide usage range from chemistry to food. However, the current market growth mainly concerns the use of ethanol as fuel. The objective of this project was to intensify ethanol production from low purity syrup 2, which is a substrate from sugar beet, in order to reduce the consumptions of energy and water for its production. To do this, in partnership with UNGDA and ADEME, we have conducted research on high-gravity fermentations in order to increase the ethanol concentration at the end of the fermentation. With the coming of a state of the art and four visits in production facilities, a three points research strategy has been established. The first point consisted of fermentation medium composition finding in order to increase the final ethanol concentration at the end of the fermentation. The second point was to determine if the nutrients requirements were limited only during the growth phase or, on the contrary, if nutriments were beneficial throughout the fermentation. The latter point was to use the overall results to define a fermentation process, to obtain a final ethanol concentration as high as possible. These results show that it is possible to achieve high gravity fermentation from low purity syrup and reach a final ethanol concentration of 15.2 % (v/v). The application of this work in production facilities could save per liter of pure ethanol between 20 and 30% energy for distillation, between 35 and 49 % water for the production of fermentation media from SBP and decrease from 23 to 38 % of the volume of waste produced after distillation
Electrochemical reduction of CO2 catalysed by Geobacter sulfurreducens grown on polarized stainless steel cathodes
Polarized stainless steel cathodes in pure cultures of Geobacter sulfurreducens generated reduction currents of up to 30 A/m2 even when the sole electron acceptor contained in solution was completely reduced. It was shown here that these currents were driven by the carbon dioxide that was provided to the solution. It was postulated that CO2 reduction consumed succinate and produced glycerol, which remained stored inside the cells and was released under the effect of stress
Testing Models of Intrinsic Brightness Variations in Type Ia Supernovae, and their Impact on Measuring Cosmological Parameters
For spectroscopically confirmed Type Ia supernovae we evaluate models of
intrinsic brightness variations with detailed data/Monte Carlo comparisons of
the dispersion in the following quantities: Hubble-diagram scatter, color
difference (B-V-c) between the true B-V color and the fitted color (c) from the
SALT-II light curve model, and photometric redshift residual. The data sample
includes 251 ugriz light curves from the 3-season Sloan Digital Sky Survey-II,
and 191 griz light curves from the Supernova Legacy Survey 3-year data release.
We find that the simplest model of a wavelength-independent (coherent) scatter
is not adequate, and that to describe the data the intrinsic scatter model must
have wavelength-dependent variations. We use Monte Carlo simulations to examine
the standard approach of adding a coherent scatter term in quadrature to the
distance-modulus uncertainty in order to bring the reduced chi2 to unity when
fitting a Hubble diagram. If the light curve fits include model uncertainties
with the correct wavelength dependence of the scatter, we find that the bias on
the dark energy equation of state parameter is negligible. However,
incorrect model uncertainties can lead to a significant bias on the distance
moduli, with up to ~0.05 mag redshift-dependent variation. For the recent SNLS3
cosmology results we estimate that this effect introduces an additional
systematic uncertainty on of ~0.02, well below the total uncertainty.
However, this uncertainty depends on the samples used, and thus this small
-uncertainty is not guaranteed in future cosmology results.Comment: accepted by Ap
Intensification de la brique fermentation alcoolique de substrats betteraviers (et autres substrats) pour la production d'éthanol
L'éthanol est un composé à usages très variés allant de la chimie à l'agroalimentaire. Cependant, la croissance actuelle du marché se fait essentiellement autour de l'utilisation de l'éthanol en tant que carburant. L'objectif de ce projet est d'intensifier la production d'éthanol à partir du sirop basse pureté, produit de la seconde cristallisation des jus d'extraction de betterave, afin de diminuer les consommations en énergie et en eau pour la production d'éthanol. Pour ce faire, en partenariat avec l'UNGDA et l'ADEME, nous avons mené des travaux de recherche sur les fermentations à haute densité afin d'obtenir des vins à teneur plus élevée en éthanol. A l'issu d'un état de l'art et de quatre visites dans des ateliers de production, une stratégie de recherche en trois points a été établie. Le premier point a consisté en la recherche d'une composition de milieu de fermentation permettant d'augmenter la concentration finale en éthanol. Le second point a eu pour but de déterminer si les besoins en nutriments se limitaient uniquement à la phase de croissance ou au contraire si l'apport de ces nutriments était bénéfique tout au long de la fermentation. Le dernier point a quant à lui utilisé l'ensemble des résultats obtenus pour définir une conduite de procédé, permettant d'obtenir la concentration finale en éthanol la plus élevée possible. Ces résultats montrent qu'il est possible de réaliser des fermentations haute densité à partir de sirop basse pureté et d'obtenir 15,2 % (v/v) d'éthanol en fin de fermentation. L'application de ces travaux dans les ateliers de production permettrait d'économiser par litre d'éthanol pur, entre 20 et 30 % d'énergie pour la distillation, entre 35 et 49 % d'eau pour la réalisation des milieux de fermentation à partir de SBP et de diminuer de 23 à 38 % le volume de déchet produit après distillation.Ethanol is a compound with a wide usage range from chemistry to food. However, the current market growth mainly concerns the use of ethanol as fuel. The objective of this project was to intensify ethanol production from low purity syrup 2, which is a substrate from sugar beet, in order to reduce the consumptions of energy and water for its production. To do this, in partnership with UNGDA and ADEME, we have conducted research on high-gravity fermentations in order to increase the ethanol concentration at the end of the fermentation. With the coming of a state of the art and four visits in production facilities, a three points research strategy has been established. The first point consisted of fermentation medium composition finding in order to increase the final ethanol concentration at the end of the fermentation. The second point was to determine if the nutrients requirements were limited only during the growth phase or, on the contrary, if nutriments were beneficial throughout the fermentation. The latter point was to use the overall results to define a fermentation process, to obtain a final ethanol concentration as high as possible. These results show that it is possible to achieve high gravity fermentation from low purity syrup and reach a final ethanol concentration of 15.2 % (v/v). The application of this work in production facilities could save per liter of pure ethanol between 20 and 30% energy for distillation, between 35 and 49 % water for the production of fermentation media from SBP and decrease from 23 to 38 % of the volume of waste produced after distillation.TOULOUSE-INP (315552154) / SudocSudocFranceF
Optimization of very high gravity fermentation process for ethanol production from industrial sugar beet syrup
In order to reduce production costs and environmental impact of bioethanol from sugar beet low purity syrup 2, an intensification of the industrial alcoholic fermentation carried out by Saccharomyces cerevisiae is necessary. Two fermentation processes were tested: multi-stage batch and fed-batch fermentations with different operating conditions. It was established that the fed-batch process was the most efficient to reach the highest ethanol concentration. This process allowed to minimize both growth and ethanol production inhibitions by high sugar concentrations or ethanol. Thus, a good management of the operating conditions (initial volume and feeding rate) could produce 15.2% (v/v) ethanol in 53 h without residual sucrose and with an ethanol productivity of 2.3 g L h−1
Combining phosphate species and stainless steel cathode to enhance hydrogen evolution in microbial electrolysis cell (MEC)
Microbial electrolysis cells (MEC) must work around neutral pH because of microbial catalysis at the anode. To develop a hydrogen evolution cathode that can work at neutral pH remains a major challenge in MEC technology. Voltammetry performed at pH 8.0 on rotating disk electrodes showed that the presence of phosphate species straightforwardly multiplied the current density of hydrogen evolution, through the so-called cathodic deprotonation reaction. The mechanism was stable on stainless steel cathodes whereas it rapidly vanished on platinum. The phosphate/stainless steel system implemented in a 25 L MEC with a marine microbial anode led to hydrogen evolution rates of up to 4.9 L/h/m2 under 0.8 V voltage, which were of the same order than the best performance values reported so far.
Keywords: Hydrogen; Microbial electrolysis cell (MEC); Stainless steel; Phosphat
Cosmological parameters from large scale structure - geometric versus shape information
The matter power spectrum as derived from large scale structure (LSS) surveys
contains two important and distinct pieces of information: an overall smooth
shape and the imprint of baryon acoustic oscillations (BAO). We investigate the
separate impact of these two types of information on cosmological parameter
estimation, and show that for the simplest cosmological models, the broad-band
shape information currently contained in the SDSS DR7 halo power spectrum (HPS)
is by far superseded by geometric information derived from the baryonic
features. An immediate corollary is that contrary to popular beliefs, the upper
limit on the neutrino mass m_\nu presently derived from LSS combined with
cosmic microwave background (CMB) data does not in fact arise from the possible
small-scale power suppression due to neutrino free-streaming, if we limit the
model framework to minimal LambdaCDM+m_\nu. However, in more complicated
models, such as those extended with extra light degrees of freedom and a dark
energy equation of state parameter w differing from -1, shape information
becomes crucial for the resolution of parameter degeneracies. This conclusion
will remain true even when data from the Planck surveyor become available. In
the course of our analysis, we introduce a new dewiggling procedure that allows
us to extend consistently the use of the SDSS HPS to models with an arbitrary
sound horizon at decoupling. All the cases considered here are compatible with
the conservative 95%-bounds \sum m_\nu < 1.16 eV, N_eff = 4.8 \pm 2.0.Comment: 18 pages, 4 figures; v2: references added, matches published versio
Merger Histories in Warm Dark Matter Structure Formation Scenario
Observations on galactic scales seem to be in contradiction with recent high
resolution N-body simulations. This so-called cold dark matter (CDM) crisis has
been addressed in several ways, ranging from a change in fundamental physics by
introducing self-interacting cold dark matter particles to a tuning of complex
astrophysical processes such as global and/or local feedback. All these efforts
attempt to soften density profiles and reduce the abundance of satellites in
simulated galaxy halos. In this paper, we explore a somewhat different approach
which consists of filtering the dark matter power spectrum on small scales,
thereby altering the formation history of low mass objects. The physical
motivation for damping these fluctuations lies in the possibility that the dark
matter particles have a different nature i.e. are warm (WDM) rather than cold.
We show that this leads to some interesting new results in terms of the merger
history and large-scale distribution of low mass halos, as compared to the
standard CDM scenario. However, WDM does not appear to be the ultimate
solution, in the sense that it is not able to fully solve the CDM crisis, even
though one of the main drawbacks, namely the abundance of satellites, can be
remedied. Indeed, the cuspiness of the halo profiles still persists, at all
redshifts, and for all halos and sub-halos that we investigated. Despite the
persistence of the cuspiness problem of DM halos, WDM seems to be still worth
taking seriously, as it alleviates the problems of overabundant sub-structures
in galactic halos and possibly the lack of angular momentum of simulated disk
galaxies. WDM also lessens the need to invoke strong feedback to solve these
problems, and may provide a natural explanation of the clustering properties
and ages of dwarfs.Comment: 11 pages, 17 figures, MNRAS submitted, high-res figures can be found
at http://www-thphys.physics.ox.ac.uk/users/AlexanderKnebe/publications.html,
replaced with accepted version (warmon masses corrected!
Single-field inflation constraints from CMB and SDSS data
We present constraints on canonical single-field inflation derived from WMAP
five year, ACBAR, QUAD, BICEP data combined with the halo power spectrum from
SDSS LRG7. Models with a non-scale-invariant spectrum and a red tilt n_s < 1
are now preferred over the Harrison-Zel'dovich model (n_s = 1, tensor-to-scalar
ratio r = 0) at high significance. Assuming no running of the spectral indices,
we derive constraints on the parameters (n_s, r) and compare our results with
the predictions of simple inflationary models. The marginalised credible
intervals read n_s = 0.962^{+0.028}_{-0.026} and r < 0.17 (at 95% confidence
level). Interestingly, the 68% c.l. contours favour mainly models with a convex
potential in the observable region, but the quadratic potential model remains
inside the 95% c.l. contours. We demonstrate that these results are robust to
changes in the datasets considered and in the theoretical assumptions made. We
then consider a non-vanishing running of the spectral indices by employing
different methods, non-parametric but approximate, or parametric but exact.
With our combination of CMB and LSS data, running models are preferred over
power-law models only by a Delta chi^2 ~ 5.8, allowing inflationary stages
producing a sizable negative running -0.063^{+0.061}_{-0.049} and larger
tensor-scalar ratio r < 0.33 at the 95% c.l. This requires large values of the
third derivative of the inflaton potential within the observable range. We
derive bounds on this derivative under the assumption that the inflaton
potential can be approximated as a third order polynomial within the observable
range.Comment: 32 pages, 7 figures. v2: additional references, some typos corrected,
passed to JCAP style. v3: minor changes, matches published versio
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