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Extrusion is a widely used process in the industry to produce foods with specific technological properties (color, texture, aroma, etc.). Its use dates back to the 1950s, mainly in extrusion cooking. Extrusion cooking is considered as a thermoplastic process, whose treatment is done at high temperature and with a short residence time. The mechanical action combined with the high temperature allows the modification of the internal structure of the matrix introduced and therefore its properties. Two types of extruders can be used, with different performance and capabilities, single-screw extruders, and twin-screw extruders. The mechanical treatment of the extruders can be carried out directly in the dry process, or by addition of solvents, and in this context, it is the twin-screw extrusion that is preferred. The twin-screw extruder is a tool that allows to work continuously in many different conditions, which has favored its use in very different fields such as the paper or the chemical industry. It is an instrument increasingly studied in the context of the biorefinery, since it allows the treatment of both green plants, such as alfalfa, and dry residues such as cakes or straw.

International audience; Extrusion is a widely used process in the industry to produce foods with specific technological properties (color, texture, aroma, etc.). Its use dates back to the 1950s, mainly in extrusion cooking. Extrusion cooking is considered as a thermoplastic process, whose treatment is done at high temperature and with a short residence time. The mechanical action combined with the high temperature allows the modification of the internal structure of the matrix introduced and therefore its properties. Two types of extruders can be used, with different performance and capabilities, single-screw extruders, and twin-screw extruders. The mechanical treatment of the extruders can be carried out directly in the dry process, or by addition of solvents, and in this context, it is the twin-screw extrusion that is preferred. The twin-screw extruder is a tool that allows to work continuously in many different conditions, which has favored its use in very different fields such as the paper or the chemical industry. It is an instrument increasingly studied in the context of the biorefinery, since it allows the treatment of both green plants, such as alfalfa, and dry residues such as cakes or straw..

International audience; Extrusion is a widely used process in the industry to produce foods with specific technological properties (color, texture, aroma, etc.). Its use dates back to the 1950s, mainly in extrusion cooking. Extrusion cooking is considered as a thermoplastic process, whose treatment is done at high temperature and with a short residence time. The mechanical action combined with the high temperature allows the modification of the internal structure of the matrix introduced and therefore its properties. Two types of extruders can be used, with different performance and capabilities, single-screw extruders, and twin-screw extruders. The mechanical treatment of the extruders can be carried out directly in the dry process, or by addition of solvents, and in this context, it is the twin-screw extrusion that is preferred. The twin-screw extruder is a tool that allows to work continuously in many different conditions, which has favored its use in very different fields such as the paper or the chemical industry. It is an instrument increasingly studied in the context of the biorefinery, since it allows the treatment of both green plants, such as alfalfa, and dry residues such as cakes or straw.

International audience; Extrusion is a widely used process in the industry to produce foods with specific technological properties (color, texture, aroma, etc.). Its use dates back to the 1950s, mainly in extrusion cooking. Extrusion cooking is considered as a thermoplastic process, whose treatment is done at high temperature and with a short residence time. The mechanical action combined with the high temperature allows the modification of the internal structure of the matrix introduced and therefore its properties. Two types of extruders can be used, with different performance and capabilities, single-screw extruders, and twin-screw extruders. The mechanical treatment of the extruders can be carried out directly in the dry process, or by addition of solvents, and in this context, it is the twin-screw extrusion that is preferred. The twin-screw extruder is a tool that allows to work continuously in many different conditions, which has favored its use in very different fields such as the paper or the chemical industry. It is an instrument increasingly studied in the context of the biorefinery, since it allows the treatment of both green plants, such as alfalfa, and dry residues such as cakes or straw.

Bioconversion to methane lignocellulosic biomass is one of the most promising alternatives for the production of methane from anaerobic digestion. However, lignocellulosic biomass has various bio-physicochemical characteristics due to their biochemical composition and diverse structural organization. Moreover, their low biodegradability in anaerobic condition requires pretreatment before methanation to optimize methane production. This work aims to evaluate the influence of the characteristics of a wide range of lignocellulosic substrates on their anaerobic biodegradability and correlations between their bio-physical-chemical characteristics and biomethane potential, and study the effects of fungal pretreatment in the presence of Ceriporiopsis subvermispora on the biogas potential of lignocellulosic biomass selected in this study and characterize their changes of their characteristics before and after the fungal pretreatment. The characterization of 36 representative lignocellulosic biomass of a wide range of potentially mobilized deposits allowed to highlight the linear correlations between biomethane potential of biomass and some of their bio-physical-chemical characteristics, of which the lignin content and biochemical oxygen demand. The forest and agricultural biomass exhibited distinct characteristics of the aerobic and anaerobic biodegradability. The results of fungal pretreatment of the 5 biomass indicated that the white rot fungus Ceriporiopsis subvermispora reacts distinctly depending on the pretreated biomass. For some biomass, fungal pretreatment leads to significant increase of methane production and the bioconversion rate of methane. This species presents the ability to selectively degrade lignin on some biomasses, in others, the ability to non-selectively degrade polysaccharides and lignins. In addition, for both strains of Ceriporiopsis subvermispora tested, different metabolisms were highlighted on the same biomass. The results of compositions and those of the structural analysis of biomass (initials, autoclaved, controls, and pretreated with Ceriporiopsis subvermispora) showed that their structure can be modified without observing a significant transformation of their biochemical composition., La bioconversion en méthane de biomasses lignocellulosiques est l’une des alternatives les plus prometteuses pour la production de méthane issu de la digestion anaérobie. Toutefois, les biomasses lignocellulosiques présentent des caractéristiques bio-physico-chimiques très variables en raison leur composition biochimique et de l’organisation structurale très diverses. Par ailleurs, leur faible biodégradabilité en conditions anaérobie nécessite de les prétraiter avant méthanisation pour optimiser la production de méthane. Ce travail vise à évaluer l’influence des caractéristiques d’une large gamme de substrats lignocellulosiques sur leur biodégradabilité anaérobie et les corrélations entre leurs caractéristiques bio-physico-chimiques et le potentiel biométhanogène, et d’étudier les effets du prétraitement fongique en présence de Ceriporiopsis subvermispora sur le potentiel biométhanogène de biomasses lignocellulosiques sélectionnées dans la présente étude et de caractériser les changements de leurs caractéristiques après le prétraitement fongique. La caractérisation de 36 biomasses lignocellulosiques représentatives d’une large gamme de gisements potentiellement mobilisables a permis de mettre en évidence les corrélations linéaires entre le potentiel biométhanogène des biomasses et certaines de leur caractéristiques bio-physico-chimiques, dont la teneur en lignine et la demande biochimique en oxygène. Les biomasses sylvicoles et agricoles ont montré des caractéristiques distinctes de la biodégradabilité aérobie et anaérobie. Les résultats de prétraitement fongique sur les 5 biomasses ont permis de mettre en évidence que le champignon de pourriture blanche Ceriporiopsis subvermispora réagit distinctement selon la biomasse prétraitée. Pour certaines biomasses, le prétraitement fongique conduit à augmenter significativement la production de méthane et la vitesse de bioconversion en méthane. Cette espèce présente la capacité de dégrader sélectivement la lignine sur certaines biomasses et, sur d’autres, celle de dégrader de manière non-sélective des polysaccharides et des lignines. De plus, pour les deux souches de Ceriporiopsis subvermispora testées, des métabolismes différents ont été mis en évidence sur une même biomasse. Les résultats de compositions et ceux de l’analyse structurale des biomasses (initiales, autoclavées, contrôles, et prétraitées par Ceriporiopsis subvermispora) ont montré que leur structure peut être modifiée sans toutefois observer une transformation significative de leur composition biochimique.

Bioconversion to methane lignocellulosic biomass is one of the most promising alternatives for the production of methane from anaerobic digestion. However, lignocellulosic biomass has various bio-physicochemical characteristics due to their biochemical composition and diverse structural organization. Moreover, their low biodegradability in anaerobic condition requires pretreatment before methanation to optimize methane production. This work aims to evaluate the influence of the characteristics of a wide range of lignocellulosic substrates on their anaerobic biodegradability and correlations between their bio-physical-chemical characteristics and biomethane potential, and study the effects of fungal pretreatment in the presence of Ceriporiopsis subvermispora on the biogas potential of lignocellulosic biomass selected in this study and characterize their changes of their characteristics before and after the fungal pretreatment. The characterization of 36 representative lignocellulosic biomass of a wide range of potentially mobilized deposits allowed to highlight the linear correlations between biomethane potential of biomass and some of their bio-physical-chemical characteristics, of which the lignin content and biochemical oxygen demand. The forest and agricultural biomass exhibited distinct characteristics of the aerobic and anaerobic biodegradability. The results of fungal pretreatment of the 5 biomass indicated that the white rot fungus Ceriporiopsis subvermispora reacts distinctly depending on the pretreated biomass. For some biomass, fungal pretreatment leads to significant increase of methane production and the bioconversion rate of methane. This species presents the ability to selectively degrade lignin on some biomasses, in others, the ability to non-selectively degrade polysaccharides and lignins. In addition, for both strains of Ceriporiopsis subvermispora tested, different metabolisms were highlighted on the same biomass. The results of compositions and those of the structural analysis of biomass (initials, autoclaved, controls, and pretreated with Ceriporiopsis subvermispora) showed that their structure can be modified without observing a significant transformation of their biochemical composition., La bioconversion en méthane de biomasses lignocellulosiques est l’une des alternatives les plus prometteuses pour la production de méthane issu de la digestion anaérobie. Toutefois, les biomasses lignocellulosiques présentent des caractéristiques bio-physico-chimiques très variables en raison leur composition biochimique et de l’organisation structurale très diverses. Par ailleurs, leur faible biodégradabilité en conditions anaérobie nécessite de les prétraiter avant méthanisation pour optimiser la production de méthane. Ce travail vise à évaluer l’influence des caractéristiques d’une large gamme de substrats lignocellulosiques sur leur biodégradabilité anaérobie et les corrélations entre leurs caractéristiques bio-physico-chimiques et le potentiel biométhanogène, et d’étudier les effets du prétraitement fongique en présence de Ceriporiopsis subvermispora sur le potentiel biométhanogène de biomasses lignocellulosiques sélectionnées dans la présente étude et de caractériser les changements de leurs caractéristiques après le prétraitement fongique. La caractérisation de 36 biomasses lignocellulosiques représentatives d’une large gamme de gisements potentiellement mobilisables a permis de mettre en évidence les corrélations linéaires entre le potentiel biométhanogène des biomasses et certaines de leur caractéristiques bio-physico-chimiques, dont la teneur en lignine et la demande biochimique en oxygène. Les biomasses sylvicoles et agricoles ont montré des caractéristiques distinctes de la biodégradabilité aérobie et anaérobie. Les résultats de prétraitement fongique sur les 5 biomasses ont permis de mettre en évidence que le champignon de pourriture blanche Ceriporiopsis subvermispora réagit distinctement selon la biomasse prétraitée. Pour certaines biomasses, le prétraitement fongique conduit à augmenter significativement la production de méthane et la vitesse de bioconversion en méthane. Cette espèce présente la capacité de dégrader sélectivement la lignine sur certaines biomasses et, sur d’autres, celle de dégrader de manière non-sélective des polysaccharides et des lignines. De plus, pour les deux souches de Ceriporiopsis subvermispora testées, des métabolismes différents ont été mis en évidence sur une même biomasse. Les résultats de compositions et ceux de l’analyse structurale des biomasses (initiales, autoclavées, contrôles, et prétraitées par Ceriporiopsis subvermispora) ont montré que leur structure peut être modifiée sans toutefois observer une transformation significative de leur composition biochimique.

In this study, the effect of total solid content (TS) on thermophilic hydrogen production from wheat straw was investigated. Six TS contents ranging from wet to dry conditions (10–34% TS) were tested in batch tests. A decrease of H 2 yields was observed and three statistical groups were distinguished according to the TS content: wet conditions (10% and 14% TS) with 15.3 ± 1.6 NmlH 2 g TS −1 , intermediate conditions (19% TS) with 6.4 ± 1.0 NmlH 2 g TS −1 and dry conditions (25–34% TS) with 3.4 ± 0.8 NmlH 2 g TS −1 . Such a decrease in biohydrogen yields was related to a metabolic shift with an accumulation of lactic acid under dry conditions. Concomitantly, a microbial population shift was observed with a dominance of species related to the class Clostridia under wet conditions, and a co-dominance of members of Bacilli , Clostridia classes and Bacteroidetes phylum under dry conditions.

International audience; Anaerobic digestion (AD) of lignocellulosic residues, such as cereal straws, depends on many factors that influence substrate characteristics, particularly its biochemical composition, and thus biogas production: straw variety, growing stage, storage conditions, etc. However, impacts of straw morphological fractions on AD have never been evaluated. For the first time, the anaerobic degradation of five different fractions of wheat straw (internodes, leaves, nodes, chaffs and rachis) was evaluated. The results indicate that these fractions present strong and significant differences in terms of ash content, organic matter, soluble phase and fibers distribution. Based on their biomethane potential, it is possible to classify these fractions into three categories: stem structures (internodes and nodes) with a methane potential of 141 +/- 14 N mL g(VS)(-1), ear structures (chaffs and rachis) with 186 +/- 4 N mL g(VS)(-1) and leaves with 242 +/- 7 N mL g(VS)(-1). However, similar and low biohydrogen potential was found for every fraction (around 10 +/- 2 N mL g(VS)(-1)). These results show that selection of straws with higher contents of leaves, rachis and chaffs could significantly increase methane potential, while biohydrogen production would require pretreatment steps. The study suggests to investigate on optimization of the wheat straw variety or harvesting methods as a low cost approach to increase methane potential of agricultural residues.

Biogas processes, containing low water content, present many economical and practical advantages: low energy consumption, high loading rate, low digestate post treatments... These observations led to the development at large scale of the solid-state anaerobic digestion of lignocellulosic residues, such as wheat straw. However, the digester optimization is currently limited by a lack of fundamental knowledge. The aim of this thesis is to better optimize the process degradation taking into account the effects of process parameters on the interaction between the substrate and the micro-organisms. Original strategies and innovative analytic tools were developed to allow a precise study of dry media. Results showed that water content is the main parameter that controls the process, while its start-up depends on the quantity of micro-organisms. Moreover, despite a higher risk of process failure, fine milling of the lignocellulosic residues is recommended to improve the microbial action.; Les procédés de production de biogaz à faibles teneurs en eau présentent de nombreux avantages économiques et pratiques : consommations énergétiques réduites, fortes charges d’alimentation, peu de post-traitements des digestats… Ce constat a permis de développer à grande échelle la digestion par voie sèche des résidus lignocellulosiques, tels que les pailles de céréales. Cependant, l’optimisation de ces digesteurs est actuellement limitée par un manque de connaissances fondamentales. L’objectif de cette thèse est d’optimiser le processus de dégradation par la prise en compte de l’effet des paramètres de procédés sur les interactions entre le substrat et les micro-organismes. Des stratégies originales et des outils d’analyses innovants ont été développés pour permettre une étude précise des milieux secs. Les résultats montrent que la teneur en eau est le paramètre principal pour contrôler le procédé, tandis que le démarrage dépend de la quantité de micro-organismes. De plus, malgré un risque accru de dysfonctionnement du procédé lorsque les substrats sont broyés finement, ce prétraitement est recommandé pour faciliter l’action microbienne.