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Air gasification of Solid Recovered Fuels (SRF) from wood, tire, plastics and sewage sludge has been performed in a pilot fixed bed reactor. As wastes contain pollutants precursors, it is of great interest regarding technical and environmental aspects to study their behavior in air gasification. Five fuels have been studied: Poplar, SRF wood, and three different mixtures of SRF wood and 20% of either tire (mix A), or plastics (mix B) or sewage sludge (mix C). After confirming their capacity of substituting raw wood in order to produce synthetic gas (syngas), emissions analyses have been performed on syngas, condensable matter and remaining char. A focus on sulfur, nitrogen and heavy metals brought to light differences and similarities between different SRF and raw wood. Proceedings of the 26th European Biomass Conference and Exhibition, 14-17 May 2018, Copenhagen, Denmark, pp. 478-485

Air gasification of Solid Recovered Fuels (SRF) from wood, tire, plastics and sewage sludge has been performed in a pilot fixed bed reactor. As wastes contain pollutants precursors, it is of great interest regarding technical and environmental aspects to study their behavior in air gasification. Five fuels have been studied: Poplar, SRF wood, and three different mixtures of SRF wood and 20% of either tire (mix A), or plastics (mix B) or sewage sludge (mix C). After confirming their capacity of substituting raw wood in order to produce synthetic gas (syngas), emissions analyses have been performed on syngas, condensable matter and remaining char. A focus on sulfur, nitrogen and heavy metals brought to light differences and similarities between different SRF and raw wood. Proceedings of the 26th European Biomass Conference and Exhibition, 14-17 May 2018, Copenhagen, Denmark, pp. 478-485

La biomasse est une source d’énergie renouvelable qui peut contribuer de manière significative à la réduction de la consommation de combustibles fossiles. L’utilisation de déchets agricoles ou agro-industriels tels que les grignons d’olives est particulièrement pertinente. La gazéification est une technique prometteuse de valorisation énergétique des déchets pour ce type de résidus lignocellulosiques. La technologie est cependant adaptée à un panel relativement limité de combustibles solides ayant des spécifications définies, qui doivent donc être caractérisées correctement. Le but de cette étude était d’analyser et de comparer des grignons d’olives de 3 origines différentes par des techniques complémentaires telles que la spectroscopie infrarouge à transformer de Fourier, la thermogravimétrie couplée à l’analyse calorimétrique différentielle et la pyrolyse suivie d’une chromatographie en phase gazeuse / spectrométrie de masse (Py-CG/SM). Les résultats soulignent la nature complexe des grignons qui sont principalement organiques. En plus des principaux composés organiques (cellulose, hémicelluloses et lignine), la présence de plusieurs constituants organiques mineurs a été montrée. La Py-CG/SM a montré que le gaz produit par pyrolyse contient plusieurs produits de dégradation de la matière lignocellulosique et de l’huile d’olive. L’influence du procédé d’extraction de l’huile d’olive (à deux phases ou à trois phases) a également été mise en évidence. La dégradation thermochimique des grignons suit un mécanisme complexe mais la composition des grignons répond à la plupart des spécifications requises par la gazéification. Biomass is a renewable energy source that can make a significant contribution to reducing fossil fuels consumption. The use of agricultural or agro-industrial waste such as olive mill solid residues is particularly relevant. Gasification is a promising waste-to-energy technique for this type of lignocellulosic residues. The technology however is adapted to a relatively limited panel of solid waste fuels of defined specifications, which must therefore be characterized properly. The purpose of this study was to analyze and compare olive mill solid residues from 3 different origins by complementary techniques such as Fourier transform infrared spectroscopy, thermogravimetry coupled to differential scanning calorimetry and analytical pyrolysis combined with gas chromatography/mass spectrometry (Py-CG/SM). The results underlined the complex nature of the residues, which are mainly organic. In addition to the major compounds (cellulose, hemicelluloses and lignin), the presence of several minor organic constituents was shown. Py-CG/SM showed that the gas produced by pyrolysis contains several degradation products of lignocellulosic material and olive oil. The influence of the olive oil extraction process (two-phase or three-phase) was also highlighted. The thermochemical degradation of olive mill residues follows a complex pathway but the composition of the residues meets most of the requirements parameters for gasification.

La biomasse est une source d’énergie renouvelable qui peut contribuer de manière significative à la réduction de la consommation de combustibles fossiles. L’utilisation de déchets agricoles ou agro-industriels tels que les grignons d’olives est particulièrement pertinente. La gazéification est une technique prometteuse de valorisation énergétique des déchets pour ce type de résidus lignocellulosiques. La technologie est cependant adaptée à un panel relativement limité de combustibles solides ayant des spécifications définies, qui doivent donc être caractérisées correctement. Le but de cette étude était d’analyser et de comparer des grignons d’olives de 3 origines différentes par des techniques complémentaires telles que la spectroscopie infrarouge à transformer de Fourier, la thermogravimétrie couplée à l’analyse calorimétrique différentielle et la pyrolyse suivie d’une chromatographie en phase gazeuse / spectrométrie de masse (Py-CG/SM). Les résultats soulignent la nature complexe des grignons qui sont principalement organiques. En plus des principaux composés organiques (cellulose, hémicelluloses et lignine), la présence de plusieurs constituants organiques mineurs a été montrée. La Py-CG/SM a montré que le gaz produit par pyrolyse contient plusieurs produits de dégradation de la matière lignocellulosique et de l’huile d’olive. L’influence du procédé d’extraction de l’huile d’olive (à deux phases ou à trois phases) a également été mise en évidence. La dégradation thermochimique des grignons suit un mécanisme complexe mais la composition des grignons répond à la plupart des spécifications requises par la gazéification. Biomass is a renewable energy source that can make a significant contribution to reducing fossil fuels consumption. The use of agricultural or agro-industrial waste such as olive mill solid residues is particularly relevant. Gasification is a promising waste-to-energy technique for this type of lignocellulosic residues. The technology however is adapted to a relatively limited panel of solid waste fuels of defined specifications, which must therefore be characterized properly. The purpose of this study was to analyze and compare olive mill solid residues from 3 different origins by complementary techniques such as Fourier transform infrared spectroscopy, thermogravimetry coupled to differential scanning calorimetry and analytical pyrolysis combined with gas chromatography/mass spectrometry (Py-CG/SM). The results underlined the complex nature of the residues, which are mainly organic. In addition to the major compounds (cellulose, hemicelluloses and lignin), the presence of several minor organic constituents was shown. Py-CG/SM showed that the gas produced by pyrolysis contains several degradation products of lignocellulosic material and olive oil. The influence of the olive oil extraction process (two-phase or three-phase) was also highlighted. The thermochemical degradation of olive mill residues follows a complex pathway but the composition of the residues meets most of the requirements parameters for gasification.

AbstractClimate change can alter peatland plant community composition by promoting the growth of vascular plants. How such vegetation change affects peatland carbon dynamics remains, however, unclear. In order to assess the effect of vegetation change on carbon uptake and release, we performed a vascular plant‐removal experiment in two Sphagnum‐dominated peatlands that represent contrasting stages of natural vegetation succession along a climatic gradient. Periodic measurements of net ecosystem CO2 exchange revealed that vascular plants play a crucial role in assuring the potential for net carbon uptake, particularly with a warmer climate. The presence of vascular plants, however, also increased ecosystem respiration, and by using the seasonal variation of respired CO2 radiocarbon (bomb‐14C) signature we demonstrate an enhanced heterotrophic decomposition of peat carbon due to rhizosphere priming. The observed rhizosphere priming of peat carbon decomposition was matched by more advanced humification of dissolved organic matter, which remained apparent beyond the plant growing season. Our results underline the relevance of rhizosphere priming in peatlands, especially when assessing the future carbon sink function of peatlands undergoing a shift in vegetation community composition in association with climate change.

AbstractClimate change can alter peatland plant community composition by promoting the growth of vascular plants. How such vegetation change affects peatland carbon dynamics remains, however, unclear. In order to assess the effect of vegetation change on carbon uptake and release, we performed a vascular plant‐removal experiment in two Sphagnum‐dominated peatlands that represent contrasting stages of natural vegetation succession along a climatic gradient. Periodic measurements of net ecosystem CO2 exchange revealed that vascular plants play a crucial role in assuring the potential for net carbon uptake, particularly with a warmer climate. The presence of vascular plants, however, also increased ecosystem respiration, and by using the seasonal variation of respired CO2 radiocarbon (bomb‐14C) signature we demonstrate an enhanced heterotrophic decomposition of peat carbon due to rhizosphere priming. The observed rhizosphere priming of peat carbon decomposition was matched by more advanced humification of dissolved organic matter, which remained apparent beyond the plant growing season. Our results underline the relevance of rhizosphere priming in peatlands, especially when assessing the future carbon sink function of peatlands undergoing a shift in vegetation community composition in association with climate change.