4 research outputs found

    Couplage de la méthanisation et des électrotechnologies : intentisification de la production de biogaz et du séchage du digestat

    No full text
    The limitation of the biogas production related to the accessibility of the substrates with a low biochemical methane potential, as well as the constraints of spreading which lead to the drying of the digestate, in order to stabilize or to transport the dried digestate, are two issues for the development of the methanisation process. The cellular disintegration’s effect induced by Pulsed Electrical Field (PEF) pretreatment on biogas production is evaluated on different substrates. The applied field’s strength is varied between 500 and 3600 V/cm and the corresponding cell disintegration index were calculated. The influence of PEF pretreatment on methane production was examined in a 500 mL batch reactor using the experimental design methodology and integrating different methods of preparation (size of particles, preheating, hygenisation). The obtained results show that PEF treatment can significantly increase the biogas production (+5.2 to +12.5% CH4). For the drying of the digestates, a convective drying system with hot air at a moderate temperature (40 to 70°C) is used. On the one hand, the effects of air velocity and drying temperature are evaluated. On the other hand, the effects of pre-processing by PEF, by microwaves, and after a freeze thawing cycle were also tested. Using the second Fick's law, the effective diffusion coefficients are identified and it was concluded that PEFs are ineffective for drying the digestates under the tested drying conditions.La limitation de la production de biogaz liĂ©e aux substrats mobilisables Ă  faible potentiel mĂ©thanogĂšne et, les contraintes d’épandage qui conduisent au sĂ©chage du digestat, en vue de sa stabilisation ou de son transport, sont deux enjeux pour le dĂ©veloppement du procĂ©dĂ© de mĂ©thanisation. L’effet de la dĂ©sintĂ©gration cellulaire induite par un prĂ©traitement par Champs Électriques PulsĂ©s (CEP) sur la production de biogaz a Ă©tĂ© Ă©valuĂ© sur diffĂ©rents substrats. L’intensitĂ© de champ appliquĂ© a variĂ© entre 500 et 3600 V∙cm-1 et les indices de dĂ©sintĂ©gration cellulaire correspondants ont Ă©tĂ© calculĂ©s. L’influence du prĂ©traitement par CEP sur la production de mĂ©thane en rĂ©acteur batch de 500 mL a Ă©tĂ© Ă©tudiĂ©e en utilisant la mĂ©thodologie des plans d’expĂ©riences et en intĂ©grant diffĂ©rents modes de prĂ©paration (taille de particules, prĂ©chauffage, hygiĂ©nisation). Les rĂ©sultats obtenus montrent que le traitement CEP peut significativement intensifier la production de biogaz (+5,2 Ă  +12,5 % de CH4). Pour le sĂ©chage des digestats, un systĂšme de sĂ©chage convectif par air chaud Ă  tempĂ©rature modĂ©rĂ©e (40 Ă  70°C) a Ă©tĂ© utilisĂ©. D’une part, les effets de la vitesse d’air et de la tempĂ©rature de sĂ©chage ont Ă©tĂ© Ă©tudiĂ©s. D’autre part, les effets de prĂ©traitements par CEP, par micro-ondes, et aprĂšs un cycle de congĂ©lation/dĂ©congĂ©lation ont Ă©galement Ă©tĂ© testĂ©s. Nous avons identifiĂ©, en utilisant la seconde loi de Fick, les coefficients effectifs de diffusion et conclu Ă  l’inefficacitĂ© des CEP pour le sĂ©chage des digestats et dans les conditions de sĂ©chage testĂ©es

    Coupling of anaerobic digestion and electrotechnologies : enhancement of the biogas production and of drying of the digestate

    No full text
    La limitation de la production de biogaz liĂ©e aux substrats mobilisables Ă  faible potentiel mĂ©thanogĂšne et, les contraintes d’épandage qui conduisent au sĂ©chage du digestat, en vue de sa stabilisation ou de son transport, sont deux enjeux pour le dĂ©veloppement du procĂ©dĂ© de mĂ©thanisation. L’effet de la dĂ©sintĂ©gration cellulaire induite par un prĂ©traitement par Champs Électriques PulsĂ©s (CEP) sur la production de biogaz a Ă©tĂ© Ă©valuĂ© sur diffĂ©rents substrats. L’intensitĂ© de champ appliquĂ© a variĂ© entre 500 et 3600 V∙cm-1 et les indices de dĂ©sintĂ©gration cellulaire correspondants ont Ă©tĂ© calculĂ©s. L’influence du prĂ©traitement par CEP sur la production de mĂ©thane en rĂ©acteur batch de 500 mL a Ă©tĂ© Ă©tudiĂ©e en utilisant la mĂ©thodologie des plans d’expĂ©riences et en intĂ©grant diffĂ©rents modes de prĂ©paration (taille de particules, prĂ©chauffage, hygiĂ©nisation). Les rĂ©sultats obtenus montrent que le traitement CEP peut significativement intensifier la production de biogaz (+5,2 Ă  +12,5 % de CH4). Pour le sĂ©chage des digestats, un systĂšme de sĂ©chage convectif par air chaud Ă  tempĂ©rature modĂ©rĂ©e (40 Ă  70°C) a Ă©tĂ© utilisĂ©. D’une part, les effets de la vitesse d’air et de la tempĂ©rature de sĂ©chage ont Ă©tĂ© Ă©tudiĂ©s. D’autre part, les effets de prĂ©traitements par CEP, par micro-ondes, et aprĂšs un cycle de congĂ©lation/dĂ©congĂ©lation ont Ă©galement Ă©tĂ© testĂ©s. Nous avons identifiĂ©, en utilisant la seconde loi de Fick, les coefficients effectifs de diffusion et conclu Ă  l’inefficacitĂ© des CEP pour le sĂ©chage des digestats et dans les conditions de sĂ©chage testĂ©es.The limitation of the biogas production related to the accessibility of the substrates with a low biochemical methane potential, as well as the constraints of spreading which lead to the drying of the digestate, in order to stabilize or to transport the dried digestate, are two issues for the development of the methanisation process. The cellular disintegration’s effect induced by Pulsed Electrical Field (PEF) pretreatment on biogas production is evaluated on different substrates. The applied field’s strength is varied between 500 and 3600 V/cm and the corresponding cell disintegration index were calculated. The influence of PEF pretreatment on methane production was examined in a 500 mL batch reactor using the experimental design methodology and integrating different methods of preparation (size of particles, preheating, hygenisation). The obtained results show that PEF treatment can significantly increase the biogas production (+5.2 to +12.5% CH4). For the drying of the digestates, a convective drying system with hot air at a moderate temperature (40 to 70°C) is used. On the one hand, the effects of air velocity and drying temperature are evaluated. On the other hand, the effects of pre-processing by PEF, by microwaves, and after a freeze thawing cycle were also tested. Using the second Fick's law, the effective diffusion coefficients are identified and it was concluded that PEFs are ineffective for drying the digestates under the tested drying conditions

    Caractérisation de la matiÚre organique de biomasses résiduelles, biodéchets et déchets ménagers - Focus sur analyse thermique et biodégradabilité

    No full text
    International audienceLe dĂ©veloppement de multiples filiĂšres de gestion des dĂ©chets potentiellement biodĂ©gradables nĂ©cessite de disposer d’outils de caractĂ©risation de la matiĂšre organique. Qu’il s’agisse d’une valorisation matiĂšre (production d’amendement organique) ou d’une valorisation Ă©nergie (production de mĂ©thane par voie biologique), de nombreux tests biologiques sont mis en Ɠuvre pour caractĂ©riser ces dĂ©chets afin d’évaluer leur stabilitĂ© ou leur biodĂ©gradabilitĂ©. Cependant, les protocoles opĂ©ratoires sont souvent longs et couteux, et nĂ©cessitent le recours Ă  des tests de caractĂ©risation complĂ©mentaires visant Ă  dĂ©terminer les propriĂ©tĂ©s physico-chimiques de la matiĂšre organique. Depuis une vingtaine d’annĂ©es, les mĂ©thodes d`analyse thermique ont Ă©tĂ© testĂ©es pour vĂ©rifier si ces mĂ©thodes simples, rapides et peu couteuses permettraient d’évaluer la biorĂ©activitĂ© de biomasses. Les travaux publiĂ©s sont prometteurs mais la plupart ne concernent que la caractĂ©risation de composts, en vue d’estimer leur stabilitĂ©.Nous nous sommes intĂ©ressĂ©s Ă  la caractĂ©risation de dĂ©chets par analyse calorimĂ©trique diffĂ©rentielle couplĂ©e Ă  la thermogravimĂ©trie. Le premier objectif a Ă©tĂ© d’étudier l’effet de traitements biologiques, aĂ©robie et anaĂ©robie, sur des dĂ©chets organiques de diffĂ©rentes origines et sur leurs propriĂ©tĂ©s bio-physico-chimiques : Analyse Globale : MatiĂšre Volatile (MV), Demande Chimique en OxygĂšne (DCO), Carbone Organique Total (COT) et charge organique de la fraction dissoute (COD) ; Analyse de la matiĂšre organique : ProtĂ©ines et lipides, Indice d’Humification (ISH), fractionnement van Soest « Fraction Soluble (SF), HĂ©micellulose (HEM), Cellulose (CELL), Fraction RĂ©siduelle (RES) » ; Analyse de l`activitĂ© biologique : Demande Biologique d’OxygĂšne en 28 jours (DBO28), Potentiel BiomĂ©thanogĂšne (PBM). Une analyse en composantes principales (ACP) a permis de confronter l’ensemble des rĂ©sultats quantitatifs des analyses thermiques aux donnĂ©es bio-physico-chimiques. Cette analyse a montrĂ© de bonnes corrĂ©lations des paramĂštres thermiques avec les paramĂštres bio-physicochimiques. Ces rĂ©sultats ouvrent des perspectives sur l’utilisation des mĂ©thodes thermiques pour Ă©valuer la stabilitĂ©/biodĂ©gradabilitĂ© de dĂ©chets organiques

    Effect of thermal pretreatment at 70 degrees C for one hour (EU hygienization conditions) of various organic wastes on methane production under mesophilic anaerobic digestion

    No full text
    International audienceThe impact of hygienization as mild thermal pretreatment on the methane production of various organic wastes was investigated, including digestate issued from hydrolysis tank, thickened sludge from a municipal wastewater treatment plant (MWWTP sludge) and from a mixed domestic-industrial wastewater treatment plant (D-I WWTP sludge), sludge from a meat-processing plant (MP sludge), sieving rejection from a pork slaughterhouse, pork liver, cattle slurry, cattle scraping slurry and date seeds. They were thermally pretreated at 70 degrees C for one hour and subsequently put into AD digesters incubated at 37 degrees C for individual methane potential test. The modified Gompertz model was employed to evaluate the kinetic parameters of methane production curves (R-2 = 0.944-0.999). The results were compared with the untreated samples. Significant enhancement of methane potentials induced by thermal treatment (p < 0.05) was observed when it comes to the pork liver (+8.6%), the slaughterhouse sieving rejection (+11.1%), the thickened MWWTP sludge (+12.5%) and the digestate issued from hydrolysis tank (+18.0%). The maximum methane production rates of the 4 substrates mentioned above were increased by thermal pretreatment as well (from 13.5% to 64%, p < 0.05). The lag time of the methane production was shortened for the digestate from hydrolysis tank and the MWWTP sludge (by 48.6% and 62.2% respectively, p < 0.05). No significant enhancement was obtained for the cattle slurry, the cattle scraping slurry and the D-I WWTP sludge. Additionally, the maximum methane production rate and the methane potential were reduced by thermal pretreatment for the MP sludge and the date seeds respectively (p < 0.05). In this paper, possible mechanisms were discussed to explain the different methane production behaviors of substrates after the mild thermal pretreatment
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