6 research outputs found
Valorisation de la mélasse de caroube par une approche bioraffinerie
This PhD thesis deals with the valorization of the solid waste generated by the Lebanese carob molasse process with the aim to produce bioenergy or high added-value platform molecules. The chemical analysis of this waste has highlighted that it contains 45% (w/w) sugars, which can be used as a substrate for alcoholic or lactic fermentation, the production of biohydrogen by dark fermentation, or as a carbon source for the growth of microalgae in a phycoremediation process (water treatment process based on algae/microalgae) for the removal of pharmaceutical micropollutants. Experimental results have shown that high ethanol yield and productivity could be achieved through alcoholic fermentation in the liquid phase using extracts from carob waste as the substrate, provided the culture medium was enriched by complementary nutrients (especially a nitro-gen source) to enhance the growth of the yeast Saccharomyces cerevisiae; in parallel, the direct production of ethanol from the solid waste based on solid-state fermentation was also proved to be efficient, provided humidity was accurately controlled. In addition, lactic fermentation per-formed with immobilized Lactobacillus rhamnosus on alginate beads was shown to constitute a potential alternative to bioethanol for the extracts from carob waste. An enriched culture medium was, however, necessary, together with the use of an invertase enzyme as a pretreatment so as to maximize the yield and the productivity of lactic acid. Using microorganism immobilization lead to the opportunity to recycle at least five times alginate beads in successive culture cycles. Another potential alternative to the above-mentioned valorization pathways was proved to lie in the dark fermentation process for biohydrogen production, directly using the solid waste. While attractive yields were reached, a strong dependence on the particle size from grinding pretreatment was emphasized, as in solid-state fermentation; moreover, iron supplementation in the culture medium was compulsory, in addition to nitrogen supplementation already described when fermentation was carried out in the liquid phase. Finally, when the carob waste was used as a substrate for the growth of the algae Ankistrodesmus braunii in a phycoremediation process, a removal yield of the initial diclofenac content about 90% could be reached under mixotrophic conditions, even though only one third of the diclofenac removed was effectively metabolized.Cette thĂšse de doctorat porte sur la valorisation du dĂ©chet solide issu de la prĂ©paration de la mĂ©lasse de caroube libanaise pour la production de bioĂ©nergie et de molĂ©cules Ă valeur ajoutĂ©e. Lâanalyse de la composition de ce dĂ©chet a montrĂ© quâil contient 45 % (g/g) de sucres, substrats exploitables pour la fermentation alcoolique ou lactique, la production de biohydrogĂšne, ou comme source de carbone pour la croissance dâune algue dans un procĂ©dĂ© de phycoremĂ©diation (traitement des eaux par les algues) pour lâĂ©limination de micropolluants pharmaceutiques. Les rĂ©sultats obtenus ont montrĂ© que la fermentation alcoolique en phase liquide Ă partir dâextraits de dĂ©chet de caroube peut conduire Ă des rendements Ă©levĂ©s en bioĂ©thanol sous rĂ©serve dâenrichir le milieu de culture par les Ă©lĂ©ments nĂ©cessaires pour la croissance de la levure Saccharomyces cerevisiae (en particulier lâazote), tandis quâil est possible de produire directement le bioĂ©thanol sur le dĂ©chet par fermentation en milieu solide sous rĂ©serve de contrĂŽler prĂ©cisĂ©ment lâhumiditĂ©. Nous avons Ă©galement dĂ©montrĂ© que la fermentation lactique par immobilisation de Lactobacillus rhamnosus sur des billes dâalginate constitue une alternative possible au bioĂ©thanol pour les sucres extraits du dĂ©chet. Cependant, un enrichissement du milieu de culture, ainsi que lâutilisation dâune invertase en prĂ©traitement sont nĂ©cessaires afin de maximiser le rendement et la productivitĂ© de lâacide lactique. Lâimmobilisation des microorganismes a permis de rĂ©utiliser les mĂȘmes billes dâalginate au cours de cinq cycles successifs de production. Une autre alternative potentielle aux voies prĂ©cĂ©dentes est la fermentation sombre pour la production de biohydrogĂšne directement Ă partir du dĂ©chet. Si des rendements intĂ©ressants ont Ă©tĂ© atteints, il faut noter que comme prĂ©cĂ©demment dans le cas de la fermentation solide du dĂ©chet, une forte dĂ©pendance aux conditions initiales de broyage a Ă©tĂ© mise en Ă©vidence ; de plus, Ă la carence en azote qui obligeait Ă supplĂ©menter les milieux en fermentation en phase liquide sâajoutent des besoins en fer. Enfin, lâutilisation du dĂ©chet comme substrat carbonĂ© dans un procĂ©dĂ© de phycoremĂ©diation avec lâalgue Ankistrodesmus braunii a montrĂ© que lâĂ©limination de 90% du diclofĂ©nac initial pouvait ĂȘtre atteinte en conditions de mixotrophie, mĂȘme si seulement un tiers du diclofĂ©nac Ă©liminĂ© est effectivement mĂ©tabolisĂ© par lâalgue
Valorization of carob molasse through a biorefinery approach
Cette thĂšse de doctorat porte sur la valorisation du dĂ©chet solide issu de la prĂ©paration de la mĂ©lasse de caroube libanaise pour la production de bioĂ©nergie et de molĂ©cules Ă valeur ajoutĂ©e. Lâanalyse de la composition de ce dĂ©chet a montrĂ© quâil contient 45 % (g/g) de sucres, substrats exploitables pour la fermentation alcoolique ou lactique, la production de biohydrogĂšne, ou comme source de carbone pour la croissance dâune algue dans un procĂ©dĂ© de phycoremĂ©diation (traitement des eaux par les algues) pour lâĂ©limination de micropolluants pharmaceutiques. Les rĂ©sultats obtenus ont montrĂ© que la fermentation alcoolique en phase liquide Ă partir dâextraits de dĂ©chet de caroube peut conduire Ă des rendements Ă©levĂ©s en bioĂ©thanol sous rĂ©serve dâenrichir le milieu de culture par les Ă©lĂ©ments nĂ©cessaires pour la croissance de la levure Saccharomyces cerevisiae (en particulier lâazote), tandis quâil est possible de produire directement le bioĂ©thanol sur le dĂ©chet par fermentation en milieu solide sous rĂ©serve de contrĂŽler prĂ©cisĂ©ment lâhumiditĂ©. Nous avons Ă©galement dĂ©montrĂ© que la fermentation lactique par immobilisation de Lactobacillus rhamnosus sur des billes dâalginate constitue une alternative possible au bioĂ©thanol pour les sucres extraits du dĂ©chet. Cependant, un enrichissement du milieu de culture, ainsi que lâutilisation dâune invertase en prĂ©traitement sont nĂ©cessaires afin de maximiser le rendement et la productivitĂ© de lâacide lactique. Lâimmobilisation des microorganismes a permis de rĂ©utiliser les mĂȘmes billes dâalginate au cours de cinq cycles successifs de production. Une autre alternative potentielle aux voies prĂ©cĂ©dentes est la fermentation sombre pour la production de biohydrogĂšne directement Ă partir du dĂ©chet. Si des rendements intĂ©ressants ont Ă©tĂ© atteints, il faut noter que comme prĂ©cĂ©demment dans le cas de la fermentation solide du dĂ©chet, une forte dĂ©pendance aux conditions initiales de broyage a Ă©tĂ© mise en Ă©vidence ; de plus, Ă la carence en azote qui obligeait Ă supplĂ©menter les milieux en fermentation en phase liquide sâajoutent des besoins en fer. Enfin, lâutilisation du dĂ©chet comme substrat carbonĂ© dans un procĂ©dĂ© de phycoremĂ©diation avec lâalgue Ankistrodesmus braunii a montrĂ© que lâĂ©limination de 90% du diclofĂ©nac initial pouvait ĂȘtre atteinte en conditions de mixotrophie, mĂȘme si seulement un tiers du diclofĂ©nac Ă©liminĂ© est effectivement mĂ©tabolisĂ© par lâalgue.This PhD thesis deals with the valorization of the solid waste generated by the Lebanese carob molasse process with the aim to produce bioenergy or high added-value platform molecules. The chemical analysis of this waste has highlighted that it contains 45% (w/w) sugars, which can be used as a substrate for alcoholic or lactic fermentation, the production of biohydrogen by dark fermentation, or as a carbon source for the growth of microalgae in a phycoremediation process (water treatment process based on algae/microalgae) for the removal of pharmaceutical micropollutants. Experimental results have shown that high ethanol yield and productivity could be achieved through alcoholic fermentation in the liquid phase using extracts from carob waste as the substrate, provided the culture medium was enriched by complementary nutrients (especially a nitro-gen source) to enhance the growth of the yeast Saccharomyces cerevisiae; in parallel, the direct production of ethanol from the solid waste based on solid-state fermentation was also proved to be efficient, provided humidity was accurately controlled. In addition, lactic fermentation per-formed with immobilized Lactobacillus rhamnosus on alginate beads was shown to constitute a potential alternative to bioethanol for the extracts from carob waste. An enriched culture medium was, however, necessary, together with the use of an invertase enzyme as a pretreatment so as to maximize the yield and the productivity of lactic acid. Using microorganism immobilization lead to the opportunity to recycle at least five times alginate beads in successive culture cycles. Another potential alternative to the above-mentioned valorization pathways was proved to lie in the dark fermentation process for biohydrogen production, directly using the solid waste. While attractive yields were reached, a strong dependence on the particle size from grinding pretreatment was emphasized, as in solid-state fermentation; moreover, iron supplementation in the culture medium was compulsory, in addition to nitrogen supplementation already described when fermentation was carried out in the liquid phase. Finally, when the carob waste was used as a substrate for the growth of the algae Ankistrodesmus braunii in a phycoremediation process, a removal yield of the initial diclofenac content about 90% could be reached under mixotrophic conditions, even though only one third of the diclofenac removed was effectively metabolized
Optimization of lactic acid production using immobilized Lactobacillus Rhamnosus and carob pod waste from the Lebanese food industry
Efficiency of mixed physical and electrochemical treatments on liquid effluents from an anaerobic digester
International audienc
Towards a Better Understanding of the Removal of Carbamazepine by Ankistrodesmus braunii: Investigation of Some Key Parameters
International audienceNowadays, water pollution by pharmaceuticals is a major issue that needs an urgent solution, as these compounds, even when found at trace or ultra-trace levels, could have harmful effects on organisms. Carbamazepine (CBZ) is a pharmaceutical product that is detected as a micropollutant in many water resources. Different treatment methods were lately employed for the removal of CBZ, which are often cheap but inefficient or efficient but expensive. Yet, there are limited available studies on the elimination of this molecule by algae despite their well-known highly adaptive abilities. In this study, the biological treatment of CBZ was carried out using the green microalgae, Ankistrodesmus braunii (A. braunii), which has been reported to be particularly resistant to CBZ toxicity in the literature. The respective effects of the culture medium, the initial inoculum, and CBZ concentrations were studied on CBZ removal. Lastly, the mechanism of CBZ elimination by A. braunii was investigated. The presented data clearly demonstrates that the presence of this molecule did not completely repress A. braunii growth or the ability of these algae to remove CBZ; after 60 days of incubation, the highest percentage of CBZ elimination achieved was 87.6%. Elimination was more successful in Bold's basal medium than in proteose peptone medium. Finally, the removal mechanism was also investigated to provide a better understanding of the transformation mechanism of this molecule. It was shown that the main removal mechanism was the bioaccumulation of CBZ by A. braunii cells, but the biotransformation of the initial CBZ into metabolites was also observed