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Munns, Craig Christopher Robert. "Development of physio-chemical pretreatments and mixed microbial cultures for the conversion of lignocellulosic biomass to useful products." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28768.
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There is increasing interest in producing biofuels; biofuels are preferable to fossil fuels as the biomass from which they are derived is seen as a renewable source, as opposed to fossil fuels which are a finite resource. “First Generation” biofuels are derived from food crops such as grains and sugar cane. The use of food crops is not sustainable in this age of increasing food insecurity. A promising alternative appears to be what is termed “Second Generation” feedstocks, such as energy crops like Miscanthus spp., and agricultural by-products. The problem with the use of second generation feedstocks is firstly that the sugars are locked up in the cell wall polymers (CWP), which need to be released by physio-chemical pre-treatments, that are costly and time consuming. The second problem is that not all the sugars that are released from CWP are able to be utilised by wild type product-forming organisms. However, model chassis organisms can be genetically modified to utilise these sugars and /or produce enzymes to degrade biomass which reduces the time and costs involved in the process. While engineering these organisms to utilise a range of monosaccharides has already been successful, engineering them to produce degradation enzymes is proving to be problematic. A potentially more effective system is to use co-cultures of both cellulose-degrading and product-forming organisms. Since this is a novel approach it is not known whether the two organisms are able to live together without any adverse effects. The aims of this study were firstly to determine whether mixed cultures of both cellulose-degrading and potential product-forming organisms could survive in the presence of one another, secondly whether the cellulose-degrading organisms could degrade potential feedstock down into their monosaccharide building blocks and thirdly whether the potential product-forming organisms could survive and utilise these monosaccharides for growth and potential fermentation. It was discovered that C. hutchinsonii can degrade both paper and Triticum aestivum straw polymers into their monosaccharide components and that B. subtilis can survive on the sugars released by C. hutchinsonii. It was also discovered that C. hutchinsonii and B. subtilis 168 can only tolerate an ethanol concentration of up to 2% (v/v) and that this is below the baseline for a biofuel system to be economically viable. Likewise, C. hutchinsonii and B. subtilis 168 have an even poorer tolerance for butanol; growth is inhibited by < 1% butanol in its growth media. A series of physio-chemical pre-treatments were developed in order to make the monosaccharides present in the cell wall polymers more accessible to microbial saccharification. Sequential pre-treatments, both physical milling and chemical hydrolysis in tandem, had the greatest effect on the bio chemistry of the biomass, but that these physio-chemical pre-treatments produced inhibitory compounds in the medium that retarded microbial growth. Attempts were made to genetically modified Bacillus subtilis 168 to produce lactic acid and ethanol by over expressing the native ldh gene under the highly-expressed promoter of the cspD gene and by integrating the fused pdc:adh gene from Z. mobilis under the same promoter. Transformation of B. subtilis to over express LDH was successful, with PCR confirmation of the correct insertion and enzyme activity for the ldh both in vitro and in vivo, with the latter producing more lactic acid aerobically than the wild type. Transformation of B. subtilis to express pdc:adh and subsequent production of ethanol was not successful.
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Badalato, Nelly. "Structure de déchets lignocellulosiques : effets sur la colonisation, les communautés microbienne et les performances de méthanisation, caractérisés par des approches fonctionnelles et haut-débit." Electronic Thesis or Diss., Paris, AgroParisTech, 2014. http://www.theses.fr/2014AGPT0002.
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La méthanisation des composés lignocellulosiques présente un fort intérêt en raison de leur haut potentiel énergétique et de leur abondance, notamment dans les ordures ménagères résiduelles. Toutefois, leur complexité de structure et de composition rend ces matériaux difficilement dégradables en conditions anaérobies et l’utilisation de prétraitements est généralement requise afin d’améliorer leurs rendements de biodégradation. Outre l’effet de ces prétraitements sur la biodégradation de ces composés, la colonisation des lignocelluloses par les micro-organismes cellulolytiques est une étape clé pour l’efficacité de sa dégradation. Dans ce cadre, le travail de thèse a pour objectifs de mieux comprendre le déterminisme de la colonisation de déchets, d’établir le lien entre la colonisation des déchets lignocellulosiques et l'efficacité de leur dégradation et enfin de caractériser plus finement les mécanismes et interactions mises en jeu au sein de la biomasse. Afin de répondre à ces questions, une approche transversale a été développée, combinant des modèles de cultures de souches pures et des systèmes de méthanisation en laboratoire par des communautés complexes. Des approches intégratives ont été appliquées à l’étude de ces systèmes, couplant des analyses haut-débit (métagénomique/(méta)protéomique), un suivi physico-chimique de la biodégradation et des caractérisations physico-chimiques des composés lignocellulosiques étudiés. L’ensemble des résultats met en évidence le rôle des propriétés chimiques, micro-et macro¬structurales des composés lignocellulosiques dans leur récalcitrance, leur performances de dégradation et la réponse du compartiment microbien. La réalisation de la première étude de protéomique totale et quantitative sur la souche pure cellulolytique Clostridium cellulolyticum, modèle des Clostridia cellulolytiques mésophiles, a permis de mettre en évidence que la vitesse maximale de biodégradation du mouchoir en papier est supérieure à celle du coton et que cette dégradation est associée à un profil métabolique particulier, à une colonisation plus rapide et plus étendue et à une modulation quantitative du système cellulasique. D’autre part, une étude sur un système plus réaliste pour l’étude de la méthanisation des déchets lignocellulosiques a confirmé la bonne concordance entre ce système et le système modèle utilisé et a également permis de mettre en évidence les effets substrats sur la structure des communautés microbienne avec la dominance de la classe Bacteroidia en présence de mouchoir en papier et la forte proportion de la classe Spirochaetes en présence de coton. Enfin l’étude des effets de broyages très fins de la paille de blé et du carton plat ont mis en évidence les limites de ces prétraitements sur les performances de leur dégradation, avec l’effet positif modéré du broyage fin de la paille. Ils ont également montré la sensibilité des communautés microbiennes aux changements de surface du substrat, qui se manifeste par l'émergence de communautés parfois différentes en fonction du prétraitement mécanique appliqué. En conclusion, ce travail a permis de traiter sous un angle nouveau les questions liées à la récalcitrance des déchets lignocellulosiques en abordant à la fois les aspects structuraux, écologiques et fonctionnels. Ces résultats alimentent le corps de connaissances fondamentales sur les bioprocédés. Ils confirment que les matériaux lignocellulosiques sont particuliers parmi les déchets non-dangereux et qu’une exploitation plus large de leur potentiel énergétique nécessiterait la mise en œuvre de procédés spécifiquement adaptésLignocellulosic materials have a high energy potential and are abundant, especially in municipal solid waste and their methanization is a promising waste-to-energy bioprocess. However, owing to their highly complex and heterogeneous structure, they are recalcitrant to anaerobic conditions and the use of pre-treatments is usually required to improve their biodegradation yields. Besides, lignocellulose colonization by cellulolytic microorganisms is a key step for an efficient biodegradation. In this context, the PhD work aimed to better understand the factors affecting waste colonization, to establish the link between lignocellulosic waste colonization and its biodegradation efficiency and to characterize more precisely the mechanisms and interactions within the biomass. A transversal approach was developed, combining cultures of model pure strains and lab-scale methanization microcosms with a complex biomass. Integrated approaches were applied to these studies, combining high-throughput analyses (metagenomics/(meta) proteomics), physico-chemical monitoring of bioconversion and finally physico-chemical characterization of substrates. The main results highlight the important role of lignocellulosic materials chemical and micro-and macro -structural features for their recalcitrance, their biodegradation efficiency and the response of the microbial compartment. The first global quantitative proteomic study on the cellulolytic model Clostridium cellulolyticum was conducted. Results showed an increased biodegradation rate of the facial tissue compared to cotton. This enhanced biodegradation was associated to a particular metabolic profile, a faster and more extensive colonization and finally a quantitative modulation of the cellulasic system. On the other hand, study of lignocellulosic waste methanization confirmed the good agreement between this more realistic system and the above-described model system. It also provided new information about the effects of substrate on microbial community structure. Noticeably, Bacteroidia members predominated in the presence of tissue and a high proportion of Spirochaetes members was observed in the presence of cotton. Finally, study of the effects of wheat straw and cardboard dry grinding revealed the limitations of these pretreatments on biodegradation efficiency. Main key points were a moderate positive effect of wheat straw fine grinding, and the sensitivity of the microbial communities to substrate surface characteristics, as evidenced by the emergence of different microbial communities according to the applied mechanical pretreatment. In conclusion, this work brings new perspectives to the study of lignocellulosic waste recalcitrance by addressing both the structural, functional and ecological aspects. These results contribute to the core fundamental knowledge on bioprocesses. They confirm that the lignocellulosic materials are specific among non-hazardous waste and require the implementation of adapted specific processes
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Monlau, Florian. "Application of pretreatments to enhance biohydrogen and/or biomethane from lignocellulosic residues : linking performances to compositional and structural features." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20178/document.
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Dans le futur, différentes sources d'énergies renouvelables comme les énergies de seconde génération produites à partir de déchets lignocellulosiques seront nécessaires pour palier à l'épuisement des énergies fossiles. Parmi ces énergies de seconde génération, le biohydrogène, le méthane et l'hythane produits à partir de procédés fermentaires anaérobies représentent des alternatives prometteuses. Cependant la production de biohydrogène et de méthane à partir de résidus lignocellulosiques est limitée par leurs structures récalcitrantes et une étape de prétraitement en amont des procédés fermentaires est souvent nécessaire. Ce travail a pour but d'étudier l'impact des facteurs biochimiques et structurels des résidus lignocellulosiques sur les performances de production d'hydrogène et de méthane, pour pouvoir par la suite développer des stratégies de prétaitements adaptées. Tout d'abord, sur un panel de vingt substrats lignocellulosiques, les potentiels hydrogène et méthane ont été corrélés aux paramètres biochimiques et structurels. Les résultats ont mis en évidence que le potentiel hydrogène est uniquement corrélé positivement à la teneur en sucres solubles. La production de méthane quant à elle est négativement corrélée à la teneur en lignine et, à un moindre degré, à la cristallinité de la cellulose, mais positivement à la teneur en sucres solubles, holocelluloses amorphes et protéines. Par la suite, des stratégies de prétraitements ont été établies pour améliorer la production d'hydrogène et de méthane. Le couplage prétaitements alcalins/enzymatique ainsi que les prétraitements à l'acide dilué, efficaces pour solubiliser les holocelluloses en sucres solubles ont été appliqués en amont de la production d'hydrogène. En combinant le pretraitement alcalin avec une hydrolyse enzymatique, le potentiel hydrogène des tiges de tournesol fut multiplié par quinze. En revanche, suite aux prétraitements acides, la production d'hydrogène fut inhibée à cause de la libération de sous-produits (furfural, 5-HMF et composés phénoliques) engendrant un changement d'espèces bactériennes vers des espèces non productrices d'hydrogène. Pour la production de méthane, cinq prétraitements thermo-chimiques (NaOH, H2O2, Ca(OH)2, HCl and FeCl3) efficaces pour délignifier ou solubiliser les holocelluloses ont été étudiés. Parmi ces prétraitements, la meilleure condition fut 55°C à une concentration de 4% NaOH pendant 24 h, résulant en une augmentation du potentiel méthane variant de 29 à 44 % en fonction des tiges de tournesol. Cette condition fut par la suite validée en réacteurs anaérobies continusavec une augmentation de 26.5% de la production de méthane. Un procédé à deux étages couplant la production d'hydrogène en batch suivi de la production de méthane en continu fut aussi étudié. Néanmoins, aucune différence significative en termes d'énergie produite ne fut observée entre les procédés à deux étages (H2/CH4) et à un étage (CH4)In the future, various forms of renewable energy, such as second generation biofuels from lignocellulosic residues, will be required to replace fossil fuels. Among these, biohydrogen and methane produced through fermentative processes appear as interesting candidates. However, biohydrogen and/or methane production of lignocellulosic residues is often limited by the recalcitrant structure and a pretreatment step prior to fermentative processes is often required. Up to date, informations on lignocellulosic characteristics limiting both hydrogen and methane production are limited.Therefore, this work aims to investigate the effect of compositional and structural features of lignocellulosic residues on biohydrogen and methane performances for further developping appropriate pretreatments strategies. Firstly, a panel of twenty lignocellulosic residues was used to correlate both hydrogen and methane potentials with the compositional and structural characteristics. The results showed that hydrogen potential positively correlated with soluble carbohydrates only. Secondly, methane potential correlated negatively with lignin content and, in a lesser extent, with crystalline cellulose, but positively with the soluble carbohydrates, amorphous holocelluloses and protein contents. Pretreatments strategies were further developed to enhance both hydrogen and methane production of sunflower stalks. Dilute-acid and combined alkaline-enzymatic pretreatments, which were found efficient in solubilizing holocelluloses into soluble carbohydrates, were applied prior to biohydrogen potential tests. By combined alkaline-enzymatic pretreatment, hydrogen potential was fifteen times more than that of untreated samples. On the contrary, hydrogen production was inhibited after dilute-acid pretreatments due to the release of byproducts (furfural, 5-HMF and phenolic compounds) that led to microbial communities shift toward no hydrogen producing bacteria. Similarly, methane production, five thermo-chemical pretreatments (NaOH, H2O2, Ca(OH)2, HCl and FeCl3) found efficient in delignification or solubilization of holocelluloses, were considered. Among these pretreatments, the best conditions were 55°C with 4% NaOH for 24 h and led to an increase of 29-44 % in methane potential of sunflower stalks. This pretreatment condition was validated in one stage anaerobic mesophilic continuous digester for methane production and was found efficient to enhance from 26.5% the total energy produced compared to one stage-CH4 alone. Two-stage H2 (batch) / CH4 (continuous) process was also investigated. Nevertheless, in term of energy produced, no significant differences were observed between one-stage CH4 and two-stage H2 /CH4
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Cheng, Wei. "Pretreatment and enzymatic hydrolysis of lignocellulosic materials." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1951.
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Thesis (M.S.)--West Virginia University, 2001.Title from document title page. Document formatted into pages; contains xii, 173 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 138-142).
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Warsame, Mohamed. "Saccharification of lignocellulose." Thesis, Malmö högskola, Fakulteten för hälsa och samhälle (HS), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-25910.
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Den ökande efterfrågan på energi och den förväntade nedgången i råoljeproduktion har lett till ett enormt sökande efter nya energikällor.Cellväggen i växter består till stor del av lignocellulosa som i sin tur innehåller cellulosa och hemicellulosa. Dessa polysackarider är av stor betydelse för sökandet efter förnyelsebar energi.Cellväggen måste förbehandlas innan den kan brytas ner till enkla sockerarter. Efter nedbrytning kan monosackariderna användas till produktion av etanol eller biogas genom väl etablerade fermenteringstekniker. Syftet med denna studie var att jämföra och utvärdera några metoder som används vid degradering av lignocellulosa. Tre behandlingar har jämfört för att se vilken som ger mest avkastning i form av monosackarider. Vetehalm användes som substrat och hydrolyseras med hjälp av tre kommersiella enzymblandningar. Proverna förbehandlades före den enzymatiska reaktionen med antingen mikrovågor eller ångexplosion.Resultaten visade att en behandling med mikrovågsbestrålning eller ångexplosion kombinerad med enzymhydrolys gav högst avkastning. De slutsatser som kan dras är att en mekanisk förbehandling ökar utbytet drastiskt men är otillräcklig i sig. Ytterligare enzymatisk behandling är nödvändig att erhålla större mängder enkla sockerarter från lignocellulosa.The increasing energy demand and the anticipated decline in crude oil production has led to an immense search for new energy sources. Plant cell walls contain lignocellulose that conserve great amounts of energy. These polysaccharides are of high importance for the search of renewable energy sources. Pretreatment of the cell wall is necessary in order to hydrolyse it to its component sugars. Once degraded to monomeric sugars it can be fermented to either ethanol or biogas through established fermentation technologies.The aim of this thesis was to compare and evaluate some of the methods used for sacchrification of lignocellulose. Three treatments where compared to determine which is highest yielding. These are enzymatic hydrolysis, microwave irradiation and steam explosion.Wheat straw was used as substrate and hydrolysed by three commercial enzyme mixtures. Samples were pretreated before the enzymatic reaction with either microwave or steam explosion. Results showed that a treatment of either microwave irradiation or steam explosion combined with enzyme hydrolysis gives the highest yield in monomeric sugars. The conclusions that can be drawn are that mechanical pretreatment increases yield drastically but is insufficient in its self. Further enzymatic treatment of wheat straw is necessary to obtain high amounts of simple sugars.
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Brandt, Agnieszka. "Ionic liquid pretreatment of lignocellulosic biomass." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9166.
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This thesis is concerned with the thermal treatment of lignocellulosic biomass using ionic liquids for the purpose of comminution via dissolution, for fractionating the biological composite and for obtaining aqueous solutions of carbohydrate monomers from the pulp via enzymatic hydrolysis. A major focus was the relationship between the choice of the anion and the effectiveness of the treatment. The synthesis of a range of 1-butyl-3-methylimidazolium ionic liquids with strongly hydrogen-bond basic anions was accomplished. Selected, process-relevant physicochemical properties were measured, such as the Kamlet-Taft solvent polarity, hygroscopicity and thermal stability. It was shown that 1-butyl-3-methylimidazolium acetate is not stable at 120°C, while other ionic liquids e.g. 1-butyl-3-methylimidazolium hydrogen sulfate exhibit very good long-term thermal stability. It was shown that hydrogen-bond basic 1-butyl-3-methylimidazolium ionic liquids attract more than stoichiometric quantities of water when exposed to air, suggesting that ionic liquid pretreatment under anhydrous conditions is difficult to achieve. Dissolution of air-dried wood chips in 1-butyl-3-methylimidazolium ionic liquids was attempted. It was shown that the large particle size and the moisture contained in the biomass hamper complete dissolution. The hydrogen-bond basicity of the ionic liquid, described by the Kamlet-Taft parameter ß, was correlated with the ability to expand as well as partially and anisotropically dissolve wood chips. Pretreatment of lignocellulosic biomass with 1-butyl-3- methylimidazolium methyl sulfate, 1-butyl-3-methylimidazolium hydrogen sulfate and 1-butyl-3-methylimidazolium methanesulfonate was explored and high saccharification yields were reported. It was found that successful application of methyl sulfate and hydrogen sulfate ionic liquids requires addition of water and that comparatively high water contents are tolerated. Fractionation of lignocellulose into an insoluble cellulose fraction, a solubilised hemicellulose fraction and a lignin containing precipitate was achieved. The influence of water content, pretreatment time and biomass type on the enzymatic saccharification yield and the extent of hemicellulose solubilisation, hydrolysis and dehydration were examined.
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Corredor, Deisy Y. "Pretreatment and enzymatic hydrolysis of lignocellulosic biomass." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/693.
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Kvillborn, Carin. "Enzymatic Pretreatment of Lignocellulose Rich Waste for Improved Biogas Production." Thesis, Linköpings universitet, Tema vatten i natur och samhälle, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-104974.
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The present study aimed to investigate the methane yield from anaerobic digestion of a lignocellulosic substrate subjected to different pretreatments. The lignocellulosic forest residues materials were milled and then pretreated with the organic solvent NMMO (N-Methylmorpholine N-oxide) and/or the lignolytic enzymes laccase and versatile peroxidase at a dosage of 60 U g-1 total solids (TS) substrate. The amount of methane produced was studied in a biomethane potential assay with inocula from a thermophilic biogas reactor treating municipal waste. All samples were run in triplicates. Due to the large amount of samples, two biomethane potential assays were conducted: series 10 & 20 and series 30 & 40. The gas production results show that NMMO-treated forest residues yielded 130 NmL CH4 g-1 volatile solids (VS) substrate and the untreated forest residues yielded 95 NmL CH4 g-1 VS substrate for series 10 & 20. For series 30 & 40, both untreated and NMMO-treated forest residues yielded 140 NmL CH4 g-1 VS substrate. NMMO-treatment appears to be favourable and no advantages from the enzyme pretreatment could be seen in terms of gas yield. An analysis of the reaction fluid after the enzymatic treatment showed presence of phenols, an indication of successful lignin hydrolysis.Studien avsåg att undersöka metanutbytet från anaerob nedbrytning med förbehandlad lignocellulosa som substrat. Lignocellulosamaterialet, i form av skogsavfall, maldes och förbehandlades därefter med det organiska lösningsmedlet NMMO (N-metylmorfolin-N-oxid) och/eller de lignolytiska enzymerna laccase och versatile peroxidas med dosen 60 U g-1 torrsubstanshalt (TS). Mängden producerad metan undersöktes i en biometanpotentialanalys med inocula från en termofil biogasreaktor, som behandlade hushållsavfall. Triplikat av varje prov användes för att öka den statistiska stabiliteten. På grund av det stora antalet prover genomfördes studien i två omgångar: Serie 10 & 20 samt serie 30 & 40. Resultaten visade att det NMMO-behandlade skogsavfallet gav 130 NmL CH4 g-1 organisk substans (VS) och det obehandlade skogsavfallet gav 95 NmL CH4 g-1 VS i serie 10 & 20. Både obehandlat och NMMO- behandlat skogsavfall gav 140 NmL CH4 g-1 VS i serie 30 & 40. Förbehandling med NMMO verkar vara fördelaktig medan enzymbehandling endast resulterade i en smärre ökning av gasproduktionen. En analys av vätskan efter enzymbehandlingen visade förekomst av fenoler, vilket visar på en lyckad ligninnedbrytning.
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Narayana, Swamy Naveen. "Supercritical Carbon Dioxide Pretreatment of Various Lignocellulosic Biomasses." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1269524607.
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Moxley, Geoffrey W. "Studies of Cellulosic Ethanol Production from Lignocellulose." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/43372.
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At present, the worldâ s transportation sector is being principally supplied by fossil fuels. However, energy consumption in this sector is drastically increasing and there are concerns with supply, cost, and environmental issues with the continuing use of fossil fuels. Utilizing non-petroleum ethanol in the transportation sector reduces the dependence on oil, and allows for cleaner burning of gasoline.
Lignocellulose materials are structurally composed of five types of polymeric sugars, glucan, galactan, mannan, arabinan, and xylan. NREL has developed a quantitative saccharification (QS) method for determining carbohydrate composition. We proposed a new protocol based on the NREL 2006 Laboratory Analytical Procedure â Determination of Structural Carbohydrates and Lignin in Biomassâ (Sluiter et al. 2006a) with a slight modification, in which xylose concentration was determined after the secondary hydrolysis by using 1% sulfuric acid rather than 4% sulfuric acid. We found that the current NREL protocol led to a statistically significant overestimation of acid-labile xylan content ranging from 4 to 8 percent.
Lignocellulosic biomass is naturally recalcitrant to enzymatic hydrolysis, and must be pretreated before it can be effectively used for bioethanol production. One such pretreatment is a fractionation process that separates lignin and hemicellulose from the cellulose and converts crystalline cellulose microfibrils to amorphous cellulose. Here we evaluated the feasibility of lignocellulose fractionation applicable to the hurds of industrial hemp. Hurds are the remaining material of the stalk after all leaves, seeds, and fiber have been stripped from the plant. After optimizing acid concentration, reaction time and temperature, the pretreated cellulosic samples were hydrolyzed to more than 96% after 24 hours of hydrolysis (enzyme loading conditions of 15 FPU/g glucan Spezyme CP and 60 IU/g glucan Novozyme 188) at the optimal pretreatment condition (> 84% H3PO4, > 50 °C and > 1 hour). The overall glucose and xylose yields were 89% (94% pretreatment; 96% digestibility) and 61%, respectively. All data suggest the technical feasibility of building a biorefinery based on the hurds of industrial hemp as a feedstock and a new lignocellulose fractionation technology for producing cellulosic ethanol. The choice of feedstock and processing technology gives high sugar yields, low processing costs, low cost feedstock, and low capital investment.
Master of Science
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Sierra, Ramirez Rocio. "Long-term lime pretreatment of poplar wood." Texas A&M University, 2005. http://hdl.handle.net/1969.1/3316.
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Lignocellulosic biomass (e.g., poplar wood) provides a unique and sustainable resource
for environmentally safe organic fuels and chemicals. The core of this study is the
pretreatment step involved in bioconversion processes. Pretreatment is required to realize
high yields vital to commercial success. The focus of the pretreatment step is to
methodically change key features of the biomass to favor enzymatic hydrolysis.
This work assesses the compositional changes due to oxidative and non-oxidative longterm
lime pretreatment of poplar wood (up to 4 weeks of pretreatment) at mild
temperatures (25ºC to 65ºC), and their effect on the enzymatic yield of glucan and xylan.
The most important pretreatment yield of lignin was 54 g lignin remaining/100 g lignin
in raw biomass, and was accomplished for 4-week lime pretreatment at 65ºC in oxidative
conditions. The corresponding pretreatment yields of glucan and xylan were 85.9 g glucan
recovered/100 g glucan in raw biomass and 80.2 g xylan recovered/100 g xylan in raw
biomass respectively.
For poplar wood oxidatively pretreated with lime for 4 weeks at 65ºC and
enzymatically hydrolyzed with an enzyme loading of 15 FPU/g glucan in raw biomass
during a 3-day period, the best overall yields of glucan and xylan, were 80.7 g glucan
hydrolyzed/100 g glucan in raw biomass and 66.9 g xylan hydrolyzed/100 g xylan in raw
biomass respectively. The corresponding hydrolysis yields were 94.0 g glucan
hydrolyzed/100 g glucan in treated biomass and 83.5 g xylan hydrolyzed/100 g xylan in
treated biomass respectively.
Because there is a previous study of long-term lime pretreatment of corn stover (Kim,
2004), the data obtained in this work show the effect of using woody lignocellulose as
substrate. From the comparison, resulted that in the case of poplar wood oxidatively pretreated at
65ºC for 4 weeks, less lignin was removed and more carbohydrates were solubilized,
however the hydrolysis yield of glucan was almost equal and the hydrolysis yield of xylan
was higher than the reported by Kim for corn stover oxidatively pretreated at 55ºC for 4
weeks. The overall yield of glucan resulted lower in the case of poplar wood because of the
lower pretreatment yield of glucan. Thus, it is important to complete the mass balances
including an analysis on the pretreatment liquor to determine if the solubilized glucan was
degraded.
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Schneider, L. (Laura). "Mechanocatalytic pretreatment of lignocellulosic barley straw to reducing sugars." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526216478.
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Abstract Biomass conversion methods represent bioeconomic solutions for the sustainable production of value added commodities (chemicals and materials) as well as for energy purposes, either in solid (pellets), liquid (transport fuels) or gaseous (combustion gases e.g. biomethane) form. Lignocellulosic biomass as a renewable source available in immense quantity, is considered to be one of the most promising natural sources, with high potential in the replacement of conventional transportation fuels and reduction of greenhouse gas emissions. This thesis provides new insights into mechanocatalysis, which as yet is a novel technique in catalytic biomass conversion. The mechanocatalytic approach combines chemical catalysis and mechanical assisted processing driven by ball milling. Lignocellulosic barley straw was impregnated or merely mixed with the catalyst (formic acid, acetic acid, sulfuric acid, oxalic acid dihydrate and potassium pyrosulfate) and ball milled under various conditions yielding the selective depolymerization of lignocellulose into water-soluble xylo-oligosaccharides. Subsequent hydrolysis at moderate temperatures resulted in the formation of valuable reducing sugars, mainly xylose, galactose, arabinose and glucose, which constitute the basic materials for transportation fuel and chemical production. Reducing sugar release of 53.4 wt% with low by-product formation was observed within short milling durations using sulfuric acid as a catalyst in mechanocatalysis. Likewise, oxalic acid dihydrate and potassium pyrosulfate as a novel catalyst, successfully converted barley straw to reducing sugars (42.4 wt% and 39.7 wt%, respectively), however longer milling durations were required. In comparison, lower saccharification (<10 wt%) was obtained by employing formic acid and acetic acid in mechanocatalysis. Harsh milling conditions initiated a temperature increase within the reaction vessel resulting in enhanced sugar release. Likewise, greater sugar release was observed with increased catalyst amount and acidity. The results revealed that the balance of these factors is crucial for efficient catalytic conversion of barley strawTiivistelmä Biomassan konvertointimenetelmät mahdollistavat biotalouden hengen mukaisesti uusia ratkaisuja kemikaalien ja materiaalien kestävään tuotantoon sekä biomassan energiakäyttöön eri muodoissa (kuten pelletit, biopolttoaineet ja biokaasu). Lignoselluloosapohjaista, uusiutuvaa biomassaa, kuten tässä työssä tutkittua ohran olkea, on runsaasti saatavilla. Lignoselluloosa onkin yksi lupaavimmista raaka-aineista korvaamaan fossiilisia polttoaineita ja vähentämään kasvihuonekaasupäästöjä. Väitöskirjatutkimus antaa uutta tietoa ohran oljen mekaanis–katalyyttisestä käsittelystä, mikä on suhteellisen uusi menetelmä biomassan katalyyttisessä muokkauksessa. Menetelmässä yhdistetään kemiallinen katalyysi ja mekaaninen muokkaus (jauhatus) kuulamyllyllä. Lignoselluloosa (ohran olki) impregnoitiin tai sekoitettiin tutkitun katalyytin (muurahaishappo, etikkahappo, rikkihappo, oksaalihappodihydraatti, kaliumpyrosulfaatti) kanssa ja käsiteltiin erilaisissa mekaanis–katalyyttisissä olosuhteissa. Lignoselluloosan selektiivinen depolymerointi muodosti vesiliukoisia oligosakkarideja ja edelleen hydrolyysin kautta pelkistyneitä sokereita (pääasiassa ksyloosia, galaktoosia, arabinoosia ja glukoosia), joita voidaan käyttää biopolttoaineiden ja -kemikaalien valmistuksessa. Tutkimuksen tulosten perusteella rikkihappokatalyytillä saatiin 53,4 massa-% ohran oljen sisältämistä pelkistyneistä sokereista vapautettua lyhyillä käsittelyajoilla. Lisäksi sivutuotteiden muodostuminen oli vähäistä. Vastaavasti oksaalihappodihydraatti (sokerisaanto 42,4 massa-%) ja kaliumpyrosulfaatti (sokerisaanto 39,7 massa-%) toimivat uusina katalyytteinä hyvin, mutta vaativat rikkihappokatalyyttiä pidemmät jauhatusajat. Sen sijaan muurahaishapolla ja etikkahapolla sokerisaanto oli erittäin alhainen (alle 10 massa-%) mekaanis–katalyyttisessä käsittelyssä. Tutkimuksessa todettiin, että voimakas jauhatus vaikutti selkeästi reaktiolämpötilan nousuun käsittelyn aikana, mikä edisti korkeampaa sokerisaantoa. Vastaavasti sokerisaantoa voitiin parantaa katalyyttimäärällä ja happamuudella. Tulokset osoittavat, että näiden muuttujien tasapaino on ratkaisevaa ohran oljen tehokkaan katalyyttisen muuntamisen kannalta
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Kitsos, Haralambos Minas. "Swelling pretreatment of lignocellulosic materials to promote enzymatic hydrolysis." Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/11780.
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Siddaramu, Thara Gejjalagere. "EVALUATION OF DIFFERENT PRETREATMENT APPROACHES FOR DISRUPTING LIGNOCELLULOSIC STRUCTURES." OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/703.
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AN ABSTRACT OF THE THESIS OF Thara G. Siddaramu, for the Master of Science degree in Civil and Environmental Engineering, presented on February 5, 2011, at Southern Illinois University Carbondale. TITLE: EVALUATION OF DIFFERENT PRETREATMENT APPROACHES FOR DISRUPTING LIGNOCELLULOSIC STRUCTURES MAJOR PROFESSOR: Dr. Yanna Liang There are two major steps in biofuel production- pretreatment of lignocellulosic materials and enzymatic hydrolysis. The present study investigated the ability of two pretreatment methods, namely traditional oven and microwave oven treatments for disrupting lignocellulosic structures. The substrates tested were Jatropha seed cake and sweet sorghum bagasse. In recent years, Jatropha curcas also known as physic nut or purging nut has attracted extensive attention due to its several unique characteristics. Similarly, sweet sorghum has the potential to provide great value to energy sectors and food industries being that the entire plant is rich in various sugars and nutrients. Both crops can adapt to various climates, and can withstand extended drought conditions compared to other crops. Additionally, both Jatropha seed cakes and sweet sorghum bagasse are good sources of lignin and carbohydrates, which could be used for production of biofuels only if the sugars can be unlocked. Several treatment methods such as mechanical, physical, chemical and biological treatments have been reported to breakdown the cellulosic structure of biomass. However, other low cost and quicker methods, such as ovenpretreatment and microwave irradiation have not been evaluated for Jatropha seed cake and Sweet Sorghum Bagasse (SSB), respectively. Composition change of Jatropha seed cake samples was evaluated upon lime pretreatment at 100 oC with different parameters. With a lime dose of 0.2 g and a water content of 10 ml per gram of cake and a treatment period of 1 h, 38.2 ± 0.6% of lignin was removed. However, 65 ± 16% of hemicellulose was also lost under this condition. For all the treatments tested, cellulose content was not affected by lime supplementation. Through further examining total reducing sugar (TRS) release by enzymatic hydrolysis after lime pretreatment, results indicated that 0.1 g of lime and 9 ml of water per gram of cake and 3 h pretreatment produced the maximal 68.9% conversion of cellulose. Without lime pretreatment, the highest cellulose conversion was 33.3%. Finally, this study shows that Jatropha seed cake samples could be hydrolyzed by enzymes. Even though the cellulose content was not high for this Jatropha cake sample, the fractionation by lime presented in this study opened the door for other applications, such as removal of lignin and toxicity for use as animal feed and fertilizer. The microwave radiation pretreatment of SSB was evaluated with or without lime (0.1 g/g bagasse) at 10 ml water/g bagasse for 4 min. TRS release over 72-h enzymatic hydrolysis was different for samples treated differently and at different solid loadings. The TRS concentration was increased by 2 and 5-fold from 0 to 24 hours in non lime-pretreated and lime-pretreated samples, respectively. Further incubation of samples for 48 and 72 h did not result in increased TRS. Comparing different solid loadings of samples treated with or without lime, 1% solid content resulted in 1.4 times higher TRS increase than that of 5% solid concentration. Therefore, lime was effective in disintegrating lignocellulosic structures and making cellulose more accessible for saccharification. Higher solid loadings which can lead to higher sugar concentrations are desired for downstream biofuel production. But, as shown in this study, higher concentration of bagasse samples decreased rate of cellulose hydrolysis due to poorer mixing efficiency and hindrance to interactions between enzymes and solid materials. Thus, an optimal solid content needs to be determined for maximal cellulose hydrolysis and for preparing the hydrolysates for downstream processes, either bioethanol or lipid production.
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Mancini, Gabriele. "Different approaches to enhance the biogas production from the anaerobic digestion of lignocellulosic materials." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1250/document.
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La production de biogaz par digestion anaérobie (DA) est une technologie renouvelable de longue date et un bioprocessus en croissance continue. Les matériaux lignocellulosiques (ML) présentent plusieurs caractéristiques qui les rendent particulièrement attrayants parmi les substrats couramment employés dans les bioréacteurs anaérobies. En particulier, les ML sous la forme de résidus agricoles ont été reconnus comme la matière première la plus appropriée pour la production de biométhane en raison de leur haute disponibilité, de leur faible coût, de leur durabilité et de leur absence de concurrence directe avec la production alimentaire. Cependant, leur récurrence à la conversion biologique entrave leur application pour la production à grande échelle de biogaz et nécessite une étape de prétraitement pour améliorer la dégradabilité microbienne. En plus des défis posés par la structure lignocellulosique, la fourniture de oligo-éléments (OE) a souvent été jugée insuffisante dans les digesteurs de biogaz. La croissance microbienne dépend de la disponibilité et de la quantité optimale de plusieurs OE spécifiques, constituants essentiels des cofacteurs dans les systèmes enzymatiques impliqués dans la biochimie de la formation de méthane. Différents prétraitements chimiques, à savoir le N-méthylmorpholine-N-oxyde (NMMO), le procédé organosolv et un prétraitement alcalin à l'aide de NaOH ont été étudiés pendant plusieurs expériences en lots pour améliorer les rendements de production de biogaz différents peau, coquille de fève de cacao et paille de blé). Les changements dans la cristallinité de la cellulose, la valeur de rétention d'eau et la composition chimique ont été évalués pour mieux évaluer l'effet des différents prétraitements étudiés sur la structure lignocellulosique. En outre, l'addition de différentes doses de Fe, Co, Ni et Se sur la DA de paille de riz a été étudiée, évaluant l'influence de l'origine de l'inoculum, ainsi que la performance et l'effet synergique de la combinaison d'un prétraitement alcalin avec addition de trace éléments avant la DA de paille de riz. La biodisponibilité des OE lors des tests de potentiel de biométhane par lots a également été évaluée en appliquant une technique d'extraction séquentielle. Les trois prétraitements étudiés étaient des méthodes efficaces pour améliorer la production de biométhane à partir des LM utilisées. Le rendement en biométhane de la DA de paille de riz a augmenté de 82 et 41% respectivement après le NMMO et le prétraitement organosolv. Comparé à la même expérience, le prétraitement NMMO, organosolv et NaOH a permis d'améliorer la DA de la paille de blé, ce qui affecte différemment la composition chimique de la LM brute. Le rendement cumulatif de production de biométhane de 274 mL de CH4/g VS obtenu avec la paille de blé non traitée a été augmenté de 11% par le prétraitement du NMMO et de 15% par le prétraitement organosolv et alcalin. Les coquilles de noisettes et de fèves de cacao, qui n'avaient jamais été étudiées auparavant comme substrats AD, présentaient un bon potentiel de production de biogaz, avec des rendements cumulatifs de biométhane respectivement de 223-261 et 199-231 mL CH4/g VS pour les charges non traitées. Cependant, les prétraitements à la fois de NMMO et d'organosolv n'ont pas conduit à une amélioration significative des rendements de production de biométhane de ces deux LM. La supplémentation des OE n'a eu qu'un effet mineur par rapport aux méthodes de prétraitement. L'ajout de Fe, Co, Ni et Se n'a pas entraîné d'amélioration significative de la DA de paille de riz, alors que l'utilisation du prétraitement de NaOH au cours de la même expérimentation a provoqué une augmentation considérable de la DA, augmentant la production de biogaz de 21%. L'effet négligeable observé après la supplémentation des OE sur la paille de riz pourrait être lié à sa structure lignocellulosique complexe qui nécessite une amélioration de l'hydrolyse qui est l'étape limitanteBiogas production via anaerobic digestion (AD) is a long-standing renewable technology and a continuously growing bioprocess worldwide. Lignocellulosic materials (LMs) present several features that make them especially attractive among the organic substrates commonly employed in anaerobic bioreactors. In particular, LMs under the form of agricultural residues have been acknowledged as the most suitable feedstock for biomethane production due to their high availability, low cost, sustainability and no direct competition with food and feed production. However, their recalcitrance to biological conversion hinders their application for full-scale production of biogas and requires a pretreatment step to improve the LM microbial degradability. In addition to the challenges posed by the lignocellulosic structure, the supply of trace elements (TEs) has often been found insufficient within biogas digesters. The microbial growth depends on the availability and optimal amount of several specific TEs, which are essential constituents of cofactors in enzyme systems involved in the biochemistry of methane formation. Different chemical pretreatments, namely the solvent N-methylmorpholine-N-oxide (NMMO), the organosolv process, and an alkaline pretreatment using NaOH, were investigated during several batch experiments to enhance the biogas production yields from different LMs (i.e. rice straw, hazelnut skin, cocoa bean shell and wheat straw). Changes in the cellulose crystallinity, water retention value and chemical composition were assessed to better evaluate the effect of the different pretreatments studied on the lignocellulosic structure. Furthermore, the addition of different doses of Fe, Co, Ni and Se on the AD of rice straw was studied, evaluating the influence of the inoculum origin, as well as the performance and synergistic effect of combining an alkaline pretreatment with the addition of trace elements prior to the AD of rice straw. The bioavailability of TEs during batch biomethane potential tests was also evaluated applying a sequential extraction technique. The three pretreatments investigated were effective methods for enhancing the biomethane production from the employed LMs. The biomethane yield from the AD of rice straw increased by 82 and 41% after the NMMO and organosolv pretreatment, respectively. When compared within the same experiment, the NMMO, organosolv and NaOH pretreatment were able to improve the AD of wheat straw, differently affecting the chemical composition of the raw LM. The cumulative biomethane production yield of 274 mL CH4/g VS obtained with the untreated wheat straw was enhanced by 11% by the NMMO pretreatment and by 15% by both the organosolv and alkaline pretreatment. Hazelnut skin and cocoa bean shell, which were never investigated before as AD substrates, showed a good potential for biogas production, with cumulative biomethane yields of 223-261 and 199-231 mL CH4/g VS, respectively, for the untreated feedstocks. However, both NMMO and organosolv pretreatments did not lead to a significant enhancement of the biomethane production yields from these two LMs. The TE supplementation had only a minor effect compared to the pretreatment methods. The addition of Fe, Co, Ni and Se did not result in a significant improvement of the AD of rice straw, whereas the use of the NaOH pretreatment, during the same batch experiment, caused a considerable enhancement of the AD, increasing the biogas production yield by 21%. The negligible effect observed after TE supplementation on the AD of rice straw could be linked to its complex lignocellulosic structure, which requires an enhancement of the hydrolysis, which, rather than the methanogenesis, is the rate-limiting step
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Du, Bowen Chambliss C. Kevin. "Effect of varying feedstock-pretreatment chemistry combinations on the production of potentially inhibitory degradation products in biomass hydrolysates." Waco, Tex. : Baylor University, 2009. http://hdl.handle.net/2104/5319.
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Ricciotti, Federica. "Plasma based pretreatments of lignocellulosic biomass for Biogas and Bioethanol production." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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The aim of this project provides the use of a lignocellulosic biomass microbubble reactor in order to analyse the pre-treatment of cellulose and maize for, respectively, Bioethanol and Biogas production. Because of lignin recalcitrance, dielectric barrier discharge plasma is used to improve the solubility and accessibility of these feedstock. The novel reactor combined with this plasma source generates highly oxidative species (O3, H2O2, and OH radicals) close to the gas-liquid interface. The cellulose has been treated under different conditions such as treatment time (30 min, 60 min, 90 min and 120 min) and pH buffer solution (pH 3, pH 7 and pH 9). The maize biomass has been reacted under 5 different conditions (Control sludge, Untreated raw maize, Plasma treated washed maize, Plasma treated unwashed maize, Bubble treated unwashed maize). The optimal operating condition, for cellulose biomass, that produced the highest glucose concentration results with pH 3 and with 30 min treatments. On the other hand, maize samples treated with plasma, both washed and unwashed, generate more biogas than bubble treatment, control sludge or untreated raw maize.
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Moharreri, Ehsan. "Optimization, Scale Up and Modeling CO2-Water Pretreatment of Guayule Biomass." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1313013654.
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Ruffell, John. "Pretreatment and hydrolysis of recovered fibre for ethanol production." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1369.
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Energy utilization is a determining factor for the standards of living around the world, and the current primary source of energy is fossil fuels. A potential source of liquid fuels that could ease the strain caused by diminishing petroleum resources is bioethanol.
Effective exploitation of biomass materials requires a pretreatment to disrupt the lignin and cellulose matrix. The pretreatment utilized for this research was oxygen delignification, which is a standard process stage in the production of bleached chemical pulp.
The model substrate utilized as a feedstock for bioethanol was recovered fibre. An analysis of the substrates digestibility resulted in a hexose yield of approximately 23%, which justified the need for an effective pretreatment.
An experimental design was performed to optimize the delignification conditions by performing experiments over a range of temperature, caustic loadings, and reaction times. Equations were developed that outline the dependence of various response parameters on the experimental variables. An empirical model that can predict sugar concentrations from enzymatic hydrolysis based on the Kappa number, enzyme loading, and initial fibre concentration was also developed.
A study of hydrolysis feeding regimes for untreated recovered fibre (87 Kappa), pretreated recovered fibre (17 Kappa), and bleached pulp (6 Kappa) showed that the batch feeding regime offers reduced complexity and high sugar yields for lower Kappa substrates.
In order to evaluate the possibility of lignin recovery, the pH of delignification liquor was reduced by the addition of CO₂ and H₂SO₄, resulting in up to 25% lignin yield. An experiment that looked at effect of post-delignification fibre washing on downstream hydrolysis found that a washing efficiency of approximately 90% is required in order to achieve a hexose sugar yield of 85%.
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Teghammar, Anna. "Biogas Production from Lignocelluloses : Pretreatment, Substrate Characterization, Co-digestion and Economic Evaluation." Doctoral thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3654.
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Biogas production from organic materials can be used as a renewable vehicle fuel, provide heat and generate electricity and can thereby reduce the greenhouse gas emissions. This thesis focuses on the biogas production based on lignocelluloses. There is an abundant availability of lignocelluloses, constituting 50% of the total biomass worldwide. However, the biomass recalcitrance limits the microbial degradation as well as the biogas production from these types of materials. In the present work different pretreatment methods have been performed in order to decrease the biomass recalcitrance and improve the biogas production. Steam explosion pretreatment, together with the addition of sodium hydroxide and hydrogen peroxide, has been performed on lignocellulosic-rich paper tube residuals. The pretreatment has resulted in methane yields of up to 493 NmL/gVS, which is an increase by 107% compared with untreated material. Furthermore, the use of an organic solvent, N-methylmorpholine-N-oxide (NMMO), was evaluated as a pretreatment method for spruce (both chips and milled), rice straw, and triticale straw. The NMMO pretreatment resulted in 202, 395, 328, and 362 NmL CH4/g carbohydrates produced of these substrates, respectively, corresponding to an increase of between 400-1,200% compared with the untreated version of the same material. Moreover, the paper tube residuals have been co-digested with an unstable nitrogen-rich substrate mixture, mainly based on municipal solid waste. The addition of the lignocellulosic-rich paper tubes in a co-digestion process showed stabilizing effects and prevented the accumulation of volatile fatty acids with a subsequent reactor failure. Additionally, synergistic effects have been found leading to between 15-33% higher methane yields when paper tubes were added to the co-digestion process compared with the yields calculated from the methane potentials of the two substrates. Substrate characterization analysis can be used to study the changes on the lignocellulosic components after the pretreatment, relating the changes to the performance in the anaerobic digestion. Increased accessible surface area, measured by the Simons’ stain and the enzymatic adsorption methods, as well as decreased crystallinity, determined by using the Fourier Transform Infrared Spectroscopy, can all be linked to improved biogas production after pretreatment. Finally, the NMMO pretreatment on forest residues has been financially evaluated for an industrial scale process design. The base case that was evaluated simulated a case where pretreated forest residues were co-digested with the organic fraction of municipal solid waste to obtain optimal nutritional balance for the anaerobic digestion. This process has been found to be economically feasible with an internal rate of return of 20.7%.Akademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 24 maj 2013, klockan 10.00 i KA,Kemigården 4, Göteborg
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Avery, Greg M. "A Life Cycle Assessment of Ionic Liquid Pretreatment for Lignocellulosic Biomass." University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1481273168926691.
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Periyasamy, Karthik. "Production de bioéthanol à partir de biomasse lignocellulosique en utilisant des enzymes cellulolytiques immobilisées." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI024/document.
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L'objectif global de cette étude était de produire du bioéthanol à partir de biomasse lignocellulosique en utilisant des enzymes libres ou immobilisées de type xylanase, cellulase et β-1,3-glucanase. L'isolement de la souche AUKAR04 de Trichoderma citrinoviride a permis de produire par fermentation solide ces trois enzymes à un taux de 55 000, 385 et 695 UI / gd, respectivement. L’activité biochimique des enzymes libres a été caractérisée en faisant varier différents paramètres : pH, température et concentration en cations métalliques, et les paramètres cinétiques correspondants ont été identifiés. Par la suite, les enzymes ont été immobilisées en phase solide, soit sous forme d’agrégats sans support de type (combi-CLEA), soit par association avec des nanoparticules magnétiques bifonctionnalisées (ISN-CLEA). Ces dernières ont fourni de meilleures performances en termes de stabilité thermique, d’activité et d’aptitude à réutilisation après un temps de conservation prolongé. Le substrat végétal utilisé (SCB : bagasse de canne à sucre) a été prétraité chimiquement par cuisson à l'ammoniac, permettant d’éliminer 40% de la lignine initiale tout en préservant 95% de glucane, 65% de xylane et 41% d'arabinane. L’hydrolyse enzymatique du substrat prétraité a permis une conversion de la cellulose en 87% de glucose, et une conversion des hémicelluloses (arabinoxylanes) en 74% de xylose et 64% d'arabinose, chiffres notoirement supérieurs à l'activité des enzymes libres. L'analyse chimique et structurale du substrat a été faite par spectrométrie ATR-FTIR et DRX, et par analyse TGA. L’étude FTIR a prouvé l’efficacité du traitement enzymatique en montrant que les hémicelluloses et la cellulose subissent une dépolymérisation partielle par l’action simultanée des trois enzymes immobilisées dans les ISN-CLEA. L’étude TGA a montré que la stabilité thermique des échantillons prétraités à l'ammoniac puis traités par des enzymes est notoirement améliorée. L’analyse DRX a montré que l'indice de cristallinité du substrat prétraité à l’ammoniac puis traité par l'ISN-CLEA a augmenté de 61,3 ± 1%, par rapport au substrat avant traitement enzymatique. La fermentation par la levure Saccharomyces cerevisiae LGP2Y1 utilisée en monoculture, à partir d’un hydrolysat enzymatique contenant 103,8 g / L de glucose, a produit 42 g / L d'éthanol en 36 h de fermentation. Le rendement métabolique global atteint ainsi environ 79% du rendement théorique. La fermentation en co-culture avec Saccharomyces cerevisiae LGP2Y1 et Candida utilis ATCC 22023 d’un hydrolysat à 107,6 g / L de glucose et 41,5 g / L de xylose a produit 65 g / L d'éthanol en 42 h de fermentation. Ainsi, en co-culture fermentaire, le rendement métabolique global atteint environ 88 % du rendement théoriqueThe overall objective of the study was to produce bioethanol from lignocellulosic biomass by using free and immobilized xylanase, cellulase and β-1, 3-glucanase. Specifically, this study was focused on the isolation of Trichoderma citrinoviride strain AUKAR04 and it produces xylanase (55,000 IU/gds), Cellulase (385 IU/gds) and β-1, 3-glucanase (695 IU/gds) in solid state fermentation. Then the free enzymes were biochemically characterized such as effect of pH, temperature and metal ion concentration and kinetics parameters. Then the enzymes were subjected to two types of immobilization using carrier-free co-immobilization (combi-CLEAs) method and immobilized on bifunctionalized magnetic nanoparticles (ISN-CLEAs) with higher thermal stability, extended reusability and good storage stability. Liquid ammonia pretreatment removed 40% lignin from the biomass and retained 95% of glucan, 65% of xylan and 41% of arabinan in sugarcane bagasse (SCB). SCB was enzymatically hydrolyzed and converted to 87% glucose from cellulose and 74% of xylose, 64% of arabinose from the hemicelluloses which is remarkably higher than the activity of the free enzymes. Chemical and structural analysis of SCB was done by ATR-FTIR, TGA and XRD. FTIR result showed a successful pretreatment of the SCB raw material. It showed that hemicelluloses and cellulose are partially depolymerized by the action of xylanase, cellulase and β-1,3-glucanase in ISN-CLEAs. TGA studies showed that the thermal stability of the ammonia pretreated and enzymatically treated samples have improved remarkably. XRD results showed that the crystallinity index of the ISN-CLEAs treated SCB increased to 61.3±1% when compared to the ammonia-treated SCB. Mono-culture fermentation using Saccharomyces cerevisiae LGP2Y1 utilized SCB hydrolysate containing 103.8 g/L of glucose and produced 42 g/L ethanol in 36 h of fermentation. The overall metabolic yield achieved was about 79% of theoretical yield. Co-culture fermentation using Saccharomyces cerevisiae LGP2Y1 and Candida utilis ATCC 22023 utilized SCB hydrolysate containing 107.6 g/L of glucose and 41.5 g/L xylose and produced 65 g/L ethanol in 42 h of fermentation. The overall metabolic yield in co-culture fermentation achieved was about 88 % of the theoretical yield
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Auer, Lucas. "Vers la maîtrise des communautés microbiennes lignocellulolytiques : impact de la source d'inoculum et du prétraitement du substrat sur le fonctionnement des communautés." Thesis, Toulouse, INSA, 2016. http://www.theses.fr/2016ISAT0050/document.
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La lignocellulose est le composant principal des parois végétales et donc le biopolymère végétal le plus abondant sur Terre. Sa transformation en molécules d’intérêt industriel est donc une voie prometteuse pour diminuer la consommation de ressources fossiles. Au sein de la plateforme des carboxylates, la transformation de la lignocellulose repose sur l’utilisation de communautés bactériennes. Mais s’ils sont augmentés par des approches de prétraitement du substrat, les rendements sont encore faibles. Afin de les améliorer, nous avons ici testé les capacités de dégradations de communautés microbiennes issues de l’enrichissement de rumen bovin et d’intestin de termites. Afin de caractériser l’effet de la source d’inoculum et du prétraitement du substrat sur le fonctionnement des communautés sélectionnées, une approche de séquençage 16S a été utilisée. Celle-ci a permis la comparaison des compositions de communautés obtenues, mais également de leurs dynamiques au cours de la transformation du substrat lignocellulosique. Les conditions de culture imposées semblent avoir un effet très fort sur la composition des communautés sélectionnées puisque malgré leurs différences, celles-ci présentent d’importantes similitudes et sont bien plus proches que ne l’étaient les inocula initiaux. Enfin, les communautés associées à la dégradation du substrat lignocellulosique montrent des dynamiques très marquées, caractérisées par une importante baisse de diversité et la dominance de quelques populations bactériennes seulement lors du maximum de dégradationLignocellulose is the main component of vegetal cell wall and is thus the most abundant biopolymer on Earth. Its conversion into industrially relevant molecules is of concern to reduce fossil resources consumption. In the dedicated carboxylates platform, lignocellulose conversion relies on the metabolic potential of microbial consortia, but lignocellulose transformation rates can still be improved, despite substrate pretreatment approaches. In order to improve these rates, we here tested the transformation capacities of microbial communities originated from cow rumen and termite guts. 16S sequencing was used to characterize the effects of inoculum source and substrate pretreatment on the selected communities’ functioning. It allowed the comparison between obtained communities, but also between their dynamics during lignocellulose transformation. Culture conditions appeared to have a strong effect on the selected communities, which presented high similarities despite differences between initial inocula. Finally, communities associated to lignocellulose degradation showed marked dynamics, with a strong decrease in diversity indexes and the dominance of a few bacterial populations during the degradation maximum
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Loku, Umagiliyage Arosha. "PRETREATMENT OF SWEET SORGHUM BAGASSE TO IMPROVE ENZYMATIC HYDROLYSIS FOR BIOFUEL PRODUCTION." OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1259.
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With recent emphasis on development of alternatives to fossil fuels, sincere attempts are being made on finding suitable lignocellulosic feedstocks for biochemical conversion to fuels and chemicals. Sweet Sorghum is among the most widely adaptable cereal grasses, with high drought resistance, and ability to grow on low quality soils with low inputs. It is a C4 crop with high photosynthetic efficiency and biomass yield. Since sweet sorghum has many desirable traits, it has been considered as an attractive feedstock. Large scale sweet sorghum juice extraction results in excessive amounts of waste sweet sorghum bagasse (SSB), which is a promising low cost lignocellusic feed stock. The ability of two pretreatment methods namely conventional oven and microwave oven pretreatment for disrupting lignocellulosic structures of sweet sorghum bagasse with lime [Ca(OH)2] and sodium hydroxide [NaOH] was evaluated. The primary goal of this study was to determine optimal alkali pretreatment conditions to obtain higher biomass conversion (TRS yield) while achieving higher lignin reduction for biofuel production. The prime objective was achieved using central composite design (CCD) and optimization of biomass conversion and lignin removal simultaneously for each alkali separately by response surface method (RSM). Quadratic models were used to define the conditions that separately and simultaneously maximize the response variables. The SSB used in this study was composed of cellulose, hemicellulose, and lignin in the percentage of 36.9 + 1.6, 17.8 + 0.6, and 19.5 + 1.1, respectively. The optimal conditions for lime pretreatment in the conventional oven at 100 °C was 1.7 (% w/v) lime concentration (=0.0024 molL-1), 6.0% (w/v) SSB loading, 2.4 hr pretreatment time with predicted yields of 85.6% total biomass conversion and 35.5% lignin reduction. For NaOH pretreatment, 2% (w/v) alkali (=0.005 molL-1), 6.8% SSB loading and 2.3 hr duration was the optimal level with predicted biomass conversion and lignin reduction of 92.9% and 50.0%, respectively. More intensive pretreatment conditions removed higher amount of hemicelluloses and cellulose. Microwave based pretreatments were carried out in a CEM laboratory microwave oven (MARS 6-Xpress Microwave Reactions System, CEM Corporation, Matthews, NC) and with varying alkali concentration(0.3 - 3.7 % w/v) at varying temperatures (106.4 - 173.6 °C), and length of time (6.6 - 23.4 min). The NaOH pretreatment was optimized at 1.8 (% w/v) NaOH, 143 °C, 14 min time with predicted yields of 85.8% total biomass conversion and 78.7% lignin reduction. For lime pretreatment, 3.1% (w/v) lime, 138 °C and 17.5 min duration was the optimal level with predicted biomass conversion and lignin reduction of 79.9% and 61.1%, respectively. Results from this study were further supported by FTIR spectral interpretation and SEM images.
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Orejuela, Lourdes Magdalena. "Lignocellulose deconstruction using glyceline and a chelator-mediated Fenton system." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/81255.
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Non-edible plant biomass (lignocellulose) is a valuable precursor for liquid biofuels, through the processes of pretreatment and saccharification followed by fermentation into products such as ethanol or butanol. However, it is difficult to gain access to the fermentable sugars in lignocellulose, and this problem is principally associated with limited enzyme accessibility. Hence, biomass pretreatments that destroy native cell wall structure and allows enzyme access are required for effective biomass conversion techniques. This research studied two novel pretreatment methods on two wood species: 1) a deep eutectic solvent (DES) that, under heat, swells lignocellulose and partially solubilizes cell wall materials by causing breakage of lignin-carbohydrate linkages and depolymerization of the biomass components, and 2) a chelator-mediated Fenton reaction (CMF) that chemically modifies the nanostructure of the cell wall through a non-enzymatic cell wall deconstruction. After pretreatment, utilizing analytical techniques such as nuclear magnetic spectroscopy, wide angle x-ray scattering, and gel permeation chromatography, samples were analyzed for chemical and structural changes in the solubilized and residual materials.
After single stage DES (choline-chloride-glycerol) and two stage, CMF followed by DES pretreatments, lignin/carbohydrate fractions were recovered, leaving a cellulose-rich fraction with reduced lignin and hemicellulose content as determined by compositional analysis. Lignin and heteropolysaccharide removal by DES was quantified and the aromatic-rich solubilized biopolymer fragments were analyzed as water insoluble high molecular weight fractions and water-ethanol soluble low molecular weight compounds. After pretreatment for the hardwood sample, enzyme digestibility reached a saccharification yield of 78% (a 13-fold increase) for the two stage (DES/CMF) pretreated biomass even with the presence of some lignin and xylan remained on the pretreated fiber; only a 9-fold increase was observed after the other sequence of CMF followed by DES treatment. Single stage CMF treatment or single stage DES pretreatment improved 5-fold glucose yield compared to the untreated sample for the hardwood sample. The enhancement of enzymatic saccharification for softwood was less than that of hardwoods with only 4-fold increase for the sequence CMF followed by DES treatment. The other sequence of treatments reached up to 2.5-fold improvement. A similar result was determined for the single stage CMF treatment while the single stage DES treatment reached only 1.4-fold increase compared to the untreated softwood. Hence, all these pretreatments presented different degrees of biopolymer removal from the cell wall and subsequent digestibility levels; synergistic effects were observed for hardwood particularly in the sequence DES followed by CMF treatment while softwoods remained relatively recalcitrant. Overall, these studies revealed insight into two novel methods to enhance lignocellulosic digestibility of biomass adding to the methodology to deconstruct cell walls for fermentable sugars.Ph. D.
Wood is a valuable material that can be used to produce liquid biofuels. Wood main components are biopolymers cellulose, hemicellulose and lignin that form a complex structure. Nature has locked up cellulose in a protective assembly that needs to be destroyed to gain access to cellulose, convert it to glucose and then ferment it to bioalcohol. This process is principally associated with limited enzyme accessibility. Therefore, biomass pretreatments that deconstruct native cell wall structure and allow enzyme access are required for effective biomass conversion techniques. This research studied two novel pretreatment methods on two wood species: 1) a deep eutectic solvent called glyceline that, under heat, swells wood and partially solubilizes cell wall materials by causing breakage of bonds and converting it into smaller molecules (monomers and oligomers), and 2) a chelator-mediated Fenton system (CMF) that chemically modifies the structure of the cell wall. Pretreatments were tested individually and in sequence in sweetgum and southern yellow pine. After pretreatments, utilizing analytical techniques, fractions were investigated for chemical and structural changes in the solubilized and residual materials. Treated wood samples were exposed to enzymatic conversion. A maximum 78% of glucose yield was obtained for the glyceline followed by CMF pretreated wood. For yellow pine only a 24% of glucose yield was obtained for the CMF followed by glyceline treatment. All these pretreatments presented different degrees of biopolymer removal from the cell wall and subsequent enzyme conversion levels. Overall, these studies revealed insight into two novel methods to enhance wood conversion adding to the methodology to deconstruct cell walls for fermentable sugars.
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Kim, Tae Hyun Lee Yoon Y. "Bioconversion of lignocellulosic material into ethanol pretreatment, enzymatic hydrolysis, and ethanol fermentation /." Auburn, Ala., 2004. http://repo.lib.auburn.edu/EtdRoot/2004/FALL/Chemical_Engineering/Dissertation/KIM_TAE_24.pdf.
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Yan, Lishi. "Kinetic characterization of hot water and dilute acid pretreatment of lignocellulosic biomass." Thesis, Washington State University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3628899.
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Acidic aqueous-phase pretreatment is a promising approach that has been directed at maximizing intermediates yields (e.g. sugars, sugar degradation products, and lignin) from biomass for fuel and chemical production. This dissertation explores the kinetic fundamentals of biomass hydrolysis in acidic aqueous-phase with different catalysts (e.g. sulfuric acid, metal chlorides), operating conditions (e.g. temperature, time pressure), and equipment configurations (e.g. batch, flowthough).
The kinetic analysis revealed that crystalline cellulose is insusceptible to hydrolysis compared with agarose at low temperature (e.g.140 °C), while it decomposed rapidly at elevated temperature (e.g. 220 °C). Higher temperature with reduced time was desirable for glucose production whereas lower temperature with prolonged time was preferred for xylose generation. In acidic conditions, furfural and levulinic acid were stable whereas 5-hydroxymethylfurfural was susceptible to decomposition with high rate constant. MgCl2 can promote the cleavage of C-O-C bond in polysaccharides (e.g. agarose) and enhance the subsequent dehydration reaction to 5-hydroxymethylfurfural. Unlike transition metal chlorides and H2SO4, MgCl2 has little ability to induce retro aldol and rehydration reactions to generate byproducts like lactic acid and levulinic acid. Mg2+ possessing hgiher activity than other alkali and alkaline earth metal chlorides (Na+ and Ca2+) resulted in 40.7% yield and 49.1% selectivity of 5-hydroxymethylfurfural.
Dissolution of biomass was significantly enhance using acidic hot water flowthrough pretreatment at 200—280°C. Significant cellulose removal accompanied with the transformation of cellulose I to cellulose II and amorphous cellulose were observed when temperature was above 240 °C for water-only and 220 °C for dilute acid. Approximately100% of the xylan and ∼90% of the cellulose were solubilized and recovered. Up to 15% of the lignin was solubilized, while the remaining lignin was insoluble. Over 90% sugar yields were obtained from pretreated whole slurries using less than 10 FPU/g cellulase plus hemicellulase enzyme.
A kinetic model was developed to depict the biomass degradation in flowthrough system. This model predicted the sugar generation more precisely than the conventional homogeneous first-order reaction models. Mass transfer limitations were minimized using 4mm biomass particle sizes with 4g biomass loading at 25mL/min flow rate, produced hydrolyzate slurries with 13g/L potential sugar concentrations.
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Sathitsuksanoh, Noppadon. "Lignocellulose Saccharification via Cellulose Solvent Based Fractionation Followed by Enzymatic Hydrolysis: the Last Obstacle to Integrated Biorefineries." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77259.
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The production of biofuels and biobased products from low-cost abundant renewable non-food lignocellulosic biomass will be vital to sustainable development because it will bring benefits to the environment, the economy, and the national security. The largest technical and economic challenge for emerging biorefineries is cost-effective release of fermentable sugars from recalcitrant structure of lignocellulosic biomass.
Cellulose- and organic-solvent-based lignocelluloses fractionation (COSLIF) technology was employed to overcome biomass recalcitrance. Surface response methodology (SRM) showed that optimal COSLIF pretreatment conditions were 85% (w/v) H₃PO₄ and ~50 °C, regardless of moisture contents in biomass from 5-15% (w/w) for common reed. Under these conditions, the pretreated biomass was hydrolyzed fast with high glucan digestibilities at low enzyme loadings (i.e., one FPU of cellulase per gram of glucan). Crystallinity index (CrI) measurements by X-ray diffraction (XRD) and cross polarization/magic angle spinning (CP/MAS) ¹³C nuclear magnetic resonance (NMR), and cellulose accessibility to cellulase (CAC) determinations of COSLIF-pretreated biomass confirmed that highly ordered hydrogen-bonding networks in cellulose fibers of biomass were disrupted through cellulose dissolution in a cellulose solvent. This disruption of hydrogen bonding networks among cellulose chains resulted in a drastic increase in CAC values. Fourier transform infrared (FTIR) analyses on COSLIF-pretreated biomass revealed conformational changes in specific hydrogen bonding among cellulose chains due to COSLIF.
While CrI is believed to be a key substrate characteristic that impacts enzymatic cellulose hydrolysis, studies in this thesis showed CrI values varied greatly depending on measurement techniques, calculation approaches, and sample preparation conditions. A correlation between CAC values and glucan digestibility of pretreated biomass showed that substrate accessibility is a key substrate characteristic impacting enzymatic cellulose hydrolysis.
In summary, COSLIF can effectively overcome biomass recalcitrance. The resulting pretreated biomass has high CAC values, resulting in fast hydrolysis rates and high enzymatic glucan digestibilities of COSLIF-pretreated biomass at low enzyme usage.Ph. D.
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Hassanpour, Morteza. "Biorefining of sugarcane bagasse based on acid-catalysed glycerol pretreatment." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/207573/1/Morteza_Hassanpour_Thesis.pdf.
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The thesis investigated biorefining of sugarcane bagasse into value-added products. A glycerol-based fractionation method was developed at laboratory and pilot scales to convert sugarcane bagasse into fermentable sugar and high-quality lignin. The fermentable sugar was used for microbial oil production with applications in biofuel, biochemical, food and feed industries. The generated lignin had physico-chemical properties suitable for biochemical and polymer production. The thesis proposes methods to generate new revenue streams for Australian sugarcane industry.
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Aghazadeh, Mahdieh. "The Effect of Different Lignocellulosic Biomass and Different Pretreatment Methods on Cellulase Activity." Fogler Library, University of Maine, 2011. http://www.library.umaine.edu/theses/pdf/AghazadehM2011.pdf.
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Wang, Yumei [Verfasser], Antje [Akademischer Betreuer] Spieß, and Jochen [Akademischer Betreuer] Büchs. "Interaction of Solvents and Mechanical Pretreatment with Enzymatic Lignocellulose Hydrolysis / Yumei Wang ; Antje Spieß, Jochen Büchs." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1162498846/34.
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Tan, Xin. "Effect of Organosolv Lignin and Extractable Lignin on Enzymatic Hydrolysis of Lignocelluloses." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613752000022518.
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Wiermans, Lotte [Verfasser], Walter [Akademischer Betreuer] Leitner, and Martina [Akademischer Betreuer] Pohl. "Oxidative pretreatment and biocatalytic valorization of lignocellulosic biomass / Lotte Wiermans ; Walter Leitner, Martina Pohl." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/112733705X/34.
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Carey, Bobby D. Jr. "FIELD IMPLEMENTATION OF PHANEROCHAETE CHRYSOSPORIUM BIOMASS PRETREATMENT: FUNGAL IDENTIFICATION AND INOCULATION TECHNIQUES." UKnowledge, 2014. http://uknowledge.uky.edu/bae_etds/25.
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Scaling biological pretreatment from the bench scale to the production scale may be more economical if unsterilized feedstock are used, however these allow for microbial competition from contaminates. An accurate and rapid method for identifying the desired biological pretreatment organism is necessary to confirm the presence of the desired organism when contaminates are morphologically similar to the target organism. Traditional methods, such as visual identification, sequencing, and selective plating can be time consuming and are sometimes still inconclusive. Based on methods described in the literature, plasmid DNA containing the marker genes gus (�-glucuronidase), LacZ, and gfp (green fluorescence protein) incorporated into the lignin-degrading basidiomycete Phanerochaete chrysosporium would result in a rapid genetic test for the desired organism. The presence of these genes can be confirmed either through an X-Gluc (cyclohexylammonia salt), X-Gal histochemical assay or observing the gfp’s fluorescence by a specially equipped confocal microscope. Each reporter systems will allow for rapid, reliable identification of the target species. This study will report on the success of the transformation methods in creating a transformed fungus to be used in the context of a large-scale fermentation operation.
Additionally, a novel in-harvest lignocellulose feedstock biological pretreatment inoculation trial was performed comparing lignolytic performance between fungal inoculum application techniques. Optimization of carbohydrate availability for enhanced saccharification was determined by analyzing glucose release by treated and non-treated unsterilized switchgrass. This study also focused on identifying parameters to enhance saccharification efficacy at the farm-scale.
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Aslanzadeh, Solmaz. "Pretreatment of cellulosic waste and high rate biogas production." Doctoral thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3684.
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The application of anaerobic digestion technology is growing worldwide, mainly because of its environmental benefits. Nevertheless, anaerobic degradation is a rather slow and sensitive process. One of the reasons is the recalcitrance nature of certain fractions of the substrate (e.g., lignocelluloses) used for microbial degradation; thus, the hydrolysis becomes the rate-limiting step. The other reason is that the degradation of organic matter is based on a highly dynamic, multi-step process of physicochemical and biochemical reactions. The reactions take place in a sequential and parallel way under symbiotic interrelation of a variety of anaerobic microorganisms, which all together make the process sensitive. The first stage of the decomposition of the organic matter is performed by fast growing (hydrolytic and acid forming) microorganisms, while in the second stage the organic acids produced are metabolized by the slow growing methanogens, which are more sensitive than the acidogens; thus, methanogenesis becomes the rate-limiting step. The first part of this work evaluates the effects of a pretreatment using an organic solvent, N-methylmorpholine-N-oxide (NMMO), on cellulose-based materials in order to overcome the challenge of biomass recalcitrance and to increase the rate of the hydrolysis. NMMO-pretreatment of straw separated from the cattle and horse manure resulted in increased methane yields, by 53% and 51%, respectively, in batch digestion tests. The same kind of pretreatment of the forest residues led to an increase by 141% in the methane production during the following batch digestion assays. The second part of this work evaluates the efficacy of a two-stage process to overcome the second challenge with methanogenesis as the rate-limiting step, by using CSTR (continuous stirred tank reactors) and UASB (up flow anaerobic sludge blanket) on a wide variety of different waste fractions in order to decrease the time needed for the digestion process. In the two-stage semi-continuous process, the NMMO-pretreatment of jeans increased the biogas yield due to a more efficient hydrolysis compared to that of the untreated jeans. The results indicated that a higher organic loading rate (OLR) and a lower retention time could be achieved if the material was easily degradable. Comparing the two-stage and the single-stage process, treating the municipal solid waste (MSW) and waste from several food processing industries (FPW), showed that the OLR could be increased from 2 gVS/l/d to 10 gVS/l /d, and at the same time the HRT could be decreased from 10 to 3 days, which is a significant improvement that could be beneficial from an industrial point of view. The conventional single stage, on the other hand, could only handle an OLR of 3 gVS/l/d and HRT of 7 days.
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Simon, William E. "INVESTIGATION OF PHANEROCHAETE CHRYSOSPORIUM AND CLOSTRIDIUM THERMOCELLUM FOR IMPROVED SACCHARIFICATION OF LIGNOCELLULOSE UNDER NONSTERILE CONDITIONS." UKnowledge, 2015. http://uknowledge.uky.edu/bae_etds/35.
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Current research efforts are directed at developing competitive processes that can utilize lignocellulose as a feedstock for biorefineries. The purpose of this study was to investigate methods of processing lignocellulosic material so that its monosacharides can be more easily accessed for fermentation, the lack of which is hindering the economics and widescale adoption of lignocellulosic biorefining. The monosaccharides are of interest because they can be used by Clostridium beijerinckii downstream of P. chrysosporium and C. thermocellum in a sequential bioprocess to produce butanol. Butanol is an attractive biofuel because it can be utilized without modifying current transportation infrastructure. Butanol is also used as a starting material in organic synthesis. In the first study, the potential for C. thermocellum' s (ATCC 27405) cellulase system to operate outside its optimal temperature range in a high-solids environments was assessed by quantification of the fermentation products lactate, acetate, and ethanol and by quantification of xylose, glucose, and cellobiose remaining. Additionally, the lignin degrading white-rot fungus Phanerochaete chrysosporium RP 78 was investigated as a potential pretreatment for lignocellulose. Elevated temperatures required for Clostridium thermocellum fermentation were examined as a means to improve poor competiveness that is characteristic of P. chrysosporium on unsterile corn stover substrate.
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Dong, Y. (Yue). "Bifunctionalised pretreatment of lignocellulosic biomass into reducing sugars:use of ionic liquids and acid-catalysed mechanical approach." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526216775.
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Abstract Lignocellulosic biomass is the most abundant renewable raw material on the earth and it is so far the most suitable and promising resource for the production of biofuels to replace long-term use of fossil oil. This research aims to convert lignocellulose-based industrial residuals, fibre sludge (FS) from a pulp mill and pine sawdust (PSD) from a sawmill, into platform sugars by two different bifunctionalised pretreatments of lignocellulosic biomass. The bifunctionalised pretreatment combines the ordinary pretreatment (deconstruction) of lignocellulosic biomass with lignocellulosic polysaccharides saccharification. The outcome from both pretreatments can be further transformed into biofuels and chemicals. PSD and FS were converted into platform sugars by acid-catalysed mechanical depolymerisation in a planetary ball mill in the first part of this research. The efficiency of the conversion was mainly affected by the transferred energy caused by collisions, the total milling time, acid concentration and moisture content in the reaction. Approximately 30 wt% of the sugars was yielded from PSD and FS both in the short milling process with a low acid/substrate (A/S) concentration without any prior treatment. The second part of this research focuses upon the conversion of FS into platform sugars using hydroxyalkylimidazolium hydrogen sulphate ionic liquids (ILs). Around 29 wt% of the sugars was produced from FS using an IL/water mixture. The added water acted as a co-solvent and played a critical role in the utilisation of these ILs. The blended water reduced the viscosity of the ILs and enhanced the mass transfer between solvent and solute. In addition, the anions of the ILs provided their acidic property in an aqueous solution and offered an acidic environment for hydrolysis simultaneouslyTiivistelmä Lignosellulossapohjainen biomassa on runsaimmin saatavilla oleva ja yksi lupaavimmista raaka-aineista biopolttoaineiden valmistukseen korvaamaan fossiilisia polttoaineita. Väitöskirjassa tutkitaan teollisuuden lignoselluloosapohjaisten sivutuotteiden, selluteollisuuden kuitulietteen ja sahateollisuuden sahanpurun (mäntypuru), muuntamista sokereiksi kahdella erilaisella ns. bifunktionaalisella esikäsittelyllä, joissa yhdistyvät lignoselluloosabiomassan perinteinen esikäsittely (hajotus) ja polysakkaridien sokeroituminen. Muodostuneet sokerit voidaan edelleen muuntaa biopolttoaineiksi ja -kemikaaleiksi. Tutkimuksen ensimmäisessä vaiheessa sahanpuru ja kuituliete muunnettiin sokereiksi happokatalysoidussa mekaanisessa käsittelyssä, joka tehtiin kuulamyllyssä. Reaktiossa katalyyttisen käsittelyn tehokkuuteen vaikuttivat erityisesti jauhatuksen kineettinen energia, jauhatusaika, happokonsentraatio ja reaktioseoksen kosteus. Tulosten perusteella todettiin, että ilman lähtöaineen esikäsittelyä sekä sahanpurun että kuitulietteen sokerisaanto oli noin 30 massa% lyhyen, matalassa happokonsentraatiossa tehdyn jauhatuksen jälkeen. Tutkimuksen toisessa vaiheessa kuituliete muutettiin sokereiksi käyttämällä ionista liuotinta (IL), hydroksialkyyli-imidatsoliumvetysulfaattia. Sokerisaanto kuitulietteestä oli noin 29 massa% IL-vesiseoksessa. Vesi toimi reaktiossa apuliuottimena ja sen rooli on keskeinen ionisten liuottimien käytössä. Sekoittunut vesi laski ionisen liuottimen viskositeettia sekä edisti aineensiirtoa liuottimen ja liukenevan aineen välillä. IL:n anionit lisäsivät happamuutta vesiliuoksessa ja mahdollistivat happamat olosuhteet samanaikaiselle hydrolyysille
Abstract Biomasse aus Lignocellulose ist der am häufigsten vorkommende nachwachsende Rohstoff der Erde und wird aktuell als eine der besten Alternativen für die Produktion von Biokraftstoffen gesehen. Diese sollen langfristig die fossilen Öl-basierten Produkte ersetzen. Diese Forschungsarbeit untersucht die Herstellung von Zucker aus Lignocellulose basierten Abfällen. Faserschlamm aus der Zellstoffindustrie und Kiefern-Sägemehl aus der Holzverarbeitung wurden durch zwei unterschiedliche Bifunktionelle Vorbehandlungen aufgespalten. Diese Bifunktionelle Vorbehandlung kombiniert zwei Schritte in einem Prozess; die gewöhnliche Dekonstruktion der Biomasse und die Verzuckerung von Polysacchariden aus der Lignocellulose. Das so erzeugte Produkt dient als Ausgangsstoff für die weitere Herstellung von Biokraftstoffen und Chemikalien. Im ersten Teil dieser Forschungsarbeit wurden Kiefern-Sägemehl und Faserschlamm in einer Planeten-Kugelmühle zermahlen und gleichzeitig durch eine Säure depolymerisiert. Der Wirkungsgrad dieser säurekatalysierten mechanischen Depolymerisation wurde hauptsächlich durch die Übertragung der Reibungsenergie, der Mahldauer der Zerkleinerung, der Konzentration der Säure und der Feuchtegehalt der Proben beeinflusst. Etwa 30 wt% Zucker wurde so durch den kurzen Zermahlungsprozess aus Kiefern-Sägemehl und Faserschlamm gewonnen. Dabei wurden die Proben nicht vorbehandelt und enthielten eine geringe Säure/Probe Konzentration. Der zweite Teil der Forschungsarbeit untersucht die Umwandlung von Faserschlamm in Zucker mittels der Ionischen Flüssigkeit (ILs) Hydroxyalkyl Imidazolium Hydrogensulfat. Aus den Faserschlamm Proben konnte 29 wt% Zucker durch eine Mischung von ILs und Wasser gewonnen werden. Das zugesetzte Wasser spielte als Co-Lösemittel eine wichtige Rolle in der Nutzung der Ionischen Flüssigkeit, dessen Viskosität so reduziert wurde. Dies führte zu einem erhöhten Stoffübergang zwischen dem Lösemittel und dem Solvat. Zusätzlich sorgten die Anionen der Ionischen Flüssigkeit für ein saures Milieu in der wässrigen Lösung und ermöglichten so eine gleichzeitige Hydrolyse
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Kato, Dawn M. "APPLICATIONS OF GAS CHROMATOGRAPHY/MASS SPECTROMETRY AND CAPILLARY ELECTROPHORESIS FOR THE ANALYSIS OF LIGNOCELLULOSIC BIOMASS PRETREATMENT." UKnowledge, 2014. http://uknowledge.uky.edu/chemistry_etds/45.
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The focus of this dissertation centers on the development and applications of gas chromatography/mass spectrometry and capillary electrophoresis methodologies to quantify monomeric compositions of the β-O-4 linkages in lignin. Pretreatment is a required step in the utilization of lignocellulosic biomass for biofuels. Lignin is the target of pretreatment because it hinders the accessibility of enzymes and chemicals to cellulose. The effects of pretreatment are commonly assessed utilizing enzymatic saccharification and lignin assays. However, these techniques do not elucidate the effects of pretreatment on the monomeric make up of lignin.
The overarching hypothesis of this dissertation is that changes in individual monolignol content upon pretreatment can be observed from quantification. To test the hypothesis, a pretreatment, solution phase Fenton chemistry, was conducted on various lignocellulosic biomass feedstocks. Enzymatic saccharification studies showed a significant increase in glucose production upon Fenton pretreatment, however, lignin assays did not show a significant decrease in lignin content.
Project two of this dissertation aimed to synthesize analytical standards in order to develop a quantitative thioacidolysis technique. The successful synthesis of the three arylglycerols were conducted utilizing and epoxidation reaction scheme which was hypothesized to produce a single diastereomer, as supported by GC/MS and chiral CE analysis. Upon method development, a quantitative thioacidolysis GC/MS method was applied to untreated and Fenton treated biomass. Results from this project revealed there was no significant change in the three lignin monomers. To verify the method, quantitative thioacidolysis GC/MS method was applied to a pretreatment method known to degrade lignin, alkaline peroxide pretreatment. The results of this project showed a significant change in monolignol concentrations upon alkaline peroxide pretreatment.
Analytical degradative techniques, such as thioacidolysis, has traditionally assessed lignin as monomeric ratios. However, as this dissertation showed, upon alkaline peroxide pretreatment, no significant change was seen in the monomeric ratios, but there was a significant difference in all three monolignol concentrations. These results support the overall hypothesis that changes in individual monolignol content upon pretreatment can be observed from quantification. The works of this dissertation provides an analytical method which contributes to the elucidation of lignin.
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Wan, Caixia. "Microbial Pretreatment of Lignocellulosic Biomass with Ceriporiopsis Subvermispora for Enzymatic Hydrolysis and Ethanol Production." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1299689015.
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Ponnaiyan, Thehazhnan Konguvel Ponnaiyan. "Aspects Critical to Advancing Ionic Liquid Pretreatment Technique as a Viable Approach for Lignocellulosic Biomass Conversion." University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1471652917.
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Yavas, Sinem. "Conversion Of Lignocellulosic Biomass Into Nanofiber By Microfluidization And Its Effect On The Enzymatic Hydrolysis." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612340/index.pdf.
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Lignocellulosic biomass is under extensive investigation as a bioethanol and bio-based materials feedstock. However, the complex structural and chemical mechanisms of lignocellulosic plant, which cause resistance to deconstruction during saccharification, require a pretreatment process. In this study, raw materials (corn bran, wheat bran and wheat straw) were selected because of their production and consumption in Turkey and also their accessibilities to be used as bioethanol source. Microfluidization pretreatment (high-pressure fluidization), which stands as a new approach for nano-cellulosic fibers production, was studied at 500 bar and 2000 bar to observe the qualitative and quantitative modifications in enzymatic hydrolysis depending on its effects on lignocellulosic structure. Optimum cellulase concentrations were determined for microfluidized samples as 4.5 U/g dry biomass for wheat bran, corn bran and 6.0 U/g dry biomass for wheat straw samples for the first 150 min interval. Effective usage of solid loads were found as 5.0 %, 2.5 %, and 7.5 % (dw/v) for wheat bran, wheat straw and corn bran, respectively. X-ray diffraction and SEM results of the microfluidized samples have indicated that the pretreatment has increased crystallinity index of all the samples and resulted in a scattered structure. Comparisons with other methods (softening, dilute-acid and lime pretreatments) have shown that microfluidization is advantageous over others by reducing the time required for enzymatic hydrolysis and thus can be a promising alternative pretreatment.
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Ketsub, Napong. "Development of an integrated process for biogas production from sugarcane trash." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/235046/1/Napong_Ketsub_Thesis.pdf.
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This project is the systematic study on how to utilise sugarcane trash for biogas production using an integrated process. A suitable pretreatment for sugarcane trash preparation was successfully developed and a key microbial response was identified during anaerobic digestion of the pretreated sugarcane trash. Moreover, the pretreatment and anaerobic digestion process was designed to integrate with hydrothermal carbonisation to utilise anaerobic digestion residue for further improvement of process performance. Biogas production was improved via the proposed integrated process, which has the ability to be developed further as a commercial fuel source.
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Chang, Chen-Wei. "Bioconversion of sugarcane bagasse and soybean hulls for the production of a generic microbial feedstock." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/bioconversion-of-sugarcane-bagasse-and-soybean-hulls-for-the-production-of-a-generic-microbial-feedstock(0144bdd8-5444-468d-9f0f-50613a79be67).html.
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Lignocellulose, mostly from agricultural and forestry resources, is a potential renewable material for sustainable development of biorefineries. From previous studies, reducing sugar production through biological pretreatment involves two steps: solid-state fermentation (SSF) for delignification, followed by enzymatic hydrolysis by adding celluloytic enzymes (cellulase and xylanase etc.). In the process described in this thesis, the necessary enzymes are produced in-situ and the hydrolysis proceeds directly after the solid-state fermentation. Enzyme hydrolysis releases free amino nitrogen (FAN), reducing sugar and many other potential nutrients from the fermented materials. This method additionally avoids the need for removal of inhibitors compared with conventional chemical pretreatment processes. A range of solid-state fermentations were carried out to investigate the effect of washing procedure, particle size and nitrogen supplement on Trichoderma longibrachiatum growth. From these preliminary studies it was concluded that nitrogen supplementation is a crucial factor to improve significantly the fungi growth and production of feedstock using sugarcane bagasse as raw material. In order to evaluate the influence of environmental humidity on petri dish experiments, moist environments were investigated, with over 75% relative humidity to limit water evaporation from solid-state fermentation. The results showed that moist environments gave approximately 1.85 times the reducing sugar yield than dry environments. The process of simultaneous enzymatic hydrolysis of substrates and fungal autolysis were also studied. The degree of hydrolysis was affected by initial fermented solid to liquid ratio, temperature and pH range. The optimal conditions for subsequent hydrolysis of fermented solids were determined. The optimal solid to liquid ratio, 4% (w/w), temperature 50°C and pH 7 were established. The highest final reducing sugar, 8.9 g/L and FAN, 560 mg/L, were measured after 48 h. The fungal autolysis was identified by image analysis as well as by the consumption of nutrient and the release of free amino nitrogen and phosphorous. Solid state fermentation in a multi-layer tray bioreactor and a packed-bed bioreactor were also developed, with moist air supply for oxygen provision and heat removal. Fermented solids in the multi-layer bioreactor led to the highest subsequent hydrolysis yield on reducing sugar, FAN and Inorganic Phosphorous (IP), 222.85 mg/g, 11.56 mg/g and 19.9 mg/g, respectively. These series of fermentation experiments illustrate the feasibility for the application of consolidated bioprocessing, through simultaneous pretreatment and enzyme production as a more economic and environment-friendly process compared with those reported for chemical pretreatment followed by commercial enzyme process. A growth kinetic model regarding both growth and respiration is also proposed. Ethanol production was studied using the generic feedstock produced from sugarcane bagasse and soybean hulls. Total ethanol yield reached 0.31 mg g-1 (61.4% of theoretical yield) after 30 h of submerged fermentation. The result of subsequent fermentation has already shown the potential of the generic microbial feedstock to be used to produce varied products depending on the microorganism utilised.
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Mubazangi, Munyaradzi. "Optimization of the conversion of lignocellulosic agricultural by-products to bioethanol using different enzyme cocktails and recombinant yeast strains." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/6891.
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Thesis (MSc)--Stellenbosch University, 2011.ENGLISH ABSTRACT: The need to mitigate the twin crises of peak oil and climate change has driven a headlong rush to biofuels. This study was aimed at the development of a process to efficiently convert steam explosion pretreated (STEX) sugarcane bagasse into ethanol by using combinations of commercial enzyme cocktails and recombinant Saccharomyces cerevisiae strains. Though enzymatic saccharification is promising in obtaining sugars from lignocellulosics, the low enzymatic accessibility of the cellulose and hemicellulose is a key impediment thus necessitating development of an effective pretreatment scheme and optimized enzyme mixtures with essential accessory activities. In this context, the effect of uncatalysed and SO2 catalysed STEX pretreatment of sugarcane bagasse on the composition of pretreated material, digestibility of the water insoluble solids (WIS) fraction and overall sugar recovery was investigated. STEX pretreatment with water impregnation was found to result in a higher glucose recovery (28.1 g/ 100 bagasse) and produced WIS with a higher enzymatic digestibility, thus was used in the optimization of saccharification and fermentation. Response surface methodology (RSM) based on the 33 factorial design was used to optimize the composition of the saccharolytic enzyme mixture so as to maximize glucose and xylose production from steam exploded bagasse. It was established that a combination of 20 FPU cellulase/ g WIS and 30 IU -glucosidases/ g WIS produced the highest desirability for glucose yield. Subsequently the optimal enzyme mixture was used to supplement enzyme activities of recombinant yeast strains co-expressing several cellulases and xylanases in simultaneous saccharification and fermentations SSFs. In the SSFs, ethanol yield was found to be inversely proportional to substrate concentration with the lowest ethanol yield of 70% being achieved in the SSF at a WIS concentration of 10% (w/v). The ultimate process would however be a one-step “consolidated” bio-processing (CBP) of lignocellulose to ethanol, where hydrolysis and fermentation of polysaccharides would be mediated by a single microorganism or microbial consortium without added saccharolytic enzymes. The cellulolytic yeast strains were able to autonomously multiply on sugarcane bagasse and concomitantly produce ethanol, though at very low titres (0.4 g/L). This study therefore confirms that saccharolytic enzymes exhibit synergism and that bagasse is a potential substrate for bioethanol production. Furthermore the concept of CBP was proven to be feasible.
AFRIKAANSE OPSOMMING: Die behoefte om die twee krisisse van piek-olie en klimaatsverandering te versag, het veroorsaak dat mense na biobrandstof as alternatiewe energiebron begin kyk het. Hierdie studie is gemik op die ontwikkeling van 'n proses om stoomontplofde voorafbehandelde (STEX) suikerriet bagasse doeltreffend te omskep in etanol deur die gebruik van kombinasies van kommersiële ensiem mengsels en rekombinante Saccharomyces cerevisiae stamme. Alhoewel ensiematiese versuikering belowend is vir die verkryging van suikers vanaf lignosellulose, skep die lae ensiematiese toeganklikheid van die sellulose en hemisellulose 'n hindernis en dus is die ontwikkeling van' n effektiewe behandelingskema en optimiseerde ensiemmengsels met essensiële bykomstige aktiwiteite noodsaaklik. In hierdie konteks, was die effek van ongekataliseerde en SO2 gekataliseerde stoomontploffing voorafbehandeling van suikerriet bagasse op die samestelling van voorafbehandelde materiaal, die verteerbaarheid van die (WIS) breuk van onoplosbare vastestowwe in water (WIS), en die algehele suikerherstel ondersoek. Daar was bevind dat stoomontploffing behandeling (STEX) met water versadiging lei tot 'n hoër suikerherstel (21.8 g/ 100g bagasse) en dit het WIS met ‘n hoër ensimatiese verteerbaarheid vervaardig en was dus gebruik in die optimalisering van versuikering en fermentasie. Reaksie oppervlak metodologie (RSM), gebasseer op die 33 faktoriële ontwerp, was gebruik om die samestelling van die ‘saccharolytic’ ensiemmengsel te optimaliseer om sodoende die maksimering van glukose en ‘xylose’ produksie van stoomontplofde bagasse te optimaliseer. Daar was bevestig dat ‘n kombinasie van 20 FPU sellulase/ g WIS en 30 IU ‘ -glucosidases/ g’ WIS die hoogste wenslikheid vir glukose-opbrengs produseer het. Daarna was die optimale ensiemmengsel gebruik om ensiemaktiwiteit van rekombinante gisstamme aan te vul, wat gelei het tot die medeuitdrukking van verskillende ‘cellulases’ en ‘xylanases’ in gelyktydige versuikering en fermentasie SSFs. In die SSFs was daar bevind dat die etanol-produksie omgekeerd proporsioneel is tot substraat konsentrasie, met die laagste etanolopbrengs van 70% wat bereik was in die SSF by ‘n WIS konsentrasie van 10% (w/v). Die uiteindelike proses sal egter 'n eenmalige "gekonsolideerde" bioprosessering (CBP) van lignosellulose na etanol behels, waar die hidrolise en fermentasie van polisakkariede deur' n enkele mikroorganisme of mikrobiese konsortium sonder bygevoegde ‘saccharolytic’ ensieme bemiddel sal word. Die ‘cellulolytic’ gisstamme was in staat om vanself te vermeerder op suikerriet bagasse en gelyktydig alkohol te produseer, al was dit by baie lae titres (0.4 g/L). Hierdie studie bevestig dus dat ‘saccharolytic’ ensieme sinergisme vertoon en dat bagasse 'n potensiële substraat is vir bio-etanol produksie. Daar was ook onder meer bewys dat die konsep van CBP uitvoerbaar is.
The National Research Foundation (NRF) for financial support
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Reynolds, Wienke [Verfasser]. "Modeling and scale-up of hydrothermal pretreatment in compressible lignocellulosic biomass fixed-beds with changing properties / Wienke Reynolds." München : Verlag Dr. Hut, 2019. http://d-nb.info/1192567641/34.
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Pachón-Morales, John Alexander. "Torrefaction and grinding of lignocellulosic biomass for its thermochemical valorization : influence of pretreatment conditions on powder flow properties." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC051.
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Une technologie prometteuse pour répondre à la demande croissante en énergie renouvelable est la gazéification de biomasse lignocellulosique pour la production de biocarburants de deuxième génération. Ce procédé nécessite une alimentation en biomasse sous forme de poudre. Les problèmes de convoyage et de manipulation liés à la faible coulabilité de la biomasse broyée sont un verrou pour l’industrialisation des procédés BtL. La torréfaction comme procédé de prétraitement, en plus d'augmenter densité énergétique de la biomasse, peut influencer également les propriétés des particules obtenues après broyage, et en conséquence, l’écoulement des poudres. L'évaluation de l'écoulement des poudres de biomasse sous différentes conditions de consolidation est essentielle pour concevoir des technologies de manipulation et de convoyage efficaces.L'objectif de ce travail est d'évaluer l'effet des conditions de torréfaction et de broyage sur l’écoulement de poudres de biomasse. Une première partie consiste en une étude expérimentale dans laquelle la coulabilité d'échantillons torréfiés sous différentes intensités a été évaluée à l'aide d'un appareil de cisaillement annulaire. La coulabilité est corrélée à l'intensité de la torréfaction (mesurée par la perte de masse globale) pour deux essences différentes. La forme des particules semble être le paramètre qui influence de manière prédominante la coulabilité des poudres à l'état consolidé. La caractérisation de la coulabilité à l’état non consolidée a été effectuée à l'aide d'un tambour rotatif par l’analyse des avalanches des poudres. Des corrélations entre les caractéristiques des particules et la coulabilité sont ainsi établies. La modélisation de l'écoulement de la biomasse à l'aide de la Méthode des Éléments Discrets (DEM) constitue une deuxième partie de cette recherche. La taille submillimétrique des particules de biomasse, ainsi que leur faible densité, leur forme allongée et leur comportement cohésif sont des défis pour l’implémentation d’un modèle de réaliste d’écoulement particulaire en DEM. Un modèle DEM des particules de biomasse est mis en œuvre à l'aide d'une représentation simplifiée (assemblement de sphères) à gros grains de la forme des particules, ainsi que d'un modèle de force cohésif. Une procédure systématique de calibration des paramètres DEM permet d'obtenir un ensemble de paramètres ajustés. L'évolution expérimentale des contraintes de cisaillement d’une poudre dans un état consolidé peut alors être reproduite de façon réaliste. De même, le comportement d’avalanche des poudres dans un tambour tournant est également bien reproduit par les simulations, de façon qualitative et quantitative. Ces résultats mettent en évidence le potentiel des simulations DEM pour étudier l'effet des caractéristiques des particules, qui sont influencées par la torréfaction et les conditions de broyage, sur le comportement d'écoulement de la biomasse en poudreGasification of lignocellulosic biomass for production of second-generation biofuels is a promising technology to meet renewable energy needs. However, feeding and handling problems related to the poor flowability of milled biomass considerably hinder the industrial implementation of Biomass-to-Liquid processes. Torrefaction as pretreatment step, in addition to improving energy density of biomass, also affects the properties of the milled particles (namely size and shape) that significantly influence flow behavior. The evaluation of biomass flow characteristics under different flow conditions is essential to design efficient and trouble-free handling solutions.The aim of this work is to assess the effect of the torrefaction and grinding conditions on the biomass flow behavior. A first part consists of an experimental study in which the flow properties of samples torrefied under different intensities were obtained using a ring shear tester. Flowability is correlated to the intensity of torrefaction, as measured by the global mass loss, for two different wood species. Particle shape seems to be the predominant parameter influencing flowability of powders in a consolidated state. Characterization of non-consolidated flowability through avalanching analysis using an in-house rotating drum was also conducted. Correlations between particle characteristics and flow behavior are thus established.The modelling of biomass flow using the Discrete Element Method (DEM) constitutes a second major part of this research. Challenging aspects of biomass particle modeling are their submillimetric size, low density, elongated shape and cohesive behavior. A material DEM model is implemented using a simplified (multisphere) upscaled representation of particle shape, along with a cohesive contact model. A systematic calibration procedure results in an optimal set of DEM parameters. The experimental shear stress evolution and yield locus can then be realistically reproduced. The avalanching behavior of the powders is also well captured by simulations, both qualitatively and quantitatively. These results highlight the potential of DEM simulations to investigate the effect of particle characteristics, which are driven by torrefaction and grinding conditions, on the flow behavior of powdered biomass
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Yoo, Juhyun. "Technical and economical assessment of thermo-mechanical extrusion pretreatment for cellulosic ethanol production." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/9190.
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Doctor of PhilosophyDepartment of Grain Science and Industry
Sajid Alavi
The Renewable Fuel Standard (RFS) in the Energy Independence and Security Act of 2007 has set the goal of 36 billion gallons of annual ethanol production in the U.S. by 2022, which is equivalent to 17.5% of the current gasoline consumption in the U.S. However, corn ethanol is expected to plateau at a level of 7.3% of current gasoline consumption on an energy-equivalent basis. Thus, it is essential to utilize a variety of substrates including lignocellulosic biomass from perennial energy crops such as switch grass, crop residues such as corn and sorghum stover, and agri-industrial co-products such as soybean hulls and wheat bran. Lignocellulosic substrates have a recalcitrant nature and require a pretreatment step that is critical for efficient enzymatic hydrolysis of cellulose and hemicellulose to fermentable sugars. In this study, soybean hulls were used as a model substrate for cellulosic ethanol. A novel thermo-mechanical pretreatment process using extrusion was investigated and compared with two traditional pretreatment methods, dilute acid and alkali hydrolysis, with regard to structural changes in the lignocellulosic substrate, and glucose and ethanol yields. The effect of extrusion parameters, such as barrel temperature, in-barrel moisture and screw speed, on glucose yield from soybean hulls was determined. Optimum processing conditions were screw speed of 350 rpm, maximum barrel temperature of 80C and 40% in-barrel moisture content, resulting in 95% cellulose conversion to glucose. Compared with untreated soybean hulls, the cellulose to glucose conversion of soybean hulls increased by 69.5, 128.4 and 132.2% for dilute acid, alkali and thermo-mechanical pretreatments, respectively. Glucose and other hexose sugars such as mannose and galactose were effectively fermented by Saccharomyces cerevisiae, resulting in ethanol yields of 13.04–15.44 g/L. Fermentation inhibitors glycerol, furfural, 5-(hydroxymethyl)-2-furaldehyde (HMF) and acetic acid were found in the thermo-mechanically pretreated substrate, ranging in concentrations from 0.072–0.431, 0–0.049, 0–0.023 and 0.181–0.278 g/L, respectively, which were lower than those reported from acid hydrolyzed substrates. The economic feasibility of commercial cellulosic ethanol production processes employing dilute acid hydrolysis and thermo-mechanical pretreatment were compared using a system dynamics modeling approach. It was concluded that low feedstock cost and high sugar conversion are important factors that can make cellulosic ethanol production commercially viable. Thermo-mechanical pretreatment was a more promising technology as compared to dilute acid hydrolysis because of the lower capital and operating costs, and higher sugar conversion.
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Ishola, Mofoluwake M. "Novel application of membrane bioreactors in lignocellulosic ethanol production : simultaneous saccharification, filtration and fermentation (SSFF)." Doctoral thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3705.
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Biofuels production and utilisation can reduce the emission of greenhouse gases, dependence on fossil fuels and also improve energy security. Ethanol is the most important biofuel in the transportation sector; however, its production from lignocelluloses faces some challenges. Conventionally, lignocellulosic hydrolysis and fermentation has mostly been performed by separate hydrolysis and fermentation (SHF) or simultaneous saccharification and fermentation (SSF). SHF results in product inhibition during enzymatic hydrolysis and increased contamination risk. During SSF, suboptimal conditions are used and the fermenting organism cannot be reused. Bacterial contamination is another major concern in ethanol production, which usually results in low ethanol yield. In these studies, the above-mentioned challenges have been addressed. A novel method for lignocellulosic ethanol production ‘Simultaneous saccharification filtration and fermentation (SSFF)’ was developed. It circumvents the disadvantages of SSF and SHF; specifically, it uses a membrane for filtration and allows both the hydrolysis and fermentation to be carried out at different optimum conditions. SSFF also offers the possibility of cell reuse for several cultivations. The method was initially applied to pretreated spruce, with a flocculating strain of yeast Saccharomyces cerevisiae. SSFF was further developed and applied to pretreated wheat straw, a xylose rich lignocellulosic material, using encapsulated xylose fermenting strain of S. cerevisiae. High solids loading of 12% suspended solids (SS) was used to combat bacterial contamination and improve ethanol yield. Oil palm empty fruit bunch (OPEFB) was pretreated with fungal and phosphoric acid in order to improve its ethanol yield. An evaluation of biofuel production in Nigeria was also carried out. SSFF resulted in ethanol yield of 85% of the theoretical yield from pretreated spruce with the flocculating strain. Combination of SSFF with encapsulated xylose fermenting strain facilitated simultaneous glucose and xylose utilisation when applied to pretreated wheat straw; this resulted in complete glucose consumption and 80% xylose utilisation and consequently, 90% ethanol yield of the theoretical level. High solids loading of 12% SS of pretreated birch resulted in 47.2 g/L ethanol concentration and kept bacterial infection under control; only 2.9 g/L of lactic acid was produced at the end of fermentation, which lasted for 160 h while high lactic acid concentrations of 42.6 g/L and 35.5 g/L were produced from 10% SS and 8% SS, respectively. Phosphoric acid pretreatment as well as combination of fungal and phosphoric pretreatment improved the ethanol yield of raw OPEFB from 15% to 89% and 63% of the theoretical value, respectively. In conclusion, these studies show that SSFF can potentially replace the conventional methods of lignocellulosic ethanol production and that high solids loading can be used to suppress bacterial infections during ethanol productions, as well as that phosphoric acid pretreatment can improve ethanol yield from lignocellulosic biomass.Thesis for the degree of Doctor of Philosophy at the University of Borås to be publicly defended on 31 October 2014, 10.00 a. m. in room E310, University of Borås, Allégatan 1, Borås.
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Lennartsson, Patrik. "Zygomycetes and cellulose residuals : hydrolysis, cultivation and applications." Doctoral thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3608.
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Zygomycetes is a class of fungi living worldwide as saprobes, as part of mycorrhizae, and as parasites. Humans have used some zygomycetes for centuries in the production of traditional foods, e.g. Indonesian tempe. In the present thesis, the experimental focus was on two zygomycetes strains, Mucor indicus CCUG 22424 and Rhizopus sp. IT. One of the distinguishing features of M. indicus is its dimorphism. The different cell forms were influenced by the culturing conditions. After inoculation, when the initial spore concentration was high (6-8×106 spores/ml), yeast-like growth dominated under anaerobic conditions. With a smaller inoculum, yielding 1-2×105 spores/ml, and access to oxygen, filamentous forms dominated. Only negligible differences in ethanol yield (390-420 mg/g hexoses), productivity (3-5 g/l/h), and inhibitor tolerance were observed. Differential expressions of probably four genes were observed between the yeast-like and filamentous growth forms. Lignocelluloses are a suitable substrate for cultivating zygomycetes, as they occur in abundance, particularly since zygomycetes, unlike Saccharomyces cerevisiae, can utilise pentoses. Lignocelluloses require pretreatment to achieve efficient hydrolysis of the cellulose. N-methylmorpholine-N-oxide (NMMO) was tested for pretreatment of spruce and birch. Reducing wood chip size and/or prolonged pretreatment, promoted hydrolysis yield. Best yields were achieved from <2 mm chips and 5 h pretreatment. The hydrolysate was used for fermentation with M. indicus, resulting in 195 and 175 mg ethanol/g wood, and 103 and 86 mg fungal biomass/g wood, from spruce and birch respectively. Orange peel is another potential substrate. However, the hydrolysate contained 0.6 % (v/v) D-limonene, ten times higher than the concentration inhibiting S. cerevisiae. M. indicus was more resistant and successfully fermented the hydrolysate, producing 400 mg ethanol/g hexoses and 75 mg fungal biomass/g sugars. Both M. indicus and Rhizopus sp. grew in 1.0 % and 2.0 % D-limonene, although the latter was unable to grow in the hydrolysate. A third substrate was also used, spent sulphite liquor (SSL), which is a by-product from sulphite paper pulp mills. The SSL was diluted to 50 % and used for airlift cultivations of Rhizopus sp. In 1.0 vvm aeration, up to 340 mg biomass/g sugars was produced. Prolonged cultivations generally decreased the protein (from 500 to 300 mg/g) and lipid (from 70 to 20 mg/g) contents. In contrast, the cell wall fraction, measured as alkali-insoluble material (AIM), increased (160-280 mg/g), as did the glucosamine (GlcN) content (220-320 mg GlcN/g AIM). The produced fungal biomass could serve as animal feed, e.g. for fish.Akademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 9 februari 2012, klockan 10.00 i KS101, Kemigården 4, Göteborg.
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Lee, Jungeun. "Sustainable Production of Microbial Lipids from Renewable Biomass: Evaluation of Oleaginous Yeast Cultures for High Yield and Productivity." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/35300.
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Doctor of PhilosophyDepartment of Grain Science and Industry
Praveen V. Vadlani
Microbial lipids derived from oleaginous yeasts are a promising alternative source of edible oils due to the following advantages: no requirement of broad lands; availability of year-round production; and no food versus fuels controversy. Oleaginous yeast has an inherent ability to accumulate lipids inside cells and their lipids are preferable as starting materials in oleo-chemical industries because of their distinct fatty acid composition. Lignocellulosic biomass is a promising substrate to supply carbon sources for oleaginous yeast to produce lipids due to the high content of polysaccharides and their abundancy. Lignocellulosic-based sugar streams, which can be generated via pretreatment and enzymatic hydrolysis, contained diverse monosaccharides and inhibitors. The major objectives of this study were: 1) to develop a novel purification method to generate clean sugar stream using sorghum stalks after acid pretreatment; 2) to optimize fermentation conditions for Trichosporon oleaginosus to achieve high yields and productivity of microbial lipids using lignocellulosic hydrolysates; 3) to investigate the potentials of sorghum stalks and switchgrass as feedstocks for microbial lipid production using oleaginous yeast strains, such as T. oleaginosus, Lipomyces starkeyi, and Cryptococcus albidus; 4) to develop an integrated process of corn bran based-microbial lipids production using T. oleaginosus; and 5) to develop bioconversion process for high yields of lipids from switchgrass using engineered Escherichia coli. In our investigation, major inhibitory compounds of lignocellulosic hydrolysates induced by pretreatment were acetic acid, formic acid, hydroxymethyl furfural (HMF) and furfural. The activated charcoal was effective in removing hydrophobic compounds from sorghum stalk hydrolysates. Resin mixtures containing cationic exchangers and anionic exchangers in 7:3 ratio at pH 2.7 completely removed HMF, acetic acid, and formic acid from sorghum stalk hydrolysates. T. oleaginosus was a robust yeast strain for lipid production. In the nitrogen-limited synthetic media, total 22 g/L of lipid titers were achieved by T. oleaginosus with a lipid content of 76% (w/w). In addition, T. oleaginosus efficiently produced microbial lipids from lignocellulosic biomass hydrolysates. The highest lipid titers of 13 g/L lipids were achieved by T. oleaginosus using sorghum stalk hydrolysates with a lipid content of 60% (w/w). L. starkeyi and C. albidus also successfully produced microbial lipids using lignocellulosic hydrolysate with a lipid content of 40% (w/w). Furthermore, corn bran was a promising feedstock for microbial lipid production. The highest sugar yields of 0.53 g/g were achieved from corn bran at the pretreatment condition of 1% acid and 5% solid loading. Microbial lipids were successfully produced from corn bran hydrolysates by T. oleaginosus with lipid yields of 216 mg/g. Engineered E. coli also effectively produced lipids using switchgrass as feedstocks. E. coli ML103 pXZ18Z produced a total of 3.3 g/L free fatty acids with a yield of 0.23 g/g. The overall yield of free fatty acids was 0.12 g/g of raw switchgrass and it was 51 % of the maximum theoretical yield. This study provided useful strategies for the development of sustainable bioconversion processes for microbial lipids from renewable biomass and demonstrated the economic viability of a lignocellulosic based-biorefinery.