Strategies to increase the sugar concentration and overall sugar recovery from steam pretreated wheat straw and corn stover
Notice bibliographique
Résumé
Wheat straw is available in western Canada and it is a potential feedstock for bio-ethanol production as it can be effectively fractionated into simple sugars using acid catalyzed, steam pretreatment followed by enzymatic hydrolysis. Steam pretreatment is usually a compromise whereby conditions that facilitate effective enzymatic hydrolysis at low enzyme loadings usually sacrifice the recovery of the hemicellulose component. Previous work that tried to optimize the pretreatment to maximize hemicellulose recovery was usually done at the expense of using unacceptably high enzyme loadings to hydrolyze the cellulosic fraction. The goal in this thesis was to determine the highest possible amount of sugar that could be solubilized after both pretreatment and enzymatic hydrolysis while using low enzyme loadings and high solids concentration. It was anticipated that the optimum conditions for maximizing the total soluble sugar yield would still result in the degradation of a portion of the hemicellulose. The biomass handling conditions were first investigated to identify the best possible conditions to maximize sugar recovery. An optimized moisture content combined with the explosive decompression resulted in the highest xylose recovery. It was also found that H₂SO₄ could be used at a loading of 1.5% w/w to produce a substrate with similar chemical composition, sugar recovery and ease of enzymatic hydrolysis to what was obtained when using 3% SO₂ as the catalyst. The pretreatment conditions were then varied to determine the effect of pretreatment severity on the recovery of total soluble sugars. The highest soluble sugar yield of 75% was obtained after pretreatment at 190°C, 8 min and 1.5% H₂SO₄. This is among the highest sugar yields that have been reported and comparable to those reported when using a three-fold higher enzyme loading. However, at these conditions only 52% of the original xylan was recovered. A less severely treated substrate with 70% xylan recovery achieved a total soluble sugar yield of 72% when the “cellulase mixture” was supplemented with xylanases. Thus, pretreatments at lower severities followed by enzymatic hydrolysis using a “cellulase mixture” with xylanase supplementation may be an effective approach to improve the total soluble sugar yield when processing wheat straw.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».