The first part of the dissertation presented a potentially novel aerobic, thermophilic, and cellulolytic bacterium identified as Brevibacillus sp. Strain JXL which was isolated from swine waste. Strain JXL can utilize a broad range of carbohydrates including: cellulose, carboxymethylcellulose (CMC), xylan, cellobiose, glucose, and xylose. In two different media supplemented with crystalline cellulose and CMC at 57°C under aeration, strain JXL produced a basal level of cellulases as FPU of 0.02 IU/ml in the crude culture supernatant. When glucose or cellobiose was used besides cellulose, cellulase activities were enhanced ten times during the first 24 h, but with no significant difference between the effects caused by these two simple sugars. After the end of the 24 hour period, however, culture with glucose demonstrated higher cellulase activities compared with that from cellobiose. Similar trend and effect on cellulase activities were also observed when glucose or cellobiose served as a single substrate. The optimal doses of cellobiose and glucose for cellulase induction were 0.5 and 1%. These inducing effects were further confirmed by scanning electron microscopy (SEM) images, which indicated the presence of extracellular protuberant structures. These cellulosome-resembling structures were most abundant in culture with glucose, followed by cellobiose and without sugar addition. With respect to cellulase activity assay, crude cellulases had an optimal temperature of 50°C and optimal pH range of 6-8. These cellulases also had high thermotolerance as demonstrated by retaining more than 50% activity after 1 h at 100°C. In summary, this is the first study to show that the genus Brevibacillus may have strains that can degrade cellulose. In the second part of the dissertation, the effect of Cellulose- and Organic-Solvent based Lignocellulose Fractionation (COSLIF) (Zhang, Y.-H. P.; Ding, S.-Y.; Mielenz, J. R.; Elander, R.; Laser, M.; Himmel, M.; McMillan, J. D.; Lynd, L. R. Biotechnol. Bioeng.2007, 97 (2), 214−223) pretreatment conditions on sweet sorghum bagasse (SSB) feedstock was studied using Response Surface Methodology (RSM). Batch experimental matrix was set up based on response surface method's central composite design in two factors to determine the effects of reaction time and temperature on the yield of simple sugars after a sequential pretreatment-enzyme hydrolysis process. Accordingly, changes in delignification, total reducing sugar (TRS) yield, glucan retention, digestibility and overall sugar yields resulting from various combinations of reaction times and temperatures were determined. The results suggested that both pretreatment temperature and reaction time were significant factors, although temperature was more so than reaction time. COSLIF pretreatment conditions of 50°C and 40 min were found to be the optimum pretreatment conditions for the saccharification of SSB. At the end of pretreatment and enzymatic hydrolysis, maximum values of 51.4% delignification, 85% overall glucose yield, and 44% overall xylose yield at an ACCELERASE®1500 loading of 0.25 mL/g sweet sorghum bagasse were achieved. Optimum ACCELERASE®1500 dosage of 0.1 mL/g of sweet sorghum bagasse was identified which resulted in an overall glucose yield of 82.2%±1.05. An effort has also been made to prescribe predictive models which represented the correlation between independent variables (reaction time and temperature), and dependent variables (delignification, and overall glucose yield) using RSM. The significance of the correlations and adequacy of these models were statistically tested for the selected objective functions. The outcomes suggested very competent and statistically adequate regression models which provided quantitative information both for delignification and overall glucose yield for the batch experiments studied.

No description available.

京都大学 / 新制・課程博士 / 博士(農学) / 甲第23939号 / 農博第2488号 / 新制||農||1089(附属図書館) / 学位論文||R4||N5374(農学部図書室) / 京都大学大学院農学研究科応用生命科学専攻 / (主査)教授 渡邊 隆司, 教授 梅澤 俊明, 教授 森 直樹 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Les zéolithes, aluminosilicates cristallins poreux, sont des catalyseurs acides hétérogènes très largement utilisés dans l’industrie chimique. Ces catalyseurs permettent de répondre très précisément à de nombreuses exigences économiques et environnementales contemporaines. Pour cela, les zéolithes s’appuient sur des propriétés uniques, comme la sélectivité de forme, ou encore la présence d’une double acidité de Lewis et de Brønsted, pour offrir de nouveaux outils à la synthèse organique. Ce sont plus de 230 structures qui ont été décrites à ce jour mais ce sont bien des centaines de milliers d’assemblages possibles, ce qui laisse un vaste choix quant à l’expansion de cette recherche. Dans ce travail, nous avons cherché à (i) mieux comprendre la cristallisation des zéolithes en présence d’un déchet issu de l’industrie sucrière, la bagasse de canne à sucre ; (ii) pour cela, différentes techniques ont été employées et développées afin de permettre une caractérisation précise de chaque zéolithe, notamment leur acidité, paramètre clé de leur réactivité ; (iii) une fois bien identifiés, ces catalyseurs ont été engagés dans des réactions modèles, une réaction de Diels-Alder ainsi qu’une acylation de Friedel-Crafts. Ainsi, un catalyseur le plus « idéal » possible regroupant toutes les propriétés requises aura pu être conçu sur mesure. Cette thèse s’essaie à une meilleure compréhension de la croissance cristalline des aluminosilicates poreux, et cela, via la synthèse de différentes zéolithes dont les propriétés intrinsèques sont optimisées puis utilisées de façon à obtenir les meilleurs résultats dans des réactions de catalyse acide ; en accord avec la chimie verte et ses préceptes. / Zeolites are crystalline porous aluminosilicates and useful heterogeneous catalysts in chemical industries. They represent one of the significant solutions to main environmental concerns. Thanks to their particular properties like shape selectivity and intrinsic acidities of Lewis and Brønsted, zeolites offer unbeatable abilities in organic synthesis. More than 230 structures have already been discovered, which afford thousands discovery and offer a lot of possibilities.This work was focused on (i) a better understanding of zeolite crystallisation in the presence of an additional component from sugar industry, sugarcane bagasse; (ii) several characterization techniques have been used for a precise structure – properties understanding, mainly for their acidity; (iii) tailored-made catalysts have been tested in model reactions like Diels-Alder and Friedel-Crafts acylation. Hence, optimal catalysts exhibiting required properties could be prepared. This Thesis also aimed to explain zeolite crystallization thanks to sacrificial additional template.BEA, MFI, FAU and LTA zeolites have been prepared then optimized for catalytic testing in different reactions, while keeping in mind the Green Chemistry concept.

Ce travail de thèse porte sur l’extraction et la caractérisation mécanique des fibres de canne à sucre. A partir de la bagasse de canne à sucre, résidu fibreux de l’industrie sucrière, des techniques d’extractions sont mises en place afin d’extraire des fibres techniques, dont l’analyse des propriétés chimiques et physico-mécaniques définira par la suite, les domaines d’application textile possibles. Les fibres de canne obtenues ont d’abord été étudiées d’un point de vue physique et morphologique, à partir de mesures et d’observations de leurs sections et de leurs profils. Ainsi, l’analyse de la distribution en diamètre et en longueur des fibres ont été étudiés avec l’établissement de paramètres de centrage barbe et hauteur (longueur pondérée à la masse), ont permis de déterminer leurs tailles moyennes, leurs finesses et leurs dispersions tout en vérifiant l’effet des conditions de traitement. Ont ainsi été obtenus différents types de fibres, présentant des propriétés mécaniques (en flexion et en traction) variées en relation avec les changements de structure dus à l’extraction. Les performances mécaniques de ces fibres restent comparables aux autres fibres naturelles, confirmant ainsi leur potentiel textile. Une première piste de valorisation de ces fibres a été envisagée lors de la fabrication d’un fil de canne à sucre. Des essais de filature ont ainsi été menés sur micro-filature, en 100% fibres de canne mais aussi en mélange 30-70% coton/bagasse.Enfin, une introduction à l’approche environnementale basée sur l’analyse de cycle de vie, a été succinctement abordée, ouvrant le champ à d’autres études. Les résultats montrent que le potentiel textile de la canne à sucre est quantifiable, et que ses fibres extractibles, sont comparables à d’autres fibres naturelles non conventionnelles utilisés dans le domaine textile. / This doctoral dissertation deals with extraction and mechanical characterization of sugarcane fibers. From bagasse, the fibrous residue left from the sugar mill, several extraction conditions were investigated in order to extract technical sugarcane fibers. At first, morphological and physical characterization were analyzed, based on their sections and longitudinal profiles. Thus, mean size, fiber fineness and scattering were studied regarding adjusting parameters barbe and hauteur, for the fiber length distribution as weighted mean. Different types of technical fibers were obtained and their mechanical characterization as bending and tensile properties linked with the extraction conditions. Mechanical performances of the extracted fibers are common to other natural fibers that confirm their textile potential. To valorize these fibers, some experiments were conducted by producing sugarcane yarn. A micro-spinning were piloted for a 100% bagasse and 30/70% cotton/bagasse yarn made. Finally, an introduction to an environmental approach was analyzed, based on the lifecycle analysis from the sugarcane culture to the fiber extraction, opening new perspectives to study. The results show that good fibers can be extracted from sugarcane, thanks to its chemical and physical composition, but also can be characterized for textile application.

L'accumulation de déchets agricoles tels que la bagasse et le développement d’alternatives aux polymères issus de la pétrochimie ont reçu une attention croissante au cours des deux dernières décennies, due à l'augmentation de la population et à la préoccupation croissante pour la préservation de l'environnement. Cette étude tente de résoudre ces problèmes à l’aide de deux approches principales.La première est liée à des composites à base de papier et de liant naturel et la seconde est associée à la préparation et à la caractérisation de dérivés cellulosiques présentant des propriétés cristaux liquides. En ce qui concerne les composites à base de papier et de liant naturel, la modification par dénaturation d’isolat de protéines de soja (SPI), l'ajout d'acrylamide et le changement de pH améliorent certaines propriétés et rendent les SPI plus utiles et acceptables dans diverses applications. Des expériences préliminaires ont été menées pour déterminer la concentration optimale de SPI permettant d’obtenir des propriétés mécaniques et physiques maximales. Des concentrations de 0,5%, 2,5%, et 5% ont été utilisées et 2.5% correspond à la concentration optimale. Pour augmenter les propriétés adhésives du SPI, l’acrylamide a été utilisé comme un modificateur supplémentaire dans des proportions 1,5%, 2,5% et 5%. L’addition nucléophile de l'acrylamide aux chaînes de protéines en milieu alcalin améliore les propriétés de solubilité du SPI et augmente ses propriétés adhésives. L'effet supplémentaire de l'acrylamide sur le SPI est prononcé sur les propriétés mécaniques et physiques. Comme la charge nette du SPI peut être modifiée en faisant varier le pH du milieu aqueux, la corrélation entre les propriétés mécaniques et physiques des feuilles de papier et le pH du SPI a été étudiée. Les pH utilisés ont été 3, 5, 7 et 10, où le pH 5 est le point isoélectrique (IEP) du SPI.A ce pH, le nombre de charges positives et négatives est pratiquement identique. La seconde approche a consisté à préparer et caractériser une série de dérivés cellulosiques 4 - alkyoxybenzoyloxypropyl (ABPC-n). Ces dérivés ont été synthétisés par estérification d'hydroxypropylcellulose (HPC) avec un DS 3 par l'acide 4- alkoxybenzoic portant 1, 2, 3, 4, 7, 8, 10, 12 et 14 atomes de carbone dans la chaîne latérale. D'autre part, de la pâte debagasse a été préparée et caractérisée à partir bagasse égyptienne. L’Hydroxypropylation a ensuite été menée sur la cellulose obtenue et de l’HPC partiellement substituée a été obtenue. En outre, l'estérification de ce dernier avec des acides 4-alkyloxybenzoic portant 2, 10 et 12 atomes de carbone dans la chaîne latérale a été réalisée et les dérivés ont été désignés (ABPC-m). La structure moléculaire du HPC partiellement substitué et des deux esters (ABPC-n et-m ABPC) a été confirmée par spectroscopies infrarouge à transformée de Fourier (FT-IR) et 1H RMN. Les phases cristal liquide (LC) et les transitions de phases ont été étudiées par microscopie en lumière polarisée (PLM) et calorimétrie différentielle à balayage (DSC), respectivement. Pour étudier les propriétés lyotropiques, différentes concentrations de ces échantillons ont été dissous dans le diméthylacétamide (DMA) (20, 30, 40, 50 et 60% en poids) et la concentration critique a été déterminée par réfractométrie en mesurant l'indice de réfraction des solutions dans le DMA et en traçant l’évolution des indices de réfraction en fonction des concentrations. Pour ABPC-n, nous avons observé que les températures de transition vitreuse (Tg) et de compensation (Tc) diminuent avec la longueur de la chaîne alkoxy et que la gamme mésomorphique (Tm-Tc) diminue avec la longueur de la chaîne alkoxy. / The present study deals with utilization of Egyptian bagasse in both conventional and non-conventional fields. The conventional application is devoted to papermaking, where bagasse pulp is the most appropriate pulp for this purpose due to the suitability of fiber length and high cellulose and hemicellulose contents. The non-conventional application is dedicated to the preparation of cellulosic derivatives having liquid crystalline properties.The first approach deals with using modified soy protein isolate (SPI) as binder for cellulosic fibers in paper composites. Modification of SPI was carried out through i) denaturation with urea and NaOH. ii) addition of acrylamide to the denatured SPI. iii) changing pH of SPI. These types of modification were used to improve the adhesion properties of SPI. Pronounced mechanical and physical properties of paper sheets filled with 0.5, 2.5 or 5% denatured SPI was obtained upon using 2.5%. The optimum condition of SPI addition was used in ii and iii modifications. The additional effect of acrylamide on SPI was pronounced where the mechanical and physical properties were enhanced. Correlation between the mechanical and physical properties of paper sheets with the pH of SPI was studied. The used pHs were 3, 5, 7 and 10.The results showed that the maximum breaking length was obtainedAbstract - xix -at the isoelectric point of SPI at pH 5 (at the isoelectric point (IEP) the number of positive and negative charges on the polyion is the same, giving a net charge of zero) and it began to decrease when the pH is increased to pH 10. Both the burst index and the tear index showed parallel trends.In the second approach, a series of 4- alkyoxybenzoyloxypropyl cellulose (ABPC-n) samples were synthesized via the esterification of hydroxypropyl cellulose (HPC) with 4-alkoxybenzoic acid bearing alkoxy chain with different lengths. On the other hand, cellulose was isolated in pure form from Egyptian bagasse pulp. Hydroxypropylation was then conducted on the isolated cellulose. 4-alkyoxybenzoyloxypropyl cellulose (ABPC-m) samples were synthesized via the esterification of the latter product with the same acid, bearing 2, 10 and 12 carbon atoms in the side chain and characterized.The molecular structure of both esters (ABPC-n and ABPC-m) was confirmed by Fourier transform infrared (FT-IR) and 1H NMR spectroscopy. The liquid crystalline (LC) phases and transition behaviors were investigated using polarized light microscopy (PLM), and differential scanning calorimetry (DSC), respectively. The lyotropic behavior of the derivatives was investigated in DMA solutions using PLM andAbstract - xx -the critical concentration was firstly determined via refractive index measurements.

La présente étude vise à valoriser des résidus agroindustriels comme matériaux pour l’habitat et la construction. Dans ce contexte, les travaux de recherche s’articulent autour de deux axes majeurs : le développement d’un liant alternatif et l’élaboration de matériaux composites à partir de ce liant alternatif et des matériaux végétaux. Deux liants composés utilisant des cendres de bagasse, nommés cendres de bagasse-chaux et ciment-cendres de bagasse ont été étudiés. A partir de ces liants composés, deux types de matériaux composites incluant des matériaux végétaux ont été élaborés : un composite incorporant des granulats de bagasse et de coco et un autre renforcé par des pulpes d’eucalyptus. Les propriétés physiques, chimiques, mécaniques et hydriques de ces matériaux ont été déterminées. Les résultats obtenus montrent que la calcination des cendres de bagasse à 600°C et la sélection des particules de taille inférieure à un diamètre seuil compris entre 45 et 63µm augmentent sa réactivité. Le liant composé cendres de bagasse-chaux est susceptible de développer une résistance à la compression de l’ordre de 39MPa à 28 jours, une valeur supérieure à celle des liants composés matériaux pouzzolaniques-chaux étudiés dans la littérature. Grace à sa faible alcalinité, ce liant composé préserve mieux les matériaux végétaux vis à vis de leur minéralisation et leur fragilisation comparativement au liant à base de ciment. L’incorporation de pulpes cellulosiques dans le liant composé cendres de bagasse-chaux permet d’obtenir des matériaux composites ayant des propriétés à la flexion comparables à celles d’un composite ciment-pulpes cellulosiques. / The present study aims to add value to agroindustrial residues as housing and building materials. In this context, the research works revolve around two main lines: the development of an alternative binder using agroindustrial residues and the production of composite materials from this alternative binder and plant resources. Two composed binder using bagasse ash, named bagasse ash lime and cement-bagasse ash, were optimised and produced. Using these composed binder, two kinds of composite materials including plant resources were produced: one composite developed with vegetable aggregates and another one reinforced with eucalyptus pulps. The physical, chemical, mechanical and hydric properties of these materials were investigated. The results show that the bagasse ash recalcination at 600 °C and the selection of the particles under a diameter limit (between 45 and 63 µm) improve its reactivity. Blended with slaked lime, the composed binder obtained with these parameters is likely to develop a compressive strength higher than 39 MPa at 28 days; this value is higher than the compressive strength of pouzzolanic material and lime based binder studied in the literature. In addition, due to the lower alkalinity of the interstitial solution of this composed binder, related to the lime consumption by the pouzzolanic material, it better protects vegetable materials from mineralization than the binders based on Portland cement. The incorporation of the cellulosic pulps in the composed binder lime-bagasse ash produces composite materials with a similar flexural behaviour as a composite made with cement and cellulosic pulp.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Conventional, advanced and fractionation pretreatment technologies were employed to recover and/or enhance the efficacy of the main constituents present in lignocellulosic biomass. Bamboo and triticale bran are novel feedstocks and hence their response towards treatment is unknown. Thus, to assist with the characterisation of these feedstock, in terms of the amount of sugar released during acid and enzymatic hydrolysis, use were made of conventional pretreatment technologies. Pretreatment involved the use of either the conventional single-stage dilute-acid or the conventional acid-catalysed steam-explosion process at times, temperatures and acid concentration ranging between 5 to 40 min, 120 to 214°C, and 0.002 to 0.055 (H3O+) gmol/L, respectively. For additional comparison, results were also obtained from an established feedstock namely sugarcane bagasse, by subjecting it to the single-stage dilute-acid process, at similar pretreatment conditions employed during the treatment of the other feedstocks. Sugarcane bagasse and bamboo, upon pretreatment and enzymatic hydrolysis, both yielded a similar combined sugar recovery yield of 78.0% and 81.2%, respectively. Alternatively, only 55.3% (w/w) of the total sugar content in triticale bran could be recovered. Triticale bran consists predominantly of hemicellulose which, compared to cellulose, the main constituent in sugarcane bagasse and bamboo, is more susceptible to degradation. Thus, to enhance the combined sugar recovery yield, it is recommended that triticale bran be treated at less severe pretreatment conditions, in order to preserve the hemicellulose. To further enhance the amount of sugar (i.e. cellulose and hemicellulose) that can be recovered from sugarcane bagasse, the use of a two- rather than one-stage dilute acid process was proposed. The single-stage dilute acid process, despite being the subject of many research efforts, failed to recover more than 83% (w/w) of the total sugar content in sugarcane bagasse. Following an extensive literature study, it was concluded that sugarcane bagasse comprises a hemicellulose and cellulose fraction which dictates the use of different pretreatment conditions in order to ensure their effective recovery. The use of a more advance two-step dilute acid process was therefore proposed as it allows for multiple-sets of pretreatment conditions which accommodate the requirements set forth by each of the polysaccharides present in sugarcane bagasse. With the assistance of response surface methodology, a 4.8% (w/w) improvement over the single-stage method was calculated for the two-stage process, by assuming both pretreatment technologies operated at optimum pretreatment conditions. This improvement, which is similar to the 7.7% (w/w) obtained with substrates other than sugarcane bagasse, was accredited to the use of multiple-sets of pretreatment conditions. Both low and high severity pretreatment conditions were applied to maximise the recovery of hemicellulose and cellulose, respectively. In the case of bamboo however, little can be gained by using the two- in lieu of the one-stage method, as similar pretreatment conditions are required to maximise both hemicellulose and cellulose recovery. Alternatively, a three- rather than a two-stage process needs to be applied, when treating triticale bran, to accommodate for an additional set of pretreatment conditions required to recover arabinan, a third polysaccharide. In order to realise the full potential of sugarcane bagasse, use was made of a fractionation method, which in addition to the recovery of polysaccharide (i.e. cellulose and hemicellulose), also allowed for the recovery of the polyphenolic content (i.e. lignin) thereof. Limited by the complexity of the fractionation process, sugarcane bagasse was selected as the preferred substrate to be subjected to fractionation, mainly because of its availability in the South African (established sugar milling industry), and ease of treatment using both conventional (e.g. single-stage) and advanced (e.g. two-stage) pretreatment technologies. A novel fractionation technology, involving the use of the ionic liquid 1-butyl-3- mehylimidazolium methyl sulphate ([BMiM]MeSO4), was devised to separate the main constituents of sugarcane bagasse. Although other ionic liquid fractionation examples also exist in literature, processes used caused production of multi-component product streams with 34% (w/w) of the original lignin and hemicellulose being recovered in the same product stream. Tests conducted during the present study confirmed these results and further indicated that the production of multi-constituent product streams could not be avoided by using acetone, an acetone-water mixture or a sodium hydroxide solution as the solvent in a subsequent solvent extraction step. Hence, to avoid the production of multi-component product streams, a hemicellulose pre-extraction step, comprising the single-stage dilute acid process, was introduced to extract and recover 75% (w/w) of the hemicellulose content. The remaining solid was subjected to ionic liquid treatment whereafter it was effectively separated into cellulose and lignin enriched product streams through solvent extraction. Up to 73% (w/w) of the original lignin and cellulose content was recovered using optimum operating conditions (120 min; 125°C). Comparison of the novel ionic liquid ([BMiM]MeSO4) with 1-ethyl-3-methylimidazolium acetate, an established ionic liquid, identified the former to be the superior delignification solvent whereas the latter contributed more towards the digestibility of the residual solids. In conclusion, methods for the effective recovery of polysaccharides and polyphenol units from established (i.e. sugarcane bagasse) and novel (i.e. bamboo, triticale bran) lignocellulosic feedstocks have been demonstrated through the application of conventional (single-stage), advanced (two-stage) and fractionation pretreatment technologies. Economic improvement is promised through the application of these constituents as they may serve as precursor chemicals for the production of value-added products that may replace the fuel and chemicals currently derived from fossil carbon resources. / AFRIKAANSE OPSOMMING: Konvensionele, gevorderde en fraksionering voorafbehandeling tegnologieë is gebruik om die herwinning en gebruiksaamheid van die hoofbestanddele wat in lignosellulose biomassa aanwesig is, te verbeter. Bamboes en tritikale semels is nuwe rou materiale en dus is hul reaksie op behandeling onbekend. Ten einde die karaktereienskappe van hierdie rou materiale, in terme van die hoeveelheid suiker wat gedurende die suur- en suiker ensimatiese-hidrolise vrygestel word, te bepaal, is gebruik gemaak van konvensionele voorbehandeling tegnologieë. Voorbehandeling behels die gebruik van óf die konvensionele enkelstadium vedunde-suur óf die konvensionele suur-gekataliseerde stoomontploffingsproses; by tye, temperature en suurladings wat wissel tusen 5 en 40 minute, 120 tot 214°C, en 0.002 tot 0.055 (H3O+)gmol/L, onderskeidelik. Vir verdere vergelykings is resultate vanaf ’n gevestigde rou materiaal, naamlik suikerriet reste, verkry, deur dit te onderwerp aan ’n enkelstadium verdunde suur proses met dieselfde voorbehandeling toestande wat gegeld het gedurende die behandeling van die ander roumateriale. Tydens voorbehandeling en ensimaties-hidrolise het suikerriet reste en bamboes ’n gelyke gekombineerde terugwinnings opbrengs van 78.0% en 81.2% suiker, onderskeidelik, gelewer. Daar kon egter net 55.3% (w/w) van die totale suikerinhoud van tritikale semels herwin word. Tritikale semels bestaan hoofsaaklik uit hemisellulose, wat meer vatbaar is vir degradasie ten opsigte van sellulose, die hoof bestanddeel van suikerriet reste en bamboes. Om dus die gekombineerde suikerherwinnings-opbrengs te verbeter, word daar voorgestel dat tritikale semels aan minder strawwe toestande onderwerp word, om sodoende die hemisellulose te bewaar. Om verder die hoeveelheid suiker (d.w.s glukose en xilose) wat vanuit suikerriet reste herwin kan word, te verbeter, is die gebruik van ’n twee- in plaas van ’n eenstadium verdunde suur proses, voorgestel. Die enkelstadium verdunde suur proses het, ten spyte daarvan dat dit al die onderwerp van verskillende navorsing projekte was, nie daarin geslaag om meer as 83% (w/w) van die totale suikerinhoud vanuit die suikerriet reste te herwin nie. Na ’n uitgebreide literatuurstudie is daar tot die slotsom gekom dat suikerriet reste bestaan uit ’n hemisellulose deel en ’n sellulose deel wat die gebruik van verskillende voorbehandeling toestande noodsaak, om sodoende effektiewe herwinning daarvan te verseker. Die aanwending van ’n meer gevorderde twee-stap verdunde suur proses is dus voorgestel, aangesien dit van veelvoudige-stelle voorbehandelings toestande, soos vereis deur die polisakkariedes in suikerriet reste, gebruik maak. Deur die toepassing van reaksie oppervlakte metodologie, is ’n 4.2% verbetering op die enkel-stadium metode vir die twee-stadium proses behaal deur aan te neem dat beide van hierdie prosesse, by optimum kondisies vir maksimale suiker herwinning, uitgevoer is. Hierdie verbetering is soortgelyk aan die 7.7% (w/w) verbetering wat voorheen met andersoortige substrate (uitgesonder suikerriet reste) verkry is. Sodanige verhoging word toegeskryf aan die gebruik van veelvoudige stelle van voorbehandeling toestande, wat beide meer en minder strawwe toestande insluit, om sodoende die herwinning van xilose en glukose onderskeidelik te maksimeer. In die geval van bamboes, is die twee-stadium metode nie superieur tot die een-stadium metode nie, aangesien soortgelyke voorbehandeling-toestande benodig word om beide die herwinning van xilose en glukose te maksimeer. Alternatiewelik moet ’n drie-stadium in plaas van ’n twee-stadium proses gebruik word wanneer tritikale semels behandel word aangesien ’n bykomende stel voorbehandeling toestande benodig word om arabinan, ’n derde polisakkaried, te herwin. Om sodoende die volle potensiaal van suikerriet reste te ontgin, is gebruik gemaak van ʼn fraksioneringstegnologie. Waar konvensionele voorbehandeling metodes slegs fokus op die herwinning van polisakkariedes (naamlik sellulose en hemisellulose), kan die fraksioneringsproses ook die poli-fenoliese inhoud (naamlik lignien) in lignosellulose, herwin. Weens die ingewikkeldheid van die fraksioneringsproses, is suikerriet reste gekies as die mees geskikte substraat vir fraksionering, hoofsaaklik omdat dit veral in die Suid- Afrikaanse konteks, maklik beskikbaar is en omdat dit ook maklik is om met beide die konvensionele (bv. die enkel-stadium) en die gevorderde (bv. die twee-stadium) voorbehandeling proses behandel te word. ʼn Nuut ontwikkelde fraksionering tegnologie wat gebruik maak van die ioniese vloeistof 1-butiel-3-metielimidazolium metielsulfaat ([BMiM]MeSO4) is ontwikkel, om die hoofbestanddele in suikerriet reste van mekaar te skei. Literatuur bevat verskeie voorbeelde waar ioniese vloeistowe gebruik word vir fraksionering. Die doeltreffendheid van hierdie prosesse is egter deur die produksie van multi-komponent produkstrome, waartydens tot en met ekwivalente hoeveelhede hemisellulose en lignien in dieselfde produkstrome herwin is, beperk. Hierdie resultate is tydens die studie deur middel van toetse bevestig. Sodanige toetse het ook aangedui dat die produksie van multi-komponent produkstrome nie deur die gebruikmaking van asetoon, ʼn asetoon-water mengsel of ʼn natrium hidroksied oplosmiddel, wat deel maak van ʼn opvolgende oplossing-ekstraksie-stap, vermy kon word nie. Om gevolglik die vervaardiging van multi-komponent produkstrome te vermy, is ʼn hemisellulose vooraf-ekstraksie stap, bestaande uit die enkel-stap verdunde suur proses, gebruik, om sodoende 75% (w/w) van die hemisellulose inhoud in suikerriet reste, te herwin. Die oorblywende vastestof was onderwerp aan ioniese vloeistof behandeling waarna dit effektiewelik geskei is in onderskeidelik, sellulose en lignien verrykte produkstrome, verkry deur gebruikmaking van ʼn oplossing-ekstraksie-stap. Tot en met 73% (w/w) van die oorspronklike lignien en sellulose inhoud was herwin deur gebruik te maak van optimale behandelingskondisies (120 min, 125°C). ʼn Vergelyking tussen die nuut-geïdentifiseerde ioniese vloeistof ([BMiM]MeSO4) en 1-etiel-3-metielimidazolium asetaat, ʼn gevestigde ioniese vloeistof, het aangetoon dat eersgenoemde ʼn superieure delignifikasie oplosmiddel is terwyl laasgenoemde ʼn groter bydra tot die verteerbarheid van die oorblywende reste lewer. Ten slotte het hierdie studie, metodes vir die effektiewe herwinning van polisakkariedes en poli-fenoliese eenhede, vanaf gevestigde (bv. Suikerriet reste) en nuwe (bv. bamboes en tritikale semels) lignosellulose rou materiale, gedemonstreer, deur telkens van konvensionele (enkel-stadium), gevorderde (twee-stadium) en fraksionerings voorbehandeling tegnologieë gebruik te maak. Ekonomiese verbetering kan dus verwag word indien hierdie bestanddele as voorloper chemikalieë vir die produksie van waarde toegevoegde produkte aangewend word, aangesien sodanige produkte die plek kan inneem van brandstof en chemikalieë wat tans vanuit fossielbronne vervaardig word.

Surplus sugarcane bagasse, estimated at a maximum of 0,9x106 tons/year, represents an annual renewable resource which is readily available at the mill site and is a suitable potential source of alternative fuels and chemical feedstocks. This work contains an extensive literature survey which covers the production of C5- and C6- sugars from lignocelluloses by chemical hydrolysis and the pretreatment of cellulosic materials for enzymatic hydrolysis of the cellulose fraction. This survey was then used to determine the final direction of this research into the utilisation of bagasse for the production of fermentable sugars. It was decided that research should be directed at the dilute acid hydrolysis of the bagasse hemicellulose fraction to determine whether this fraction could be selectively hydrolysed from the complex lignocellulose structure and to obtain xylose yields under different hydrolysis conditions. Acids, especially acetic acid, are liberated from bagasse by steaming at elevated temperatures. In this acid medium the hemicelluloses are hydrolysed and become soluble. Autohydrolysis tests on whole bagasse indicate that hemicellulose hydrolysis becomes significant at temperatures above 140°C. However, the autohydrolysis liquor would still require dilute mineral acid hydrolysis to convert the pentose oligomers to their monomeric forms. Dilute sulphuric and batch hydrolysis of whole bagasse hemicellulose has thus been investigated at a solid to liquid ratio of 1:15 over the following temperature and acid concentrations ranges : 80° to 150°C and 3 to 40 g/l acid. Xylose, glucose, furfural and acetic acid formation and sulphuric acid consumption were monitored during these hydrolyses. Hemicellulose hydrolysis to produce mainly xylose is readily achieved over the entire range of acid hydrolysis conditions tested with little removal of the other bagasse components (lignin and cellulose). At the upper end of the temperature range acid concentrations below 20 g/l are sufficient for hemicellulose hydrolysis due to the effect of temperature on reaction rate. The bagasse hemicellulose consists of two fractions, an easily hydrolysable portion containing 165 mg of potential xylose/g bagasse and a resistant fraction containing 105 mg of potential xylose/g bagasse. A first order reaction model has been developed using the batch acid hydrolysis results. It is based on two hemicellulose fractions reacting simultaneously to give a common product (xylose) and predicts total xylose yield as a function of hydrolysis time for a given set of hydrolysis conditions. The encouraging xylose yields obtained during the batch hydrolyses led to the design of a continuous hydrolysis reactor to process bagasse at low liquid to solid ratios to determine whether xylose yields similar to the batch hydrolysis yields could be obtained at the same hydrolysis conditions. The continuous hydrolyses showed that for the conditions tested the xylose yields are unaffected by the decrease in liquid to solid ratio (down to 3,6:1) and it would appear that reactor performance is still controlled by reaction kinetics. A number of reactor configurations for the industrial production of pentoses from bagasse hemicelluloses are also proposed. / Thesis (M.Sc.)-University of Natal. Durban, 1982.

Submitted in fulfillment of the requirements Of the degree of Masters in applied science: Biotechnology, Durban University of Technology, Durban, South Africa, 2016. / Anaerobic dark fermentation is an efficient biological process to produce hydrogen from waste material. In South Africa, this technology has not been explored adequately to extract energy from biological wastes. Within the KwaZulu Natal region of South Africa, the sugar industry is a prominent venture that produces mass quantities of sugarcane bagasse amongst other waste products. This by-product can be an ideal source of substrate for biohydrogen generation. In this study, sugarcane bagasse was used as the main substrate for biohydrogen production by anaerobic fermentation using sewage sludge as the inoculum. Different pre-treatment methods were employed to maximize the release of fermentable sugars from the lignocellulosic biomass. Among the different pre-treatment methods employed, the maximum sugar yield (294.4 mg/g) was achieved with 0.25% H2SO4 for 60 minutes at 121°C. Prior to inoculation, the sewage sludge was also subjected to thermal pre-treatment to eliminate methanogens. Thermal pre-treatment of inoculum sludge for 30 min was effective in eliminating methanogens. Fluorescence in situ hybridization was used to positively identify the hydrogen producing bacteria present before and after treatment. The pre-treated substrate and inoculum was integrated into a dark fermentation process to further optimize the effect of pH, substrate to biomass, iron and magnetite nanoparticles on hydrogen production. The maximum hydrogen production (1.2 mol/mol glucose) was achieved at a pH range of 5-6, a substrate to biomass ratio of 3.5, and iron and magnetite nanoparticle concentration of 200 mg/L. Microbial analysis using quantitative polymerase chain reaction has confirmed the dominance of Clostridium spp. in the reactor. The highest hydrogenase gene activity (number of copies of hydrogenase gene expression/ng DNA) was recorded in the reactor supplemented with magnetite nanoparticles with lowest being in the raw sludge. There was a direct positive correlation between the hydrogenase gene copy number and the hydrogen yield obtained at different reactor conditions. Scanning electron microscopy was a useful to visually analyse the interaction of microorganisms with activated sludge. This study highlights the significance of anaerobic microorganisms from waste sludge being able to utilize agricultural waste material to produce biohydrogen which could be further scaled up for continuous hydrogen production. In addition, statistical tools used to predict the possible sugar (Design of experiments) and hydrogen yields (Gompertz model) produced would be helpful in saving time during full-scale operation of biohydrogen producing reactors. / M