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A series of investigations were undertaken in vitro and in vivo to investigate the nutritive value of cottonseed (WCS), the rumen microbial degradation of oilseeds and legume seeds, and the effects of gossypol on the rumen microbial (bacterial, protozoal and fungal) fermentation, and on the growth of animal cells in culture. An HPLC (High Performance Liquid Chromatography) method for the analysis of gossypol in WCS and in rumen liquor of sheep fed with WCS was also studied. Six oilseeds namely WCS (Gossypium sp.), mustard seed (Brassica sp.) (cv. Albatross), linseed (Linum sp.) (cv. Antares) and three cultivars of rape seeds (Brassica spp.) (cv. Bienvenu, cv. Libravo and cv. Samourai) were incubated with rumen contents in consecutive batch culture (CBC) and examined for their microbial dry matter (DM) degradation. For comparison, another selection of legume seeds namely narbon seed (Vicia narbonensis), mungbean seed (Phaseolus aureus) (cv. Satin), two cultivars of cowpeas (Vigna unguiculata) (cv. Banjo and cv. Caloona), and lablab seed (Lablab purpureus) (cv. Highworth) were also examined for their DM degradation. The oilseeds tended to show lower DM losses, gas production and volatile fatty acids (VFA) concentration than the legume seeds. It is uncertain whether the presence of fat, fractions within fibre such as xylose and lignin, and/or antinutrients such as gossypol in WCS and glucosinolates in rape seeds might contribute to the low fermentation. Although legume seeds are known to contain many antinutrients such as tannins, lectins, protease inhibitors and cyanogenic glycosides, they appeared more readily fermentable than the oilseeds. The overall results suggest that gossypol would affect the numbers of rumen protozoa and fungi, but gossypol was not the only factor and probably not even a major factor influencing the nutritive value of whole cottonseed. In particular much more detailed analysis on the plant cell wall structures such as the proportions of different sugars, and the amounts of lignin-carbohydrate complexes present would need to be performed to determine whether such factors might limit the degradability and fermentability of whole cottonseed. There is also possibility that antinutrients other than gossypol such as pigments tannins and flavanoids may also affect the rumen ecosystem.

La digestion anaérobie représente un des acteurs majeurs du développement durable et de l'économie circulaire dans le concept « des déchets à l'énergie ». Compte-tenu de la grande diversité des déchets organiques, son développement passe par l'optimisation de la co-digestion. D’où la nécessité de développer des outils simples pour caractériser les substrats et pour prédire les performances des digesteurs afin d'optimiser leur fonctionnement. Cette thèse porte sur la caractérisation de la biodégradation des substrats solides par digestion anaérobie et l'optimisation de leur co-digestion à l'aide d'une approche de modélisation simple. En premier lieu, un nouveau protocole pour la quantification du potentiel méthane en mode batch a été mis en œuvre, intégrant une phase d'acclimatation entre l’inoculum et le substrat. Ensuite, un modèle simple a été développé sur la base du fractionnement de la matière organique en trois sous-fractions. Cette approche a permis de développer une base de données incluant les cinétiques et les potentiels en méthane (BMP) de 50 substrats. En second lieu, des expériences de co-digestion de deux substrats solides ont été menées en mode semi-continu à une charge appliquée (cva) constante puis à des charges appliquées croissantes. Les rendements expérimentaux en méthane ont toujours été supérieurs aux valeurs des BMP des mélanges calculées à partir des BMP de chaque substrat, soulignant l'importance de la respiration endogène. Quatre modèles incluant la respiration endogène avec des hypothèses différentes ont été proposés et évaluées pour prédire la production de méthane brute de digesteurs semi-continus en utilisant les données des substrats (BMP et cinétiques) acquises en mode batch. Deux modèles pour lesquels la production expérimentale de méthane à des cva croissantes correspondait bien aux données modélisées ont été validés. L'approche de modélisation retenue a été ensuite appliquée à des mélanges plus complexes de 3 et 5 substrats ainsi qu’à des biodéchets. Enfin, la réponse d’un digesteur fonctionnant en mode de production flexible, c’est-à-dire recevant des surcharges organiques ponctuelles régulièrement a été également modélisée avec succès. L'approche de modélisation proposée fournit un outil simple, pouvant être utilisé par les bureaux d'études, les constructeurs et les exploitants d’unités de méthanisation pour l'optimisation des mélanges de co-digestion et de la cva à utiliser en mode continu. Cela doit permettre de réduire le risque de défaillance et d’optimiser la rentabilité des unités de co-digestion. / Anaerobic digestion represents one of the major actors of sustainable development and the circular economy in the concept of "Waste to Energy". Given the great diversity of organic waste, its development requires the optimisation of co-digestion. Hence, it is needed to develop simple tools to characterize substrates and predict digester performance in order to optimize their operation. This thesis focuses on the characterization of biodegradation of solid substrates by anaerobic digestion and optimization of co-digestion using a simple modelling approach. First, a new batch protocol was implemented to quantify the Biochemical Methane Potential (BMP), integrating an acclimatization phase between the inoculum and the substrate. Then, a simple model was developed based on the fractionation of organic matter into three sub-fractions. This approach has allowed to develop a database including kinetics and BMPs of 50 substrates. Second, co-digestion experiments of two solid substrates were conducted in semi-continuous mode at a constant organic loading rate (OLR) and then at increasing applied loads. The experimental methane yields were always higher than the BMP values of the mixtures calculated from the BMPs of each substrate, underlining the importance of endogenous respiration. Four models including endogenous respiration with different assumptions were proposed and evaluated to predict raw methane production from semi-continuous digesters using substrate data (BMP and kinetics) acquired in batch mode. Two models for which the experimental methane production at increasing OLR corresponded well to the modelled data were validated. The chosen modelling approach was then applied to more complex mixtures of 3 and 5 substrates and to bio-waste. Finally, the response of a digester operated in flexible production mode, i.e. receiving regular punctual organic overloads, was also successfully modelled. The proposed modelling approach provides a simple tool that can be useful to design offices, manufacturers and operators of co-digestion units for the optimisation of feed mixtures and OLR to be used in continuous mode. This should reduce the risk of failure and optimise the profitability of co-digestion units.

Typescript. / Digitized by Kansas Correctional Industries

Eight cecally fistulated geldings were used in a randomized 4 x 4 Latin square design to observe the effect varying levels of dietary starch had on cecal environment. The 4 treatment rations contained 2 g starch/kg BW (Diet 2), 4 g/kg BW (Diet 4), 6 g/kg BW (Diet 6), or 8 g/kg BW (Diet 8). The rations were comprised of a commercial pelleted feed to meet 2 g starch/kg BW in each treatment, with ground corn used to fulfill the remaining starch requirements in each diet. Soybean meal was added to ensure diets were iso-nitrogenous, and cottonseed hulls were used to equalize dry matter intake. A 21 day adaptation period was allowed before cecal contents were sampled. Samples were drawn 4 hours after the morning meal and were immediately tested for pH. Samples were used to count total anaerobic bacteria and lactic acid bacteria, as well as determine methane activity, ammonia activity, volatile fatty acids, and in vitro dry matter digestibility (IVDMD). Stoichiometric calculations were performed to give an indirect measure of fermented hexose, methane, and carbon dioxide. Diet did not influence dry matter intake (DMI), however it did have an effect on starch intake (P < 0.0001) and caused a linear increase in starch consumption as the amount of offered starch increased (P < 0.0001). Diet did not influence the pH of the cecum (P > 0.05), although a tendency for a linear decrease (P < 0.06) in pH from 6.92 ? 6.58 occurred when dietary starch increased. Total anaerobic bacteria and lactic acid bacteria were unaffected by treatment diets (P > 0.05). Propionate production was affected by dietary treatment (P < 0.05), causing a quadratic increase (P = 0.04) from 8.26 to 14.13 mM as starch in the diets increased. Diet did not affect the production of acetate, butyrate, or ammonia (P > 0.05). Results found that stoichiometric calculations and IVDMD values were not affected by diet (P > 0.05). These results show that starch intake influenced the production of fermentative by-products, which caused decreases in pH, although there was no observed increase in the bacterial populations of the cecum.

Anaerobic co-digestion of organic fraction of municipal solid waste (OFMSW), with thickened waste activated sludge (TWAS) and primary sludge (PS) has the potential to enhance (biodegradation) of solid waste, increase longevity of existing landfills and lead to more sustainable development by improving waste to energy production. This study reports on mesophilic batch anaerobic biological methane potential (BMP) assays carried out with different concentrations and combinations (ratios) of OFMSW, TWAS (microwave (MW) pre-treated and untreated) and PS to assess digester stability and potential improved specific biodegradability and potential increased specific biogas production by digestion of OFMSW with PS and TWAS in various tri-substrate mixtures. Results indicated improvements in specific biogas production with concomitant improvements in COD and volatile solid (VS) removal for co-digestion of OMSW, TWAS and PS vs. controls. In terms of improvements in biogas production and digester stability the OFMSW:TWAS:PS:50:25:25 ratio with or without TWAS MW treatment was deemed best for further continuous digester studies. At a 15d HRT which is the regulatory policy in the province of Ontario for municipal mesophilic anaerobic TWAS:PS treatment, co-digestion of OFMSW:TWAS:PS, and OFMSW:TWASMW:PS resulted in a 1.38 and 1.46 fold relative improvement in biogas production and concomitant waste stabilization when compared to TWAS:PS and TWASMW:PS digestion at the same HRT and volumetric VS loading rate respectively. Treatment of OFMSW with PS and TWAS provides beneficial effects that could be exploited at MWWTP that are being operated at loading rates less than design capacity.

Swedish people today are generally interested in environmental issues. One can assume that this would affect the way people act in their daily lives. However, research has shown that when it comes to attitudes and behavior, there is what has been described as “a gap”. Concern for the environment does not automatically mean that people act in an environmentally friendly way. The fact is that there are many barriers that prevent a so-called pro environmental behavior. This study deals with some of the factors that can influence a specific behavior, namely the sorting of food waste in the City of Lidingö – a municipality in Sweden that works to increase the number of subscribers of food waste collection. The waste is a valuable substrate when producing biogas, which is considered a renewable fuel. By replacing fossil fuels with biogas, the amounts of greenhouse gases that reach the atmosphere can be reduced. A questionnaire was sent out to more than 800 local citizens (of which half of them are subscribers of food waste collection) with questions about values, beliefs, motivation factors and opinions about efforts linked to the sorting of food waste. The results show that sustainability reasons are strong when it comes to why people decide to sort out food waste, and that a number of the subscribers of food waste collection consider it a moral obligation to take action in this matter. Several barriers, especially in the form of economic issues, preclude others from sorting. A need for more information, when it comes to the significance of this behavior, is also evident. As the thesis has its focus on pro-environmental behavior, factors in Stern’s Value-belief-norm theory, are used as the basis for the analysis. Blake’s model of barriers between environmental concern and action is used when studying what it is that prevents people from sorting out their food waste.

Eight cecally fistulated geldings were used in a randomized 4 x 4 Latin square design to observe the effect varying levels of dietary starch had on cecal environment. The 4 treatment rations contained 2 g starch/kg BW (Diet 2), 4 g/kg BW (Diet 4), 6 g/kg BW (Diet 6), or 8 g/kg BW (Diet 8). The rations were comprised of a commercial pelleted feed to meet 2 g starch/kg BW in each treatment, with ground corn used to fulfill the remaining starch requirements in each diet. Soybean meal was added to ensure diets were iso-nitrogenous, and cottonseed hulls were used to equalize dry matter intake. A 21 day adaptation period was allowed before cecal contents were sampled. Samples were drawn 4 hours after the morning meal and were immediately tested for pH. Samples were used to count total anaerobic bacteria and lactic acid bacteria, as well as determine methane activity, ammonia activity, volatile fatty acids, and in vitro dry matter digestibility (IVDMD). Stoichiometric calculations were performed to give an indirect measure of fermented hexose, methane, and carbon dioxide. Diet did not influence dry matter intake (DMI), however it did have an effect on starch intake (P < 0.0001) and caused a linear increase in starch consumption as the amount of offered starch increased (P < 0.0001). Diet did not influence the pH of the cecum (P > 0.05), although a tendency for a linear decrease (P < 0.06) in pH from 6.92 ? 6.58 occurred when dietary starch increased. Total anaerobic bacteria and lactic acid bacteria were unaffected by treatment diets (P > 0.05). Propionate production was affected by dietary treatment (P < 0.05), causing a quadratic increase (P = 0.04) from 8.26 to 14.13 mM as starch in the diets increased. Diet did not affect the production of acetate, butyrate, or ammonia (P > 0.05). Results found that stoichiometric calculations and IVDMD values were not affected by diet (P > 0.05). These results show that starch intake influenced the production of fermentative by-products, which caused decreases in pH, although there was no observed increase in the bacterial populations of the cecum.

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 188-201). Also available in electronic version. Access restricted to campus users.

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