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<p>  </p> <p>The potential of lignocellulose for producing fermentable sugars as feedstock to manufacture fuels, chemicals, and materials for decarbonization remains untapped due to costly logistics and conversion processes. Pelleting technology offers a solution by addressing logistical issues and impacting downstream conversion, though it comes with its own costs. An overview of recent advances in pelleting technologies and their impact on bioconversion highlights the importance of understanding variables and product attributes. The interplay between pelleting and pretreatment processes, considering various feedstocks, is crucial for future design. Practical considerations such as energy consumption, costs, and environmental impacts must not be overlooked, along with exploration of cutting-edge technologies and strategies in this field. This work further presents a comprehensive investigation into the recalcitrance of pelleted corn stover to enzymatic digestion prior to any pretreatment.</p> <p>The potential of lignocellulose for producing fermentable sugars as feedstock to manufacture fuels, chemicals, and materials for decarbonization remains untapped due to costly logistics and conversion processes. Pelleting technology offers a solution by addressing logistical issues and impacting downstream conversion, though it comes with its own costs. An overview of recent advances in pelleting technologies and their impact on bioconversion highlights the importance of understanding variables and product attributes. The interplay between pelleting and pretreatment processes, considering various feedstocks, is crucial for future design. Practical considerations such as energy consumption, costs, and environmental impacts must not be overlooked, along with exploration of cutting-edge technologies and strategies in this field. </p> <p>This dissertation further presents a comprehensive investigation into the recalcitrance of pelleted corn stover to enzymatic digestion prior to any pretreatment. One aspect focuses on the role of high moisture pelleting in enhancing the enzymatic digestibility of corn stover before pretreatment, along with the relevant substrate characteristics. The pelleting process increases the digestibility of unpretreated corn stover, resulting in a glucan conversion increase from 8.2% to 15.5% at a 5% solid loading using 1 FPU Cellic® CTec2 per gram of solids. Under the same enzymatic hydrolysis conditions, the conversion of glucan remains higher for pelleted corn stover compared to its non-pelleted counterpart, even though both samples underwent identical milling processes and passed through the same screen to minimize particle impact. Compositional analysis reveals that loose and pelleted corn stover have similar non-dissolvable compositions, albeit with differences in their extractives. Using microcrystalline cellulose (Avicel) as a substrate, the presence of corn stover extractives results in a lower sugar yield compared to using citrate buffer instead, particularly for extractives from pelleted corn stover. This indicates a more negative impact of pelleted corn stover extractives on the activity of employed enzyme, CTec2. However, pelleted corn stover still shows increased overall glucan conversion compared to loose corn stover, suggesting improved digestibility of non-dissolvable components after milling and washing. The improvement in digestibility of pelleted material can be attributed to factors such as reduced particle size, enhanced substrate accessibility, and hydrolysis of cross-linking structures induced by the pelleting process. These findings offer valuable insights for the development of processing strategies aimed at sustainable and efficient utilization of lignocellulose.</p> <p>Furthermore, this dissertation delves into the profound impact of extractives on enzymatic hydrolysis, prompting a thorough examination of the composition and characteristics of extractives derived from pelleted corn stover, as well as their effects on enzymatic conversion. In contrast to previous reports, it is discovered that water extractable materials actually enhance the enzymatic hydrolysis of extractive-free stover, while the enzyme activities diminish when using microcrystalline cellulose as a substrate. This divergent behavior of extractives is attributed to the presence of lignin, which may interact with inhibitory compounds like phenolics, thereby mitigating the detrimental effects of soluble inhibitors or insoluble lignin, or both. These findings significantly advance our fundamental understanding of the intrinsic behavior of extractives and contribute to the optimization of schemes for efficient and cost-competitive enzymatic conversion of lignocellulose. </p>

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Este estudo comparou o efeito de dietas com palha de milho com ou sem blocos com multinutrientes na variação de peso de 24 caprinos com 8 meses de idade e peso médio de 11 kg (±0,61) , durante 6 meses da época seca. No final deste período foi conduzido um estudo de digestibilidade \"in vivo\" em 8 caprinos sendo 4 por tratamento. Os blocos com multinutrientes aumentaram o consumo total (g dia -1) de MS (519,71 vs 278,95; p<0,001), MO (369,32 vs 219,93; p<0,001) , PB (67,83 vs 12,47; p<0,001), FDN (292,66 vs 183,62; p<0,001), FDA (208,28 vs 126,15; p<0,001) , Hemicelulose (83,13 vs 57,48; p <0,001), Ca (6,04 vs 0,81; p<0,001) e P 5,24 vs 0,75; p<0,001). Os blocos com multinutrientes estimularam um aumento do consumo da palha de milho e dos nutrientes dela provenientes. Os valores encontrados, expressos em g/animal/dia, foram: MS (339,50 vs 278,95; p<0,01), MO (271,97 vs 219,93; p<0,05), PB (14,85 vs 12,46; p<0,01) FDN (235,71 vs 183,62; p<0,01), FDA (154,24 vs 126,14; p<0,01), hemicelulose (82,38 vs 57,48; p< 0,001). Os caprinos na dieta suplementada com blocos com multinutrientes tiveram uma taxa de crescimento maior (9,17 vs -7,99 g dia -1; p<0.001), coeficientes de digestibilidade (%) da MS (61,13 vs 46,64 ; p<0,05 ), MO (64,35 vs 51,92; p<0,05), PB (69.48 vs -5.60; &lt;p=0.01), FDN (55,54 vs 45.10; p< 0,05 ), FDA (53,31 vs 43,32; p<0,05 ) e da hemicelulose ( 65,08 vs 52,31; p<0,05 ), energia (64.95 vs 57.31; p<0.05), do que os não suplementados. O consumo de EM (70 vs 30 Kcal/ kg 0.75; p<0.001) and PBD (6,81 vs -0,12 g/ kg 0.75; p<0,001 foi maior no grupo suplementado. Os resultados indicam que os blocos com multinutrientes podem reduzir as perdas de peso vivo e a taxa de mortalidade de caprinos durante a época da seca., com custos relativamente baixos. / This study investigated the effect of feeding maize stover alone or with multinutrient block on the growth of 24 mozambican Landim goats aging 8 months with 11 kg (±0.61) average body weight, during the dry season. At the end of growth trial, a 5 day metabolism experiment on 4 goats from each treatment was conducted. Supplementation increased total intake (g day -1) of DM (519.71 vs 278.95; p<0.001), OM (369.32 vs 219.93; p<0.001) , CP (67.83 vs 12.47, p<0.001), NDF (292.66 vs 183.62, p<0.001), ADF (208.28 vs 126.15; p<0.001) , Hemicelullose (83.13 vs 57.48; p <0.001), Ca (6,04 vs 0,81; p<0,001) and P(5,24 vs 0,75; p<0,01). Multinutrient block promoted higher intake of maize stover DM (339.50 vs 278.95; p<0.01), OM (271.97 vs 219.93; p<0.05), CP (14.85 vs 12.46; p<0.01), FDN (235.71 vs 183.62; p<0.01), FDA (154.24 vs 126.14; p<0.01) and hemicelullose. (82,38 vs 57,48; p=0,001). Goats on diet supplemented with blocks had higher growth rate (9.17 vs 7.99 g day -1; p<0.01), and higher digestibility (%) of DM (61.13 vs 46.64 ; p<0.05), OM (64.35 vs 51.92; p<0.05), CP (69.48 vs -5.60; p<0.01), NDF (55.54 vs 45.10; p<0.05), ADF (53.31 vs 43.32; p<0.05) hemicelullose (65.08 vs 52.31; p<0.05) and energy (64.95 vs 57.31; p<0.05). The ME intake (70 vs 30 Kcal/ kg 0.75; p<0.001) and DCP ( 6,81 vs -0,12 g/ kg 0.75; p<0,001) were higher for supplemented than unsupplemented one. Results indicate that low cost multinutrient block could reduce the BW losses and the mortality rate of goats during the dry season.

Este estudo comparou o efeito de dietas com palha de milho com ou sem blocos com multinutrientes na variação de peso de 24 caprinos com 8 meses de idade e peso médio de 11 kg (±0,61) , durante 6 meses da época seca. No final deste período foi conduzido um estudo de digestibilidade \"in vivo\" em 8 caprinos sendo 4 por tratamento. Os blocos com multinutrientes aumentaram o consumo total (g dia -1) de MS (519,71 vs 278,95; p<0,001), MO (369,32 vs 219,93; p<0,001) , PB (67,83 vs 12,47; p<0,001), FDN (292,66 vs 183,62; p<0,001), FDA (208,28 vs 126,15; p<0,001) , Hemicelulose (83,13 vs 57,48; p <0,001), Ca (6,04 vs 0,81; p<0,001) e P 5,24 vs 0,75; p<0,001). Os blocos com multinutrientes estimularam um aumento do consumo da palha de milho e dos nutrientes dela provenientes. Os valores encontrados, expressos em g/animal/dia, foram: MS (339,50 vs 278,95; p<0,01), MO (271,97 vs 219,93; p<0,05), PB (14,85 vs 12,46; p<0,01) FDN (235,71 vs 183,62; p<0,01), FDA (154,24 vs 126,14; p<0,01), hemicelulose (82,38 vs 57,48; p< 0,001). Os caprinos na dieta suplementada com blocos com multinutrientes tiveram uma taxa de crescimento maior (9,17 vs -7,99 g dia -1; p<0.001), coeficientes de digestibilidade (%) da MS (61,13 vs 46,64 ; p<0,05 ), MO (64,35 vs 51,92; p<0,05), PB (69.48 vs -5.60; &lt;p=0.01), FDN (55,54 vs 45.10; p< 0,05 ), FDA (53,31 vs 43,32; p<0,05 ) e da hemicelulose ( 65,08 vs 52,31; p<0,05 ), energia (64.95 vs 57.31; p<0.05), do que os não suplementados. O consumo de EM (70 vs 30 Kcal/ kg 0.75; p<0.001) and PBD (6,81 vs -0,12 g/ kg 0.75; p<0,001 foi maior no grupo suplementado. Os resultados indicam que os blocos com multinutrientes podem reduzir as perdas de peso vivo e a taxa de mortalidade de caprinos durante a época da seca., com custos relativamente baixos. / This study investigated the effect of feeding maize stover alone or with multinutrient block on the growth of 24 mozambican Landim goats aging 8 months with 11 kg (±0.61) average body weight, during the dry season. At the end of growth trial, a 5 day metabolism experiment on 4 goats from each treatment was conducted. Supplementation increased total intake (g day -1) of DM (519.71 vs 278.95; p<0.001), OM (369.32 vs 219.93; p<0.001) , CP (67.83 vs 12.47, p<0.001), NDF (292.66 vs 183.62, p<0.001), ADF (208.28 vs 126.15; p<0.001) , Hemicelullose (83.13 vs 57.48; p <0.001), Ca (6,04 vs 0,81; p<0,001) and P(5,24 vs 0,75; p<0,01). Multinutrient block promoted higher intake of maize stover DM (339.50 vs 278.95; p<0.01), OM (271.97 vs 219.93; p<0.05), CP (14.85 vs 12.46; p<0.01), FDN (235.71 vs 183.62; p<0.01), FDA (154.24 vs 126.14; p<0.01) and hemicelullose. (82,38 vs 57,48; p=0,001). Goats on diet supplemented with blocks had higher growth rate (9.17 vs 7.99 g day -1; p<0.01), and higher digestibility (%) of DM (61.13 vs 46.64 ; p<0.05), OM (64.35 vs 51.92; p<0.05), CP (69.48 vs -5.60; p<0.01), NDF (55.54 vs 45.10; p<0.05), ADF (53.31 vs 43.32; p<0.05) hemicelullose (65.08 vs 52.31; p<0.05) and energy (64.95 vs 57.31; p<0.05). The ME intake (70 vs 30 Kcal/ kg 0.75; p<0.001) and DCP ( 6,81 vs -0,12 g/ kg 0.75; p<0,001) were higher for supplemented than unsupplemented one. Results indicate that low cost multinutrient block could reduce the BW losses and the mortality rate of goats during the dry season.

<p>Kukuruzovina je žetveni ostatak i potencijalni supstrat za proizvodnju biogasa. Direktivom 2018/2001 definisan je tzv. RED metod za obračunavanje ušteda emisija gasova s efektom staklene bašte&ndash; GHG. Metod je primenjiv za silažu kukuruza i stajnjak kao supstrat za proizvodnju biogasa, ali se na neadekvatan način obračunavaju emisije GHG za kukuruzovinu. Cilj je bio da se predlože unapređenja RED metoda kojima bi se prevazišli identifikovani problemi, kao i da se ispita uticaj primene unapređenog metoda na ocenu ušteda emisija GHG energetskog iskorišćenja biogasa iz kukuruzovine, tj. na ocenu održivosti. Uštede emisija GHG za sve razmatrane slučajeve primene RED metoda u osnovnoj i unapređenoj formi, imale su vrednost nižu od postavljenog kriterijuma od 70 %, tj. nisu održivi. Predloženo je da se RED metod unapredi ukidanjem pravila da se ne obračunavaju emisije GHG pre ubiranja žetvenih ostataka i da je potrebno da se navede da je ostatak fermentacije ko-produkt proizvodnje i korišćenja biogasa, kao i da je primena alokacije emisija GHG na biogas i ostatak fermentacije obavezna u slučaju primene ostatka fermentacije na polja sa kojih nisu ubirani žetveni ostaci.</p> / <p>Corn stover is a crop residue and potential substrate for biogas production. Directive<br />2018/2001 defines so-called RED method for determination of greenhouse gas (GHG)<br />emission savings. In the case of energy utilization of biogas produced from corn stover,<br />savings are calculated in an inadequate manner. The objective was to suggest the<br />improvements of the RED method in order to overcome the identified problems, as well<br />as to investigate the impact of the application of the improved method on the evaluation<br />of GHG emission savings, i.e. the the sustainability evaluation. The results of the GHG<br />emission savings, using the basic and the improved forms of RED method, show that all<br />considered cases had a value lower than the set criterion of 70%, i.e. they are not<br />sustainable. It was suggested to improve the RED method by abolishing the rule that<br />GHG emissions prior to collection of crop residue are not accounted. Also, it should be<br />noted that the digestate is a co-product of biogas production as well that the application<br />of the GHG emissions allocation to biogas and the digestate is mandatory in the case<br />when digestate is used on fields other than those used for substrate provision.</p>

Rising world petroleum prices and global warming are contributing to interest in renewable energy sources, including energy produced from agricultural crops and waste sources of biomass. A network of small mobile pyrolysis units may be the most cost effective system to convert biomass from agricultural feedstocks to bio-crude oil. Mobile pyrolysis units could be moved to the feedstock production fields thereby greatly simplifying feedstock logistics. In the North Central (NC) region of the U.S., possible feedstocks are corn stover, energy sorghum, and switchgrass. A grid-based Geographic Information System (GIS) program was developed to identify optimum locations for mobile pyrolysis units based on feedstock availability in the NC region. Model builder was used to automate the GIS analysis. Network analysis was used to find the best route to move the mobile pyrolysis units to new locations and to identify the closest refinery to transport the bio-crude oil. To produce bioenergy from feedstocks, the removal of biomass from agricultural fields will impact the hydrology and sediment transport in rural watersheds. Therefore, the hydrologic effects of removing corn stover from corn production fields in Illinois (IL) were evaluated using the Soil Water Assessment Tool (SWAT). The SWAT model was calibrated and validated for streamflow and sediment yields in the Spoon River basin in IL using observed data from the USGS. The modeling results indicated that as residue removal rates increased, evapotranspiration (ET) and sediment yields increased, while streamflows decreased. Biochar is a carbon-based byproduct of pyrolysis. To ensure that the mobile pyrolysis system is economically and environmental sustainable, the biochar must be land applied to the feedstock production fields as a soil amendment. An assessment of hydrologic changes due to the land application of biochar was made using the SWAT model in the Spoon River basin and changes in soil properties due to incorporation of biochar into the soil obtained from laboratory experiments by Cook et al. (2012). Model simulations indicated that a biochar application rate of 128 Mg/ha decreased water yield, and sediment yield in surface runoff and increased soil moisture and ET.

The severe effects associated with global warming and the rapid increase in oil prices are the driving forces behind the demand for clean carbon–neutral and biofuels such as bioethanol. Research studies are now focusing on using lignocellulosic biomass for bioethanol production due to concerns about food security and inflation. The chosen feedstock for this study was maize stover, given that it is the most abundant agricultural residue in South Africa. Maize stover consists of structural carbohydrates that can be enzymatically converted into fermentable sugars. The major drawback in the production of bioethanol from lignocellulosic biomass has been its high equipment and operational costs due to the use of acids and high enzyme loadings. The aim of this study was to investigate the possibility of optimizing the enzyme hydrolysis of pre–treated maize stover without further increasing the amount of enzymes. The maximum glucose yield attained was 690 ± 35 mg of glucose per gram of substrate which is equivalent to a conversion efficiency of 119%. The preferred pre–treatment method used was 3% sulphuric acid for 60 minutes at 121oC and the enzymatic hydrolysis process was performed at a 5% substrate loading, 50oC and pH 5.0 using 30 FPU per gram of cellulose in the presence of 1.25 g.L–1 of Tween 80 for 48 hours. The addition of Tween 80 increased the glucose yields by 23 % and thus, it has the potential of lowering the overall process costs by increasing the glucose yield without further addition of enzymes. Keywords: Bioethanol, maize stover, lignocellulosic biomass, pre–treatment, enzymatic hydrolysis / Thesis (M.Sc. Engineering Sciences (Chemical Engineering))--North-West University, Potchefstroom Campus, 2011.

The severe effects associated with global warming and the rapid increase in oil prices are the driving forces behind the demand for clean carbon–neutral and biofuels such as bioethanol. Research studies are now focusing on using lignocellulosic biomass for bioethanol production due to concerns about food security and inflation. The chosen feedstock for this study was maize stover, given that it is the most abundant agricultural residue in South Africa. Maize stover consists of structural carbohydrates that can be enzymatically converted into fermentable sugars. The major drawback in the production of bioethanol from lignocellulosic biomass has been its high equipment and operational costs due to the use of acids and high enzyme loadings. The aim of this study was to investigate the possibility of optimizing the enzyme hydrolysis of pre–treated maize stover without further increasing the amount of enzymes. The maximum glucose yield attained was 690 ± 35 mg of glucose per gram of substrate which is equivalent to a conversion efficiency of 119%. The preferred pre–treatment method used was 3% sulphuric acid for 60 minutes at 121oC and the enzymatic hydrolysis process was performed at a 5% substrate loading, 50oC and pH 5.0 using 30 FPU per gram of cellulose in the presence of 1.25 g.L–1 of Tween 80 for 48 hours. The addition of Tween 80 increased the glucose yields by 23 % and thus, it has the potential of lowering the overall process costs by increasing the glucose yield without further addition of enzymes. Keywords: Bioethanol, maize stover, lignocellulosic biomass, pre–treatment, enzymatic hydrolysis / Thesis (M.Sc. Engineering Sciences (Chemical Engineering))--North-West University, Potchefstroom Campus, 2011.

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