Thesis (Ph. D.)--Brigham Young University. Dept. of Chemical Engineering, 2006. / Includes bibliographical references (p. 175-181).

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009. / Title from title screen (site viewed October 13, 2009). PDF text: xiv, 183 p. : ill. (some col.) ; 1 Mb. UMI publication number: AAT 3358961. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (M.S.)--University of Iowa, 2009. / Thesis supervisor: Lea-Der Chen. Includes bibliographical references (leaves 110-114).

Thesis (Ph.D.)--Baylor University, 2007. / In abstract "5, 2, 9, 8, 12, 25, and 3" are subscript. In abstract "5 and 2 are superscript. Includes bibliographical references (p. 180-187).

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [149]-161).

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The aim of this investigation was to study the kinetics of readily biodegradable soluble substrate, and the interactions between the bioflocculation process and such kinetics. Several batch test experiments were performed at different soluble-substratebiomass ratios in order to evaluate its impact on the kinetics and the order of the reaction. Similarly the consumption of dissolved substrate was compared using two different bacterial suspensions: (1) flocculated suspension; and (2) dispersed cells suspensions. In this research flocculated biomass from a complete mixed activated sludge (CMAS) system was tested using sequencing batch reactors (SBR). Results indicate that when the So/Xo ratio is low (below 0.3) the removal of readily biodegradable soluble substrate can be well described by first-order kinetics with an asymptotic non-biodegradable portion for both flocculated and dispersed cells suspensions. However, it was found that the dissolved COD consumption for freely dispersed cells proceeds at a faster rate than for flocculated suspensions.

Lignocellulosic biomass is one of the most valuable alternative energy sources because it is renewable, widely available, and environmentally friendly. Unfortunately, enzymatic hydrolysis of biomass has been shown to be a limiting factor in the conversion of biomass to chemicals and fuels. This limitation is due to inherent structural features (i.e., acetyl content, lignin content, crystallinity, surface area, particle size, and pore volume) of biomass. These structural features are barriers that prevent complete hydrolysis; therefore, pretreatment techniques are necessary to render biomass highly digestible. The ability to predict the biomass reactivity based solely on its structural features would be of monumental importance. Unfortunately, no study to date can predict with certainty the digestibility of pretreated biomass. A concerted effort with Auburn University and Michigan State University has been undertaken to study hydrolysis mechanisms on a fundamental level. Predicting enzymatic hydrolysis based solely on structural features (lignin content, acetyl content, and crystallinity index) would be a major breakthrough in understanding enzymatic digestibility. It was proposed to develop a fundamental understanding of the structural features that affect the enzymatic reactivity of biomass. The effects of acetyl content, crystallinity index (CrI), and lignin content on the digestibility of biomass (i.e., poplar wood, bagasse, corn stover, and rice straw) were explored. In this fundamental study, 147 poplar wood model samples with a broad spectrum of acetyl content, CrI, and lignin were subjected to enzymatic hydrolysis to determine digestibility. Correlations between acetyl, lignin, and CrI and linear hydrolysis profiles were developed with a neural network model in Matlab®. The average difference between experimentally measured and network-predicted data were ±12%, ±18%, and ±27% for 1-, 6-, and 72-h total sugar conversions, respectively. The neural network models that included cellulose crystallinity as an independent variable performed better compared to networks with biomass crystallinity, thereby indicating that cellulose crystallinity is more effective at predicting enzymatic hydrolysis than biomass crystallinity. Additionally, including glucan slope in the 6-h and 72-h xylan slope networks and glucan intercept in the 6-h and 72-h xylan intercept networks improved their predictive ability, thereby suggesting glucan removal affects later-stage xylan digestibility.

The increasing U.S. dependence on imported oil; the contribution of fossil fuels to the greenhouse gas emissions and the climate change issue; the current level of energy prices and other environmental concerns have increased world interest in renewable energy sources. Biomass is a large, diverse, readily exploitable resource. This dissertation examines the biomass potential in Eastern Texas by examining a 44 county region. This examination considers the potential establishment of a 100-megawatt (MW) power plant and a 20 million gallon per year (MMGY) ethanol plant using lignocellulosic biomass. The biomass sources considered are switchgrass, sugarcane bagasse, and logging residues. In the case of electricity generation, co-firing scenarios are also investigated. The research analyzes the key indicators involved with economic costs and benefits, environmental and social impacts. The bioenergy production possibilities considered here were biofeedstock supported electric power and cellulosic ethanol production. The results were integrated into a comprehensive set of information that addresses the effects of biomass energy development in the region. The analysis indicates that none of the counties in East Texas have sufficient biomass to individually sustain either a 100% biomass fired power plant or the cellulosic ethanol plant. Such plants would only be feasible at the regional level. Co-firing biomass with coal, however, does provide a most attractive alternative for the study region. The results indicate further that basing the decision solely on economics of feedstock availability and costs would suggest that bioenergy, as a renewable energy, is not a viable energy alternative. Accounting for some environmental and social benefits accruing to the region from bioenergy production together with the feedstock economics, however, suggests that government subsidies, up to the amount of accruing benefits, could make the bioenergies an attractive business opportunity for local farmers and investors.