Low cost cellulosic wastes like paper sludge, municipal wastes, solid wastes from food, packing etc. contain a high amount of cellulose which can be converted to bioethanol by two steps: (1) solubilization of cellulosic fibers to monosaccharides (2) conversion of monosachharides to bioethanol via fermentation. At present the implementation of this technology has been deterred by high cost for enzymes. Enzymatic hydrolysis of cellulosic fibers shows a biphasic behavior with an initial fast step followed by a slow step leading to low cellulose conversion rates. Low hydrolytic conversion rates necessitate the use of a high enzyme dosage to obtain meaningful cellulose conversion rates which make the implementation of this entire technology economically infeasible. The objective of this study is to get a better understanding of the mechanism of enzymatic hydrolysis of fibers to glucose and to investigate the effect of cationic polymers on enzymatic hydrolysis rates. To achieve the first objective, we performed experiments so as to study changes in morphological and physiochemical properties like fiber length, percentage of fines, crystallinity index, kink angle, kink index, mean curl, total organic carbon and glucose production with time. We used bleached kraft softwood, hardwood, and unbleached softwood fiber as cellulosic substrate and pergalase as cellulase enzyme. All of the experiments were carried out at experimental conditions of a temperature of 50 .C and a pH of 5.0 which maximize enzymatic activity. We studied the impact of recycling and refining on hydrolysis rates by measuring total organic carbon and glucose production. We found that refining increases enzymatic conversion rates by about as much as 20 %, however refining being energy intensive makes its implementation economically unfavorable. We found a novel way of enhancing hydrolysis rates by the use of cationic polyacrylamides. The effect of cationic polacrylamides was studied on both hardwood and softwood fibers at similar experimental conditions. Cationic polyacrylamides produced a maximum rate increase of 20 % in hydrolytic conversion rates for hardwood fibers. Even though, the increase in hydrolysis rates for softwood fibers was smaller than hardwood fibers, it was still significant. We further studied the effect of parameters like polymer concentration, cationicity and molecular weight to find a relation between properties of polymers and the increase in enzymatic hydrolysis.

Thesis (Ph.D.)--Tufts University, 2003. / Adviser: Daniel C. Jansen. Submitted to the Dept. of Civil Engineering. Includes bibliographical references (leaves 146-152). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (PhD) - Swinburne University of Technology, 2006. / Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Civil Engineering, Swinburne University of Technology - 2006. Typescript. Includes bibliographical references.

Thesis (Ph.D. Earth and Ocean Sciences)--University of Waikato, 2007. / Title from PDF cover (viewed February 26, 2008) Includes bibliographical references (p. 148-164)

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 241-249). Also available in electronic version. Access restricted to campus users.

Thesis (M.S.)--University of Tennessee, Knoxville, 2002. / Title from title page screen (viewed Feb. 27, 2003). Thesis advisor: Atul Sheth. Document formatted into pages (ix, 70 p. : ill. (some col.)). Vita. Includes bibliographical references (p. 67-69).

Thesis (PH.D.)--Michigan State University. Chemical Engineering, 2008. / Title from PDF t.p. (viewed on Aug. 11, 2009) Includes bibliographical references (p. 179-189). Also issued in print.

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Orientador: Ana Tereza Caceres Cortez / Banca: Clauciana Schmidt Bueno de Moraes / Banca: Tânia Maria de Campos Leite / Resumo: O aumento da produção de industrializados, o alto crescimento populacional nas cidades e hábitos de consumo pautados na "cultura do descartável" trazem como consequência uma ampliação da produção de resíduos, e, por conseguinte, geram graves impactos socioambientais. Esta questão está relacionada a muitas ciências, inclusive à Geografia, uma vez que se refere às relações do homem com o espaço, influenciando na administração e no planejamento urbano das cidades. Nesse contexto, a presente dissertação tem como objeto de estudo os Ecopontos geridos pela administração pública municipal de Rio Claro (SP), os quais recebem diferentes tipos de resíduos sólidos provenientes dos pequenos geradores das residências na área urbana. Através da realização de entrevistas, aplicação de questionários, trabalhos de campo e elaboração de mapas temáticos, observamos os Ecopontos quanto a seus limites, como, por exemplo, o grau de contribuição da população com o descarte de resíduos, e suas possibilidades, como a seleção de materiais que podem ser reciclados. Objetivando prevenir descartes irregulares de resíduos e impactos ambientais decorrentes destes, os Ecopontos revelam-se importantes como estrutura de apoio ao gerenciamento de resíduos sólidos urbanos domiciliares, colaborando para a destinação final ambientalmente adequada destes resíduos e, consequentemente, para manter a limpeza da cidade / Abstract: The increase in the production of industrialized products, high increase of the population in cities and consumption habits guided by the "culture of the disposable", brings as a consequence the expansion of waste production, therefore generates serious social and environmental impacts. This question is related in many sciences including the Geography, since these actions are linked in man's relations with space, influencing in the management and urban planning of cities. In this problematic, the dissertation have as object of study the Ecopontos, places managed by the municipal public administration of Rio Claro (SP) that receive different types of solid waste from the small generators of the residences in the urban area. Through interviews, the application of questionnaires, fieldwork and making thematic maps, the Ecopontos were observed in their limits, for example the degree of population's contribution to waste disposal, and possibilities, like the selection of materials that can be recycled. With the objective to prevent irregular waste disposals and respective environmental impacts, the importance of the Ecopontos is revealed in the operation of these as a support structure for the management of solid urban household waste, aiming at the final environmental disposal of these wastes to maintain the city's cleanliness / Mestre