Thesis (M.S. in chemical engineering)--Washington State University, December 2006. / Includes bibliographical references.

Thesis (M.S. in mechanical engineering)--Washington State University, August 2006. / Includes bibliographical references.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / "Sponsored by: CLP Research Institute." "HKUST project no.: CLPRI02/03.EG01." Includes bibliographical references (leaves 76-83). Also available in electronic version.

Thesis (M.E.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references (p. [85]-87, 2nd sequence). Also available via the World Wide Web.

Thesis (Ph. D.) University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 1, 2007) Includes bibliographical references.

Thesis (M.S.)--Baylor University, 2006. / Includes bibliographical references (p. 134-141).

Percolating packed bed digesters were operated successfully in a batch mode using a wheat straw - dairy manure substrate of between 21 and 27% total solids. The vessels used had a nominal 10 1 volume and were constructed of perspex. Temperatures of 25-35°C were used, recirculation rates of 0-15 litres.hr-1 (the digesters having a diameter of 0.18 metres thus corresponding to superficial flow rates of between O and 0.382 l/m2 /hr), solid : liquid ratios of 1:1 to 4:1 and bed heights of 0.26 to 2.05 metres. The optima found were a temperature of 35°C, recirculation rate of 3 litres.hr1-, a solid: liquid ratio of 2:1 and a bed height of 1.5 metres. Experiments were conducted for periods of up to 70 days, though operation beyond a 40 day period was found to produce little extra biogas. The performance compared favourably with other high solids waste digesters with gas yields of 0.305 m 3 /kg VS added and solids losses of 47% volatile solids and 64% cellulose being obtained over a 40 day period. No major problems of inhibition or blocking occurred. Linking of digesters in series via their recirculation systems was found to be advantageous. Gas yields were found to be increased by approximately 18% and solids losses increased by approximately 20% when the waste was treated in this semicontinuous manner. These increases were found to be a result of the rapid transfer of well-adapted bacteria to the fresh digester. Lag phase in the fresh digester was reduced by three days and potentially inhibitory levels of volatile fatty acids were not present. Concentrations of up to around 5000 ppm VFAs were found during the start-up of batch digesters causing some inhibition of gas production. During semi-continuous operation however concentrations of around 2000 ppm were developed when fresh digesters were linked in, no inhibition occurred and in fact this concentration proved stimulatory to gas production. Experimentation into the optimum retention time of a maximum of three digesters in series was conducted, with retention times of 90, 60 and 30 days being considered. A 30 day retention period was found to depress gas production due to unstable conditions when fresh digesters were added by up to 32% compared with Batch Operation. Gas production was increased at both 60 and 90 day retention times by amounts similar to those previously stated. A retention time of 60 days was found to be optimum as little extra gas was produced after this time, with volatile solids losses being increased by only 9.3% by operating for a further 30 days. Colonisation of the solid substrate was shown to be rapid, by the use of adenosine 51 triphosphate analysis, gas production rate and electron microscope analysis. In addition a dynamic bacterial population appeared to be present in the solid phase with the rates of growth and attachment being approximately equal to the rates of decay and detachment. When digesters were operating in their steady phase, methanogens were present in the liquor at concentrations of between 10 6 - 10 7 /ml and non-methanogens at between 10 7 - 108 /ml showing a large population of bacteria to be present for the inoculation of fresh digesters.

The semi-continuous digestion of poultry litter and manure was carried out in 51 digesters at 35°C to determine the potential of each waste for methane production, and to investigate the relationships between gas yield (GY) and loading rate (LR). GY's obtained were 0.327 m3 kg VS added-1 for litter and 0.397 m kg VS added-1 for manure. During the digestion of litter, GY increased both with increasing retention time (RT) and influent concentration. For manure GY increased with influent concentration up to 2.6 - 4.1% VS after which further increases caused reductions in GY due to ammonia inhibition which reached 4274 mgl of NH4 + - N. The effects of raised concentrations of NH4 + - N on manure batch digesters seeded with sludge adapted to different levels of NH4 - N was investigated by shock loading NH4C1 or NH4 HCO3. High adapted seed was more tolerant of NH4C1 than low adapted seed whereas the opposite was true for NH4 HCO3 which at low levels had a stimulatory effect on low adapted seed. Long term effects of raised NH4 + -N concentrations were examined by adding NH4Cl to semi-continuously fed manure digesters. Increasing NH4 concentrations to 3062 mgl-1 and 4324 mgl-1 reduced GY's to 88% and 73°^ of control levels respectively. After periods of up to 22 weeks exposure to these concentrations GY's failed to regain untreated values indicating that complete adaptation had not occurred. The potential for digestion of poultry wastes at high solids concentrations (up to 27% TS) was tested in a packed bed type digester. Successful hydrolysis and acidogenesis occurred but methanogenesis was inhibited by NH4 + - N concentrations of up to 13,314 mgl -1. Replacing the liquor allowed intiation of Methane production during the digestion of manure but not litter. A study of Monod growth kinetics revealed that the increase in GY obtained with increasing influent concentration was due to the dependence of digester effluent concentration on RT but not influent concentration. Models were developed to describe the uninhibited digestion of litter and the inhibited digestion of manure.

The work presented in this thesis includes experimental investigation using a basic fluidised bed to gasify woodchips and cold modelling studies to improve the fluid bed reactor dynamics incorporating bed internals, such as draft tubes and jets. Low grade fuel gas was produced from woodchips as feedstock, in a 154 mm i/d fluidised bed as the main experimental part of the project using air as the gasifying medium. The influence of a number of process variables on the gasification process were studied including fuel feedrates, temperatures and bed heights, with respect to their effects on quality and quantity of the fuel gas produced. It was found that fuel gas of about 6 MJ/Nm3 can be obtained with temperatures in excess of 700 °c and with fuel feedrates in excess of 3.5 times stoichiometric. The process also benefitted from increasing the static bed heights of the fluidised bed, which was due to the better separation of the combustion and gasification zones. The cold modelling studies coducted using a 2-D glass model employing a draft tube a nd jet system, and using a novel photographic technique produced more realistic data. This showed that both the systems in question produced induced recirculation rates which can be controlled by the process variables such as bed height, bed and jet velocities. Further studies employing these systems for biomass conversion should prove that a better fuel gas quality and quantity can be achieved. In addition a variety of feedstocks can be utilised using the same reactor configuration.

Made available in DSpace on 2014-06-11T19:31:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-05-29Bitstream added on 2014-06-13T20:41:47Z : No. of bitstreams: 1 terrazas_wdm_dr_arafcf_parcial.pdf: 48029 bytes, checksum: cf95252f8151f14699804fc2932ff015 (MD5) Bitstreams deleted on 2014-06-27T19:00:46Z: terrazas_wdm_dr_arafcf_parcial.pdf,Bitstream added on 2014-06-27T19:02:02Z : No. of bitstreams: 1 terrazas_wdm_dr_arafcf.pdf: 414848 bytes, checksum: 5ac66324b77e55b12cd32a9f3b9954e6 (MD5) / Universidade Estadual Paulista (UNESP) / No presente trabalho, inicialmente foi feito um estudo da Metodologia de Superfície de Resposta (RSM) que tem sido adotada com muita freqüência na otimização com várias aplicações na biotecnologia. Foi feita uma revisão na literatura científica dos conhecimentos existente, onde se priorizou as bases teóricas da RSM que consiste em: trabalho preliminar, onde são determinados as variáveis independentes e seus níveis; seleção do projeto experimental com a previsão e verificação da validade da equação do modelo e, representação gráfica da equação do modelo e determinação das condições ótimas de operação. Em seguida a RSM foi aplicada na otimização de biomassa pela levedura recombinante Pichia pastoris. Pichia pastoris que é uma levedura metilotrófica, geneticamente manipulada para expressar proteínas heterólogas que são de grande valor biotecnologico na pesquisa básica e em usos industriais na produção de grande variedade de proteínas heterólogas. Glicerol quinase (GK; EC 2.7.1.30) é uma enzima chave no metabolismo do glicerol e catalisa glicerol para glicerol-3- fosfato na biossíntese de fosfolípidos. Nessa etapa foi conduzido um estudo para determinar um meio otimizado para a produção de biomassa máxima pela recombinante Pichia pastoris com cultivo em frascos agitados usando 2,31% (p/v) de glicerol como fonte de carbono. A otimização foi realizada por metodologia de superfície de resposta (RSM). Em experimentos preliminares, realizados seguindo um planejamento Plackett-Burman, o conteúdo de glicerol (Gli) e tempo de crescimento (t) foram selecionados como os fatores mais importantes na produção de biomassa. Assim, os ensaios subsequentes foram realizados para a otimização da produção de biomassa, seguindo um delineamento composto central rotacionado... / In this study, was initially used to study the response surface methodology (RSM) has been adopted frequently in optimization with many applications in biotechnology. A review of scientific literature on existing knowledge, which prioritized the theoretical foundations of RSM consisting of: preliminary work, where they are certain independent variables and their levels; project selection with the prediction and experimental verification of the validity of equation model and graphical representation of the model equation and determination of optimal operating conditions. RSM was then applied to the optimization of biomass by recombinant yeast Pichia pastoris in GK4 clone obtained from a previous selection of four clones from a cloning process of genetically modified yeast. Pichia pastoris is a methylotrophic yeast that has been genetically engineered to express heterologous proteins that are prized for basic research and industrial biotechnology purposes in the production of wide variety of heterologous proteins. Glycerol kinase (GK; EC 2.7.1.30) is a key enzyme in glycerol metabolism and catalyzes glycerol to glycerol-3-phosphate in the biosynthesis of phospholipids. The present study was undertaken to determine an optimized medium for the maximal biomass production of recombinant Pichia pastoris in shaker cultures using 2.31% (w/v) glycerol as the carbon source. Optimization was carried out by response surface methodology (RSM). In preliminary experiments, performed following a Plackett-Burman design, glycerol content (Gly) and growth time (t) were selected as the most important factors on biomass production. Therefore, subsequent experiments were carried out for optimization biomass production, following a central composite rotatable design as a function of Gly and time. Gly showed to have a significant... (Complete abstract click electronic access below)