Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Boyan, Barbara; Committee Chair: Wick, Timothy; Committee Member: Brockbank, Kelvin; Committee Member: Nenes, Athanasios; Committee Member: Sambanis, Athanassios. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--University of Canterbury, 2009. / Typescript (photocopy). "January, 2009." Includes bibliographical references (p. 213-227). Also available via the World Wide Web.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xv, 220 p.; also includes graphics (some col.). Includes bibliographical references (p. 189-201). Available online via OhioLINK's ETD Center

As celulases e as xilanases são enzimas que hidrolisam a celulose e a xilana, respectivamente, contidas nos resíduos lignocelulósicos. A possibilidade de aplicar estas enzimas na produção de etanol vem sendo objeto de diversos estudos. No entanto, ainda não há uma tecnologia economicamente viável para a produção deste biocombustível a partir da biomassa lignocelulósica. Entre os microrganismos que apresentam altos títulos para estas enzimas, incluem-se linhagens de Penicillium echinulatum; porém, ainda faltam dados de sua fisiologia e estudos da produção de enzimas em biorreator. Neste trabalho, empregou-se a linhagem mutante celulolítica desreprimida S1M29 de P. echinulatum e o meio de cultivo foi composto por celulose, sacarose, solução de sais, Tween 80, farelo trigo e farelo de soja. Avaliou-se o efeito de diferentes temperaturas e pHs na produção das enzimas. O efeito da concentração da celulose sobre as atividades enzimáticas foi avaliada em regime descontínuo (RD) e regime descontínuo alimentado (RDA). Verificou-se que a temperatura mais apropriada para a produção de celulases e xilanases é de 28ºC e dentre os valores de pHs avaliados, o pH 6,0 apresentou a maior produção das enzimas. O aumento da concentração da celulose no RD proporcionou maiores atividades para endoglicanases, porém o mesmo não foi obtido para xilanases. Para FPA (Filter Paper Activity), aumentos proporcionais nas atividades foram obtidos somente com concentrações de até 3% de celulose em RD, condição que também proporcionou as maiores atividades de - glicosidases. O RDA incrementou as atividades de FPA, endoglicanases e xilanases, mas não de -glicosidases. Estes resultados contribuem para a otimização de processos e para a produção econômica de enzimas por P. echinulatum, visando o desenvolvimento de tecnologias economicamente viáveis para produção de etanol a partir de materiais lignocelulósicos. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-06-11T13:29:22Z No. of bitstreams: 1 Dissertacao Laisa dos Reis.pdf: 1870988 bytes, checksum: 956ace97d10d44f22cb5eba7cea275d1 (MD5) / Made available in DSpace on 2014-06-11T13:29:23Z (GMT). No. of bitstreams: 1 Dissertacao Laisa dos Reis.pdf: 1870988 bytes, checksum: 956ace97d10d44f22cb5eba7cea275d1 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Cellulases and xylanases are enzymes that hydrolyze cellulose and xylan respectively, which are found in lignocellulosic residues. Although the applicability of these enzymes in the ethanol production has been the subject of several studies, an economically viable technology for the production of biofuel from lignocellulosic biomass is currently not available. Strains of Penicillium echinulatum are among the microorganisms that have high titers of these enzymes. However, data related to physiology and enzyme production in bioreactor for such strains are still missing. A cellulolytic mutant strain of P. echinulatum S1M29 and a culture medium composed of cellulose, sucrose, salt solution, Tween 80, wheat bran and soybean meal were used in this study. The effect of different temperatures and pHs during the enzymes production was evaluated. The effect of cellulose concentration in the enzymatic activity was evaluated in batch cultivation (BC) and fed-batch cultivation (FBC). It was found that the appropriate temperature for the production of cellulases and xylanases is 28°C, while the higher enzyme production occurred at pH 6.0. The high cellulose concentration in BC provided the greatest activities for endoglicanases, but the same result was not obtained for xylanases. For Filter Paper Activity (FPA), proportional increases in activity were obtained only with concentrations up to 3% of cellulose in BC, which is also linked to the highest activities for -glucosidases. FBC increased the activities of FPA, endoglucanases and xylanases, but it did not increase the -glucosidases activities. Such results contribute towards the optimization of enzyme production using P. echinulatum and the development of economically viable technologies for the production of ethanol from lignocellulosic materials.

Devido à crescente preocupação com as questões ambientais envolvendo as emissões de gases que potencializam o efeito estufa e outros problemas associados aos combustíveis fósseis, o hidrogênio aparece como uma fonte de energia alternativa capaz de promover o desenvolvimento de forma sustentável. A produção de hidrogênio via fermentação anaeróbia é uma das rotas mais atraentes atualmente, envolvendo processos físicos, químicos e biológicos com inúmeras interações entre gases, líquidos e sólidos. No entanto, as pesquisas atuais têm dedicado especial atenção às características químicas e biológicas. Muitos reatores em escala real e de laboratório ainda são dimensionados por correlações empíricas, mas a compreensão dos fenômenos hidrodinâmicos envolvidos na produção de hidrogênio é um precursor necessário para a aplicação em projetos de escala industrial. Para otimizar o desempenho do reator, é essencial compreender a dinâmica das fases em seu interior. Neste contexto, o objetivo deste trabalho é empregar técnicas de fluidodinâmica computacional (CFD) para estudar e otimizar o comportamento fluidodinâmico de um reator anaeróbio sequencial em batelada (ASBR). Para tanto, foi adotada uma modelagem bifásica, tridimensional e turbulenta conduzida com o programa computacional OpenFOAM. Diferentes condições operacionais, configurações geométricas, bem como diferentes modelos, foram avaliados. Os resultados obtidos no estudo das forças interfaciais reforçam a importância e a necessidade de validar as simulações com dados experimentais, devido à grande variação nos resultados obtidos em cada caso simulado. Do ponto de vista das configurações geométricas e operacionais, observa-se que modificações na vazão e no sentido da recirculação, bem como alterações na geometria dos distribuidores afetam significativamente a velocidade de mistura e a energia cinética turbulenta no interior do reator. Estas modificações afetam a transferência de massa, a qual influencia diretamente na cinética das reações e possibilita uma maior produção e hidrogênio. Determinar o comportamento do reator de forma precisa é um precursor para propor alterações que melhorem a sua eficiência. / Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2015-02-23T13:55:23Z No. of bitstreams: 1 Dissertacao Guilherme Zanella Maurina.pdf: 2001909 bytes, checksum: f1de7c235fc3a85355a86042b3c96826 (MD5) / Made available in DSpace on 2015-02-23T13:55:23Z (GMT). No. of bitstreams: 1 Dissertacao Guilherme Zanella Maurina.pdf: 2001909 bytes, checksum: f1de7c235fc3a85355a86042b3c96826 (MD5) / PETROBRAS, Brasil / Due to the growing concern with environmental issues involving the emission of gases that enhance the greenhouse effect and other problems associated with fossil fuels, hydrogen arises as an alternative source of energy capable of promoting development on a sustainable manner. Hydrogen production via anaerobic fermentation is currently one of the most attractive routes, involving physical, chemical and biological processes with numerous interactions between gas, liquid and solid. However, current research has devoted special attention to chemical and biological characteristics. Many full-scale and laboratory-scale reactors are still dimensioned using empirical correlations, but the understanding of hydrodynamic phenomena involved in the production of hydrogen is a necessary precursor for the application in industrial scale projects. To optimize the performance of the reactor, it is critical to understand the dynamics of the phases inside. In this context, the aim of this work is to employ computational fluid dynamics (CFD) techniques to study and optimize the fluid dynamic behavior of an anaerobic sequential batch reactor (ASBR). Thus, a two-phase, threedimensional and turbulent modeling was adopted, and simulations were conducted with the computer program OpenFOAM. Different operating conditions, geometric configurations and different models were evaluated. The results obtained in the study of interfacial forces reinforce the importance and the need to validate the simulations with experimental data, due to the large variation in the results obtained in each simulated case. Concerning geometric and operational settings, it was observed that changes in flow direction and recirculation, as well as changes in the geometry of distributors, affect significantly the velocity and the turbulent kinetic energy inside the reactor. These changes affect the mass transfer, which directly influences the reaction kinetics and enables greater production of hydrogen. The accurate establishment of the reactor behavior is a precur or to propose changes in order to improve its efficiency.

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Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2007. / Innovation in biotechnology research has resulted in a number of fungi being identified for diverse industrial applications. One such fungus, which is the subject of this study and has been one of the most intensively studied, is Phanerochaete chrysosporium. Much research has been done in developing optimized membrane bioreactor systems for the cultivation of these fungi because of their potent industrial applications. This research, however, has been hampered by the lack of a thorough understanding of the kinematics of flow, as well as the dynamics of the flow through these devices. Previous analyses of momentum transfer in membrane bioreactors have been entirely based on horizontally orientated bioreactor systems, and ignored the different modes of operations of membrane bioreactors. These models also ignored the osmotic pressure effects brought about by the retention of solutes on the membrane surface. In this study, analytical and numerical solutions to the Navier-Stokes equations for the description of pressure, velocity, and volumetric flow profiles in a single fibre capillary membrane bioreactor (SFCMBR) were developed. These profiles were developed for the lumen and shell sides of the SFCMBR, taking into account osmotic pressure effects, as well as gel and/or cake formation on the lumen surface of the membrane. The analytical models developed are applicable to horizontal and vertical systems, as well as dead-end, continuous open shell, closed-shell, and shell side crossflow modes.

Thesis (M.Tech-Chemical Engineering)--Cape Technikon, Cape Town, 2001 / The white-rot fungus (WRF), Phanerochaete chrysosporium, is a well known microorganism which produces ligninolytic enzymes. These enzymes can play a major role in the bioremediation of a diverse range of environmental aromatic pollutants present in industrial effluents. Bioremediation of aromatic pollutants using ligninolytic enzymes has been extensively researched by academic, industrial and government institutions, and has been shown to have considerable potential for industrial applications. Previously the production of these enzymes was done using batch cultures. However, this resulted in low yields of enzyme production and therefore an alternative method had to be developed. Little success on scale-up and industrialisation of conventional bioreactor systems has been attained due to problems associated with the continuous production of the pollutant degrading enzymes. It was proposed to construct an effective capillary membrane bioreactor, which would provide an ideal growing environment to continuously culture an immobilised biofilm of P; chrysosporium (Strain BKMF-1767) for the continuous production of the ligninolytic enzymes, Lignin(LiP) and Manganese(MnP) Peroridase. A novel membrane gradostat reactor (MGR) was shown to be superior to more conventional systems of laboratory scale enzyme production (Leukes et.al., 1996 and Leukes, 1999). This concept was based on simulating the native state ofthe WRF, which has evolved on a wood-air interface and involved irnmobilisng the fungus onto an externally skinless ultrafiltration membrane. The MGR however, was not subjected to optimisation on a laboratory scale. The gradostat reactor and concept was used in this work and was operated in the deadend filtration mode. The viability of the polysulphone membrane for cultivation of the fungus was investigated. The suitability of the membrane bioreactor for enzyme production was evaluated. The effect of microbial growth on membrane pressure and permeability was monitored. A possible procedure for scaling up from a single fibre membrane bioreactor to a multi-capillary system was evaluated. Results indicated that the polysulphone membrane was ideal for the cultivation of P chrysosporium, as the micro-organism was successfully immobi1ised in the macrovoids of the membrane resulting in uniform biofilm growth along the outside of the membrane. The production of Lignin and Manganese Peroxidase was demonstrated. The enzyme was secreted and then transported into the permeate without a rapid decline in activity. Growth within the relatively confined macrovoids of the membrane contributed to the loss of membrane permeability. A modified Bruining Model was successfully applied in the prediction of pressure and permeability along the membrane The study also evaluated the effect of potential1y important parameters on the production of the enzymes within the membrane bioreactor. These parameters include air flow (Ch concentration), temperature, nutrient flow, relative redox potential and nutrient concentrations A sensitivity analyses was performed on temperature and Ch concentration. The bioreactor was exposed to normal room temperature and a controlled temperature at 37°C. The reactors were then exposed to different O2 concentration between 21% and 99"10. It was found that the optimum temperature fur enzymes production is 3TJC. When oxygen was used instead of air, there was an increase in enzyme activity. From the results obtained, it was clear that unique culture conditions are required for the production of LiP and MnP from Phanerochaete chrysosporium. These culture conditions are essential fur the optimisation and stability of the bioreactor.

Thesis (MTech (Chemical Engineering))--Peninsula Technikon, 2001 / Certain fungi have been shown to excrete extracellular enzymes, including peroxidases, laccases, etc. These enzymes are useful for bioremediation of aromatic pollutants present in industrial effluents (Leukes, 1999; Navotny et aI, 1999). Leukes (1999) made recent significant development in the form of a capillary membrane gradostat (fungal) bioreactor that offers optimal conditions for the production of these enzymes in high concentrations. This system also offers the possibility for the polluted effluent to be treated directly in the bioreactor. Some operating problems relating to continuous production of the enzymes and scale-up of the capillary modules, were, however, indentified. In an attempt to solve the above-mentioned identified problems the research group at Peninsula Technikon considered a number of alternative bioreactor configurations. A pulsed packed bed bioreactor concept suggested by Moreira et at. (1997) was selected for further study. Their reactor used polyurethane pellets as the support medium for the fungal biofilm and relied upon pulsing of the oxygen supply and recycle of nutrient solution in order to control biomass accumulation. These authors reported accumulation due to the recycle of proteases that were believed to destroy the desired ligninases. We experimented with a similar concept without recycle to avoid backrnixing and thereby overcome protease accumulation. In our work, a maximum enzyme productivity of 456 Units.L1day·1 was attained. Since this was significantly greater than the maximum reported by Moreira et aI, 1997 (202 Units.L-1day-I) it appeared that the elimination of recycle had significant benefits. In addition to eliminating recycle we also used a length / diameter (L / D) ratio of 14: 1 (compared with 2.5: 1 used by Moreira et aI, 1997) in order to further reduce backrnixing. Residence time distributions were investigated to gain insight into mechanisms of dispersion in the reactor. It was found that the pulsed packed bed concept presented problems with regard to blockage by excess biomass. This led us to consider the advantages of a fluidized bed using resin beads. Accordingly, growth of fungi on resin beads in shake flasks was investigated with favorable results. An experimental program is proposed to further investigate the fluidized bed concept with a view to extending the operation time of the bioreactor. From our literature survey to date, packed bed fungal bioreactors are still the best reactor configuration for continuous production ofligninolytic enzymes. An interesting study of the application of laccases to the degradation of naphthalene and MTBE is described in an addendum to this thesis.

Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2016. / The oxidation of microbial ferrous iron is an important sub-process in the bioleaching process. Several studies focussing on microbial ferrous iron oxidation have been investigated and reported in various studies. These studies were carried out using stirred tank bioreactors and shake flasks at optimum conditions. However, these studies could not describe the context of heap bioleach system. Packed column system may describe heap bioleaching, and most studies on microbial ferrous iron oxidation were performed under flooded conditions, which do not represent solution flow dynamics in a heap situation. Biooxidation of ferrous iron oxidation kinetics of Acidiobacillus ferrooxidans was studied in a packed-bed bioreactor to investigate the kinetics in a system that mimics the solution flow dynamic of a heap bioleach operation at low-temperature conditions. This was done in a batch mode operation, with glass marble (15 mm) as reactor packing. The pH of the bioreactor was maintained at pH 1.35 ± 0.05 and aeration at 500 ml/min. Unstructured models known as Monod and Hansford were used to describe the experimental data in determining the kinetics of bio-oxidation.