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1
Planchat, Jean-François. « Groupes d'automates et Cstar-algèbres ». Paris 7, 2010. http://www.theses.fr/2010PA077116.
Texte intégralRésumé :
Cette thèse se propose d'introduire et d'étudier quelques Cstar-algèbres naturellement associées à tout sous-groupe de type fini SGS du groupe des automorphismes d'un arbre enraciné régulier. On s'intéressera particulièrement au cas où SGS est un groupe d'automate afin d'illustrer, et parfois préciser, les propriétés de ces algèbres. Deux chapitres seront consacrés à l'étude du point suivant : étant donné une de ces Cstar-algèbres, sous quelles conditions sur SGS cette dernière contient-elle la Cstar-algèbre régulière de SGS ? Nous verrons que cette question est reliée à la taille des stabilisateurs de sous-arbres ; nous étudierons ainsi ces sous-groupes dans le cas où SGS est un groupe d'automate. Par ailleurs, nous montrerons que ces algèbres permettent parfois d'obtenir des résultats sur la Cstar-algèbre régulière du groupe et sur certaines algèbres introduites par V. NekrashevychThis PHD dissertation aims to introduce and study some Cstar-algebras naturally associated with any finitely generated subgroup SGS of the automorphism group of a regular rooted tree. We will especially be interested with the case of SGS an automata group, in order to illustrate, and sometimes specify the properties of these algebras. Two chapters will be devoted to the study of the following point: given one of these Cstar-algebras, under what conditions on the group SGS does this latter algebra contain the regular Cstar-algebra of SGS? We will see that this question is related to the size of the stabilizers of sub-trees; we will thus study these subgroups when SGS is an automata group. Besides, we will show that these algebras sometimes allow to obtain results on the regular Cstar-algebra of the group and on certain algebras introduced by V. Nekrashevych
2
Tanaka, Ken. « Control of solution MMA polymerization in a CSTR ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq22260.pdf.
Texte intégral
3
Barbosa, Junior Vandoel Pedro. « Estrategias de controle de operação de reatores CSTR ». [s.n.], 1992. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267333.
Texte intégralRésumé :
Orientador: Rubens Maciel FilhoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: : O controle de processos químicos é um fator determinante para o bom desempenho de toda a planta. No entanto, o seu sucesso vai depender do desenvolvimento de estruturas de controle adequadas. Neste trabalho foram propostas e investigadas várias estruturas de controle com o objetivo de obter o controle de reatores químicos ¿off-line¿ e ¿on-line¿. Para tanto foram utilizadas técnicas de controle não convencionais. O sistema considerado é um reator tanque contínuo agitado (CSTR) não isotérmico para reações químicas do tipo A 'seta¿ B ou A 'seta¿ B 'seta¿ C (consideradas exotérmicas, irreversíveis e com cinéticas de primeira ordem), onde pretende-se maximizar o produto B. O estudo deste tipo de sistema tem relevância para muitos processos na indústria química e em processos biotecnológicos. Embora o sistema seja de parâmetros concentrados, o fato de ser multivariável e ter um modelo matemático determinístico não linear, leva-o a ter um comportamento dinâmico complexo. Um estudo dinâmico abrangente do sistema, para perturbações múltiplas nas variáveis de entrada, foi realizado. A metodologia proposta para analisar tais efeitos mostrou-se conveniente na definição de futuras políticas de controle e de operação. Feita a análise dinâmica do sistema iniciou-se os estudos de otimização através de um procedimento visando a definição de ¿set-point¿ para operação ótima do reator, estratégias e implementação de algoritmos de controle... Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital
Abstract: The control of chemical processes is a determining factor to a good performance of the whole plant. However, its success will be highly restricted to the development of suitable control structures. In this work, it was proposed and investigated several structures of control looking for obtaing suitable off-line and on-line control of chemical reactor. For that some non-conventional techiniques were used. A non-isothermic continuous stirred tank reactor (CSTR) to chemical reactions of the type A 'seta¿ B ou A 'seta¿ B 'seta¿ C (considered exothermic, irreversible with first order kinetics) was used as the system, where the control objective is to maximize product b. the study of this system is of major importance in many process is of the chemical and biotechnological industries. In spite of being a lumped parameter system, the process multivariable and nonlinear so that it has a complex dynamic behaviour. A comprehensive dynamic study for simultaneous perturbations of the inputs was carried out. The proposed methodology to analyse such effects showed out be very convenient in the definitions of control strategies and operational policies. Made the dynamic analyse of the system was began the optimization study through a procedure to define the set-point for the reactor optimum operation, strategies and implementation of control algorithm... Note: The complete abstract is available with the full electronic digital thesis or dissertations
Mestrado
Mestre em Engenharia Química
4
Murphy, Terry 1955. « Residence time distribution of solid particles in a CSTR ». Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79251.
Texte intégralRésumé :
When mixing in a tank is insufficient solid particles are known to form a concentration gradient along the height. The one-dimensional sedimentation dispersion model provides a relationship between mixing parameters and the solids concentration gradient. An investigation of the relationship between the solid mixing properties and the solids residence time distribution, as derived from the sedimentation dispersion model has been conducted. Experimental results show that the solids residence time distribution was a function of particle size and differed from that for the liquid phase. An empirical correlation for the solids Peclet number to predict the residence time distribution of the particles is proposed. A single parameter model to predict the solids residence time distribution as a function of particle size is presented. The influence of the particle concentration gradient on the mean conversion obtained in the reactor for two different cases is examined.
5
Ali, Fathei M. « On the nonlinear chemical dynamics of the imperfectly mixed CSTR ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ33891.pdf.
Texte intégral
6
SANTOS, Tarcísio David KOnna Nunes. « Simulação em CFP de um reator CSTR para produção de biodíesel ». Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/301.
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Este trabalho propôs um modelo matemático para um reator do tipo CSTR (continuous stirred-tank reactor) partindo de dados experimentais da cinética da reação de transesterificação entre o óleo de soja e o acetato de metila, tendo como catalisador uma enzima, a Candida Antartica. Um volume foi proposto para reator para que o tempo médio de residência da mistura reacional fosse suficiente tal que o rendimento esperado, com base nos dados obtidos pelo Matlab®, fosse obtido na saída do reator. O estudo reacional fluidodinâmico foi feito utilizando o software comercial ANSYS® versão 15.0. Duas configurações do reator foram propostas otimização, afim de tornar o processo o mais homogêneo possível, tentando atingir as configurações do reator de mistura perfeita. Os impelidores utilizados foram o tipo pás retas inclinadas e o ripo Ribbon (Âncora), afim de avaliar qual dos impelidores consegue o rendimento satisfatório com menor potência de operação. A potência requerida foi determinada através das equações para misturadores mecânicos, sendo avaliado apenas como variável a rotação das pás.
This work proposes a mathematical model to a reactor of CSTR-type (Continuous Stirred-tank reactor) starting from experimental data of the kinetics of transesterification of soybean oil and methyl acetate, with the catalyst enzyme, Candida Antarctica. A reactor volume was proposed for the average residence time of the reaction mixture was sufficient such that the expected yield, based on data obtained by Matlab, was obtained in the reactor outlet. The reaction fluid dynamic study was done using the commercial software ANSYS® version 15.0. The optimization of the reactor was proposed by comparing the reactor operation with two impellers separately in order to make the process more homogeneous as possible, trying to achieve the perfect blend of reactor configurations. The impellers used were the type inclined straight blades and Ribbon RIPO (Anchor), to determine which of the impellers can the satisfactory performance with lower power operation. The required power was determined by the equations for mechanical mixers, being rated only as a variable rotation of the blades
7
SOARES, Arianne de Freitas Barros. « Análise e avaliação entrópica de reações múltiplas consecutivas em reator CSTR ». Universidade Federal de Campina Grande, 2017. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/2022.
Texte intégralRésumé :
Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-10-19T12:15:24Z
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O presente trabalho estende a metodologia de análise e otimização de processos químicos via minimização da taxa de produção de entropia a um sistema considerado complexo e pouco explorado pela metodologia adotada. Com o intuito de determinar as condições ótimas operacionais do processo, um sistema de reações múltiplas, genéricas e consecutivas conduzidas em um reator de mistura perfeita foi analisado. Tendo em vista que o produto intermediário é o de interesse comercial, o desenvolvimento da metodologia foi baseado nos balanços de massa e energia associados ao balanço entrópico objetivando a minimização da taxa de produção de entropia da reação de interesse. Em conformidade com estudos antecedentes, o procedimento de otimização revelou que a obtenção de uma relação entre a temperatura de alimentação e a temperatura de operação é fundamental para que a condição de mínima produção de entropia seja alcançada. Se tratando da temperatura de reação, uma única condição operacional foi considerada ótima do ponto de vista da mínima produção de entropia, maximizando o rendimento do produto desejado; enquanto que a metodologia clássica de análise e otimização sugeriu diversos pontos operacionais, incluindo um que direciona o sistema para a maximização do produto indesejado em detrimento do produto de interesse. Por se tratar de reações consecutivas, um parâmetro construtivo do reator também foi analisado para alcançar a condição de mínima entropia. A otimização entrópica do tempo de residência revelou que quanto maior for seu valor menor será a taxa de produção de entropia. Uma análise econômica de modo simplificado foi aplicada ao sistema com o intuito de se configurar um critério de seleção de tal parâmetro. Os resultados obtidos revelaram uma nova condição operacional capaz de reduzir os custos energéticos do processo e melhorar o desempenho reacional do sistema.
The present study extends the methodology of analysis and optimization of chemical process by minimizing the entropy rate production to a system considered complex and still not explored by the adopted methodology. In order to determinate the optimal operational conditions of the process, a system of multiple generic and consecutive reactions conducted in a perfect mixing reactor was analyzed. Since the intermediate product is of commercial interest, the development of the methodology was based on the mass and energy balances associated with the entropic balance aiming to minimize the entropy rate production of the reaction of interest. In accordance with previous studies, the optimization procedure revealed that obtaining a relation between inlet and operating temperatures is essential to reach the minimum entropy production condition. If treating of reaction temperature, a single operational condition was considered optimal from the point of view of minimum entropy production, while the classical analysis methodology suggested several operating points. Because it is a consecutive reaction, a constructive parameter of the reactor was also analyzed to reach the minimum entropy condition. The entropic optimization of the residence time revealed that the higher its value the lower is the entropy rate production. A simplified economic analysis was applied in order to configure a selection criterion for such parameter. The results reveals a new operating condition capable of reducing the energy costs of the process and improving the reactive performance of the system.
8
Mendiburu, Díaz Henry A. « Diseño de un neurocontrolador dinámico (DBP) aplicado a un reactor químico continuo (CSTR) ». Master's thesis, Pontificia Universidad Católica del Perú, 2005. http://tesis.pucp.edu.pe/repositorio/handle/123456789/138.
Texte intégralRésumé :
La presente tesis se compone de cuatro capítulos: en el primer capítulo se plantea los objetivos de la esta investigación y se realiza una recopilación de información referente a investigaciones relacionadas con el control y la automatización de reactores químicos CSTR. En el segundo capítulo realiza una introducción teórica sobre el reactor tanque agitado continuo, así mismo se desarrolla el modelo matemático de un reactor químico de este tipo, el cual servirá para la simulación del sistema a controlar. En el tercer capítulo se lleva a cabo el desarrollo de los criterios de diseño y parámetros de sintonización de los diversos controladores implementados para aplicarlos al reactor. En el cuarto capítulo se presentan las simulaciones del sistema sometido a la acción de control de los diversos controladores, para luego elaborar un análisis de la performance de cada uno, y finalmente establecer la superioridad del neurocontrolador dinámico frente a otros controladores.Tesis
9
Hanna, Molin. « Optimal steady-state design of bioreactors in series with Monod growth kinetics ». Thesis, Uppsala universitet, Avdelningen för systemteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-338760.
Texte intégralRésumé :
Bioreactors are used to carry out bioprocesses and are commonly used in e.g. biogas production and wastewater treatment. Two common hydraulic models of bioreactors are the continuous stirred tank reactor (CSTR) and the plug-flow reactor (PFR). In this paper, a differential equation system that describes the substrate, biomass and inert biomass in the bioreactors is presented. It is used in a steady-state analysis and design of CSTRs in series. Monod kinetics were used to describe the specific growth rate and the decay of biomass was included. Using the derived systems of differential equations, two optimization problems were formulated and solved for both CSTRs in series and for a CSTR+PFR. The first optimization problem was to minimize the effluent substrate level given a total volume, and the second was to minimize the total volume needed to obtain a certain substrate conversion. Results show that the system of differential equations presented can be used to find optimal volume distributions that solves the optimization problems. The optimal volume for N CSTRs in series decreases as N increases, converging towards a configuration of a CSTR followed by a PFR. Analyzing how the decay rate affects the results showed that when the total volume was kept constant, increasing the decay rate caused less difference between the configurations. When the total volume was minimized, increasing the decay rate caused the configurations to diverge from each other. The presented model can be used to optimally divide reactors into smaller zones and thereby increasing the substrate conversion, something that could be of interest in e.g. existing wastewater treatment plants with restricted space. A fairly accurate approximation to the optimal design of N CSTRs in series is to use the optimal volume for the CSTR in the configuration with a CSTR+PFR and equally distribute the remaining volumes.Bioreaktorer används för att utföra olika biologiska processer och används vanligen inom biogasproduktion eller för rening av avloppsvatten. Två vanliga hydrauliska modeller som används vid modellering av bioreaktorer är helomblandad bioreaktor (på engelska continuous stirred tank reactor, CSTR) eller pluggflödesreaktor (på engelska plug-flow reactor, PFR). I den här rapporten presenteras ett system av differentialekvationer som används för att beskriva koncentrationerna av substrat, biomassa och inert biomassa i både CSTR och PFR. Ekvationssystemet används för analys och design av en serie CSTRs vid steady-state. Tillväxten av biomassa beskrivs av Monod-kinetik. Avdödning av biomassa är inkluderat i studien. Från ekvationssystemet formulerades två optimeringsproblem som löstes för N CSTRs i serie och för CSTR+PFR. Det första optimerinsproblemet var att minimera substrathalten i utflödet givet en total volym. I det andra minimerades den totala volymen som krävs för att nå en viss substrathalt i utflödet. Resultaten visade att ekvationssystemet kan användas för att hitta den optimala volymsfördelningen som löser optimeringsproblemen. Den optimala volymen för N CSTRs i serie minskade när antalet CSTRs ökade. När N ökade konvergerade resultaten mot de för en CSTR sammankopplad med en PFR. En analys av hur avdödningshastigheten påverkade resultaten visade att en ökad avdödningshastighet gav mindre skillnad mellan de två olika konfigurationerna när den totala volymen hölls konstant. När den totala volymen istället minimerades ledde en ökad avdödningshastighet till att de två konfigurationerna divergerade från varandra. Modellen som presenteras i studien kan användas för att fördela en total reaktorvolym i mindre zoner på ett optimalt sätt och på så vis öka substratomvandlingen, något som kan vara av intresse i exempelvis befintliga avloppsreningsverk där utrymmet är begränsat. En relativt bra approximation till den optimala designen av N CSTRs i serie är att optimera volymerna för en CSTR+PFR, använda volymen för CSTR som första volym i konfigurationen med N CSTR i serie, och sedan fördela den kvarvarande volymen lika mellan de övriga zonerna.
10
Basu, Nandini. « Nonlinear chemical phenomena in a continuously stirred tank reactor (CSTR) containing chlorine dioxide and sulfite / ». free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426045.
Texte intégral
11
Wolf, Aurel. « Darstellung von Styrol-Glycidylmethacrylat-Copolymeren mit niedrigen Molmassen durch radikalische Polymerisation im CSTR bei hohen Temperaturen ». [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=962822604.
Texte intégral
12
Temeng, Kwaku Ofosu. « The design and evaluation of a control scheme for emulsion polymerization in a tube-CSTR system ». Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/10019.
Texte intégral
13
Núñez, Venegas Oscar Julio. « Análisis de alternativas en el dominio térmico del reactor químico CSTR empleando un algoritmo correlacional interactivo ». Master's thesis, Universidad Nacional Mayor de San Marcos, 2013. https://hdl.handle.net/20.500.12672/12609.
Texte intégralRésumé :
Publicación a texto completo no autorizada por el autorEstudia las alternativas del dominio térmico del reactor continuo de tanque agitado (CSTR) mediante un algoritmo correlacional interactivo lo que permiten mejorar la eficiencia. Se ha utilizado un algoritmo para la iteración del modelo de ecuaciones diferenciales de las variables del reactor mediante el método Euler. Un segundo algoritmo fue enlazado y sincronizado con las variables del reactor, el cual, ha leído los datos, procesado y enviado las respuestas previamente obtenidas por simulación. Los algoritmos se han codificado y operado en lenguaje de programación de Java Eclipse 3,0. La correlación interactiva corrige a tiempo el ejercicio normal del reactor, aliviando de esta manera la decisión oportuna que debe tomar el ingeniero para obtener un producto de calidad con un mínimo costo y tiempo. Para la validación de algoritmo correlacional interactivo, se ha tomado los valores experimentales de la reacción de saponificación acetato de etilo (C2H5CH3COOC2H5) con hidróxido de sodio (NaOH), descrito en la literatura. El tamaño de la muestra fue de 2 593 segundos (43,2 minutos), con un error de ± 2 %, y con un nivel de confianza de 95 %. La máxima conversión de este proceso experimental ocurre a la temperatura constante de 304,6 K. El diseño es no experimental, de corte longitudinal, y el método Hipotético deductivo. Considerado las variaciones en las concentraciones, temperaturas, y flujos de los reactantes, se presentó como mejorar la eficiencia del refrigerante del reactor mediante el algoritmo que contiene las variables corregidas del mismo reactor por simulaciones con datos aleatorios y considerando un error del 2%. Se prueba que la variación de las variables es directamente proporcional a la temperatura del refrigerante.
Tesis
14
Galarce, Castro Diego Ignacio. « Concepción, diseño, implementación y operación de un biorreactor continuo para caracterización de parámetros dinámicos de sistemas elicitor-promotor-efector en biología sintética ». Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/144322.
Texte intégralRésumé :
Ingeniero Civil Químico. Ingeniero Civil en BiotecnologíaCuando se habla de ciencia e ingeniería, los métodos y herramientas utilizados son bastante distintos entre ellos. Bajo esta diferencia aparece la biología sintética, disciplina que busca diseñar y modificar organismos vivos para producir nuevas funciones y/o mejorar las ya existentes. Para ello hace uso de herramientas básicas de la ingeniería, tales como los conceptos de modularidad, estandarización, abstracción, modelamiento y diseño. Para poder estandarizar las unidades básicas de esta disciplina, los biobricks, se pueden utilizar pruebas en matraces, pero no es usual hacerlo en biorreactores. La concepción, diseño implementación y operación de uno de estos equipos constituye el objetivo principal de este proyecto. Como parte de los resultados del mismo, se estimó que el mejor modo de operar para lograr estas mediciones se compone de una cascada de CSTRs, la que fue implementada en escala de laboratorio. Para las pruebas de medición se construyeron cinco plásmidos, de los cuales cuatro fueron elaborados con técnicas usadas en biología sintética. De estos últimos, se obtuvo dos vectores con alta producción basal en LB, otro que no sintetizó la proteína esperada y sólo el último presentó un comportamiento apropiado, vale decir, producción basal baja y un aumento significativo en presencia de inductor. Para analizar el comportamiento del reactor en operación, se realizó una experiencia de distribución de tiempos de residencia. Los resultados indicaron que la diferencia entre el biorreactor, compuesto por 7 minirreactores CSTR en serie, y el modelo matemático, fue aproximadamente un 1%. En las pruebas de operación del biorreactor con bacterias, se obtuvo que la cepa con el promotor que responde a arabinosa posee un crecimiento más alto que la cepa con promotor sensible a aTc. En cambio, en términos de producción de proteína, el promotor sensible a aTc posee una inducción más fuerte. Específicamente, usando un flujo de 0,794 [mL/min], este promotor mostró una mayor productividad de proteína por biomasa, lo que lo caracteriza como un promotor fuerte.
15
Asar, Isik. « Model Predictive Control (mpc) Performance For Controlling Reaction Systems ». Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605001/index.pdf.
Texte intégralRésumé :
In this study, the performance of the Model Predictive Controller (MPC) algorithm is investigated in two different reaction systems. The first case is a saponification reaction system where ethyl acetate reacts with sodium hydroxide to produce sodium acetate and ethanol in a CSTR. In the reactor, temperature and sodium acetate concentration are controlled by manipulating the flow rates of ethyl acetate and cooling water. The model of the reactor is developed considering first principal models. The experiments are done to obtain steady state data from the reaction system and these are compared with the model outputs to find the unknown parameters of the model. Then, the developed model is used for designing SISO and MIMO-MPC considering Singular Value Decomposition (SVD) technique for coupling.
The second case is the reaction system used for the production of boric acid by the reaction of colemanite and sulfuric acid in four CSTR&rsquos connected in series. In the reactor, the boric acid concentration in the fourth reactor is controlled by manipulating the sulfuric acid flow rate fed to the reactor. The transfer functions of the process and disturbance (colemanite flow rate) are obtained experimentally by giving step changes to the manipulated variable and to the disturbance. A model-based and constrained SISO-MPC is designed utilizing linear step response coefficients. The designed controllers are tested for performance in set point tracking, disturbance rejection and robustness issues for the two case studies. It is found that, they are satisfactory except in robustness issues for disturbance rejection in boric acid system.
16
Azih, Nnaemeka Raphael. « Comparing the efficiency of CSTR and Gas-lift Anaerobic Reactor configurations in the bio-methanization of Waste Cooking Oils (WCO) ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Trouver le texte intégralRésumé :
Global industrialization has continued an upwards trend, so is the global energy demand increasing. At the moment the major source of energy is fossil-based which leaves a huge and overwhelming carbon footprint which has a devastating effect on the environment. Hence, the quest for alternative cleaner sources of energy is gaining some tremendous interest. The conversion of waste to renewable energy proves to be economical and sustainable. However, the objective of this research work is to explore alternative and more efficient methods of digesting waste cooking oil into CH4 bearing in mind the limitations of solubility of oil in solvents as experienced in previous research works. This challenged the development of a new innovative anaerobic reactor configuration which uses the energy from the gas produced within the reactor mix the oil in the reactor through the principle of convection. At the end of this experiment, the gas-lift successfully converted 9-10% of the total COD (WCO) injected into the reactor to CH4. This result shows that the reactor configuration works, and its operation can be improved on for future experiments.
17
Dastidar, Aniruddha. « ARSENITE OXIDATION BY PURE CULTURES OF THIOMONAS ARSENIVORANS STRAIN B6 IN BIOREACTOR SYSTEMS ». UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/70.
Texte intégralRésumé :
The removal of arsenic toxicity from water is accomplished by a preliminary preoxidative step transforming the most toxic form, arsenite (As (III)), to the least toxic form, arsenate (As (V)). The potential of As (III) oxidation to As (V) was initially investigated in batch reactors using the chemoautotrophic Thiomonas arsenivorans strain b6 under varying initial As (III) and cell concentrations and at optimal pH and temperature conditions (pH 6.0 and temperature 30°C). The strain b6 completely oxidized As (III) to As (V) during exponential growth phase for lower levels of As (III) concentrations (≤ 100 mg/L) but continued into stationary phase of growth for higher levels (≥ 500 mg/L). Other important factors such as oxygen and carbon limitations during biological As (III) oxidation were also evaluated. The biokinetic parameters of the strain b6 were estimated using a Haldanesubstrate inhibition model with the aid of a non-linear estimation technique.
Microbial As (III) oxidation was further investigated in continuous-flow bioreactors (CSTR and biofilm reactor) under varying As (III) loading rates. Both the reactors achieved As (III) oxidation efficiency exceeding 99% during the steady-state conditions. The reactors were also able to recover from an As (III) overloading phase establishing the resilient nature of the microorganism. The basic mass balance expressions on As (III) and biomass along with the Monod model were used to linearly estimate the biokinetic parameters in the CSTR study. However, in the biofilm study, a steady-state flux model was used to estimate the same parameters. The performance of the model was very good in simulating the transient and steady-state conditions.
Finally, the potential application of one-stage and two-stage reactor systems was investigated for the near complete removal of arsenic. Activated alumina was used as the adsorbent for the As (V) produced by the biological oxidation of As (III). The two-stage reactor process performed better than the one-stage reactor system in lowering the arsenic level below the detection limit (1 mg/L) for at least eight days of operation. However, pH fluctuations and probable competition from ions such as PO43- , SO42-, and Cl- severely impacted the performance of the reactors. Further study is needed to improve the overall efficiency of the reactor systems for achieving complete removal of arsenic for a longer operating time.
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Siripong, Chuthathip, et Supusanee Dulyakasem. « Continuous co-digestion of agro-industrial residues ». Thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-16592.
Texte intégralRésumé :
Slaughterhouse waste (SB) has high potential to be utilized in anaerobic digestion due to its high protein and lipid content. However, these are also the limiting factors of system stability. Thus, co-digestion of slaughterhouse waste with other agro-industrial residues (manure (M), various crops (VC) and municipal solid waste (MSW)) was introduced in this study to overcome this problem. The main objective of the work was to determine the operating parameters and the methane yield in semi-continuous co-digestion of slaughterhouse waste with other agro-industrial waste streams. Four continuously stirring tank reactors (CSTRs) with different substrates and mixtures (SB, SB:M, SB:VC and SB:VC:MSW) were started up operating with hydraulic retention time (HRT) of 25 days in thermophilic conditions. The highest organic loading rates which could be achieved were 0.9 g VS/L·d in digestion of SB and 1.5 g VS/L·d for the co-digestion mixtures. In these cases, average methane yields of 300, 510, 587 and 426 ml/g VS were obtained from the digestion of SB, and the co-digestion of SB:M, SB:VC and SB:VC: MSW, respectively, with methane contents in the biogas of 60-85%. The highest average methane yield of 587 ml/g VS was found in co-digestion of SB:VC, which was in accordance with the value of 592 ml/g VS detected during the batch digestion of the same mixture. Moreover, batch assays with different substrates as well as 11 different mixtures of those were also set up to investigate the methane potential and the effect of second feeding. The results showed that the co-digestion of SB:VC, SB:VC:MSW and SB:M could provide high methane potentials, where the highest methane yields of 592, 522 and 521 ml/g VS, respectively were obtained. Moreover, increasing, similar or decreasing methane yields were determined from the second feeding depending on the substrates and substrate mixtures used.Program: MSc in Resource Recovery - Sustainable Engineering
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Torres, Corrêa Nathalia. « Cinética da redução de cor ICUMSA em caldo de cana-de-açúcar por ozonização em reator RPA/CSTR para produção sulfur-free de açúcar branco ». Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11138/tde-04052016-153020/.
Texte intégralRésumé :
A clarificação do caldo de cana-de-açúcar consiste em uma das etapas mais importantes dentro de todo o processo de produção de açúcar, isso porque, é a cor do açúcar final que determina seu preço de comercialização no mercado, bem como sua qualidade. Porém, além de ter um processo de redução de cor, que ao final apresente um açúcar de qualidade, é necessário que este processo não gere resíduos, nem para o meio ambiente, nem nenhum resíduos tóxicos que esteja presente no produto final e que venha prejudicar a saúde do consumidor. Desta forma, a busca por processos alternativos à sulfitação - que é a atual operação de clarificação do caldo de cana-de-açúcar na produção de açúcar cristal branco - tornou-se mais frequente. Tais processos são conhecidos como processos oxidativos avançados(POA) e, entre eles está o uso de ozônio. Diante deste cenário avaliaram-se as melhores condições de pH, temperatura e dosagem de ozônio para a redução da cor ICUMSA do caldo de cana-de-açúcar, obtendo como condições ótimas para pH entre 1,64 a 5,0, temperaturas de 50 a 70 °C e dosagens de ozônio entre 1,34 mg O3/min a 3,82 mg O3/min. O estudo cinético da redução da cor ICUMSA do caldo de cana-de-açúcar ozonizado permitiu observar maiores reduções de cor ICUMSA após 60 min de reação, contudo a exposição do caldo a longos períodos, em pH baixos (1,64 e 3,0) associados a altas temperaturas (50 e 70 °C) levou a hidrólise da sacarose em glicose e frutose, o que inviabilizaria o processo. As análises por espectrometria de massas permitiram observar que a redução nos teores de cor ICUMSA das amostras de caldo de cana-de-açúcar ozonizadas não está associadaà eliminação das partículas promotoras de cor, mas sim da precipitação destas partículas, uma vez que não foram identificados novos compostos nas amostras analisadas, mas sim umavariação nas concentrações destes compostos, identificados como lipídios. Além de favorecer a redução da cor ICUMSA do caldo, o ozônio também se apresentou como um agente antimicrobiano, reduzindoa presença de bactérias e fungos nas amostras de caldo tratado. Aanálise em redes neurais artificiais (RNA) mostrou um bom ajuste na maioria dos casos apresentados e indicou que a variável Brix%caldo apresentou maior influência na redução da cor ICUMSA e o tempo a variável que apresentou a menor influência.Clarification of the sugarcane juice is one of the most important steps within the entire sugar production process, so why is the color of the final sugar that determines its trading price in the market as well as its quality. However, besides having a color reduction process, which ultimately makes a quality sugar, it is necessary that this process does not generate waste or to the environment, and no toxic residues are present in the final product and that may harm consumer health. Thus, the search for alternative processes to sulfite - which is the current operating clarification of sugarcane juice in white crystal sugar production - has become more frequent. Such processes are known as advanced oxidation processes (AOP), and among them is the use of ozone. In this scenario evaluated the best conditions of pH, temperature and ozone dosing for reducing ICUMSA color of sugarcane juice, optimal conditions for obtaining such pH between 1.64 to 5.0, temperatures from 50 at 70 °C and ozone O3 dosages between 1.34 mg/min to 3.82 mg O3/min. The kinetic study of the reduction of ICUMSA color of sugarcane juice ozonized allowed to observe greater reductions ICUMSA color after 60 min of reaction, however the exposure of the juice long periods at low pH (1.64 and 3.0) associated with high temperatures (50 to 70 °C) led to hydrolysis of sucrose to glucose and fructose, which would make the process. Analysis by mass spectrometry allowed to observe that the reduction in ICUMSA color content of sugarcane ozonated juice samples not associated with the elimination of promoting particles color, but the precipitation of these particles, since they were not novel compounds identified in the samples, but a variation in concentration of these compounds, identified as lipids. In addition to further reduce the ICUMSA color of juice, ozone is also presented as an antimicrobial agent, reducing the presence of bacteria and fungi on the treated juice samples. The analysis on artificial neural networks (ANN) showed good fit in most cases presented and indicated that the variable Brix%juice showed greater influence in reducing ICUMSA color and time the variable that had the least influence.
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Mabusela, Bongolwethu Professor. « The effect of initial pH on surface properties of ferric ion precipitates formed during microbial oxidation of ferrous ion by Leptospirillum ferriphilum in a CSTR ». Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2553.
Texte intégralRésumé :
Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2017.While bioleaching is a proven technology for the efficient recovery of base metals from sulphide minerals, its sustenance is dependent on the continuous availability of ferric ion, Fe3+, in soluble form, in the bioleach liquor. However, the solubility of ferric ion is low at higher pH that it tends to precipitate, resulting in the formation of ferric ion precipitates. The formation of ferric ion precipitates in bio-hydrometallurgy decreases the leaching efficiency by trapping the leached metals in solution through an adsorption mechanism which is not well understood. Although the surface properties of the precipitate could be linked to its metal adsorption properties, there has not been a detailed study that gives any indication or explanation of the adsorption mechanism. Therefore, the aim of this study was to investigate the effect of initial pH on the surface properties of ferric ion precipitate and relate this to the adsorption characteristics of the precipitate for desired metals. Biooxidation experiments catalysed by Leptospirillum ferriphilum were conducted in a CSTR with a working volume of 1L. The biooxidation experiments were conducted at pH values of 1.3, 1.5, 1.7, 1.9 and 2.2 at a constant temperature of 35 0C for 14 days. The recovered precipitates were characterized by X-ray diffraction, elemental analyses, SEM, particle size distribution (PSD) and zeta potential. Zeta potential measurements were conducted to investigate what role initial pH plays in modifying the precipitate surface charge and what role the surface charge of each precipitate plays in the nature of adsorption of copper ions onto the precipitate surface. The amount of copper adsorbed onto the precipitate was quantified by the magnitude of the change in surface charge after adsorption experiments. Quantification results showed that the amount of ferric ions precipitates formed increased from 4.31g to 13.26g with an increase in initial pH (from 1.3 to 2.2). The results also showed that significant precipitation of ferric ion occurred during the exponential phase while insignificant precipitation was observed during the stationary phase.
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Forchheim, Daniel [Verfasser], et M. [Akademischer Betreuer] Türk. « Optimisation of the reaction parameters in a batch reactor and a CSTR for the recovery of phenol from hydrothermal biomass liquefaction / Daniel Forchheim. Betreuer : M. Türk ». Karlsruhe : KIT-Bibliothek, 2014. http://d-nb.info/1056955856/34.
Texte intégral
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Ariunbaatar, Javkhlan. « Methods to enhance anaerobic digestion of food waste ». Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1176/document.
Texte intégralRésumé :
Le traitement des déchets alimentaires (FW) par digestion anaérobie peut conduire à une production d'énergie couplée à une réduction des émissions de volume et de gaz à effet de serre à partir de ce type de déchets. Néanmoins, l'obtention de la récupération du méthane la plus élevée possible dans un temps plus court avec un fonctionnement stable est difficile. Pour surmonter les obstacles de la MA de divers procédés de pré-traitement FW, la supplémentation en oligo-éléments, bioaugmentation utilisant la bouse des animaux de zoo et la comparaison des configurations de réacteurs, y compris une étape ou en deux réacteurs à cuve agités en continu (CSTR) et un réacteur à membrane anaérobie (AnMBR ) ont été étudiées dans le cadre de la présente recherche. Sur la base des résultats des expériences de traitement par lots, de pré-traitement thermique à 80 ° C pendant 1,5 heure cédés> 50% augmentation de la production de biométhane, et il a été trouvé à être plus économe en énergie que l'ozonation ou prétraitements de choc thermophiles. Parmi les différentes concentrations testées et les oligo-éléments, Fe (II) et Se (VI) des concentrations de 25 à 50 ug / L ont donné lieu à 39 et 35% d'augmentation de la production de biométhane, respectivement. Une meilleure solubilisation des protéines (6,96 ± 2,76% de plus) et de glucides récalcitrants (344,85 ± 54,31 mg / L par rapport à zéro) pourrait être obtenue avec bioaugmentation de girafe fumier (30% en volume), qui a donné un 11,24 ± 4,51% de plus production de biométhane. Un CSTR à deux étages avec digestat re-circulation de meilleurs résultats que d'un stade en raison de sa (i) une meilleure capacité d'auto-ajustement du pH; (ii) une plus grande résistance aux chocs de charge organique; (iii) de près de 100% de matières solides volatiles a été destryoed par rapport à 71% en CSTR une étape; (iv) 50 à 60% de teneur en méthane a été obtenu, alors qu'il était de 40 à 50% en une seule étape CSTR; (c) une petite quantité d'hydrogène a également été détectée à partir de la première étape du réacteur à deux étages qui en fait un système attrayant pour la production de biohythane. Bien que la séparation physique des méthanogènes rendus plus sensibles à des facteurs inhibiteurs, tels que l'ammonium et l'acide propionique. En outre, le temps de rétention hydraulique (HRT) est encore une chute de ces systèmes, d'où une AnMBR équipé d'une membrane de fluorure de vinylidène courant latéral a été proposé et exploité avec succès pour 100 d. Merci de membranes HRT a pu être réduite de 20 d à 1d, tout en conservant un rendement global d'élimination de> 97% de la demande en oxygène influent chimique (COD) et a abouti à une production de biogaz supérieure à 70% de teneur en méthaneTreatment of food waste by anaerobic digestion can lead to an energy production coupled to a reduction of the volume and greenhouse gas emissions from this waste type. Nevertheless, obtaining the highest possible methane recovery in a shorter time with a stable operation is challenging. To overcome the hurdles of AD of FW various pretreatment methods, supplementation of trace elements, bioaugmentation using zoo animals' dung and comparison of reactor configurations including one-stage and two-stage continuously stirred tank reactors (CSTR) as well as anaerobic membrane reactor (AnMBR) were studied in the scope of this research. Based on the results of the batch experiments, thermal pretreatment at 80°C for 1.5 hours yielded 46 – 52% higher biomethane production, and it is more energy efficient than ozonation or thermophilic shock pretreatments. Among the various tested concentrations and trace elements Fe (II) and Se (VI) concentrations of 25-50 ug/L resulted in 39 and 35% increase of biomethane production, respectively. A better solubilization of proteins (6.96 ± 2.76% more) and recalcitrant carbohydrates (344.85 ± 54.31 mg/L as compared to zero) could be obtained with bioaugmentation of giraffe dung (30% by volume), which yielded a 11.24 ± 4.51% higher biomethane production. A two-stage CSTR with digestate re-circulation performed better than one-stage with (i) a better pH self-adjusting capacity; (ii) a higher resistance to organic loading shocks; (iii) almost 100% volatile solids was destroyed as compared to 71% in one-stage CSTR; (iv) 50-60% methane content was obtained, while it was 40-50% in one-stage CSTR; (v) a small amount of hydrogen was also detected from the first stage of the two-stage reactor making it an attractive biohythane production system. Although physically separating the methanogens made them more sensitive to inhibitory factors, such as ammonium and propionic acid. Moreover, the long hydraulic retention time (HRT) is still the problem with these systems, hence an AnMBR equipped with a side-stream polyvinylidene fluoride membrane was proposed and a successful operation was achieved. Thanks to the membranes the HRT was able to be reduced from 20 d to 1d, while maintaining an overall removal efficiency of >97% of the influent chemical oxygen demand (COD) and yielded a higher biogas production with 70% methane content
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Rajendran, Karthik, et Gopinath Balasubramanian. « High rate biogas production from waste textiles ». Thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-20787.
Texte intégralRésumé :
Textile is a global product used by all people in the world. These textiles after the use are thrown into the trash for incineration or land filling. However an efficient way that can be used to produce more energy, in an environmentally friendly process is anaerobic digestion. Waste textiles which contain cellulosic fibers (e.g. Cotton and viscose) can be converted to biogas. In this study, the performance of a two-stage anaerobic digestion process for biogas production from four different materials, including untreated jeans, treated jeans, cotton, and starch was studied. Starch was used as an easy-to-digest material to compare its digestion with that of cellulosic materials.The two-stage processes were composed of a CSTR (for hydrolysis) and a UASB (for methanogenisis) which were investigated in two different configurations, namely (closed and open systems). In the closed system, the outlet of UASB was completely returned back to the CSTR, while in the open system the UASB outlet was sent to sewage. In a stepwise progress, the OLR was aimed to increase from 2 to 20 g Vs per L per day along with reduction in hydraulic retention time from 10 days to 1 day.The results showed that the closed system was more stable when compared to the open system. The pre-treatment of jeans by NMMO helped to produce methane as that of cotton. The hydraulic retention time was decreased to less than 9 days for treated jeans and less than 5 days for starch. The overall methane yield at OLR of 4 gVS per L per day for starch and treated jeans was 98.5% and 97.4% in the closed system, whereas in the open system the yield was 77.0% and 35.5%, respectively.Another experiment was conducted to compare the performance of two-stage process with that of a single stage process of anaerobic digestion of textiles containing polyester and cotton or viscose. Viscose textiles produced more gas compared to the cotton textile; it may be due to the higher crystalline of cotton which makes it hard to be degraded by the microorganisms. Furthermore, two-stage process could able to produce more methane than the single stage process.The parameters like total solids, volatile solids, pH, gas production, gas composition, concentration of nutrients, and COD were also analyzed for both of the experiments.
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Paim, Ágata. « COBET : abordagem termodinâmica para a otimização e o controle de processos ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/75889.
Texte intégralRésumé :
O aumento do custo e da demanda de energia, juntamente com a escassez de recursos não renováveis e o crescente apelo para a sustentabilidade dos processos, incentiva o desenvolvimento de equipamentos e sistemas mais eficientes mediante a otimização e o controle dos recursos energéticos disponíveis. A proposta deste trabalho consiste em estabelecer uma abordagem termodinâmica para o controle e a otimização de processos visando o aumento da eficiência na operação dos mesmos. Para tanto, foi desenvolvido um problema de controle ótimo formulado com base no critério de eficiência termodinâmica de acordo com a 2ª Lei, com o objetivo de otimizar a transição entre estados com respeito a taxa de geração de entropia do sistema, mantendo as variáveis controladas como restrições de desigualdade dependentes do tempo. A estratégia proposta, chamada COBET (controle baseado na eficiência termodinâmica), foi aplicada a uma coluna de destilação binária para controlar a pureza do destilado e do produto de fundo, manipulando a razão de refluxo e a taxa de transferência de calor do refervedor. O COBET apresentou ajuste simples, tempo computacional razoável e desempenho de controle aceitável, quando comparado com controladores convencionais. Foi proposta uma estratégia alternativa, de modo a aprimorar o COBET, chamada R-COBET, que consiste no uso de restrições adicionais que garantem que as variáveis de controle permaneçam entre o estado inicial e final. O R-COBET obteve um desempenho aceitável, menor integral do erro quadrático das variáveis de controle e maior lucro, quando comparado ao COBET. A fim de demonstrar a aplicabilidade da metodologia proposta a outras funções objetivo, uma função empírica de eficiência baseada na 1ª Lei da Termodinâmica foi determinada e utilizada no problema de controle ótimo, sujeito às mesmas restrições consideradas no controlador R-COBET. Também se aplicou a metodologia proposta a um reator CSTR com o intuito de controlar a temperatura e a concentração do produto, considerando-se o controlador na forma R-COBET, e obteve-se um desempenho similar ao do estudo da coluna de destilação. Com estas análises, concluiu-se que a metodologia proposta pode ser aplicada com sucesso a problemas de controle ótimo com estados final e inicial definidos.The increasing demand of energy and its rising costs, in addition to the non-renewable resources depletion and to the growing interest in the sustainability in industrial processes, stimulate the development of equipment and systems that are more efficient through the control and optimization of available energy resources. The purpose of this work is to establish a thermodynamic approach to process control and optimization, in order to improve operational efficiency. To this end, it is developed in this work an optimal control problem formulated on the basis of a thermodynamic efficiency criterion, as dictated by the 2nd Law. The principle is to optimize the transition between states with respect to thermodynamic efficiency – regarded as the square of entropy generation rate – while maintaining the controlled variables as time dependent inequality constraints. The proposed strategy, called here TEBC (Thermodynamic Efficiency Based Control) was applied to a binary distillation column in order to control distillate and bottom product purities within specifications while manipulating the reflux ratio and reboiler heat transfer rate. When compared to other controllers, TEBC presented practical tuning, reasonable computational time and acceptable control performance. An alternative strategy was also proposed in order to improve TEBC, called R-TEBC, which considers additional constraints to ensure that control variables remain between the initial and final states. The R-TEBC achieved acceptable performance, smaller integral squared error in the control variables and larger profit, when compared to TEBC. In order to demonstrate the applicability of the proposed methodology to other objective functions, an empirical efficiency function was proposed for the distillation column example and used in the optimal control problem, in the form of a R-TEBC controller. Moreover, an exothermic CSTR reactor with product concentration and reactor temperature as controlled variables was also studied, using additional constraints (R-TEBC), and the results was similar to those obtained in the distillation column. With this analysis, it was concluded that the proposed methodology can be applied to optimal control problems of this kind with fixed initial and final states.
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Oyekola, Oluwaseun Oyekanmi. « An investigation into the relationship between process kinetics and microbial community dynamics in a lactate-fed sulphidogenic CSTR as a function of residence time and sulphate loading ». Doctoral thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/5419.
Texte intégralRésumé :
Includes abstract.Includes bibliographical references (p. 183-212).
The treatment of acid mine drainage and other sulphate-laden wastewaters usingbiological sulphate reduction technology has been shown to offer several advantages.This process effectively removes the following toxicants: sulphate, heavy metals andacidity. Previous studies have also revealed that the sub-process, sulphate reduction, isinfluenced by the choice of electron donor, constituents of the microbial populationmediating the process, the feed sulphate concentration and other operationalparameters. The current work investigated the potential of an ecological approach inthe treatment of sulphate-laden wastewaters. This was based on the relationshipbetween the structure and function of the sulphate-reducing bacterial population. Themain objective was to examine the effects of feed sulphate concentration andresidence time on the kinetics of biological sulphate reduction and the communitystructure of the microbial system involved.
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Cedergren, Linnéa. « Physics-informed Neural Networks for Biopharma Applications ». Thesis, Umeå universitet, Institutionen för fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-185423.
Texte intégralRésumé :
Physics-Informed Neural Networks (PINNs) are hybrid models that incorporate differential equations into the training of neural networks, with the aim of bringing the best of both worlds. This project used a mathematical model describing a Continuous Stirred-Tank Reactor (CSTR), to test two possible applications of PINNs. The first type of PINN was trained to predict an unknown reaction rate law, based only on the differential equation and a time series of the reactor state. The resulting model was used inside a multi-step solver to simulate the system state over time. The results showed that the PINN could accurately model the behaviour of the missing physics also for new initial conditions. However, the model suffered from extrapolation error when tested on a larger reactor, with a much lower reaction rate. Comparisons between using a numerical derivative or automatic differentiation in the loss equation, indicated that the latter had a higher robustness to noise. Thus, it is likely the best choice for real applications. A second type of PINN was trained to forecast the system state one-step-ahead based on previous states and other known model parameters. An ordinary feed-forward neural network with an equal architecture was used as baseline. The second type of PINN did not outperform the baseline network. Further studies are needed to conclude if or when physics-informed loss should be used in autoregressive applications.
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Ojong, Pascal. « Investigation of the effects of co-digesting of biodegradable waste and swine manure on the biogas process ». Thesis, Linköpings universitet, Tema vatten i natur och samhälle, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-73444.
Texte intégralRésumé :
Biomass and biomass-derived waste are important renewable energy sources which plays a vital role in greenhouse gas reduction from fossil fuel. Biomass can be degraded in a process known as anaerobic digestion (AD) to produce biogas. Biogas is a mixture of methane and carbon dioxide which is utilized as a renewable source of energy. This project was based on the investigation of AD process in Nordvästra Skånes Renhållnings AB (NSR) a biogas facility in Helsingborg Sweden. A lab simulation of NSR digesters was conducted to evaluate the effects of swine manure on AD using two continuously stirred tank reactors (CSTR) R1 (control) and R2 with a working volume of 4L for 21 weeks. The study was divided into 4 periods and the investigation was carried out by increasing the organic loading rate (OLR) step wise from 2.5 to 3.6 gVSL-1day-1. To assess the effects of swine manure, the performance and stability of the reactors were monitored by collecting data from process parameters. These process parameters included biogas production, pH, volatile fatty acids, methane yield, methane content and organic solids (total and volatile solids). Increase in OLR resulted in increase biogas production in both reactors, however R2 with additional swine manure (15%) produced more biogas than R1. Methane yield was fairly stable during the experiment and had a similar trend in both reactors, but however R2 had a slightly higher average yield (730±60 mLCH4 gVS-1) than R1 (690±60 mLCH4 gVS-1) during the entire experiment. Increase OLR resulted in increase VFA in period 2; R2 with additional swine manure had a lower peak VFA concentration of 25 mM as compared to 33mM in R1. The characteristics of NSR substrate mix and swine manure provided a good buffering system (stable pH), and reactors were still running stably at 3.6 gVSL-1day-1. Furthermore swine manure was investigated to contain macro-nutrients and trace metals which might have enhanced the AD process in R2 containing more Co, Zn, Ni and Mo than R1. Since this investigation was a simulation, the waste mix used at NSR contained 7% swine manure, this made it difficult to give clearer conclusions about the effects of co-digestion of swine manure on the biogas process since the control (R1) had 7% swine manure. Keywords: Anaerobic digestion, co-digestion, swine manure, substrate mix, organic loading rate, biogas production, methane yield, VFA, process parameters, CSTR.
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Cruz, Daniel Henriques da Silva. « Acidificação de soro de queijo para produção de PHAs ». Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12420.
Texte intégralRésumé :
Mestrado em Engenharia do AmbienteA diminuição dos recursos fósseis bem como a abundância de biomassa renovável e que pode ser valorizada tem levado a encarar com boas perspectivas o processo de biorefinaria, sendo actualmente uma área em grande desenvolvimento. No sector dos plásticos os PHAs tem-se revelado uma alternativa sustentável em relação aos plásticos convencionais. O principal substrato para produzirem estes biopolímeros são os AOVs, produtos resultantes da fermentação acidogénica de resíduos orgânicos, como por exemplo o soro de queijo. Os AOV são compostos de alto valor económico devido às suas diversas aplicações. Neste trabalho foi estudado o processo de acidificação anaeróbio de soro de queijo, com a imposição na alimentação de valores de alcalinidade de 2000 e 5000 mg CaCO3/L e cargas orgânicas de 20 e 50 gCQO/L.d. Foram avaliadas as condições que produziam maior quantidade de ácidos e quais os tipos de ácidos mais produzidos em cada condição, num reactor MBBR. Foi também comparado a produção de AOV num reactor CSTR para a condição de 2000 mgCaCO3/L e 20 gCQO/L.d. Comparando as condições de 20 g CQO/Ld. e alcalinidade 2000 mg CaCO3/L e 5000 mg CaCO3/L é possível verificar que a produção de ácidos foi de 43301 mgCQO/L ± 618,3 e 5184,4 mgCQO/L ± 640,5, respectivamente, e o grau de acidificação foi de 41,6% ± 5,9 e 50,8%, respectivamente. Para a carga de 50 gCQO/L.d. e 2000 mgCaCO3/L verifica-se uma produção de ácidos de 10335,7 mgCQO/L ± 1077,6 e um grau de acidificação de 41,3%. Enquanto que para a mesma carga orgânica e alcalinidade 5000 mgCaCO3/L obteve-se 8693,6 mgCQO/L ± 1960,2 e um grau de acidificação de 30,1%. O ácido n-butírico é o mais produzido nas quatro condições. No reactor CSTR obteve-se uma média de 3555,69 mgCQO/L ± 706,89 e um grau de acidificação de 34,9%, valores estes menores do que os obtidos no MBBR nas mesmas condições. Todos os tipos ácidos são produzidos em maiores quantidades no MBBR, excepto o ácido i-valérico e n-caproico.
The decrease of fossil resources and the abundance of renewable biomass can be valued has led to face with good prospects biorefinery process , currently being an area in great development . In the plastics sector PHAs has proved to be a sustainable alternative to conventional plastics. The main substrate to produce these biopolymers are AOVs , products resulting from acidogenic fermentation of organic wastes such as cheese whey . AOVs have high economic value due to its various applications . In this work was studied,for various conditions of alkalinity , 2000 and 5000 mgCaCO3 / L and organic loading rate of 20 and 50 gCOD / L.d. that produced the largest amount of AOVs and wich kind of acids were produced in each condition , on a MBBR reactor . It was also compared the production of acids in a CSTR for the condition of 2000 mgCaCO3 /L and 20 gCOD / L.d. Comparing the conditions of 20 gCOD / L.day to 2000 mg CaCO3 / L and 5000 mg CaCO3 / L is possible to verify that the production of AOV were 43301 mgCQO/L ± 618,3 and 5184,4 mgCQO/L ± 640,5, respectively, and the degree of acidification was 41,6% ± 5,9 and 50,8% ± 3,9,respectively. For organic loading rate of 50 g COD / L.d. and 2000 mg CaCO3 / L there is a production of acids of 10335.7 mg COD / L ± 1077.6 and a degree of acidification of 41,32 %. While in the same organic loading and alkalinity of 5000 mg CaCO3 / L was obtained 8696,6 mg COD / L ± 1960,2 of AOVs and a degree of acidification of 30,1 %. N-butyric acid is the most produced AOV on all MBBR conditions. In the CSTR was obtained an average of 3555.69 COD mg / l ± 706.89 of AOVs and a degree of acidification of 34.92 %, which are lower than those obtained in the MBBR the same conditions. All kind of AOV are produced in a larger quantities on MBBR except i-valeric and n-caproic.
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Strandberg, Per Erik. « Mathematical models of bacteria population growth in bioreactors : formulation, phase space pictures, optimisation and control ». Thesis, Linköping University, Department of Mathematics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2337.
Texte intégralRésumé :
There are many types of bioreactors used for producing bacteria populations in commercial, medical and research applications.
This report presents a systematic discussion of some of the most important models corresponding to the well known reproduction kinetics such as the Michaelis-Menten kinetics, competitive substrate inhibition and competitive product inhibition. We propose a modification of a known model, analyze it in the same manner as known models and discuss the most popular types of bioreactors and ways of controlling them.
This work summarises much of the known results and may serve as an aid in attempts to design new models.
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Cruz, Rafaela Alexandra Palma. « Study of acidogenic fermentation conditions for VFAs production ». Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14907.
Texte intégralRésumé :
Mestrado em BiotecnologiaThe acidogenic fermentation is the second phase of anaerobic digestion. Volatile fatty acids (VFAs) are the main products of acidogenic fermentation and can act as substrates for hydrogen or polyhydroxyalkanoates (PHA) production. In this work, mixed microbial cultures (MMC) collected in a wastewater treatment plants were used for acidogenic fermentation of hardwood spent sulphite liquor (HSSL), a by-product of paper and pulp industry, in a continuously stirred tank reactor (CSTR), and cheese whey permeate (CWP) in a sequential batch reactor (SBR) in non-sterile conditions. In HSSL fermentation, HRT of 1.6 and 2 days were tested with a feeding concentration of 15 g COD/L. pH was left uncontrolled, but was stable around 5.0 ± 0.24 due to the buffer effect of HSSL. The highest conversion of 10 %, with 68% of sugars, and degree of acidification of 10 % were obtained at HRT 2 days and OLR of 7.7 g COD/(L·d). By using CWP a high conversion of acidogenic fermentation (> 80 %) was achieved, even at a pH below the optimal value (4.5). pH and HRT influenced sugars to VFA conversion and the profile of products. Conversion improved with pH and HRT and ethanol-type and propionic-type fermentation were identified at different pHs. Finally from the conditions tested for acidogenic fermentation of CWP, pH 4.5, HRT 24 h and 30 ºC led to the reduction of base consumption at high conversion.
A fermentação acidogénica é a segunda fase da digestão anaeróbica. Ácidos gordos voláteis (AOVs) são os principais produtos da fermentação acidogénica e podem servir como substratos na produção de hidrogénio ou polihidroxialcanoatos (PHA). Neste trabalho, culturas microbianas mistas (MMC) recolhidas numa estação de tratamento de águas residuais foram usadas para acidificar alguns componentes do licor de cozimento ao sulfito ácido (HSSL), um subproduto da indústria papeleira, num reator contínuo perfeitamente agitado (CSTR), e permeado de soro de queijo (CWP) num reator descontínuo sequencial (SBR), em condições não estéreis. Na fermentação acidogénica do HSSL, foi testado o efeito de HRTs de 1,6 e 2 dias com uma alimentação de 15 g COD/L, com 22 % de glucose e xilose. O pH não foi controlado, mas manteve-se estável em cerca de 5,0 ± 0,24 devido ao efeito tampão do HSSL. A maior conversão e grau de acidificação obtidos foram ambos de 10% com uma HRT de 2 dias e OLR de 7,7 g de COD/(L·d). O consumo de açúcares foi de 68 %. Na fermentação de CWP foi atingida uma conversão elevada (> 80%), mesmo com pH controlado a um valor inferior ao ótimo (4,5). O pH e o HRT influenciaram a conversão de açúcares em VFA e o perfil de produtos. A conversão melhorou com o pH e a HRT e fermentação do tipo etanólico e propiónico foram identificadas a pHs diferentes. Verificou-se que o conjunto de condições testadas que conduziu a uma redução do consumo de base, com elevada conversão, foi pH 4,5, HRT 24 h e 30 ºC.
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Wu, Jing. « Modélisation dynamique d’un système couplé pompe à chaleur – stockage thermique par matériaux à changement de phase : approche systémique et validation expérimentale ». Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10167/document.
Texte intégralRésumé :
Dans le domaine de la réfrigération des bâtiments, le couplage d'une pompe à chaleur (PAC) avec un stockage d'énergie thermique est un moyen significatif pour en réduire le coût de fonctionnement énergétique et pour mieux dimensionner les équipements. Un prototype de ce système couplé avec un stockage thermique par MCP (Matériaux à Changement de Phase) est construit et mis en oeuvre dans le cadre du projet ANR ACLIRSYS (Commande avancée des systèmes de réfrigération à faible inertie). L'objectif de cette thèse est d'en proposer un modèle dynamique en vue de sa commande. Dans les échangeurs de la PAC, le fluide frigorigène peut être vapeur, liquide ou un mélange des deux tandis que le MCP du stock peut être solide, liquide ou un mélange des deux. Par conséquent, un modèle de type hybride est nécessaire pour tenir compte des différentes configurations possibles afin de résoudre les équations de bilan de masse et d'énergie dont les expressions diffèrent en fonction de ces configurations. Dans ce travail, des modèles statiques sont utilisés pour le compresseur et le détendeur de la PAC, et les modèles des échangeurs de la PAC et du stock sont basés sur une représentation des écoulements par une cascade de Réacteurs Parfaitement Agités Continues (RPAC). Le mécanisme de commutation entre les diverses configurations est conçu pour garantir la continuité de l'évolution simulée du système. Cette commutation est effectuée par des opérations matricielles, ce qui permet d'aboutir à une représentation globale et très compacte du système. Les propriétés thermodynamiques du fluide frigorigène et leurs dérivées partielles sont déterminées de façon analytique à l'aide d'une équation d'état. Deux versions du modèle du stock sont proposées. Une version simplifiée du modèle de surfusion et une version plus détaillée basée sur la méthode des bilans de population. Des données expérimentales recueillies sur le prototype ont permis de valider le modèle développé. Des expérimentations en régime transitoire ont été réalisées en faisant varier les conditions opératoires. Ces données concernent le fonctionnement de la PAC seule, du stock seul et du système couplé. Un bon accord a été obtenu entre les résultats numériques et les données expérimentalesIn the area of buildings refrigeration, the use of thermal energy storage coupled with heat pump is a significant way for reducing the operating costs and optimizing the design of equipment. A prototype of refrigeration-PCM (Phase Change Material) energy storage system is built and implemented within the framework of the project ACLIRSYS (Advanced Control for Low Inertia Refrigeration Systems), funded by the French National Research Agency. The objective of my PhD thesis is to propose a dynamical physical model for the complete system. Within the evaporator and condenser of the heat pump, the refrigerant can be liquid, vapor or mixture of both, while the storage media can be solid, liquid or a mixture of both. Therefore, it is necessary to consider the discrete events associated to phase changes in order to solve the energy and mass balances in different configurations. In this work, static models are used for the compressor and the expansion valve of the heat pump. The heat exchangers of the heat pump and the storage models are based on a representation of the fluid flows by a cascade of Continuous Stirred Tank Reactors (CSTRs). In order to assure the continuity of system evolution, the switching mechanism between different configurations is established. This switching is performed by matrix operations, which permit to achieve a global and very compact representation of the system. The thermodynamic properties of the refrigerant and their partial derivatives are analytically determined by using an equation of state. Two versions of the model for the storage are proposed. A simplified version where the supercooling is assumed to take place at a constant temperature and a more detailed version based on the population balance equations. Experimental data from the prototype has been used to validate the developed model. Experiments in transient states were performed by varying the operating conditions. These date relate to the functioning of the heat pump alone, the storage alone and the coupled system. A very good agreement between the numerical results and experimental data was obtained
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Runa, Viviane Marisa Reis. « Effect of reactor configuration in the acidogenic fermentation profile ». Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/21101.
Texte intégralRésumé :
Mestrado em BiotecnologiaPolyhydroxyalkanoates (PHA) emerge as a promising alternative to the conventional plastics due to its biodegradability, biocompatibility and thermochemical properties. Several strategies have been studied in order to decrease PHA production costs and enlarge their commercialization, such as the use of pre-treated renewable substrates and the development of economically and environmentally sustainable extraction procedures. The first part of this work aimed to compare two different reactor operation modes for the production of short-chain organic acids (SCOA), preferred substrates for polyhydroxyalkanoates (PHA) production. Acidogenic fermentation was performed by mixed microbial cultures (MMC) in a continuously stirred tank reactor (CSTR) and in a sequential batch reactor (SBR) operated for 130 days and submitted to the same operational conditions. Both reactors achieved full fermentation (>90%) for an OLR of 10gCOD/L·d, with a different range and relative concentrations of fermentation products (FP). Ethanol (EtOH) was the dominant FP in the CSTR and acetic acid (HAc) the main SCOA produced, while the SBR presented butyric acid (HBu) as dominant FP, slightly higher than the HAc concentration. Although the CSTR showed a higher yield of SCOA than the SBR – 0.671 and 0.604, respectively -, the SBR presented a higher conversion of substrate into SCOA – 48% over 38%. The second part of the work focused on the PHA extraction from pure cultures of C. necator and MMC with surfactants and an enzymatic solution from the hydrolysate of the fungus P. variotii. An extraction protocol was developed for application of the extractive agents studied. Afterwards, a systematic extraction of PHA from the microbial cultures was performed and several concentrations and temperatures tested. Among the surfactants used, BRIJ 30 presented the most promising results with recoveries above 30% for the pure cultures and above 20% for the MMC. The enzymatic solution enabled the PHA extraction when used at a concentration of 10% but not in inferior percentages, indicating that application of higher concentrations should be studied.
Os polihidroxialcanoatos (PHA) apresentam-se como uma alternativa promissora aos plásticos convencionais, devido à sua biodegradabilidade, biocompatibilidade e propriedades termoquímicas. Várias estratégias têm sido estudadas para reduzir os custos de produção de PHA e ampliar a sua comercialização, como o uso substratos renováveis sujeitos a um pré-tratamento e o desenvolvimento de procedimentos de extração económica e ambientalmente sustentáveis. A primeira parte do trabalho consistiu na comparação de dois modos de operação de reator distintos para a produção de ácidos orgânicos de cadeia curta (AOCC), substratos preferidos para a produção de PHA. A fermentação acidogénica foi protagonizada por culturas microbianas mistas (CMM), num reator contínuo perfeitamente agitado (CSTR) e num reator descontínuo sequencial (SBR), operados durante 130 dias sob as mesmas condições operacionais. Ambos os reatores atingiram fermentação total (>90%) para a carga orgânica de 10gCOD/L·d, com gama de produtos de fermentação (PF) e respetivas concentrações relativas distintas. Etanol foi o PF dominante no CSTR e ácido acético (HAc) o principal AOCC produzido, enquanto o SBR apresentou dominância pelo ácido butírico (HBu), com concentração pouco acima do HAc. Apesar do CSTR ter tido maior rendimento de AOCC que o SBR - 0.671 e 0.604, respetivamente - o SBR teve uma conversão de substrato em AOCC superior – 48% comparativamente a 38%. A segunda parte do trabalho incidiu na extração de PHA de culturas puras de C. necator e CMM com aplicação de surfatantes e solução enzimática de hidrolisado do fungo P. variotii. Inicialmente, foi desenvolvido um protocolo para aplicação dos agentes extrativos em estudo. Após, foi feita a extração sistemática de PHA das culturas microbianas seguindo o protocolo desenvolvido e combinando valores de temperatura e concentração. Dos surfatantes utilizados, o BRIJ 30 apresentou resultados mais promissores com recuperações de polímero acima de 30% para as culturas puras e acima de 20% para as CMM. A solução enzimática permitiu extração de PHA em concentração de 10% mas não em concentrações inferiores, indicando que concentrações mais elevadas deverão ser estudadas.
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Mabrouk, Nesrine. « Effet anti-tumoral du GTN +/- doxorubicine dans le cancer du sein triple négatif : implication du système immunitaire ». Thesis, Bourgogne Franche-Comté, 2021. https://nuxeo.u-bourgogne.fr/nuxeo/site/esupversions/1f1d033c-28a0-48c8-a8c4-e49ea46a9f18.
Texte intégralRésumé :
Le cancer du sein (CS) est une maladie hautement complexe, hétérogène et multifactorielle. Comparé aux autres sous-types, le cancer du sein triple négatif (CSTN) représente l'un des stades les plus avancés de la maladie, et se caractérise par une forte hétérogénéité inter et intra-tumorale et une charge mutationnelle élevée, rendant les traitements très difficiles et inefficaces. L’absence d’expression des récepteurs aux œstrogènes, à la progestérone, et l’absence de surexpression du récepteur HER2, fait des chimiothérapies (exemple : la doxorubicine) adjuvantes ou néo adjuvantes, le traitement de référence chez les patients atteints de ce type de cancer. Malheureusement, le taux de réponse anatomopathologique complète en réponse à ces chimiothérapies, dépasse rarement les 50 % avec un bénéfice à long terme qui touche uniquement 30 à 50% des malades. Le laboratoire LIIC dans lequel j’ai effectué ma thèse a comme objectif de montrer qu’un donneur de monoxyde d’azote (NO), le glycéryl trinitritrate (GTN), médicament utilisé en cardiologie, peut améliorer l’efficacité thérapeutique des chimiothérapies anti-cancéreuses. Le but de mon projet de thèse consistait donc à déterminer si l’association du GTN à la doxorubicine pouvait potentialiser l’activité anti-tumorale de cette chimiothérapie dans le CSTN, et de déterminer le mécanisme par lequel cette combinaison agit en mettant l’accent sur le microenvironnement immunitaire en général, et plus particulièrement sur les cellules myéloïdes immunosuppressives, les MDSCs.Les résultats ont montré que l’association du GTN à la doxorubicine améliorait significativement l'efficacité anti-tumorale de cette dernière, dans un modèle de CSTN induit par l’injection de cellules mammaires 4T1. Cet effet est dû, en partie, à la capacité du GTN à augmenter la différenciation des LTCD4+ vers le sous-type anti-tumorale Th1, à augmenter le recrutement intra-tumoral des cellules CD8+/PD-1+ et des G-MDSCs sous-exprimant PD-L1. Cependant, le mécanisme principal par lequel le GTN agit repose essentiellement sur sa capacité à reprogrammer, en présence des ROS, ces G-MDSCs en faveur d’une diminution de leur activité immunosuppressive. En effet, les résultats ont révélé que le GTN, via la S-nitrosylation de STAT5, était capable de moduler le métabolisme lipidique, dépendant de la protéine FATP2 (Fatty Acid Transport Protein 2) de ces cellules. Ainsi une diminution de FATP2, ainsi que de tous les composants faisant partie de la voie de signalisation de cette protéine, en amont (STAT5) et en aval (PGE2), a été observée en réponse au GTN +/- doxorubicine. Tous ces effets étaient inhibés en présence d’un inhibiteur de ROS, la N-acétyl cystéines (NAC). La NAC retardait également considérablement la progression tumorale lorsqu’elle est associée à la combinaison doxorubicine / GTN.Ce travail, basé sur l’utilisation de deux molécules couramment utilisées en clinique, ouvre sans conteste une nouvelle perspective de traitement pour les patientes atteintes d’un cancer TN et cette combinaison pourra être rapidement proposée aux cliniciensBreast cancer (BC) is a highly complex, heterogeneous and multifactorial disease. Compared to other subtypes, triple negative (TNBC) represents one of the most advanced stages of the disease, and is characterized by a strong inter- and intra-tumor heterogeneity and a high mutational burden, making treatments very difficult and inefficient. The absence of estrogen and progesterone receptors expression, and the absence of HER2 receptor overexpression, makes chemotherapy (example: doxorubicin), the prior treatment in patients with this type of BC. Unfortunately, the complete anatomopathological response rate, in response to these chemotherapies, rarely exceeds 50% with a long-term benefit affecting only 30 to 50% of patients. The LIIC laboratory in which I did my thesis aims to show that a donor of nitric oxide (NO), glyceryl trinitritrate (GTN), a drug used in cardiology, can improve the therapeutic efficacy of anti-cancerous chemotherapy. The aim of my thesis project was therefore to determine whether the association of GTN with doxorubicin could potentiate the antitumor activity of this chemotherapy in TNBC, and to determine the mechanism by which this combination acts by emphasizing the immune microenvironment in general, and more particularly on immunosuppressive myeloid cells, MDSCs.The results showed that the association of GTN with doxorubicin significantly improved the anti-tumor efficacy of this chemotherapy, in a TNBC model induced by the injection of 4T1 breast cells. This effect is due, in part, to the ability of GTN to increase the differentiation of LTCD4 + in the anti-tumor linage Th1, to increase the intra-tumor recruitment of CD8 + / PD-1 + cells and of G-MDSCs down-expressing PD-L1. Nevertheless, the main mechanism by which GTN acts is essentially based on its ability to reprogram, in the presence of ROS, these G-MDSCs towards a less immunosuppressive phenotype. Indeed, the results revealed that GTN, via the S-nitrosylation of STAT5, was able to modulate the lipid metabolism of these cells, which is dependent on the protein FATP2 (Fatty Acid Transport Protein 2). Thus, a decrease in FATP2, as well as all the upstream (STAT5) and downstream (PGE2) components of this signaling pathway was observed in response to GTN +/- doxorubicin. All of these effects were inhibited in the presence of an ROS inhibitor, the N-acetyl cysteines (NAC). NAC also significantly delayed tumor progression when used in combination with doxorubicin / GTN.This work, based on the use of two molecules commonly used in the clinic, undoubtedly opens up a new treatment perspective for patients with TNBC and this combination can quickly be offered to clinicians
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Kim, Doo-Il. « Development and application of integrated ozone contactor design and optimization tools ». Diss., Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-05182007-120642/.
Texte intégralRésumé :
Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008.Jae-Hong Kim, Committee Chair ; Philip J.W. Roberts, Committee Member ; E. Michael Perdue, Committee Member ; Sotira Yiacoumi, Committee Member ; Thorsten Stoesser, Committee Member.
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Houhou, Mona. « Caractérisation de sous-populations enrichies en cellules souches cancéreuses et rôle des régulateurs de la transition épithélio-mésenchymateuse dans la plasticité tumorale dans le cancer du sein de type basal ». Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT043.
Texte intégralRésumé :
Il est généralement admis que le cancer du sein représente un ensemble de plusieurs maladies, définies comme des sous-types ayant des caractéristiques moléculaires et cliniques qui leurs sont propres. Une meilleure compréhension des mécanismes qui sous-tendent l'hétérogénéité du cancer du sein est essentielle au développement de thérapies mieux ajustées. Le concept de cellules souches cancéreuses (CSC) pourrait être un des clés de cette compréhension. A ce jour, un certain nombre de marqueurs ont été proposés pour isoler et caractériser les cellules souches dans le cancer du sein, mais aucun ne semble totalement satisfaisant.Le but de mon travail était de déterminer un marqueur ou une combinaison de marqueurs avec lesquels les fractions enrichies en CSC pourraient être isolées de manière reproductible dans le cancer du sein de sous-types basal (BLBC). En effet, les tumeurs basales représentent 15% de toutes les tumeurs mammaires, mais constituent le sous-type le plus agressif. À cet effet, j'ai analysé un certain nombre de marqueurs par analyse FACS et tri cellulaire et utilisé la capacité de formation de mammosphères (MS) comme critère de validation pour la présence de CSC. Les lignées cellulaires utilisées comme modèles étaient les SUM 159, MDA-MB-231, MDA-MB-436, HCC1143, MDA-MB-468, Hs578T et BT-549 correspondant aux modèles basal-A et B. J'ai également testé trois lignées luminales les MCF7, T47D et BT474.De tous les marqueurs testés, seules, la combinaison des protéines de surface cellulaire CD44/CD24/EpCAM et l’activité enzymatique ALDH élevée ont permis d’obtenir un enrichissement significatif en CSC. Toutefois, le niveau de l'activité ALDH est apparu inconstant d’une lignée cellulaire à une autre et selon le type de tumeurs. D'autres marqueurs membranaires ont donné des résultats mitigés dans le cancer du sein ER-. En effet, la plupart des lignées basales ont montré des profils FACS assez homogènes avec des proportions élevées de cellules CD44+. Cependant, l'association de la positivité de CD44 avec l'EMT et la souchitude, ainsi que la bonne corrélation observée dans les modèles luminaux de la population de cellules CD44+/CD24- avec l’enrichissement en CSC, nous a incité à déterminer si le niveau d'expression en CD44 faisait une différence dans les tumeurs basales. Sur cette base, j’ai montré que les cellules CD44 high présentent une forte capacité à former des MS dans toutes les lignées cellulaires testées. Cette constatation nous a incités à utiliser CD44high vs. CD44low comme critère de tri cellulaire et à utiliser ces fractions pour effectuer une analyse du transcriptome afin d'identifier d'autres marqueurs non encore déterminés, pouvant isoler des fractions cellulaires plus faibles avec un enrichissement plus élevé en CSCIt is now accepted that breast cancer is a compendium of several diseases defined as subtypesthat are associated with different clinical outcomes and molecular characteristics. A betterunderstanding of the mechanisms underlying breast cancer heterogeneity is critical to the development of better adjusted therapies. One of the keys to breast cancer heterogeneity may be explained by cancer stem cells (CSC). A number of markers have been proposed to isolate and characterize breast cancer stem cells, but none appears totally satisfactory.The purpose of my work was determine a marker or combination of markers with which CSC enriched fractions could be reproducibly isolated in basal like breast cancer (BLBC). BLBC represent 15% of all breast tumors, but are the most aggressive subtype. To this aim, I have analyzed a number of markers by FACS analysis and cell sorting and used the capacity to form mammospheres (MS) as a validation criterion for the presence of CSCs. The cell lines used as models were SUM 159, MDA-MB-231, MDA-MB-436, HCC1143, MDA-MB-468, Hs578T and BT-549 comprising both Basal A and Basal B models. I also tested three luminal models MCF7, T47D and BT474.Of all the markers tested those that most consistently allowed enrichment of CSCs were the combination of cell surface proteins CD44/CD24/EpCAM and elevated ALDH enzyme activity. However, ALDH activity appeared irregular, ranging from good to inconsistent according to the cell line. Other cell surface markers gave mixed results in ER- breast cancer because the elevated fraction of CD44+ cells found in most of basal breast cancer cell lines and their propensity to show rather homogenous FACS labeling patterns. However, the association of CD44 positivity with EMT and stemness, as well as the good correlation, we observed in luminal models, of CD44+/CD24- cell population with CSC enrichment incited us to determine whether the level of expression of CD44 could make a difference in basal like models. I show that CD44high cells present higher capacity to form MS in all cell line models tested. This prompted us to use CD44high vs. CD44low as a cell sorting criterion and use these fractions to perform transcriptome analysis in order to identify other markers yet not determined, that may point to smaller cell fractions with a higher CSC enrichment
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Dubois, Clémence. « Optimisation du traitement du cancer du sein Triple-Négatif : développement des modèles de culture cellulaire en trois dimensions, efficacité de l'Olaparib (anti-PARP1) en combinaison avec la radiothérapie et chimiorésistance instaurée par les protéines Multi Drug Résistance ». Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAS018/document.
Texte intégralRésumé :
Le cancer du sein est une maladie complexe et difficile à caractériser. Parmi les différents sous-types moléculaires, les tumeurs du sein Triple-Négatives (TN) sont particulièrement agressives et de mauvais pronostic. Elles sont caractérisées par une absence d’expression des récepteurs aux œstrogènes (ER), à la progestérone (PR), l’absence de surexpression du récepteur Human Epidermal growth factor 2 (HER2) et de fréquentes mutations sur les gènes BRCA1/2 (profil « BRCAness »). En absence de thérapies ciblées efficaces, de nombreux traitements ciblés notamment les inhibiteurs de poly-ADP-ribose polymérases (anti-PARPs) sont actuellement en cours de développement, en recherche préclinique et clinique. Basés sur le principe de létalité synthétique, les anti-PARPs ciblent les propriétés BRCAness des tumeurs TN. Dans ce contexte, ces travaux de recherche ont été orientés sur le développement d’outils diagnostics afin d’optimiser l’efficacité des anti-PARPs sur des tumeurs TN. Pour ce faire, dans un premier temps, des cultures cellulaires en 3D via la technique Liquid Overlay ainsi que des tests de cytotoxicités associés ont été développés, à partir des lignées cellulaires MDA-MB-231 et SUM1315 de phénotype TN. Ces deux modèles de sphéroïdes ont ensuite été optimisés/normalisés dans un milieu de culture synthétique intitulé OPTIPASS (BIOPASS). Dans un deuxième temps, l’efficacité d’un co-traitement combinant l’anti-PARP1 Olaparib à faibles et à fortes doses et la radiothérapie fractionnée (5x2 Gy) a été modélisée sur les deux lignées MDA-MB-231 et SUM1315, en conditions 2D et 3D. Ces expériences ont clairement mis en évidence un effet potentialisateur de l’Olaparib sur la radiothérapie (i) en présence de faibles doses de cet anti-PARP (5 µM ou inférieur) (ii) à long terme et (iii) en présence d’un fractionnement maximum (5x2 Gy). De plus, les lignées tumorales TN étudiées présentaient des différences de sensibilité vis-à-vis du co-traitement. Ainsi, une analyse transcriptomique in silico a mis en évidence des profils très différents de ces lignées hautement métastatiques et très agressives. Notamment, la lignée SUM1315 semblait présenter un engagement neuronal, suggérant son origine métastatique cérébrale. Ces résultats encourageants pourraient ouvrir de nouvelles perspectives pour le traitement des métastases cérébrales de tumeurs mammaires TN, très fréquentes chez ce sous-type. Dans un troisième temps, afin de mieux caractériser le mode d’action de l’Olaparib sur ces modèles de sphéroïdes, un dérivé fluorescent de l’Olaparib, l’Ola-FL, a été synthétisé et caractérisé. L’analyse de la pénétration et de la distribution de l’Ola-FL au sein des sphéroïdes MDA-MB-231 et SUM1315 a mis en évidence une distribution rapide et homogène du composé ainsi que sa persistance après 3h d’incubation, dans toute la profondeur des sphéroïdes et notamment dans les zones hypoxiques centrales. Enfin, l’analyse de la co-expression de deux pompes Multidrug Resistance (MDR) majeures, la MRP7 et la P-gp après le traitement des deux lignées TN avec l’Olaparib, a mis en évidence sur les cultures 2D, une expression de type relai de la MRP7 et la P-gp. Sur les sphéroïdes traités avec une faible dose d’Olaparib à long terme, une expression basale de la MRP7 et une surexpression de la P-gp ont été détectées, au sein des cellules résiduelles périphériques des sphéroïdes. Ces résultats mettent clairement en évidence l’implication des pompes d’efflux dans les mécanismes de résistances à l’Olaparib, dans ces tumeurs agressives. L’ensemble des résultats issus de la modélisation de l’action de l’Olaparib sur des sphéroïdes MDA-MB-231 et SUM1315 laissent supposer sa plus grande efficacité à faible dose et à long-terme, notamment dans les zones hypoxiques des sphéroïdes, probablement aussi à l’origine de son effet potentialisateur avec la radiothérapieBreast cancer is a very complex and heterogeneous disease. Among the different molecular subtypes, Triple-Negative (TN) breast cancers are particularly aggressive and of poor prognosis. TN tumours are characterized by a lack of estrogen receptors expression (ER), progesterone receptors expression (PR), the absence of Human Epidermal growth factor receptor 2 overexpression (HER2) of the frequent mutations on BRCA1 / 2 genes ("BRCAness" phenotype). In the absence of effective targeted therapies, many targeted therapies including poly-ADP-ribose polymerase inhibitors (anti-PARPs) are currently under development in preclinical and clinical studies. Based on the synthetic lethality concept, the anti-PARPs specifically target the BRCAness properties of TN tumors. In this context, these works were focused on the development of diagnostic tools for the optimization of TN tumours treatment with anti-PARPs. For this, firstly, 3D cell cultures formed with the Liquid Overlay technique as well as associated cytotoxicity tests were developed, from the TN breast cancer cell lines MDA-MB-231 and SUM1315. These two spheroid models were then optimized and standardized in a synthetic culture medium called OPTIPASS (BIOPASS). Secondly, the efficacy of a co-treatment combining anti-PARP1 Olaparib at low and high doses and fractioned radiotherapy (5x2 Gy) was analyzed on the two cell lines MDA-MB-231 and SUM1315 cultured in 2D and 3D conditions. These experiments clearly demonstrated a potentiating effect of Olaparib on radiotherapy (i) in presence of low doses of this anti-PARP (5 μM or inferior) (ii) at long term and (iii) in presence of the maximum fractionation (5x2 Gy). In addition, these two TN cell lines showed a heterogeneous sensitivity to the co-treatment. Thus, an in silico transcriptomic analysis revealed very different profiles of these highly metastatic and highly aggressive cell lines. Notably, the SUM1315 cell line presented a neuronal commitment, suggesting its cerebral metastatic origin. These promising results could open up new perspectives for the treatment of TN tumours brain metastases, which are very common in this subtype. Thirdly, in order to better characterize the mode of action of Olaparib on these spheroid models, a fluorescent derivative of Olaparib, Ola-FL, was synthesized and characterized. The analysis of Ola-FL penetration and distribution in MDA-MB-231 and SUM1315 spheroids showed a rapid and homogeneous distribution of the compound as well as its persistence after 3h of incubation, in all the depth of the spheroids and especially in the central hypoxic zones. Finally, the analysis of the co-expression of two major Multidrug Resistance (MDR) pumps, MRP7 and P-gp after the treatment of the two TN lines with Olaparib, revealed on 2D cultures, a relay type expression of the MRP7 and the P-gp. On spheroids treated with a low dose of Olaparib art long term (10 days), a basal expression of MRP7 and an overexpression of P-gp were detected in the peripheral residual cells of the spheroids. These results clearly highlighted the involvement of these efflux pumps in Olaparib resistance mechanisms, in these aggressive tumors. All the results resulting from the modeling of the action of Olaparib on MDA-MB-231 and SUM1315 spheroids suggest its greater efficacy at low dose and at long-term, especially in the hypoxic zones of the spheroids. This parameter might be probably at the origin of its potentiating effect with radiotherapy
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Hughes, Kevin Lewis William. « Optimisation of methane production from anaerobically digested cow slurry using mixing regime and hydraulic retention time ». Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/18869.
Texte intégralRésumé :
AD is regarded as a sustainable technology that could assist the UK Government meet internationally agreed GHG emission targets by 2050. However, the mature status of the technology is based on expensive systems that rely on high energy feedstock to be profitable. Meanwhile, the natural biodegradation of cow slurry is a recognised contributor to climate change despite having a relatively low CH4 potential because of the large volumes produced. Economic mixing is essential to the cost-effectiveness of farm AD but techniques applied are not always appropriate as slurry is a shear thinning thixotropic Herschel-Bulkley fluid and therefore challenging to mix. The apparent viscosity of slurry and the shear stress induced was most influenced by solids content (exponential change) followed by temperature (linear). Most shear thinning occurred before a rising shear rate of 20s-1 was achieved with the fluid acting near-Newtonian above. Thixotropic recovery occurred within 1 hour of resting. Rheological values were also much higher than previously reported. Highest CH4 production occurred in the first 10 days of the batch process using a range of mixing regimes with different shear rates and rest periods. During fed-batch operations, changing shear rate had a minimal effect on CH4 production using a 30-day HRT whereas shorter rest periods increased production. Specific CH4 production rate was highest when feeding and mixing coincided. However, when HRT was reduced (OLR increased) the CH4 produced by all mixed regimes significantly increased with highest values being achieved using high intensity mixing rested for short periods. Lower HRTs also requires smaller digesters. Parasitic mixing energy invariably had the most influence on net energy production. Signs of instability were evident after 20 days using the low HRT. Significant microbial adaptation was also observed as the experiments progressed. The research outcomes demonstrate that mixing regime and HRT can be managed to maximise net energy production whilst reducing capital expenditure.
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Zavatteri, Matteo. « Temporal and Resource Controllability of Workflows Under Uncertainty ». Doctoral thesis, 2018. http://hdl.handle.net/11562/979769.
Texte intégralRésumé :
Workflow technology has long been employed for the modeling, validation and execution of business processes. A workflow is a formal description of a business process in which single atomic work units (tasks), organized in a partial order, are assigned to processing entities (agents) in order to achieve some business goal(s). Workflows can also employ workflow paths (projections with respect to a total truth value assignment to the Boolean variables associated to the conditional split connectors) in order (not) to execute a subset of tasks. A workflow management system coordinates the execution of tasks that are part of workflow instances such that all relevant constraints are eventually satisfied. Temporal workflows specify business processes subject to temporal constraints such as controllable or uncontrollable durations, delays and deadlines. The choice of a workflow path may be controllable or not, considered either in isolation or in combination with uncontrollable durations. Access controlled workflows specify workflows in which users are authorized for task executions and authorization constraints say which users remain authorized to execute which tasks depending on who did what. Access controlled workflows may consider workflow paths too other than the uncertain availability of resources (users, throughout this thesis). When either a task duration or the choice of the workflow path to take or the availability of a user is out of control, we need to verify that the workflow can be executed by verifying all constraints for any possible combination of behaviors arising from the uncontrollable parts. Indeed, users might be absent before starting the execution (static resiliency), they can also become so during execution (decremental resiliency) or they can come and go throughout the execution (dynamic resiliency). Temporal access controlled workflows merge the two previous formalisms by considering several kinds of uncontrollable parts simultaneously. Authorization constraints may be extended to support conditional and temporal features. A few years ago some proposals addressed the temporal controllability of workflows by encoding them into temporal networks to exploit "off-the-shelf" controllability checking algorithms available for them. However, those proposals fail to address temporal controllability where the controllable and uncontrollable choices of workflow paths may mutually influence one another. Furthermore, to the best of my knowledge, controllability of access controlled workflows subject to uncontrollable workflow paths and algorithms to validate and execute dynamically resilient workflows remain unexplored. To overcome these limitations, this thesis goes for exact algorithms by addressing temporal and resource controllability of workflows under uncertainty. I provide several new classes of (temporal) constraint networks and corresponding algorithms to check their controllability. After that, I encode workflows into these new formalisms. I also provide an encoding into instantaneous timed games to model static, decremental and dynamic resiliency and synthesize memoryless execution strategies. I developed a few tools with which I carried out some initial experimental evaluations.
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Huang, Po-Chin, et 黃柏欽. « Incorporating a Hole-Transport Material into the Emissive Layer of Solid-State Light-Emitting Electrochemical Cells to Improve Device Performance ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/cstn6z.
Texte intégralRésumé :
碩士國立交通大學
影像與生醫光電研究所
103
Solid-state light-emitting electrochemical cells (LECs) based on ionic transition metal complexes (iTMCs) have several advantages such as high efficiency, low operation voltage and simple device structure. To improve device efficiency of iTMC-based LECs for practical applications, improving carrier balance to achieve a centered recombination zone would be an important issue. In this work, incorporating a hole-transport material (HTM) into the emissive layer of iTMC-based LECs is shown to improve device performance. When mixed with an HTM (12%), the LECs based on a Ru complex exhibit 1.9X and 1.5X enhancement in peak light output and peak external quantum efficiency (EQE) as compared to neat-film devices. Furthermore, over 2X enhancement in stabilized EQE can be achieved in LECs mixed with an HTM. It is attributed to that more centered recombination zone in LECs mixed with an HTM is beneficial in reducing exciton quenching in the recombination zone approaching extended doped layers. Estimating temporal evolution of recombination zone in the LECs mixed with an HTM by employing microcavity effect is demonstrated to confirm the physical origin for improved device performance. These results reveal that incorporaing of an HTM in the emissive layer of LECs based on an iTMC is a feasible way to improve carrier balance and thus enhances light output and device efficiency.
40
Chao, I.-Ya, et 趙怡雅. « paired indirect anodic oxidation formaldehyde in CSTER ». Thesis, 1996. http://ndltd.ncl.edu.tw/handle/03943822515696729643.
Texte intégral
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Leu, Yea-Fen, et 呂雅芬. « Decoupling Control of CSTR with Control Constraints ». Thesis, 1993. http://ndltd.ncl.edu.tw/handle/49443253549719015701.
Texte intégral
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Cheng, Hui-Ping, et 鄭惠萍. « Biodegradation of Naphthalene by Enrichment Activated Sludge in CSTR ». Thesis, 1997. http://ndltd.ncl.edu.tw/handle/17964312905672923494.
Texte intégralRésumé :
碩士東海大學
化學工程學系
85
Microbial degradation of Naphthalene by the enrichment activatedsludge of CSTR is investigated in the thesis. The mean cell residencetime is determined. The cometabolism and inhibition effects of BTX onthe biodegradation of Naphthalene is also studied in this thesis. It is found that both Benzene and Toluene can benefit the degradation ofNaphthalene, but p-Xylene will inhibit the degradation of the Naphth-alene.
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Lee, Chien-te, et 李建德. « CSTN LCD Frame Rate Controller For Image Quality Enhancement ». Thesis, 2010. http://ndltd.ncl.edu.tw/handle/08194971132122979072.
Texte intégralRésumé :
碩士國立中山大學
電機工程學系研究所
98
This thesis is mainly focused on FRC (Frame Rate Control) method which can be used for LCD panels, where a new algorithm is proposed to improve the flicker problem. The proposed algorithm can be implemented by simple digital circuits with low power consumption. The proposed design can be applied in both mono- and color- STN panels. It can generate 32768 colors in a panel without any flicker and motion line problems, which can only allow 8 colors originally. The major contribution in this thesis is to add a location number to each pixel of the panel.Notably, the numbers for all the pixels can not be a regular pattern. Otherwise, the flicker problem is resolved at the expense of a serious motion line issue. The consequence is poor display quality. To resolve both the flicker and motion line problem, we propose to employ a PRSG (Pseudo Random Sequence Generator) which generates a non-regular number sequence for all the pixels. Therefore, all the ON pixels can be dispersed on the panel in all frames.
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Hua, Jaw Shing, et 趙興華. « Bifurcation Analysis and Dynamics of a CSTR with Cascade Control ». Thesis, 1993. http://ndltd.ncl.edu.tw/handle/35355744551077576224.
Texte intégralRésumé :
碩士國立成功大學
化學工程研究所
81
In this thesis, we are interested in the rich nonlinear dynamical behaviors of a cascade control system. Since the cascade control strategy is commonly used in chemical processes and most of the processes are nonliner in nature. We use a continuous-stirred tank reactor (CSTR) implemented with a PI-P cascade control scheme as an example to study the possible complex dynamical behaviors in the three-dimensional control- parameter space. These complicated dynamics include periodic- tori, period doubling bifurcational phenamena and aperiodic oscillation of chaos. Also, new dynamical tools, sush as Poincare map, power spectrum, phase space reconstruction and Lyapunov exponent are used to analyze these complicated system dynamics. In the meantime, We also found that owing to the nonlinear characteristics of the cascade-controlled CSTR, the average conversion obtained by the unsteady operation is superior to that by the steady operation.
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Do, Young Long, et 杜永隆. « On the Indirect Anodic Oxidation of Benzyl Alcohol in the Presence of Phase Transfer Catalyst in CSTER ». Thesis, 1993. http://ndltd.ncl.edu.tw/handle/09032861090813950464.
Texte intégral
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Huang, Sheng-Jow, et 黃盛宙. « Effect of Nonidealities of CSTR on the Fate of Plasmid-bearing Microorganism ». Thesis, 1998. http://ndltd.ncl.edu.tw/handle/21380308209482064773.
Texte intégralRésumé :
碩士淡江大學
化學工程學系
86
The fate of plasmid-bearing and plasmid-free mixed cultures competing for a common substrate in nonideal CSTRs with time- invariant inputs, are examined. The nonideal reactor is modeled as two ideal CSTRs with interchange. The results obtained for Saccharomyces cerevisiaec at varying degrees of nonideality, i.e., different values of a and b, are presented in the form of operating diagrams in the D(dimensionless dilute rate)- zf(dimensionless feed substrate concentration) plane. It is found that up to three steady states, namely, the total washout, the partial washout and the coexistence steady states, may exist, but only one of them is stable, and that whenever it exists, the coexistence steady state is always stable. The coexistence region on the D-zf plane for nonideal CSTRs is always larger than that for ideal CSTRs. A higher degree of nonideality not only yields a larger coexistence region, but also makes both microbial populations be washed out at a higher dilution rate. Besides, a higher probability of plasmid loss leads to the total washout being occurred at a lower dilution rate.
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Chen, Chin-Chao, et 陳晉照. « Hydrogen Production in an Anaerobic Continuous-flow Stirred Tank Reactor (CSTR) System ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/24211274659240524966.
Texte intégralRésumé :
博士逢甲大學
土木及水利工程研究所
90
This study aimed at the hydrogen production of sewage sludge that digested the carbohydrate (glucose and sucrose). To achieve this purpose, the experimental approach was initially focused on the starting-up of hydrogen-producing digesters (continuously stirred tank reactor, CSTR), then the performance of the reactors and finally the influences of enrichment of seed sludge. The procedure for starting-up CSTR reactors for acclimating anaerobic hydrogen-producing microorganisms with sewage sludge was investigated. Initially, the feeding and mixing were in a mode of semi-continuous type; hydraulic retention time (HRT) was in an order of 20, 15, 10, 5, 2.5 and 2 days. When the pH declined to a low value (pH 5.18), it was adjusted to 6.7 with sodium hydroxide (1N). At the same time, the semi-continuous type operation was changed to a continuous type. Finally, the pH was continuously regulated around 6.7. The results indicate that this procedure could cultivate seed sludge for hydrogen production from sewage sludge and obtain a large hydrogen production in less than 60 days. This seed sludge had a hydrogen yield of 1.63 mol-H2/mol-glucose and specific hydrogen production rate (SHPR) of 321 mmol-H2/g VSS-d at the HRT of 13.3 h; hydrogen yield was 4.45 mol-H2/mol-sucrose and SHPR was 707 mmol-H2/g VSS-d. The influence of substrate on anaerobic hydrogen producing reactors seeded with sewage sludge was employed with batch tests. The results indicated that a substrate inhibition phenomenon results from higher glucose concentration, but not in higher sucrose concentration. The varieties of substrate and initial concentration influence the fermentation for hydrogen production. Using thermal pretreatment, or a low or high pH environment to obtain dominant microbes for hydrogen production from sludge is a feasible method. Based on the experimental results, hydrogen production from sludge with thermal, acid or base enrichment is higher than that of the control. The hydrogen production potential of the sludge with acid or base enrichment enhanced 200 and 333 folds than that of the control when the enrichment pH was 10 and 3, respectively. The enrichment is due to the shortening of microorganisms'' lag-time which occurs at a proper cultivation pH level. Two CSTR reactors were started up by using sewage sludge for producing hydrogen from sucrose or glucose. The substrate was fed in a continuous mode from HRT 13.3 hrs to 10, 8, 6, 5, 4, 3, and 2 hrs. The hydrogen gas production and hydrogen percentage increased when HRT decreased at long HRT and decreased with a HRT decreased at short HRT (2 hrs). Under steady state conditions, for reactor fed with glucose and sucrose, respectively, the SHPR ranged from 60 to 516 and 82 to 886 mL-H2/g VSS-hr; the yield ranged from 0.39 to 1.65 mol-H2/mol-glucose and 1.42 to 4.52 mol-H2/mol- sucrose. Kinetic models were developed to describe and predict the experimental results from the H2-producing cultures. The major volatile fatty acid (VFA) produced was butyric acid (HBu) with acetic acid and propionic acid at less quantities. The major solvent product was ethanol, whose concentration was only 15% of that of HBu, indicating that the metabolic flow favors H2 production. The model study also suggests that product formation in the continuous hydrogen-producing cultures was essentially a linear function of biomass concentration. H2 content, SHPR and yield were HRT and substrate-dependent. For each substrate two stages of HRT-dependent relationships for these three parameters were obtained. For glucose-degradation hydrogenation, the critical HRT values of the two-stages relation were 6 hrs for these three parameters. For sucrose-degradation hydrogenation, the critical HRT values of the two-stages relation were 5, 4 and 4 hrs for H2 content, SHPR and yield, respectively.
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Hsiao, Chieh-Hua, et 蕭潔華. « Effect of Nonidealities of CSTR on the Fate of Competing Microbial Populations ». Thesis, 1996. http://ndltd.ncl.edu.tw/handle/23338079135983060929.
Texte intégralRésumé :
碩士淡江大學
化學工程學系
84
The fate of two microbial populations competing purely and simply for a common substrate in nonideal CSTRs, which are subject to time-invariant external influences, are examined. The nonideal reactor is modeled as two ideal CSTRs with interchange. The results for varying degrees of nonideality, i. e., different values of α and β, are presented in the form of operating diagrams in the D(dimensionless dilute rate)-zf (dimensionless feed substrate concentration) plane. It is found that up to four steady states may exist, but only one of them is stable, and that whenever it exists, the coexistence steady state isalways stable. For zf >1, the coexistence steady state exists in at least one, and at most three ranges of dilution rate. Effects of α and β on the domain of existence of the coexistence steady state are discussed.
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Tsai, Chia-Jung, et 蔡佳蓉. « Hydrogen Production in a Recycled Anaerobic Continuous-flow Stirred Tank Reactor(CSTR) System ». Thesis, 2004. http://ndltd.ncl.edu.tw/handle/32416983303552808381.
Texte intégralRésumé :
碩士逢甲大學
土木及水利工程所
92
This study aimed at investigating the effect of biomass recycle on hydrogen production in an anaerobic continuous stirred tank reactor (CSTR). The seed sludge was obtained from Li-Ming Municipal Sewage Treatment Plant (Taichung, Taiwan) and pretreated with heat and was acclimated in a CSTR reactor over one year. This reactor was fed on 20 g COD/l of sucrose and its hydraulic retention time (HRT) was 12 hours. The pH value and temperature were regulated around 6.7 and 35℃, respectively. The effluent was precipitated and then recycled at recycle ratios of 0, 0.2, 0.4, 0.6, 0.8 and 1. When the recycle ratios increased, the volatile suspended solid (VSS) concentration increased with a peak of 14.2% at the recycle ratio 0.4. The sludge recycle increased the VSS concentration but increasing recycle ratio decreased hydrogen production. Because the substrate degradation reached 98% at each recycle ratio, increased microorganism concentrations did not increase the quantity of hydrogen. The VSS concentration increased with increasing substrate concentration. It has the best effectiveness of hydrogen production at 25 g COD/l sucrose with biomass recycle. This showed that sludge recycle aided to increase hydrogen production by increasing substrate concentration. As HRT reduced from 12 to 2 h, VSS concentration increased at first and then decreased with peak VSS concentration at HRT 8 h. The hydrogen yield (HY), hydrogen production rate (HPR) and specific hydrogen production rate (SHPR) values peaked at HRT 6 h with 2.9 mol-H2/mol sucrose, 807 mmol-H2/l/day and 244.3 mmol-H2/g VSS/day, respectively. The total bioenergy production rate obtained at HRT 6 h, 20 g COD/l of sucrose and recycle ratio of 0.2 was 848.3 KJ/l/day.
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Tsai, Meng-Lun, et 蔡孟倫. « Hydrogen fermentation with CSTR systems:exploration of temperature effects and strategies for performance enhancement ». Thesis, 2004. http://ndltd.ncl.edu.tw/handle/97261438559503381067.
Texte intégralRésumé :
碩士逢甲大學
化學工程學所
92
Abstract Recently the increasing emission of air pollutants such as: CO2, CO, NOx ,and SOx cause the green house effect in global atmosphere due to the massive usage of fossil fuels. The consumption rate of fossil fuels is also exponentially increased that may induce the shortage of energy source in the recent future. To develop a clean and new energy source will become one of the important subjects in the future. Biohydrogen has a great potential to act as an alternate with a cheap, clean and sustainable energy source. It may be the solution that not only reduces environmental pollutions, but also achieves source usage recycling. In this study, different conditions were investigated for the processes of biohydrogen production. The thermophilic bacterium was screened from sewage sludge for the dark fermentation of hydrogen production in several temperatures. First, the sludge was used for hydrogen production without acid and heat pretreatment. The result was found that the optimization hydrogen production rate is 0.26 L/h/L at a hydraulic retention time (HRT) of 6 h. with 50℃ temperature in a CSTR system. Second, the process was carried out in a continuous decrease of temperature from 50℃, 45℃, 40℃, and 35℃ with one hour heat pretreatment of the sludge at 70℃ in one bioreactor. The hydrogen production rate was performed in the order of 45℃ > 40℃ > 35℃ > 50℃. The highest hydrogen production rate was 0.77 L/h/L at 45℃ with HRT=4h. . The hydrogen bacterium became spore-form in its growth when temperature is unsuitable in the above continuous decrease of temperature process. The other process was studied that bioreactors were investigated in separated temperature at 50℃, 45℃, 40℃, and 35℃ for each bioreactor. The highest hydrogen production rate 0.77 L/h/L and hydrogen production yield 3.65 mol H2/mol sucrose were obtained at 40℃ with HRT=4h. . The hydrogen production performance in this process was in the order of 40℃ > 35℃ > 45℃ > 50℃. The metabolic pathway of microorganisms were greatly influenced by temperature effects. The hydrogen production performance was demonstrated to be related to the liquid metabolites of the pathway. When the liquid metabolite was ethanol oriented fermentation, the poorer hydrogen production performance was obtained. However, the major components of acetic acid and butyric acid were found in the liquid metabolites of the above process at 40℃., the better hydrogen production performance was resulted. The phenomenon of wash out of the bacterium was occurred in the CSTR system at low HRT process. The activated charcoal (AC) powder was added in the bioreactor to improve the situation. The flocculation of microorganism was induced as a microfilm in the surface of AC. Both hydrogen production rate and hydrogen production yield were enhanced to 1.24 L/h/L and 3.97 mol H2/mol sucrose, respectively, at 40℃ with HRT=4h. and stirring speed=105rpm. The substrate conversion was almost completed in 98.1%.