Microalgas são organismos unicelulares, eucariontes, fotossintetizantes e eficientes fixadores de gás carbônico que apresentam grande potencial para produção de ácidos graxos além de pigmentos, como os carotenóides e a clorofila, de interesse nas indústrias de alimentos, química, farmacêutica e de cosméticos. Dentre as microalgas, o microrganismo Ankistrodesmus braunii vem sendo citado como capaz de produzir grandes quantidades de lipídios, podendo corresponder a até 73% de sua massa seca, com produção de ácidos graxos insaturados, como o ácido linolênico. Esse microrganismo se destaca do ponto de vista industrial por poder ser conduzido em reatores e em meios de cultivo complexos. As fontes de nitrogênio, as concentrações empregadas destes nutrientes, bem como o tipo de processo de cultivo interferem na composição de biomassas fotossintetizantes. O uso de reatores tubulares tem sido estudado e tem se apresentado interessante por permitir a obtenção de altas concentrações celulares. Nesse sentido, este trabalho teve a finalidade de estudar o crescimento de Ankistrodesmus braunii em reator tubular com uso de diferentes quantidades de nitrato de sódio por processos descontínuo, descontínuo alimentado e semi-contínuo. Nos cultivos descontínuos, a máxima concentração celular (Xm) encontrada foi de 1588 ± 11 mg.L-1 com uso de 20 mM de NaNO3. O uso do processo descontínuo alimentado, o qual teve adição de 20 mM de NaNO3 feito num intervalo a cada 48 horas sendo iniciada a adição no primeiro dia, permitiu a obtenção de Xm = 2753 ± 7 mg.L-1; porém não foi possível eliminar a fase lag do cultivo, levando a uma produtividade em células (Px) de 351 ± 1 mg.L-1.dia-1. O processo semi-contínuo foi eficiente para eliminar a fase lag do cultivo, permitindo a obtenção de Xm = 2399 ± 5 mg.L-1 e um aumento de até 50% em Px, que chegou a valores de 525 ± 1 mg.L-1.dia-1 em cultivos com uso de 20 mM de NaNO3. Nesta condição os teores de proteínas e lipídios nas biomassas foram de 34,8 ± 0,2% e 38,6 ± 0,2%, respectivamente. Foi observado que, independentemente do tipo de processo empregado, há um decréscimo do valor do fator de conversão de nitrogênio em células (YX/N) com o aumento da adição de NaNO3. O maior valor de YX/N foi obtido no experimento com processo semi-contínuo e uso de 2 mM de NaNO3 no meio de cultivo, com valor médio de 29,1 ± 0,1 mg mg-1 ao final do segundo ciclo. Porém, nesta condição, o teor de proteínas da biomassa foi de 17,3 ± 0,4%. Já os maiores valores de YX/N encontrados nos processos descontínuo e descontínuo alimentado foram, respectivamente, de 22,5 ± 1,6 e 7,1 ± 0,1 mg mg-1. Os resultados obtidos neste trabalho evidenciam o potencial de Ankistrodesmus braunii como fonte de proteínas e lipídios para uso industrial. / Microalgae are unicellular organisms, photosynthetic eukaryotes and which have great potential for the production of fatty acids as well as pigments such as carotenoids and chlorophyll, of interest in the food industry, chemicals, pharmaceuticals and cosmetics. Among the microalgae, the microorganism Ankistrodemsus braunii has been cited as capable of producing large amounts of lipids, which may correspond to up to 73% of its dry mass, producing unsaturated fatty acids, such as linolenic acid. This microorganism stands out from the industrial point of view because it can be carried out in reactors and in complex culture media. Nitrogen sources and concentrations employed of these nutrients interfere the composition of photosynthetic biomass and type of process employed also clearly exerts its influence both the growth and the composition of the biomass obtained. The use of tubular reactors has been studied and shown to be interesting because it allows the achievement of high cell concentrations. In this sense, this work aims to study the growth of Ankistrodemsus braunii tubular reactor using different amounts of nitrogen and under different forms of cultivation. In batch cultures, the maximum cell concentration (Xm) was found to be 1588 ± 11 mg.L-1, using 20 mM NaNO3. The use of the fed batch process, which had the addition of 20 mM NaNO3 in a range of 48 to 48 hours from the first to the sixth day, afforded Xm = 2753 ± 7 mg.L-1;ever it was not possible to eliminate the lag phase cultivation, leading to a productivity of cells (Px) of 351 ± 1 mg.L-1.day-1. The semi-continuous process was effective to eliminate the lag phase of the culture, allowing to obtain Xm = 2399 ± 5 mg.L-1 and increased up to 50% the Px value, which reached values of 525 ± 1 mg.L-1.day-1 in cultures with the use of 20 mM of NaNO3. In this condition the protein levels and lipid in the biomass were 34,8 ± 0,2% and 38,6 ± 0,2%, respectively. In all culture processes, it was observed that regardless of the type of process used, there is a decrease in the amount of nitrogen conversion factor into cells (YX/N) with increasing addition of NaNO3. The highest value of YX/N was obtained in the experiment with semi-continuous process with the use of 2 mM of NaNO3 in the culture medium, with an average of 29.1 ± 0.1 mg mg-1 at the end of the second cycle. However, in this condition, the protein content of the biomass was 17.3 ± 0.4%. The best values of YX/N found in the batch and fed-batch processes were, respectively, 22.5 ± 1.6 and 7.1 ± 0.1 mg mg-1. The results of this study shows the potential of Ankistrodemsus braunii as a source of protein and lipids for industrial use.

Neste trabalho estuda-se a aplicação de um controlador preditivo não linear em reatores de policondensação visando à segurança, qualidade do produto, capacidade de “scale-up" e a produtividade. Nos processos de policondensação em batelada há formação de um produto volátil conhecido como condensado e a remoção deste torna-se necessária favorecer o avanço da reação a fim de obter alto grau de conversão. Na maioria dos trabalhos envolvendo a policondensação a separação não é levada em conta. Diante disso, desenvolveu-se um modelo de policondensação acoplado com a coluna de destilação a fim de verificar através das simulações em malha aberta o comportamento das variavéis de operação no sistema. O modelo de policondensação foi obtido na literatura (Shin et al.,1999) e em sua implementação foi levada em conta a inercia térmica entre as paredes do reator e as interações com a coluna destilação. A reação de policondensação estudada aqui corresponde à produção de polietileno-tereftalato (PET). Nesta reação, Tereftalato de dimetila (DMT) e Etilenoglicol (EG) geram como produtos grupos ésteres e metanol (M). O reator modelado corresponde ao reator piloto instalado no Laboratório de Simulação e Controle de Processos. A técnica de controle preditivo não linear (NMPC) foi implementada e testada em dois modelos de polimerização por radicais livres (sistema SISO e MIMO) e comparado com o desempenho de um controlador PID. O controlador preditivo não linear (NMPC) foi aplicado no modelo do reator de policondensação e foi utilizado um controlador PID como comparativo, nesta etapa realizou-se várias simulações em malha fechada e análises de sensibilidades. Para as análises de sensibilidades o controlador NMPC foi denominado de controlador NMPC com “feedback" e foi comparado com um controlador NMPC com retroalimentação de estado. Através dos estudos mostrou que o controlador NMPC tem um desempenho melhor do que o PID. Nos estudos de sensibilidade o controlador NMPC com “feedback" apresenta um desempenho superior ao do controlador NMPC com retroalimentação de estado. O controlador NMPC com “feedback" manteve o processo sob controle nas simulações que foram realizadas . / In this work the application of a non-linear predictive controller to policondensation reactors aiming the safety, quality of the product, capacity of scale-up and productivity is studied. In batch policondensation processes, a volatile product called condensate is generated, and its removal becomes necessary in order to favor the reaction progress as a mean to obtain high conversion rates. In most of the works involving policondensation the separation is not taken into account. Therefore, a policondensation model was developed which was coupled to a distillation column in order to verify the behavior of the variables in the system through open-loop simulations. The polycondensation model was obtained from the literature (Shin et al. ,1999) and was implemented taking into account the thermal inertia between the walls of the reactor and the interactions with the distillation column. The polycondensation reaction studied here corresponds to the production of polyethylene-terephtalate (PET). In this reaction, Dimethyl Terephtalate (DMT) and Etylene Glycol (EG) generate as products ester groups and methanol (M). The reactor that was modeled corresponds to a pilot reactor installed in the Laboratory of Simulation and Processes Control. A non linear predictive control (NMPC) was implemented and tested in two free radical polymerization models (SISO and MIMO systems) and compared with PID controllers performance. The NMPC was applied to the polycondensation model and a PID controller was also applied for comparison. In this stage several closed-loop simulations and sensitivity analyses were performed. For the sensitivity analyses the NMPC controller was denominated NMPC controller with "feedback" for comparison with an NMPC with full state feedback. The studies showed that NMPC controller has a better performance than PID. NMPC with "feedback" presents a superior performance to the NMPC with full state feedback in the presence of modeling gaps. In the simulations that were performed, the NMPC with "feedback" has kept the process under control.

A cianobactéria \' Spirulina platensis \' possui alto teor de proteína e vem sendo cultivada fotoautotroficamente para a produção de biomassa microbiana. Embora as fontes convencionais de nitrogênio utilizadas para a produção de Spirulina spp. sejam os nitratos, há a possibilidade do emprego de uréia, utilizando o processo descontínuo alimentado, com diminuição do custo de produção. O emprego do processo descontínuo alimentado repetitivo para o cultivo desta microalga utilizando a uréia como fonte de nitrogênio poderia facilitar os cultivos em escala de produção, pois não haveria a necessidade de preparo de inóculo para cada ciclo de produção, além de possibilitar o aumento da produtividade do sistema. Este trabalho tem o objetivo de verificar o comportamento do cultivo microbiano com este processo, visto que não foram encontrados na literatura tais estudos para o cultivo de \'S. platensis\'. Foi verificada a influência dos parâmetros fração de corte, tempo de alimentação de uréia e ciclos de cultivo neste tipo de processo, tendo como variáveis dependentes a concentração celular máxima (Xm), a produtividade em células (Px) e o fator de conversão de nitrogênio em células (Yx/n), bem como a composição protéica e lipídica da biomassa obtida. Os resultados obtidos permitem concluir que, de uma forma geral, uma fração de corte de 80% associada a um tempo de alimentação de 6 dias leva a melhores condições de cultivo com bons resultados nos três parâmetros cinéticos (em média, 2101 mg.L?¹, 219 mg.L?¹.d?¹ e 10,3 mg.mg?¹ para Xm, Px e Yx/n, respectivamente), que foram reprodutíveis ao longo de 3 ciclos. / \' Spirulina platensis \', with high protein content, can be cultivated photoautotrophically for the microbial biomass production. Although nitrates are the conventional source of nitrogen for the Spirulina spp. production, there is a possibility of the use of urea, in a fed-batch process, leading to a cost reduction. The application of repeated fed-batch process, using urea as nitrogen source, could propitiate the cultivation of this microorganism in a production scale, since it would not need to prepare the inoculum for each production cycle. Moreover, there is a possibility to improve the productivity of this process. The aim of this work was to verify the behavior of the microbial cultivation employing this process, since this kind of study for \' Spirulina platensis \' production was not found in literature. The influence of withdrawn rate, urea feeding time and cultivation cycles were studied, considering maximum cell concentration (Xm), cell productivity (Px), nitrogen-to-cell conversion (Yx/n), and protein and total fat contents as dependent variables. The results show that in general a 80% of withdrawn rate associated with 6 days of feeding time leads to the best cultivation conditions with satisfactory results of Xm, Px and Yx/n (2101 mg.L?¹, 219 mg.L?¹.d?¹ and 10.3 mg.mg?¹, in average, respectively), that could be reproduced through the three cycles.

The purpose of the experiment was to investigate the effect of fruit flavor compounds on biogas production from fruit wastes. The flavor compounds from different fruits were selected and synthetic medium was used throughout the experiment. The experiment was carried out both in batch and continuous process using thermophilic inoculums obtained from Söbacken waste management plant. The inhibitors were added at three different concentrations 0.05g/L, 0.5g/L and 5g/L respectively and were carried out in triplicates for batch cultivation.The result from batch cultivation showed that hexanal, (E)-2-hexanal, myrcene and octanol showed inhibitory activity. Hexanal, (E)-2-hexanal, myrcene, and octanol decreased biogas production by factor of 316.8%, 434.22%, 329.68% and 433.61% at concentration of 5g/L. Continuous experiment was carried out on Automatic Methane Potential Test System AMPTS II. Eight reactors, each with inhibitor compounds were used with a retention time of 30 days and an organic loading rate of 3g VS/day. The inhibitor concentration was increased from 0.5g/L to 5g/L and for some compounds up to 10g/L. During cultivation, several factors were measured periodically such as pH, total biogas production, biogas composition, FOS/TAC and VFA.The inhibitory effect was clearly shown at concentration higher than 0.5g/L. Addition of 5g/L hexanal, nonanal, (E)-2-hexanal, α-pinene , car-3-ene, myrcene and octanol resulted in reduction of biogas production by 81.2%, 4.67%, 50.74%, 7.06%, 24.01%, 31.84% and 52.85% respectively. When compared to batch process, continuous process required higher concentration of flavor compounds to reduce biogas production. This might be due to adaptation of cells towards toxic compounds during continuous process. / Program: Master of Science with a major in Resource Recovery-Industrial Biotechnology

A cianobactéria \' Spirulina platensis \' possui alto teor de proteína e vem sendo cultivada fotoautotroficamente para a produção de biomassa microbiana. Embora as fontes convencionais de nitrogênio utilizadas para a produção de Spirulina spp. sejam os nitratos, há a possibilidade do emprego de uréia, utilizando o processo descontínuo alimentado, com diminuição do custo de produção. O emprego do processo descontínuo alimentado repetitivo para o cultivo desta microalga utilizando a uréia como fonte de nitrogênio poderia facilitar os cultivos em escala de produção, pois não haveria a necessidade de preparo de inóculo para cada ciclo de produção, além de possibilitar o aumento da produtividade do sistema. Este trabalho tem o objetivo de verificar o comportamento do cultivo microbiano com este processo, visto que não foram encontrados na literatura tais estudos para o cultivo de \'S. platensis\'. Foi verificada a influência dos parâmetros fração de corte, tempo de alimentação de uréia e ciclos de cultivo neste tipo de processo, tendo como variáveis dependentes a concentração celular máxima (Xm), a produtividade em células (Px) e o fator de conversão de nitrogênio em células (Yx/n), bem como a composição protéica e lipídica da biomassa obtida. Os resultados obtidos permitem concluir que, de uma forma geral, uma fração de corte de 80% associada a um tempo de alimentação de 6 dias leva a melhores condições de cultivo com bons resultados nos três parâmetros cinéticos (em média, 2101 mg.L?¹, 219 mg.L?¹.d?¹ e 10,3 mg.mg?¹ para Xm, Px e Yx/n, respectivamente), que foram reprodutíveis ao longo de 3 ciclos. / \' Spirulina platensis \', with high protein content, can be cultivated photoautotrophically for the microbial biomass production. Although nitrates are the conventional source of nitrogen for the Spirulina spp. production, there is a possibility of the use of urea, in a fed-batch process, leading to a cost reduction. The application of repeated fed-batch process, using urea as nitrogen source, could propitiate the cultivation of this microorganism in a production scale, since it would not need to prepare the inoculum for each production cycle. Moreover, there is a possibility to improve the productivity of this process. The aim of this work was to verify the behavior of the microbial cultivation employing this process, since this kind of study for \' Spirulina platensis \' production was not found in literature. The influence of withdrawn rate, urea feeding time and cultivation cycles were studied, considering maximum cell concentration (Xm), cell productivity (Px), nitrogen-to-cell conversion (Yx/n), and protein and total fat contents as dependent variables. The results show that in general a 80% of withdrawn rate associated with 6 days of feeding time leads to the best cultivation conditions with satisfactory results of Xm, Px and Yx/n (2101 mg.L?¹, 219 mg.L?¹.d?¹ and 10.3 mg.mg?¹, in average, respectively), that could be reproduced through the three cycles.

Salmonella, a common food pathogen, costs more than any other pathogen in the United States in terms of health care costs and loss of work due to the illnesses it causes. Low-moisture foods, especially flour, are susceptible to being contaminated by Salmonella. Food producers want flour to be pathogen-free but to also retain the same functionality of non-treated flour. Heat treatment is the most common method employed for lowering the concentration of pathogens in food. However, heating can result in the loss of the flour’s functionality. Pantoea dispersa strain JFS has been isolated from flour as a nonpathogenic bacterial surrogate that closely matches the D-value of Salmonella in flour. Flour samples were subjected to dry heat (70, 75, and 80°C) and heat tolerance was determined by plating out at least four different time points for each temperature. The death rate of P. dispersa strain JFS was similar to (p<0.05) Salmonella. This strain of P. dispersa was then used as a surrogate for Salmonella in a continuous and batch heat treatment processes to determine the amount of kill achieved by each. The continuous process was conducted using varying levels of four independent variables: temperature, residence time, use of steam, and manipulation of initial water content. All 15 runs resulted in a reduction of at least 1.5 logs of the surrogate, with the greatest reduction being 2.5 logs. The batch process was conducted using one independent variable, temperature. All runs for the batch process resulted in a reduction of at least 2.5 logs of the surrogate, with the greatest reduction being 4.3 logs at 170°F. Both processes could be used to reduce any Salmonella present in flour.

Most research studies in the batch process control problem are focused on optimizing system performance. The methods address the problem by minimizing single criterion such as cycle time and tardiness, or bi-criteria such as cycle time and tardiness, and earliness and tardiness. This research demonstrates the use of Stochastic Utility Evaluation (SUE) function approach to optimize system performance using multiple criteria. In long production cycles, the earliness and tardiness weight (utility) of products vary depending on the time. As the time approaches the due-date, it affects contractual penalties, loss of customer goodwill and the storage period for the completed products. It is necessary to reflect the weight of products for earliness and tardiness at decision epochs to decide on the optimal strategy. This research explores how stochastic utility function using stochastic information can be derived and used to strategically improve existing approaches for the batch process control problem. This research first explores how SUE function can be applied to existing model for bi-objective problem such as cycle time and tardiness. Benchmark strategies using SUE function (NACH-SUE, MBS-SUE, No idle and full batch) are compared to each other. The experimental results show that NACH-SUE effectively improves mean cycle time and tardiness performance respectively than other benchmark strategies. Next, SUE function for earliness and tardiness is used in an existing model to develop a tri-objective problem. Typically, this problem is very complex to solve due to its trade-off relationship. However SUE function makes it relatively easy to solve the tri-objective problem since SUE function can be incorporated in an existing model. It is observed that SUE function can be effectively used for solving a tri-objective problem. Performance improvement for averaged value of cycle time, earliness and tardiness is observed under a comprehensive set of experimental conditions.

Neste trabalho estuda-se a aplicação de um controlador preditivo não linear em reatores de policondensação visando à segurança, qualidade do produto, capacidade de “scale-up" e a produtividade. Nos processos de policondensação em batelada há formação de um produto volátil conhecido como condensado e a remoção deste torna-se necessária favorecer o avanço da reação a fim de obter alto grau de conversão. Na maioria dos trabalhos envolvendo a policondensação a separação não é levada em conta. Diante disso, desenvolveu-se um modelo de policondensação acoplado com a coluna de destilação a fim de verificar através das simulações em malha aberta o comportamento das variavéis de operação no sistema. O modelo de policondensação foi obtido na literatura (Shin et al.,1999) e em sua implementação foi levada em conta a inercia térmica entre as paredes do reator e as interações com a coluna destilação. A reação de policondensação estudada aqui corresponde à produção de polietileno-tereftalato (PET). Nesta reação, Tereftalato de dimetila (DMT) e Etilenoglicol (EG) geram como produtos grupos ésteres e metanol (M). O reator modelado corresponde ao reator piloto instalado no Laboratório de Simulação e Controle de Processos. A técnica de controle preditivo não linear (NMPC) foi implementada e testada em dois modelos de polimerização por radicais livres (sistema SISO e MIMO) e comparado com o desempenho de um controlador PID. O controlador preditivo não linear (NMPC) foi aplicado no modelo do reator de policondensação e foi utilizado um controlador PID como comparativo, nesta etapa realizou-se várias simulações em malha fechada e análises de sensibilidades. Para as análises de sensibilidades o controlador NMPC foi denominado de controlador NMPC com “feedback” e foi comparado com um controlador NMPC com retroalimentação de estado. Através dos estudos mostrou que o controlador NMPC tem um desempenho melhor do que o PID. Nos estudos de sensibilidade o controlador NMPC com “feedback” apresenta um desempenho superior ao do controlador NMPC com retroalimentação de estado. O controlador NMPC com “feedback” manteve o processo sob controle nas simulações que foram realizadas . / In this work the application of a non-linear predictive controller to policondensation reactors aiming the safety, quality of the product, capacity of scale-up and productivity is studied. In batch policondensation processes, a volatile product called condensate is generated, and its removal becomes necessary in order to favor the reaction progress as a mean to obtain high conversion rates. In most of the works involving policondensation the separation is not taken into account. Therefore, a policondensation model was developed which was coupled to a distillation column in order to verify the behavior of the variables in the system through open-loop simulations. The polycondensation model was obtained from the literature (Shin et al. ,1999) and was implemented taking into account the thermal inertia between the walls of the reactor and the interactions with the distillation column. The polycondensation reaction studied here corresponds to the production of polyethylene-terephtalate (PET). In this reaction, Dimethyl Terephtalate (DMT) and Etylene Glycol (EG) generate as products ester groups and methanol (M). The reactor that was modeled corresponds to a pilot reactor installed in the Laboratory of Simulation and Processes Control. A non linear predictive control (NMPC) was implemented and tested in two free radical polymerization models (SISO and MIMO systems) and compared with PID controllers performance. The NMPC was applied to the polycondensation model and a PID controller was also applied for comparison. In this stage several closed-loop simulations and sensitivity analyses were performed. For the sensitivity analyses the NMPC controller was denominated NMPC controller with "feedback" for comparison with an NMPC with full state feedback. The studies showed that NMPC controller has a better performance than PID. NMPC with "feedback" presents a superior performance to the NMPC with full state feedback in the presence of modeling gaps. In the simulations that were performed, the NMPC with "feedback" has kept the process under control.

A MATLAB model was developed for the smoldering combustion of wastewater in the context of a decentralized residential wastewater treatment appliance. Data from a batch process sewage smoldering experiment was simulated using implicit finite-difference approximations, assuming one-dimensional transient conductive heat transfer. The time-dependent temperature profiles within the column represented the main parameters of interest and were used to verify recoverable heat energy estimations. Given that the modeling method used for this thesis represents a unique approach, the assumptions and limitations of this model are thoroughly described in the context of reproducing results for other smoldering setups. A lack of convergence is seen in the model validation section of this report. Consequently, the practicality of this particular model contains significant limitations. Theoretical applications are also discussed and analyzed in terms of comparisons to modern alternatives and prototype feasibility.

No description available.