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Submitted by Programa de Pós-graduação em Biotecnologia (mebiotec.ufba@gmail.com) on 2017-04-04T12:50:21Z No. of bitstreams: 1 Dissertação Final - Roberta Santoro.pdf: 724184 bytes, checksum: 1653221680de20af86dfe6c644807a0f (MD5) / Approved for entry into archive by Delba Rosa (delba@ufba.br) on 2017-07-03T15:53:23Z (GMT) No. of bitstreams: 1 Dissertação Final - Roberta Santoro.pdf: 724184 bytes, checksum: 1653221680de20af86dfe6c644807a0f (MD5) / Made available in DSpace on 2017-07-03T15:53:23Z (GMT). No. of bitstreams: 1 Dissertação Final - Roberta Santoro.pdf: 724184 bytes, checksum: 1653221680de20af86dfe6c644807a0f (MD5) / FAPESB / A fase de recuperação secundária do petróleo é caracterizada por processos que objetivam restaurar a pressão interna do reservatório para assim aumentar a produtividade da jazida. Em poços distantes do continente, a água do mar, que contém cerca de 0,3% de sulfato, é comumente injetada para realizar esse processo. Portanto, estes reservatórios ficam sujeitos ao crescimento de bactérias redutoras de sulfato (BRS) que produzem sulfeto causando assim grandes prejuízos a indústria petroquímica. O processo de corrosão causado pela produção de sulfeto é conhecido como souring. Uma das formas de controlar o souring é a adição de biocidas (glutaraldeído e tetrakis(hidroximetil) fosfônio sulfato (THPS), mas estes tem um potencial de gerar um significativo impacto ambiental. Acredita-se que o controle biológico seja menos impactante por se utilizar de agentes microbianos para controlar o crescimento de BRS através de processos como biocompetição. O nitrato tem sido utilizado com a intenção de estimular tal biocompetição, mas, a complexidade das interações ecofisiológicas microbianas dificultam o sucesso dessa prática. O objetivo deste trabalho, portanto, foi o de avaliar os fatores relacionados com o controle de BRS in situ através (i) o uso de nitrato como agente regulador da sulfetogênese e (ii) a produção potencial de inibidores metabólicos pelos organismos desnitrificantes. Para esse trabalho foram isoladas 80 cepas bacterianas de poços de petróleo localizados na Bacia do Recôncavo Baiano, sendo 30 separadas fisiologicamente e caracterizadas em desnitrificantes heterotróficos e/ou autotróficos. Apenas 02 cepas apresentaram capacidade inibitória contra BRS em teste de placas com Desulfovibrio vulgaris. Curvas de crescimento com D. vulgaris mostram que este micro-organismo produz maior biomassa na presença de nitrato. Nessa condição a adição de nitrato diminui significativamente a produção de sulfeto, mas, em contrapartida, aumenta significativamente a biomassa de BRS. Portanto o uso de nitrato é um paliativo momentâneo que futuramente pode agravar de forma considerável o souring por permitir o aumento da biomassa de BRS, capazes de utiliza-lo. Embora exista potencial para exclusão biocompetitiva, pouco ainda se sabe sobre as interações que controlam as atividades dessas cepas in situ (interações de BRS com bactérias redutoras de óxido de nitrogênio (BRON) que sejam capazes de utilizar o nitrato. / Secondary oil recovery strategy aims to restore by secondary means the internal pressure of the rock formation and therefore enhancing oil recovery yields. For rock formations located offshore injection of seawater rich in sulphate (0.3 %) is often used for this purpose. In this way, such oil wells are easily subjected to the activity of sulphate reducing bacteria (SRB) causing the accumulation of sulphide which is the source of corrosion. The corrosive process caused by sulphide is known as “souring”. There have been several attempts for controlling souring such as the addition of biocides in the injected seawater (glutaraldehyde and tetrakis (hydroxymethyl) phosphonium sulfate (THPS)), however, these approaches can generate considerable environmental damage. Biological control is believed to generate less environmental impact for it control BRS growth through less harmful ecological processes such as bioexclusion. Nitrate is being used with such intent because it favours the competing denitrifying bacteria against BRS. However, the eco-physiological complexity characterizing bacterial interactions make the process difficult to achieve in situ. The aim of this study is to assess factors related to the in situ controls of BRS by (i) using nitrate as a regulating mediator and (ii) the effect of denitrifying bacteria inhibitory agents against BRS. For this purpose, 80 distinct bacterial strains were first isolated from oil wells located at the Recôncavo Baiano Basin and 30 strains were physiologically characterized as autotrophic and heterotrophic denitrifying bacteria. Only 2 strains showed to be capable of producing an inhibitory substance to Desulfovibrio vulgaris (BRS). In addition, growth curves characterization showed that D vulgaris is capable of growing using nitrate as electron acceptor. In such a condition, sulphide production decreases, but, on the other hand, it also enhances D. vulgaris biomass abundance. Thus, nitrate showed to work as a palliative and with such increase in BRS biomass, the souring problem may also increase significantly with the exhaustion of nitrate in situ. Although such biomass increase has been observed, it is expected that the denitrifying bacterial isolates found in this work may assist the process of BRS control by means of exclusion and the metabolic in situ use of produced sulphide by autotrophic denitrifiers capable of using nitrate.

The thesis was processed in cooperation with Pribina s.r.o. The aim of the thesis was the monitoring of the starters of cheeses with the white fungus on the surface. The thesis was engaged in the monitoring process of a souring curve of used starters. This monitoring was based on temperature, titrating acidity and pH measured in the time interval. The souring curve was evaluated as the indirect measurement change of acidity of the starter in the time period. Further, the activity of detached starters was measured. The measurement was based on the change of pH measured in the time period. The influence of the culture medium was monitored by changes in behaviour of the bacterial cultures. The monitored starters were compounded of mezophilic and termophilic bacterial strains.

Reservoir souring refers to the increase in the concentration of hydrogen sulfide in production fluids during waterflooding. Besides health and safety issues, H₂S content reduces the value of the produced hydrocarbon. Nitrate injection is an effective method to prevent the formation of H₂S. Although the effectiveness of nitrate injection has been proven in laboratory and field applications and biology is well-understood, modeling aspect is still in its early stages. This work describes the modeling and simulation of biological reactions associated with reservoir souring and nitrate injection for souring remediation. The model is implemented in a general purpose adaptive reservoir simulator (GPAS). We also developed a physical dispersion model in GPAS to study the effect of dispersion on reservoir souring. The basic mechanism in the biologically mediated generation of H₂S is the reaction between sulfate and organic compounds in the presence of sulfate-reducing bacteria (SRB). Several mechanisms describe the effect of nitrate injection on reservoir souring. We developed mathematical models for biological reactions to simulate each mechanism. For every biological reaction, we solve a set of ordinary differential equations along with differential equations for the transport of chemical and biological species. Souring reactions occur in the areas of the reservoir where all of the required chemical and biological species are available. Therefore, dispersion affects the extent of reservoir souring as transport of aqueous phase components and the formation of mixing zones depends on dispersive characteristics of porous media. We successfully simulated laboratory experiments in batch reactors and sand-packed column reactors to verify our model development. The results from simulation of laboratory experiments are used to find the input parameters for field-scale simulations. We also examined the effect of dispersion on reservoir souring for different compositions of injection and formation water. Dispersion effects are significant when injection water does not contain sufficient organic compounds and reactions occur in the mixing zone between injection water and formation water. With a comprehensive biological model and robust and accurate flow simulation capabilities, GPAS can predict the onset of reservoir souring and the effectiveness of nitrate injection and facilitate the design of the process. / text

Submitted by Programa de Pós-graduação em Biotecnologia (mebiotec.ufba@gmail.com) on 2017-04-04T12:27:38Z No. of bitstreams: 1 DISSERTAÇÃO Final - Luiz Lázaro.pdf: 1338858 bytes, checksum: 269d38d39fa68af0cd603b45d636eb6a (MD5) / Approved for entry into archive by Delba Rosa (delba@ufba.br) on 2017-06-29T14:32:38Z (GMT) No. of bitstreams: 1 DISSERTAÇÃO Final - Luiz Lázaro.pdf: 1338858 bytes, checksum: 269d38d39fa68af0cd603b45d636eb6a (MD5) / Made available in DSpace on 2017-06-29T14:32:38Z (GMT). No. of bitstreams: 1 DISSERTAÇÃO Final - Luiz Lázaro.pdf: 1338858 bytes, checksum: 269d38d39fa68af0cd603b45d636eb6a (MD5) / As Bactérias redutoras de sulfato (BRS) são responsáveis pela corrosão de tubos de metal e estruturas de transporte de óleo em estações de petróleo (corrosão induzida por micro-organismos – CIM). Além da corrosão, a produção de sulfeto de hidrogênio por estas bactérias produz um fenômeno denominado de acidificação do óleo (souring). Para inibir a ação das BRS, o glutaraldeído tem sido utilizado em poços de petróleo como biocida, mas seu uso apresenta determinados inconvenientes, tais como contaminação das águas subterrâneas, bem como os efeitos adversos da exposição ocupacional. Como uma alternativa para a utilização de biocidas, a utilização de micro-organismos e/ou os seus bioprodutos para tentar inibir a ação das BRS mostrou-se como uma alternativa ambientalmente mais segura em vários processos industriais, por exemplo, na indústria do petróleo, na qual os micro-organismos e seus bioprodutos (biossurfactantes) podem ser usados na recuperação melhorada de petróleo e como agentes de inibição microbiana. A detecção e quantificação de bactérias redutoras de sulfato (BRS), em poços de petróleo, utilizando-se hibridação fluorescente in situ (FISH) e DAPI (4,6-dicloroamino fenol indol) são ferramentas muito úteis para o controle destas comunidades ao longo de um período de tempo, a fim de avaliar a sua distribuição temporal e espacial. O presente trabalho teve como finalidades: a detecção e quantificação de BRS em amostras de água produzida de petróleo, de modo a avaliar a influência de micro-organismos que produzem biossurfactantes na inibição do crescimento de BRS e, assim, inibir a produção de sulfeto de hidrogênio.

This work deals with dynamics of milk souring after injection with chosen dairy culture in dependence on varying conditions of cultivation and different quality of the cultural medium. The aim of this work is:  Evaluation of the influence milk heat treatment has on the rate of milk souring by chosen clear dairy cultures.  Evaluation of the influence temperature of the milk has on the rate of milk souring by chosen clear dairy cultures.  Evaluation of the influence the quality of the milk has on the rate of milk souring by chosen clear dairy cultures. In the first part of my work there will be described milk as a primary commodity, its technological and microbiology characteristics, division of dairy cultures used in general practice and their application. In the next part of the work there will be described methodology, the way the laboratory research has been made and what commodities have been used. In this part there is also mentioned how the researches was evaluated and in what way the obtained results were processed. The ending part contains description and summary of results of the research and there is hold a discussion and a comparison of the results with other authors.