309 resultados para froth flotation
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Oil is a hydrocarbon mixture of various sizes, including saturated and aromatic compounds. Natural gas is a mixture of gaseous hydrocarbons and its main component is methane. In our society, the great demand for these fuels requires fast extraction, transportation and refining, increasing the number of accidents that compromise the environment. Oil is a finite resource and it is necessary to reduce the problems related to the question concerning environmental pollution which has encouraged the search for alternative fuel sources in our country. So today we have two major biofuels: ethanol and biodiesel. Concurrently, many studies have been done directed toward the isolation of microorganisms capable of degrading petrochemical industrial wastes, most of them using as a source of isolation soil and water collected in a contaminated environment. Isolation from alternative substrates has emerged as a new strategy that has provided satisfactory results. In this work, we present the leaf-cutter ants of the Attini tribe as a source for the isolation of micro-fungi with the potential for hydrocarbon degradation. These insects have a social way of life and a highly specialized system of intra and interspecific communication, which is based on the recognition of individuals through volatile chemical compounds, the majority hydrocarbons, stored in their exoskeleton. The micro-environment exoskeleton of Attini ants (genus Atta) used in this work proved to be a rich source of microbial biodiversity, as other studies have found. The flotation isolation technique applied here allowed the achievement of 214 micro-fungi, 118 representatives of the dematiaceous fungi group and 96 hyaline filamentous fungi. They were submitted to toluene degradation tests and at least one strain of each genus presented good results, namely Teratosphaeria, Exophiala, Cladosporium, Penicillium, Aspergillus... (Complete abstract click electronic access below)
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In order to enable the reuse of the large surplus volume of petroleum produced water for irrigation of crops inedible, the quality evaluation of this water is very important. This work aimed to evaluate the effectiveness of the diffusive gradient in thin films technique (DGT) for the determination of labile Cu (II), Mn (II) and Zn (II) in petroleum produced water destined to reuse in agriculture. Samples were collected at the exit of the wastewater treatment plant (WWTP) (after separation oil/water and flotation) of a Petrobrás onshore production region. Basically, the laboratory experiments with DGT devices involved the evaluation of the behavior of the main variables of the technique for determination of analytes in the samples (diffusion coefficients, immersion time, fractionation of organic and inorganic species, and performance of diffusion gels with different porosities, among others). Also, experiments were conducted based on the solid phase extraction (SPE) protocol with Chelex- 100 resin using previously established protocols to support the study. During the project the possibility of in situ immersions in water treatment plants was evaluated. The DGT technique presented satisfactory results for determination of Mn in produced water, and can be used for in situ determinations. However, the results obtained for Cu and Zn show the need of additional studies
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This study was developed to evaluate the performance of different coagulant and pH dosages by applying the use of Dissolved Air Flotation (FAD) to enable its use in effluent treatment of the extraction process of palm oil. The study was developed in the laboratory, where studies about emulsions stability were made for the production of a synthetic effluent which best suit the characteristics of raw effluent. The synthetic water that would be used in the tests of FAD was produced, once the stability and characterization which best approached the raw wastewater was obtained. Trials tested three coagulant doses, combined with various pH ranges and five upward velocities (Va), finding an optimal range of this combination. Some operating parameters such as time and gradient of rapid mixing (20 s / 1000 s-1), time and gradient flotation (15 min / 60 s-1), chamber pressure saturation (450 kPa) and recirculation rate (20%) were set. In this way, samples were collected for analysis of the removal of turbidity parameters, suspended solids and oils and greases. This one is obtained by a correlation turbidity x oils and greases, referring to the previous analysis. The degree of removal obtained were 73,97% for turbidity, 51,4% for total suspended solids and 86,2% for oils and greases. Removal rates may be increased in later studies, by ranging the velocity gradient and flocculation parameters and the recirculation ratio, and by using lower flotation speeds to these effluent characteristics.
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Pós-graduação em Agronomia (Ciência do Solo) - FCAV
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The main article aim was to investigate the collecting system of a dissolved air flotation (DAF) unit in pilot scale. Referring to the collecting system position, two options were analyzed: (i) top manifold and (ii) bottom manifold, pipes or plates. Qualitative and quantitative essays were performed, as image and stimulusresponse tests, respectively. The results of the essays standardized were adjusted by N-continuous stirred tank reactors in series and theoretical models of dispersion (low and high). The bottom manifold (plates with orifices) was more appropriate. The results pointed out that the N-continuous stirred tank reactors in series model was more adequate to describe the hydrodynamic behavior of the DAF unit.
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Hookworms are parasitic nematodes that cause anemia and intestinal infections in dogs, especially with large worm burdens. However, the serum protein profile of this parasitological disease is still poorly understood. The present study was design to evaluate 80 asymptomatic dogs (age; 8 months–2 years) to detect the presence of the hookworm thin-shelled, morulated eggs in faeces using faecal flotation and to evaluate the serum protein fractions determined by means of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Forty dogs had an elevated quantity of eggs in faeces (+++) (PD) and 40 dogs were healthy (HD). Infected dogs showed significant increases for IgG estimated concentrations (PD 1.79±0.8 g/dL and HD 1.44±0.72 g/dL, p= 0.04), for ceruloplasmin estimated concentrations (PD 19±15 mg/dL and HD 5±3.5 mg/dL, p=0.0001), for alpha 1-acid glycoprotein estimated concentrations (PD 31.4±17.9 mg/dL and HD 13.5±12.1 mg/dL, p=0.0001) and for a non-identified protein of 23 kDa estimated concentrations (PD 641.5±194.9 mg/dL and HD 519.8± 197.9 mg/dL, p=0.007). Dogs with hookworm infection showed significant differences in the serum protein profile when compared to healthy animals.
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O objetivo desse trabalho é apresentar e discutir a determinação dos parâmetros de dispersão de ar em células mecânicas de flotação, em circuitos industriais brasileiros. Foram investigados os circuitos rougher e scavenger das usinas RPM, Taquari-Vassouras, Copebras e Fosfértil-Catalão (atual Vale Fertilizantes). Nas usinas RPM e Taquari-Vassouras, foram determinados a velocidade superficial do ar (Jg), o hold-up do ar (εg), o diâmetro médio de bolhas (d32) e o fluxo de área superficial de bolhas (Sb). Para as outras usinas, foram determinados somente o Jg e εg. Os resultados mostraram que, com exceção da RPM, todos os circuitos investigados apresentaram baixos valores para os parâmetros de dispersão do ar. Taquari-Vassouras apresentou os mais baixos valores médios para Jg e εg, respectivamente, 0,05 cm/s e 5%. Os maiores valores de Jg foram determinados no circuito rougher da Copebras, 1,17 cm/s, ao passo que a RPM apresentou os maiores valores para o hold-up e tamanho de bolha, respectivamente, 31% e 2,61mm. Os valores obtidos, para Sb, situaram-se abaixo daqueles reportados na literatura.
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Mygalin is an antibacterial molecule isolated froth the hemocytes of the spider Acanthoscurria gomesiana. It was identified as bis-acylpolyamine spermidine. We evaluated the modulator effects of synthetic Mygalin in the innate immune response. We demonstrate that Mygalin induces IFN-gamma synthesis by splenocytes increasing the nitrite secretion by splenocytes and macrophages. A specific inhibitor of iNOS abrogated Mygalin-induced nitrite production in macrophages independent of IFN-gamma activation. In addition, Mygalin-activated macrophages produced TNF-alpha but not IL-1 beta, demonstrating that Mygalin does not act directly on the inflammasome. Furthermore, this compound did not affect spontaneous or Concanavalin A-induced proliferative responses by murine splenocytes and did not induce IL-5 or apoptosis of splenocytes or bone marrow-derived macrophages. These data provide evidence that Mygalin modulates the innate immune response by inducing IFN-gamma and NO synthesis. The combined immune regulatory and antibacterial qualities of Mygalin should be explored as a strategy to enhance immune responses in infection. (C) 2012 Elsevier Inc. All rights reserved.
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Nove amostras de minerais de ferro, provenientes de diferentes minas (jazidas) pertencentes à Vale, foram o objeto desse trabalho, que buscou correlacionar a depressão das referidas amostras com amido e carboximetil celulose versus parâmetros mineralógicos e morfológicos. O amido de milho convencional se mostrou capaz de realizar ação depressora sobre todas as amostras, exceto sobre aquelas que se mostraram mais ricas em hematita compacta (HC). Tais hematitas podem ser chamadas de "problemáticas", visto que interagem fortemente com o coletor e apresentam deficiência de serem deprimidas pelo amido, exigindo elevadas dosagens para minimização de sua tendência à flotação. Carboximetil celulose não apresentou ação depressora sobre nenhuma das amostras estudadas. A flotabilidade das amostras ricas em HC pode ser minimizada pela ação do amido de milho condicionado em pH 8,0-8,5. Testes de flotação com minério itabirítico, contendo elevado percentual de hematitas compactas de pequeno tamanho de cristal, confirmaram a redução do teor de Fe no rejeito com a utilização de amido condicionado em pH≅8.
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Mining and processing of metal ores are important causes of soil and groundwater contamination in many regions worldwide. Metal contaminations are a serious risk for the environment and human health. The assessment of metal contaminations in the soil is therefore an important task. A common approach to assess the environmental risk emanating from inorganic contaminations to soil and groundwater is the use of batch or column leaching tests. In this regard, the suitability of leaching tests is a controversial issue. In the first part of this work the applicability and comparability of common leaching tests in the scope of groundwater risk assessment of inorganic contamination is reviewed and critically discussed. Soil water sampling methods (the suction cup method and centrifugation) are addressed as an alternative to leaching tests. Reasons for limitations of the comparability of leaching test results are exposed and recommendations are given for the expedient application of leaching tests for groundwater risk assessment. Leaching tests are usually carried out in open contact with the atmosphere disregarding possible changes of redox conditions. This can affect the original metal speciation and distribution, particularly when anoxic samples are investigated. The influence of sample storage on leaching test results of sulfide bearing anoxic material from a former flotation dump is investigated in a long-term study. Since the oxidation of the sulfide-bearing samples leads to a significant overestimation of metal release, a feasible modification for the conduction of common leaching tests for anoxic material is proposed, where oxidation is prevented efficiently. A comparison of leaching test results to soil water analyzes have shown that the modified saturation soil extraction (SSE) is found to be the only of the tested leaching procedures, which can be recommended for the assessment of current soil water concentrations at anoxic sites if direct investigation of the soil water is impossible due to technical reasons. The vertical distribution and speciation of Zn and Pb in the flotation residues as well as metal concentrations in soil water and plants were investigated to evaluate the environmental risk arising from this site due to the release of metals. The variations in pH and inorganic C content show an acidification of the topsoil with pH values down to 5.5 in the soil and a soil water pH of 6 in 1 m depth. This is due to the oxidation of sulfides and depletion in carbonates. In the anoxic subsoil pH conditions are still neutral and soil water collected with suction cups is in equilibrium with carbonate minerals. Results from extended x-ray absorption fine-structure (EXAFS) spectroscopy confirm that Zn is mainly bound in sphalerite in the subsoil and weathering reactions lead to a redistribution of Zn in the topsoil. A loss of 35% Zn and S from the topsoil compared to the parent material with 10 g/kg Zn has been observed. 13% of total Zn in the topsoil can be regarded as mobile or easily mobilizable according to sequential chemical extractions (SCE). Zn concentrations of 10 mg/L were found in the soil water, where pH is acidic. Electron supply and the buffer capacity of the soil were identified as main factors controlling Zn mobility and release to the groundwater. Variable Pb concentrations up to 30 µg/L were observed in the soil water. In contrast to Zn, Pb is enriched in the mobile fraction of the oxidized topsoil by a factor of 2 compared to the subsoil with 2 g/kg Pb. 80% of the cation exchange capacity in the topsoil is occupied by Pb. Therefore, plant uptake and bioavailability are of major concern. If the site is not prevented from proceeding acidification in the future, a significant release of Zn, S, and Pb to the groundwater has to be expected. Results from this study show that the assessment of metal release especially from sulfide bearing anoxic material requires an extensive comprehension of leaching mechanisms on the one hand and on weathering processes, which influence the speciation and the mobility of metals, on the other hand. Processes, which may change redox and pH conditions in the future, have to be addressed to enable sound decisions for soil and groundwater protection and remediation.