A EFICIÊNCIA DO SISTEMA DE FLOTAÇÃO NO TRATAMENTO DE ESGOTO

O presente trabalho teve o objetivo de analisar a repercussão sobre o tratamento de esgoto e o uso do método anaeróbico. Neste, mostraremos a relação entre a eficiência da remoção do fósforo e a implantação do sistema de flotação pós-reator anaeróbio. A Estação de Tratamento de Esgoto Ipanema está instalada as margens do Córrego Terra Branca, afluente do Rio Araguari, no município de Uberlândia, Minas Gerais, tendo o Departamento de Água e Esgoto de Uberlândia como responsável pela operação desta unidade. Esta estação de tratamento de esgoto atende uma população aproximadamente de 7000 habitantes residentes nos bairros Aclimação e Ipanema e, inicialmente era composta por grades grossas, uma caixa de areia, um reator anaeróbio de fluxo ascendente (RAFA), um filtro biológico e um tanque de decantação. Para a melhoria da eficiência da estação, foi implementado um tratamento complementar pós-reator de forma que este faça a adequação necessária para promoção da qualidade ambiental do efluente pós-tratamento no que se refere ao parâmetro fósforo para o lançamento no copo receptor, enquadrado na Classe 2, da Resolução do CONAMA 357/2005. O canal de tratamento por flotação em fluxo variável para receber o efluente pós-reator substituiu o polimento realizado atualmente através de filtro biológico e o tanque de decantação.

Tratamento do efluente alcalino do branqueamento da polpa de celulose pelo processo de separação por membranas

O presente trabalho estuda o reaproveitamento do efluente alcalino do branqueamento da polpa, da indústria de celulose, através de processos de separação com membranas. Para tanto, foram realizados testes com o efluente industrial para diferentes membranas e, simultaneamente, foi pesquisada a aplicação do processo de flotação como pré-tratamento para retirada de fibras do efluente. A avaliação dos resultados foi realizada por meio de determinações analíticas e monitoramento de alguns parâmetros. Os experimentos foram executados em equipamentos de bancada e piloto. A etapa de separação com membranas envolveu os processos de ultrafiltração, nanofiltração, osmose reversa e combinações destas operações. De forma a escolher um processo com retenção e fluxo permeado adequados variou-se durante os testes a pressão através das membranas e a temperatura. As análises realizadas para a caracterização do efluente foram: pH, condutividade elétrica, turbidez, sólidos totais (ST), demanda química de oxigênio (DQO), compostos organo-halogenados (AOX), ferro, magnésio, cálcio, sódio, potássio e manganês. A DQO foi o principal critério utilizado para avaliar a qualidade do permeado. Os ensaios de flotação foram realizados com e sem adição de compostos químicos auxiliares. A eficiência do processo foi avaliada através das análises de ST, condutividade elétrica, pH, recuperação de fibras, teor de alumínio, turbidez e visualmente Os resultados indicaram que todos os processos testados trouxeram uma melhoria nas características do efluente, incluindo reduções de até 90% no valor de DQO em alguns casos. O processo que apresentou a melhor performance foi a combinação UF5+ORP. A investigação preliminar sobre a flotação das fibras mostrou que, apesar de ter atingido uma remoção de fibras de 95% ainda havia a presença de partículas grosseiras, as quais poderiam causar danos aos processos com membranas. Mais estudos devem ser realizados no sentido de otimizar o processo de flotação.

Obtenção de filtro cerâmico a partir da diatomita e casca de arroz carbonizada visando tratamento de efluente têxtil

The effluents released by the textile industry have high concentrations of alkali, carbohydrates, proteins, in addition to colors containing heavy metals. Therefore, a filter was prepared aiming primarily to the removal of color. In order to prepare this filter, rice hulls and diatomite were used, which have in their structure, basically amorphous hydrated silica. The silica exists in three crystalline forms: quartz, tridymite and cristobalite. In accordance with the above considerations, this study was divided into two stages; the first corresponds to the preparation of the filter and the second to carry out the tests in the effluent/filter in order to verify the efficiency of the color removal. First, the raw material was subjected to a chemical analysis and XRD, and then the diatomite was mixed, via humid, with a planetarium windmill with 20 %, 40 %, 60 % and 80 % of rice husk ash. To the mixture, 5 % carboxymethylcellulose (CMC) was added as a binder at room temperature. The samples were uniaxially compacted into metallic matrix of 0.3 x 0.1 cm² of area at a pressure of 167 MPa by means of hydraulic press and then sintered at temperatures of 1,000 °C, 1,200 °C and 1,400 °C for 1 h and submitted to granulometry test using laser, linear retraction, water absorption, apparent porosity and resistance to bending, DTA, TMA and XRD. To examine the pore structure of the samples scanning electron microscope (SEM) was used. Also tests were carried out in a mercury porosimeter to verify the average size of the pores and real density of the samples. In the second stage, samples of the effluent were collected from a local industry, whose name will be preserved, located in Igapó, in the State of Rio Grande do Norte - RN. The effluent was first pretreated before filtration and then subjected to a treatment of flotation. The effluent was then characterized before and after filtration, with parameters of color, turbidity, suspended solids, pH, chemical and biochemical oxygen demand (COD and BOD). Thus, through the XRD analysis the formation of cristobalite α in all samples was observed. The best average size of pore was found to be 1.75 μm with 61.04 % apparent porosity, thus obtaining an average 97.9 % color removal and 99.8 % removal of suspended solid

Remoção de óleo da água de produção por flotação em coluna utilizando tensoativos de origem vegetal

In the petroleum industry, water is always present in the reservoir formation together with petroleum and natural gas and this fact provokes the production of water with petroleum, resulting in a great environmental impact. Several methods can be applied for treatment of oily waters, such as: gravitational vases, granulated media filtration systems, flotation process, centrifugation process and the use of hydrocyclones, which can also be used in a combined way. However, the flotation process has showed a great efficiency as compared with other methods, because these methods do not remove great part of the emulsified oil. In this work was investigated the use of surfactants derived from vegetable oils, OSS and OGS, as collectors, using the flotation process in a glass column with a porous plate filter in its base for the input of the gaseous steam. For this purpose, oil/water emulsions were prepared using mechanical stirring, with concentrations around 300 ppm. The air flow rate was set at 700 cm3/min and the porous plate filter used for the generation of the air bubbles has pore size varying from 16 to 40 Pm. The column operated at constant volume (1500mL). A new methodology has been developed to collect the samples, where, instead of collecting the water phase, it was collected the oil phase removed by the process in the top of the flotation column. It has been observed that it is necessary to find an optimum surfactant concentration to achieve enhanced removal efficiency. Being for OSS 1.275 mmol/L and for OGS 0.840 mmol/L, with removal efficiencies of 93% and 99%, respectively, using synthetic solutions. For the produced water, the removal in these concentrations was 75% for OSS and 65% for OGS. It is possible to remove oil from water in a flotation process using surfactants of high HLB, fact that is against the own definition of HLB (Hydrophile-Lipophile Balance). The interfacial tension is an important factor in the oil removal process using a flotation process, because it has direct interference in the coalescence of the oil drops. The spreading of the oil of the air bubble should be considered in the process, and for the optimum surfactant concentrations it reached a maximum value. The removal kinetics for the flotation process using surfactants in the optimum concentration has been adjusted according to a first order model, for synthetic water as for the produced water.

Flotação por ar dissolvido para os minerais quartzo e feldspato utilizando coletores catiônicos

The pegmatite rocks in Rio Grande do Norte are responsible for much of the production of industrial minerals like quartz and feldspar. Quartz and feldspar are minerals from pegmatite which may occur in pockets with metric to centimetric dimensions or as millimetric to sub millimetric intergrowths. The correct physical liberation of the mineral of interest, in case of intergrowths, requires an appropriate particle size, acquired by size reduction operations. The method for treating mineral which has a high efficiency fines particles recovery is flotation. The main purpose of the present study is to evaluate the recovery of quartz and potassium feldspar using cationic diamine and quaternary ammonium salt as collectors by means of dissolved air flotation DAF. The tests were performed based on a central composite design 24, by which the influence of process variables was statistically verified: concentration of the quaternary ammonium salt and diamine collectors, pH and conditioning time. The efficiency of flotation was calculated from the removal of turbidity of the solution. Results of maximum flotation efficiency (60%) were found in the level curves, plotted in conditions of low concentrations of collectors (1,0 x 10-5 mol.L-1). These high flotation efficiencies were obtained when operating at pH 4 to 8 with conditioning time ranging from 3 to 5 minutes. Thus, the results showed that the process variables have played important roles in the dissolved air flotation process concerning the flotability of the minerals.

Modelagem da transferência de massa na remoção do óleo da água produzida por flotação em coluna com uso de tensoativos de origem vegetal

The treatment of oil produced water and its implications are continually under investigation and several questions are related to this subject. In the Northeast Region Brazil, the onshore reservoirs are, in its majority, mature oil fields with high production of water. As this oil produced water has high levels of oil, it cannot be directly discarded into the environment because it represents a risk for contamination of soil, water, and groundwater, or even may cause harm to living bodies. Currently, polyelectrolytes that promote the coalescence of the oil droplets are used to remove the dispersed oil phase, enhancing the effectiveness of the flotation process. The non-biodegradability and high cost of polyelectrolytes are limiting factors for its application. On this context, it is necessary to develop studies for the search of more environmentally friendly products to apply in the flotation process. In this work it is proposed the modeling of the flotation process, in a glass column, using surfactants derived from vegetal oils to replace the polyelectrolytes, as well as to obtain a model that represents the experimental data. In addition, it was made a comparative study between the models described in the literature and the one developed in this research. The obtained results showed that the developed model presented high correlation coefficients when fitting the experimental data (R2 > 0.98), thus proving its efficiency in modeling the experimental data.

Otimização do processo de flotação de emulsão óleo/água através do planejamento fatorial completo

In recent decades, the generation of solid and liquid waste has increased substantially due to increased industrial activity that is directly linked to economic growth. For that is the most efficient process, it is inevitable generation of such wastes. In the oil industry, a major waste generated in oil exploration is produced water, which due to its complex composition and the large amount generated, has become a challenge, given the restrictions imposed by environmental laws regarding their disposal, making if necessary create alternatives for reuse or treatment in order to reduce the content of contaminants and reduce the harmful effects to the environment. This water can be present in free form or emulsified with the oil, when in the form of an emulsion of oil-water type, it is necessary to use chemicals to promote the separation and flotation is the treatment method which has proved to be more efficient, for it can remove much of the emulsified oil when compared to other methods. In this context, the object of this work was to study the individual effects and interactions of some physicochemical parameters of operations, based on previous work to a flotation cell used in the separation of synthetic emulsion oil / water in order to optimize the efficiency of the separation process through of the 24 full factorial design with center point. The response variables to evaluate the separation efficiency was the percentage of color and turbidity removal. The independent variables were: concentration of de-emulsifying, oil content in water, salinity and pH, these being fixed, minimum and maximum limits. The analysis of variance for the equation of the empirical model, was statistically significant and useful for predictive purposes the separation efficiency of the floater with R2 > 90%. The results showed that the oil content in water and the interaction between the oil content in water and salinity, showed the highest values of the estimated effects among all the factors investigated, having great and positive influence on the separation efficiency. By analyzing the response surface was determined maximum removal efficiency above 90% for both measured for turbidity as a measure of color when in a saline medium (30 g/L), the high oil concentrations (306 ppm) using low concentrations of de-emulsifying (1,1 ppm) and at pH close to neutral

Flotação por ar dissolvido na clarificação de águas com baixa turbidez utilizando sulfato de alumínio e sementes de Moringa oleifera como coagulantes

This work aims to investigate the process of Dissolved air Flotation (DAF) for clarifying water samples with low turbidity using aluminum sulphate and Moringa oleifera seeds as coagulants. The experimental procedure was carried out in a bench scale flotation unit. The influences on the pre-treatment conditions (coagulant dosage and flocculation time) and flotation parameters (superficial application rate and recirculation rate) were evaluated considering the efficiency of the process. The efficiency was evaluated by determining the turbidity of the untreated and treated water samples. The results obtained showed that turbidity reduction can be obtained very efficiently by using DAF and the latter coagulant in low turbidity water. Using aluminum sulphate in pH´s 5.0 and 6.0 better efficiencies were obtained with low concentrations (15 mg/L), achieving values of 92% of turbidity reduction. In the case of use of Moringa oleifera better efficiencies of reduction of turbidity were reported when using a concentration of 50 mg/L in all range of pH´s, achieving 86% of reduction. The zeta potential was also determined, in an attempt to aid comprehension of the coagulation mechanisms involved. The coagulation mechanisms with Moringa oleifera seeds were shown to be adsorption and charge neutralization, as well as adsorption and bridging. Concerning aluminum sulphate, the predominant mechanisms are adsorption and charge neutralization and enmeshment in a precipitate. The results indicate that for low turbidity water, Moringa oleifera seeds could potentially be a viable substitute for aluminum sulphate

Separação de cristais de estruvita de percolado de lodo por flotação por ar dissolvido

The struvite precipitation in wastewater treatments plants offer advantages to obtaining a economically viable product, containing phosphorus, nitrogen and magnesium, in a bioavailable conditions to plants. The precipitation process requires ideal conditions, but all of these aspects are difficult to obtain and may result in resistance to collect crystals during the sedimentation process. Therefore, instead find the best conditions for precipitation, we propose the dissolved air flotation as another method to retrieve the crystals. The application of dissolved air flotation method to promote separation of struvite crystals from sewage supernatant, was evaluated in a precipitation-flotation reactor (flotatest) and were compared with the precipitation-sedimentation assays (jar test). Finally, were observed that the dissolved air flotation process was as feasible as sedimentation to promote struvite crystals separation, and the pH are the most influencer factor for an efficient separation

Avaliação da flotação por ar dissolvido no polimento de efluentes de lagoa de estabilização

Experience in the use of stabilization ponds shows that this is a system with low cost, easy operation and maintenance and suitable for tropical countries. One of its disadvantages is due to high concentrations of suspended solids, mainly due to algal biomass in the effluents. Accordingly, the dissolved air flotation has been shown to be an efficient post-treatment technology. However, the efficiency of this process is related to coagulation and flocculation steps, as well as the adjustment of the involved variables in the process. The objective of this work was to evaluate the algae removal efficiency from wastewater stabilization ponds and the influence of the factors involved in the process using dissolved air flotation. For this, we used primary facultative and maturation effluents of ETE Ponta Negra in Natal. We did tests of coagulation, flocculation and flotation with the samples, using the equipment flotatest. In this process were tested coagulants aluminum sulfate and ferric chloride, and varied the factors pH, coagulant concentration, polymer concentration and rate of recirculation. At the end of the experiments were analyzed turbidity, suspended solids, color, COD and chlorophyll "a". These results were submitted to descriptive statistics to verify the efficiency of the process in general, and regression analysis to identify models that describe the process and demonstrate the factors that have greater influence on flotation. After step methodology, high values were found removal efficiency of suspended solids, reaching values greater than 90% in the best cases. It was concluded that flotation is more efficient in the facultative pond effluent using ferric chloride, and the variability of algae may negatively influence the process. Regression analyzes showed that pH is the most influential variable in the coagulation-flocculation-flotation, and its optimal value among the tested is 5.5 for both coagulants

Clarificação de suco de laranja core wash por processo de flotação auxiliado por enzimas pectinolíticas e agentes clarificantes

Pós-graduação em Engenharia e Ciência de Alimentos - IBILCE

Uso de floculador hidráulico de manta de lodo acoplado a flotador por ar dissolvido no tratamento de água de abastecimento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Texturas e propriedades reológicas dos minérios de ferro do quadrilátero ferrífero (MG) e sua utilização em beneficiamento

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ocorrência e remoção dos protozoários patogênicos Giardia spp. e Cryptosporidium spp. em sistemas de tratamento de esgoto sanitário

O propósito do presente estudo foi investigar e monitorar a remoção de cistos de Giardia spp. e oocistos de Cryptosporidium spp. por diferentes processos de uma estação de tratamento de esgoto (ETE) em escala plena, composta basicamente por tratamento preliminar, reator UASB e flotador por ar dissolvido, e verificar a ocorrência desses protozoários no lodo do reator UASB e do flotador. Além disso, avaliou-se a remoção desses parasitos pelo processo de flotação por ar dissolvido em escala de bancada (equipamento Flotateste). Analisou-se a qualidade das amostras a partir de variáveis físicas e químicas, e pela detecção de microrganismos indicadores - E. coli, coliformes totais e Clostridium perfringens. Os métodos de detecção de protozoários se basearam nas etapas de concentração (tripla centrifugação ou filtração em membrana seguida de tripla centrifugação); purificação por separação imunomagnética (IMS); detecção por reação de imunofluorescência direta (RID). As recuperações de cistos variaram de 32,6 a 67,0 % dependendo do método adotado, já para os oocistos as recuperações estiveram na faixa de 5,6 a 12,0 %. Na ETE-Monjolinho foram detectadas significativas quantidades de cistos de Giardia spp. em 100% das amostras de esgoto analisadas, com concentração média de 1,89 x 104 e 2,35 x 102 cistos.L-1 no esgoto bruto e tratado, respectivamente. Já os oocistos de Cryptosporidium spp. foram detectados em 39,0 % das amostras de esgoto, com concentração média de 1,35 x 102 oocistos.L-1 no esgoto bruto e 5,87 oocistos.L-1 em esgoto tratado (após flotador). A remoção global da ETE para remoção de Giardia spp. foi em média 2,03 log. O lodo do reator UASB e lodo do flotador apresentaram altas quantidade de (oo)cistos, constatando-se a tendência desses sistemas em concentrar os (oo)cistos por seus processos físicos. Algumas correlações significativas foram encontradas, como correlação entre a concentração de cistos no lodo e a variável sólidos totais, a concentração de cistos no esgoto bruto e as variáveis cor aparente, DQO total e particulada, e a concentração de cistos no efluente UASB e o microrganismo Clostridium perfringens. Diferentemente do flotador em escala plena, o processo do flotação por ar dissolvido em escala de bancada alcançou elevadas remoções médias de cistos de Giardia spp., entre 2,5 e 2,7 log nas diferentes condições de floculação estudadas.

Análise das principais variáveis na flotação industrial do complexo de mineração de Tapira - MG

Faced with an agribusiness expansion scenario and the increase in fertilizer consumption due to the exponential growth of the population, it is necessary to make better use of existing reserves, by obtaining products of better quality and in adequate quantities to meet demand national. In Tapira Mining Complex, Vale Fertilizantes, the phosphate concentrate is produced with content of 35.0% P2O5 from ore with content of about 8.0% P2O5, which are intended to supply Complex Industrial Uberaba and Araxá Minero Chemical Complex for the production of fertilizers. The industrial flotation step responsible for the recovery of P2O5 and hence the viability of the business is divided into the crumbly, grainy and ultrathin circuits, and, friable and granular concentrate comprise the conventional concentrated. Today only 14.7% of the mass which feeds the mill product becomes, the remainder being considered losses in the process, and the larger mass losses are located in the waste of flotation, representing 42.3%. From 2012 to 2014, the daily global mass recovery processing plants varied from 12.4 to 15.9% while the daily metallurgical recovery of P2O5 from 48.7 to 82.4%. By the degree of variability, it appears that the plant operated under different conditions. Seen this, this study aimed to analyze the influence of operational and process variables in P2O5 mass and metallurgical recoveries of industrial flotation circuits of grainy, crumbly and ultrathin. And besides was made an analysis of the effect of ore variables, as degrees, hardnesse and the ore front 02 percentage, in global recoveries of processing plant and the effect of dosages of reagents in the recoveries obtained from the bench flotation using the experimental design methodology. All work was performed using the historical database of Vale Fertilizantes of Tapira-MG, where all independent variables were dimensionless as the experimental range used. To make the statistical analysis it used the response surface technique and the values of the independent variables that maximize recoveries were found by canonical analysis. In the study of industrial flotation circuit crispy were obtained from 41.3% mass recovery and 91.3% metallurgical recovery P2O5, good values for the circuit, and the highest recoveries occur for solids concentration of the new flotation power between 45 and 50%, which values are assigned to the residence time of the pulp in cells and industrial flotation columns. The greater the number of ore heaps resumed on the higher the mass recovery, but in this scenario flotation becomes unstable because there is enormous weight variation in the feed. Higher recoveries are obtained for mass depressant dosage exceeding 120 g / t for synthetic collector dosage of 11.6%. In the study of industrial flotation circuit of the granulate were obtained 28.3% to 79.4% mass recovery and metallurgical recovery of P2O5 being considered good values for the circuit. Higher recoveries are obtained when the front ore 02 percentage is above 90%, because the ore of this front have more clear apatite. Likewise recoveries increase when the level of pulp rougher step is highest due to the high mass of circulating step receives loads. In the analysis of industrial flotation circuit of the ultrafine were obtained 23.95% of mass recovery, and the same is maximized to depressant dosage and the top collector 420 and 300 g / t, respectively. The analysis of the influence of variables ore, it was observed that higher recoveries are obtained for ores with P2O5 content above 8.0%, Fe2O3 content in the order of 28% forward and 02 of ore percentage of 83%. Hard ore percentage has strong influence on recoveries due to mass division in the circuit that is linked to this variable. However, the hard ore percentage that maximizes recoveries was very close to the design capacity of the processing plant, which is 20%. Finally, the study of the bench flotation, has noted that in friable and granular circuits the highest recoveries are achieved for a collector dosage exceeding 250 g / t and the simultaneous increase of collector dosage and synthetic collector percentage contributes to the increase recovery in the flotation, but this scenario is suitable to produce a concentrate poorer in terms of P2O5 content, showing that higher recovery is not always the ideal scenario. Thus, the results show the values of variables that provide higher recoveries in the flotation and hence lower losses in the waste.