22The two-dimensional fractal dimension (Df) of large aggregates of kaolin (> 540 μm) 23 during the shear flocculation process for kaolin solution was investigated using non-intrusive 24 in situ image-based acquisition system. Separate experiments were also carried out for three
ABSTRACT. The Araguari River basin has a huge water resource potential. However, population and industrial growth have generated numerous private and collective conflicts of interest in the multiple uses of water, resulting in the need for integrated management of water quantity and quality at the basin scale. This study used the AQUATOOL Decision Support System. The water balance performed by the SIMGES module for the period of October 2006 to September 2011 provided a good representation of the reality of this basin. The parameters studied were dissolved oxygen, biochemical oxygen demand, organic nitrogen, ammonia, nitrate and total phosphorus. The coefficients of biochemical reactions, sedimentation rates and sediment dissolved oxygen release for this period were calibrated and validated in the quality modeling using the GESCAL module. A sensitivity analysis indicated that the coefficients of carbonaceous matter decomposition, nitrification, water temperature, and sediment oxygen demand interfered more significantly in the variables of state. To prevent eutrophication in the Nova Ponte reservoir and in the other cascade reservoirs, the local River Basin Committee should adopt restrictive actions against the use of agricultural fertilizers. On the other hand, in the sub basin of the Uberabinha River, new alternatives for public water supply to the city of Uberlândia and improvements in the treatment efficiency of the main wastewater treatment plant (WWTP) should be proposed, since the biochemical oxygen demand, ammonia and total phosphorus failed to meet the requirements of COPAM (2008) in the driest months. Keywords: water, modelling, AQUATOOL, Araguari River, basin, Brazil.Modelación integrada de cantidad y calidad del agua en la cuenca del río Araguari, Brasil RESUMEN. La cuenca del río Araguari tiene un enorme potencial de recursos hídricos. Sin embargo, la población y crecimiento industrial han generado numerosos conflictos de interés, privados y colectivos, en los usos múltiples del agua, dando lugar a la necesidad de una gestión integrada de la cantidad y calidad del agua a nivel de la cuenca. En este estudio se utilizó el Sistema de Soporte de Decisión AQUATOOL. El balance hídrico realizado por el módulo SIMGES, para el período de octubre 2006 a septiembre 2011 proporcionó una buena representación de la realidad de esta cuenca. Los parámetros estudiados fueron el oxígeno disuelto, demanda bioquímica de oxígeno, nitrógeno orgánico, amonio, nitrato y fósforo total. Los coeficientes de las reacciones bioquímicas, tasas de sedimentación y demanda de oxígeno disuelto del sedimento para este período fueron calibrados y validados en la modelación de calidad del agua, mediante el módulo GESCAL. El análisis de sensibilidad indica que los coeficientes de degradación de la materia orgánica, nitrificación, temperatura del agua y demanda de oxígeno del sedimento interfirieron más significativamente en las variables de estado. Para evitar la eutrofización en el embalse de Ponte Nova y en el resto de los embalses en ...
This study sought to evaluate the effect of form and particle size distribution of formed flocs during flocculation on the removal of particulate matter (PM) by settling. The understanding of the intrinsic processes of water treatment is fundamental for the improvement of these processes, and this understanding is often limited by the use of indirect measurements. For this reason, this study evaluated the relationships among the morphology, particle size distribution (PSD), and particle volume distribution of flocs formed with mean flocculation velocity gradients (G f) from 20 to 60 s −1 and settling velocities from 0.5 to 5.0 cm s −1 at flocculation times (T f) from 10 to 60 min. A correlation analysis of all of the parameters was performed to identify the most significant direct measurement for characterizing the removal of PM. Strong correlations among parameters were observed when considering the variation with G f for a given T f , and moderate correlations were observed when considering the variation with T f for a given G f. The strong correlations that resulted from the alteration of G f were a consequence of the significant changes in the morphological characteristics, PSD, and PVD of the flocs. The lower strengths of the correlations with the variation in T f can be explained by the rapid attainment of the equilibrium steady-state between aggregation and disaggregation forces.
O material particulado presente em coleções hídricas configura-se como um grande problema na gestão deste recurso. Estas partículas podem abrigar diversas substâncias nocivas, provocar diminuição da vida útil de reservatórios, diminuir a capacidade de transporte de sistemas de drenagem, entre outros. Além disso, grande parte de substâncias dissolvidas devem ser convertidas a partículas para posterior remoção em sistemas de tratamento, durante a separação sólido-líquido. Uma das medidas para entendimento dos processos aos quais se envolvem as partículas presentes na água, os problemas agregados e forma de tratamento, é o conhecimento de sua distribuição na suspensão uma vez que fenômenos como transferência de massa, adsorção, difusão e reações bioquímicas são todos influenciados por esta distribuição. Neste sentido, este trabalho buscou avaliar a Distribuição de Tamanho de Partículas (DTP) de cinco conjuntos de amostras produzidas em laboratório a partir de ensaios conduzidos com a mesma água de estudo, variando-se as condições de obtenção das partículas (flocos). Foram produzidos conjuntos de partículas distintos e determinados os parâmetros representativos de sua distribuição de tamanho, por dois métodos: linearização função de DTP e integração da função de DTP. Ambos os métodos se mostraram ferramentas hábeis para reproduzir, a partir do parâmetro β representativo, a DTP original. A grande vantagem deste tipo de abordagem é a possibilidade de se representar por um único valor, e não mais um conjunto extenso de valores, o tamanho das partículas por faixas pré-determinadas. Além disso, pode ser possível relacionar este parâmetro com algum método de difração de luz que forneça em termo real, por meio da perturbação de sinal, a variação dos tamanhos das partículas presentes no meio. Palavras Chave: Distribuição de Tamanho de Partículas. Parâmetro representativo da DTP. Coleções hídricasParticles are present in several types of water collections and they constitute a major problem in the management of this resource. These particles can cause a sort of problems, such as: to retain harmful substances, to diminish reservoirs capacity, to reduce drainage systems capacity, among others. Moreover, much of dissolved substances must be converted to particles before removal, so that removing particles means removing most of harmful substances. In this context, the assessment of physical characteristics of particles is crucial for improving their removal. Thus, particle size distribution (PSD) is an important tool for physical and chemical removal process. This study aimed to evaluate the PSD of five sets of laboratory samples. The parameter of function which represents PSD was evaluated of two different modes: by Linearized and by integrated forms. Both methods were able to reproduce parameters of PSD. The use of a representative PSD parameter was possible, thus permitting to represent, by means of a single value, and no more by means of a set of values, the PSD in different ranges. Furthermore, it may be possible in future ...
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