Análise e projeto de hidrociclones para o espessamento do lodo gerado no tratamento de efluentes de indústrias têxteis

Abstract

The disposal of industrial and residential wastewater into water bodies has gained increasing attention of surveillance of environmental agencies. So it is increasing the contribution of scientific research groups to develop new technologies to help ensure that these discharges are less harmful to nature. The textile industry contributes a great generation of pollutants that are not properly treated when they become aggravating environmental problem. One of the raw materials of the textile industry is the sheep wool. Due to the sheep conditions are created for the industrial processing of such wool is essential that the largest possible removal of impurities by washing, then to be transformed into yarn by carding process and finally be spun and dyed. The high temperature and pH which are used in the wash contribute significantly to the generation of effluent and sludge as high amount of water used makes this effluent becomes moist enough. The most common method of treatment of this effluent is through decantation or sedimentation through biological treatment through activated sludge system. Despite presenting a good efficiency, this method is not sufficient for removing dissolved organic compounds, besides being very susceptible to the effluent composition and produce large amounts of sludge. Some options like, drying or hydrocycloning, contribute to the thickening of sludges generated during treatment of the effluent. The geometric parameters of hydrocyclones depend on the family to which it belongs, Rietema and Bradley Family settings are appearing more frequently in the work of literature when it comes to equipment with good efficiency for solid-liquid separation. The Rio Grande do Sul, among the Brazilian states, it is so prominent in the textile production and in livestock scenario, especially in wool production of sheep, so the aim of this study was to design, analyze and simulate the fluid dynamics of hydrocyclones type Rietema and Bradley for sludge thickening produced by a textile city of Bage - RS. First the physical characterization was carried effluent sludge by raising the temperature, the density of the fluid phase and the solid part of its viscosity, its solids concentration and its distribution of the average particle size. Also the chemical characterization was done by raising the pH, COD, the amount of organic matter and conductivity. Based on these results and the equations that relate efficiency with cutting diameter and the diameter of the cylindrical section of the hydrocyclone, it was possible to design and analyze the behavior of the efficiencies of Rietema and Bradley configuration hydrocyclones. It also found based on the relationship of Euler and Reynold which the hydrocyclones has lower energy expenditure for the same range of efficiency. Finally, a numerical analysis was carried out through computer simulation by CFD ANSYS software to describe the velocity profile, pressure and performance of liquid and solid phase within the hydrocyclones. The results of the physical characterization showed that the sludge has a specific weight of 1000.05 kg / m3 and the solid contained in the sludge has a specific weight of 1002.64 kg / m3 and a particle diameter of 586 m and a volume concentration of 4 ,2 %. In parametric sensitivity, the configuration hydrocyclones Rietema and Bradley behaved in much the same way. The simulation results helped in knowledge and graphic interpretation of how occurs the fluid motion and phase separation inside the hydrocyclone. In view of the tangential velocity profiles, it was observed that this is higher in the central region of the hydrocyclone, which returns ascending helical movement, the less dense phase. The pressure currents shown that this variable is greater near the walls of the hydrocyclone, which causes phase separation. To analyze the efficiency we used the Lagrangian model with solid dispersions curve in water with a median of distribution of 586 micrometers. Both hydrocyclones designed showed a 74% separation efficiency.