Estudos dos parâmetros que influenciam a floculação na sedimentação contínua

• Autor(a) principal: Lira, Juliana Rodrigues
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFU
• Texto Completo: https://repositorio.ufu.br/handle/123456789/15168
• topic: Sedimentação; Floculação; CNPQ::ENGENHARIAS::ENGENHARIA QUIMICA

Some factors may influence the sedimentation of a suspension of particles such as particle shape, density and size distribution. Particles with diameters larger settle more quickly, while the very fine particles tend to remain long in suspension. Considering that one way around the small diameter of the particles is the use of flocculating agents, this work has as one of its goals to study the effect of flocculant concentration and pH of the water on the sedimentation rate. In the experimental study was used as flocculant aluminum sulfate to aqueous suspensions of kaolin, with a polyelectrolyte as a coagulation aid. After testing different concentrations of flocculant can be observed that the settling velocities are larger for the concentration of flocculant equal to 5 mg / L suspension. As for pH, settling velocities are larger for the value 7. In a second step, experimental tests were performed in a continuous settler using suspensions with and without the use of aluminum sulfate (0.2 mg / L of suspension). The results revealed that, as expected, the concentration of solids in the underflow was greater for aqueous suspensions of kaolin with aluminum sulfate, even if not observed the formation of flakes. In these experiments, also raised the height of sediment produced in stationary operations. Experiments were carried out aiming at obtaining the constitutive equations for the pressure in solids and to sediment permeability and they perform simulations using two mathematical models, model Tiller and Chen (1988) model and Arouca (2007), in order to get numerically the final height of the sediment in steady state operations, in order to compare the experimental results. The results obtained in the resolution of the models showed that the model Tiller and Chen (1988) produced a deviation of 39.0% in the experimental result for suspensions without aluminum sulfate and 14.3% for suspensions with aluminum sulfate. Already the model Arouca (2007) resulted in values close to those obtained experimentally, with deviations of less than 3% for suspensions with and without aluminum sulfate.