The procedure usually employed for specifying a set of hydrocyclones used in Newtonian fluid-solid separation processes can be extended to the case of non-Newtonian fluids. The apparent viscosity, µapp, is the link between the two cases, and can be evaluated from the knowledge of the shear stress function, S, and the characteristic rate of shear, λ*. In order to verify the validity of this, experiments using suspensions of different solids in an aqueous solution of carboxymethylcellulose (CMC), with pseudoplastic behavior, in an AKW commercial hydrocyclone have been performed. The results obtained in this work indicated that the separation process and the pressure drop in the hydrocyclone cannot be characterized by a single apparent viscosity associated parameter.

The aim of this work was to develop a mathematical model for a continuously operating flotation tank to provide the scale-up and optimization of the separation system. The fluid dynamic of the tank was assumed to be a perfect mixture and the flotation kinetics to be a first-order reaction, as suggested by the batch operation. The experiments were carried out in a continuously operating 60 L tank, used in the treatment of a synthetic dairy waste at its isoelectric point. A mathematical model that describes the behavior of a continuously operating flotation tank used in the treatment of a synthetic dairy waste at its isoelectric point is not only proposed, but also validated with experimental data.

In this work, the application of the flotation technique by dissolved air (FAD) to the treatment of milk industry effluent (milky effluent) is analyzed. Initially, batch studies were carried out in a column built of acrylic with an external diameter of 2.5 cm and 50 cm in height. Afterwards, the performance of a flotation tank with a 5.5 L capacity in the treatment of the milky effluent was addressed. In continuous mode of operation, separation efficiencies up to 90% were obtained for the experiments carried out at a saturation pressure of 4 atm and having a ratio of feed flow rate (Qa) to saturated liquid flow rate equal to 1. The separation efficiency for flocculated milk was estimated from the overall mass balance for the flotation tank. Separation efficiencies obtained agreed very well with the experimental results collected for Qa/Q Ls ratios lower than 1.

In this work, the effect of the configuration on the collection efficiency and pressure drop in small diameter cyclones is evaluated based on neural networks (Functional Link Networks). The experiences were conducted at LSP/COPPE Laboratory in a Stairmand high efficiency prototype (Dc = 5 cm) with variable overflow diameter. Three different configurations were tested, and it is possible to observe a significant increase in the collection efficiency with the reduction of the overflow diameter.

This work deals with the performance analysis of a separation set-up characterized by the ejector-hydrocyclone association, applied in the treatment of a synthetic dairy wastewater effluent. The results obtained were compared with the results from a flotation column (cylindrical body of a hydrocyclone) operated both batch and continuously. As far as the experimental set-up studied in this work and the operating conditions imposed to the process, it is possible to reach a 25% decrease in the total effluent chemical oxygen demand (COD). This corresponds approximately to 60% of the COD of the material in suspension. The best results are obtained for ratios air flow rate-feed flow rate (Qair/Q L) greater then 0.15 and for ratios underflow rate-overflow rate (Qu/Qo) lower than 1.0.

Some applications of spouted beds have been limited by problems with spout stability. In order to overcome these limitations, research should be concentrated on describing the mechanism by which the spout is developed. This work presents a theoretical and experimental study to describe the effective solid stress distribution in the annular region of a conical spouted bed. From experimental observation, the failure state of the bed of particles at the outset of spouting is identified and related to fluid-particle properties and column dimensions. Linear and angular momentum balances for the solid phase are then formulated as a function of the bed failure state. The set of equations obtained is solved using numerical methods, and results regarding stress distribution, stability and spout shape are presented and discussed.

Results gathered from the literature on the dynamics of bubbles in liquid are correlated by means of a formulation traditionally employed to describe the dynamics of isometric solid particles. It is assumed that the shape of the bubble depends, by means of the Eotvos number, on its diameter and on the gas-liquid surface tension. The analysis reported herein includes the dynamics of the isolated bubble along with wall and concentration effects. However, the effects of gas circulation in the bubble, which result in terminal velocities higher than those of a rigid sphere, are not being considered. A limited number of experimental points are obtained employing a modified version of the Mariotte flask which permits the precise measure of bubble volume. A classic bubble column is also employed in order to measure gas holdup in the continuous phase. Experiments were carried out employing air, with distilled water, potable water, water with variable amounts of surfactant and glycerin as the liquid phase.