This study aims to characterize the complex metal-clay formed by adsorption of lead. In this work, the bentonite clay named Fluidgel was calcined at 750 ºC and was used as adsorbent for lead removal. The characterization of this clay and complex metal-clay was carried out by X-ray diffraction (XRD), Fourier transformer infrared spectroscopy (FTIR), surface area (BET method), scanning electron microscopy (SEM) and chemical composition by energy dispersive X-ray (EDX). The removal of lead from aqueous solution was carried out in a fixed bed. Dynamic experiments were performed to evaluate the effect of flowrate on adsorption efficiency. The experiments were accomplished at room temperature, the clay adsorbent particle diameter was of 0.855 mm and the flow rate varied from 0.6 to 2 mL/min. The feed concentration of lead was about 0.24 mmol/L. Comparing the chemical compositions of the clays obtained by EDX before and after removal of the lead, it was concluded that the ion exchange process might be important to lead removal. From the semi-quantitative analysis of chemical composition in clays with and without adsorbed lead it was observed a reduction of the amount of Ca2+, K+ cations and the disappearance of Na+ cations, which was caused by cation exchange process.

A aplicação de argilas para adsorção de metais pesados presentes em efluentes tem sido objeto de estudo em muitas pesquisas em virtude das inúmeras vantagens técnicas e econômicas. Este trabalho teve como objetivo obtenção de isotermas de adsorção de níquel e zinco em coluna de leito fixo utilizando como adsorvente argila bentonita calcinada a 500 ºC. Os experimentos para remoção de níquel e zinco foram conduzidos à temperatura ambiente (20 ºC - 25 ºC), pH da alimentação ajustado em 4,5, massa de argila calcinada de 15,5 g, com diâmetro médio de 0,855 mm, vazão de alimentação de 4 mL/min e concentração da solução de metal variando entre 0,5 meq/L a 4 meq/L. Os modelos de isoterma de Langmuir, Freundlich, Langmuir-Freundlich, Radke-Prausnitz, Redlich-Peterson, Sips e Toth foram ajustados aos dados de equilíbrio, sendo que o modelo de Langmuir apresentou melhor ajuste às concentrações de Ni2+ e Zn2+ adsorvido.

The use of clays for adsorption of heavy metals in wastewater has been studied in many trials because of numerous technical and economic advantages. This work aimed to evaluate the removal of nickel and zinc in fixed bed column. The experiments for the removal of nickel and zinc were conducted at room temperature (20 ºC - 25 ºC), pH adjusted at 4.5, weight of 15.5 g calcined clay,with an average diameter of 0.855mm, feeding flow rate 4 mL/min and concentration of the solution of metal between 0.5 meq/L to 4 meq/L. The Langmuir, Freundlich, Langmuir-Freundlich, Radke-Prausnitz, Redlich-Peterson, Sips and Toth models were fitted to equilibrium data, and the Langmuir model provided the best fit for adsorption isotherms.

Particle collection experiments were conducted in a fluidizing irrigated bed to evaluate the performance of mobile packings: 38 x 50 mm plain oblate spheroids 38 mm ID plain spheres and alternative perforated spheres with a 38 mm ID and 10% and 25% free areas were used as fluidizing media in a 0.264 m diameter and 1.20 m high turbulent bed contactor (TBC). Particle collection experiments were carried out above the minimum fluidization velocity, using as particulate test powder polysized alumina (size 1.5 to 5.5 mm). Experimental results demonstrated that the perforated spheres performed better in collecting particles than the other packings tested. The efficiency of particle collection was analysed based on energy consumption in the TBC, using the energetic efficiency concept. It was verified that not much more energy was consumed per unit of gas flow in fluidized beds of perforated packings than in those of conventional plain sphere packings, since the perforated spheres were more energetically efficient for particle collection than plain spheres and oblate spheroid packings.

An experimental study was carried out aiming to evaluate the performance of a three-phase fluidized bed bioreactor (FBBR) used to treat milk wastewater. In this study three different concentrations of milk wastewater substrate (462, 825 and 1473 mg O2/L) were tested. Using the same number of support particles, the results demonstrate that the average efficiency of COD removal decreased as the concentration of organic load in the substrate was increased. The growth of microorganism in the FBBR was followed by a count of viable cells in both liquid phase and the biofilms attached to the support. An increased number of viable cells were observed inside the reactor when it was used to degrade higher organic loads, with most of the cells on the support. The higher concentration of active biomass was responsible for achieving a relatively high absolute degradation of the wastewater containing the high organic load.