Considering the problems related to issue of water resources, this study aims to analyze the wastewater recovery stage of the waste, from the reverse osmosis application, to replenish water in cooling towers. The present study was based on data obtained from industrial process of residual water recovery by reverse osmosis for replacement in cooling tower connected series to a heat exchanger system. Before the system, a daily continuous discharge (purge) of 7.81m³/h was installed, which was required to maintain the silica concentrations inside the specified parameter. After the implementation of the new unit of reverse osmose, it was not necessary to perform a purge, due to the low concentration of solids dissolved in the water used for the replacement of water in the cooling tower. The reverse osmosis treatment of the tailings, in the initial stages, allowed supplying the water demand from the plant from the new system. The osmotic pressures of the processed water ranged from 0.53 to 1.61kPa. These values were considered small due to the low silica concentrations. On average, the mass transfer coefficient was 0.26kg.m-2 h-1 kPa.

O emprego de polímeros intrinsecamente condutores, como a polianilina (PAni), tem-se apresentado como alternativa de revestimento protetor contra a corrosão, pois intensifica o efeito de passivação e proteção anódica do material. Diante da dificuldade em obterem-se filmes de PAni na forma oxidada e condutor de forma auto-suportados e coesos à superfície de substratos metálicos. Realizou-se a desdopagem do polímero, com o uso da solução de NH4OH passando a PAni para estado oxidado e não condutor conhecida como PAni esmeraldina base (PAni EB). A mistura completa da PAni EB, solvente orgânico e o plastificante 4-cloro-3-metilfenol, permitiram a obtenção de uma resina. Esta foi aplicada em placas de aço AISI 1006 com o auxílio equipamento Spin Coater. O filme foi caracterizado por análise térmica TGA, onde se verificou que o revestimento é resultado da reação dos componentes, predominando a estrutura da PAni EB. As análises térmicas demostraram no binder não apresenta alterações químicas que possam modificar as propriedades eletroquímicas da PAni, e os ensaios eletroquímicos de Voltametria Cíclica e Potencial de Circuito Aberto foram realizados em solução H2SO4 2 mol.L -1 , que indicou a formação de par redox polímero-metal, o que proporciona da formação de óxidos passivantes, que viabilizam a proteção anódica do metal contra a corrosão.

Some physical, chemical or electrochemical phenomena that cause the decomposition of a material, usually metallic, they can be defined as corrosion. Analyzing the adverse means and determining its characteristics, several efficient methods can be developed to prevent it, consisting in one of them the absorption of the oxidizing agent. This technique is based on significantly reduce the concentration of the compound. As the hydrogen sulfide corrosive substance, its excessive presence in gas streams intensifies the deterioration of equipment during the contact. The objective was to absorb hydrogen sulfide from biogas. The absorption study was conducted by applying a 5% sodium hydroxide solution. The device designed consisted of a cylindrical packing column, bearing a gas inlet and a distributor at the bottom, which further supports the packing, and a liquid inlet and distributor at the top. The treated gas is released from the top of the column, and the liquid is discharged at the bottom, containing hydrogen sulfide absorbed in the form of salts. In the design, the biogas flow was 15m³/h with 3% mole hydrogen sulfide and the tower was package with Rasching rings of 1.5 inches. The calculations performed have enabled the design of an absorption column 0.10 m in diameter and 3.00 m height of the packing, causing a loss in pressure of 0.5 cm water/m column.

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