Estudo da variação de concentração de cloreto de sódio no processo de eletrocoagulação aplicado ao tratamento de água

Abstract

The availability and quality of water intended for human consumption, is one of the main concerns in the present days, which has intensified the search for alternative water treatment process. Electrocoagulation, which consists of the coagulation of pollutant particles through electrode oxidation, via electric voltage, it is an efficient alternative, since it does not require the addition of coagulants. The aim of this study was to apply electrocoagulation process in water treatment, using different concentrations of sodium chloride (NaCl), to identify the ideal concentration, which returns the best removal of color, turbidity, and solids; besides, an analysis of pH variation, electrical conductivity, and treatment cost, based on electrodes wear and electric energy consumption. Twelve electrocoagulation assays of 80 minutes were performed, using aluminum electrodes, for two water samples from the Ribeirão Jacutinga. The sample 1 with 128 uH of color, 47.1 uT of turbidity and 125 mg.L-1 of total solids, and the sample 2 with 95 uH of color, 33.4 uT of turbidity and 40 mg.L-1 of total solids. The addition of NaCl was performed in two concentration ranges, from 1 to 5 mg.L-1 for sample 1, and 50 to 250 mg.L-1 for sample 2. It was verified that, NaCl aided the removal of color and turbidity, but it increased the concentration of solids. There was a little change in pH, and an increasing in electrical conductivity. The wear of the electrodes was higher with higher concentrations of NaCl, and the energy consumption increased, due to greater passage of electric current. It was concluded that, the best efficiencies were obtained with 5 mg.L-1 of NaCl, resulting in 98.44% and 92.51% in color and turbidity removal, respectively, costing R$ 0.64 per m³ of treated water.