Remoção de boro de efluente de indústria de mineração e de efluente sintético por eletrocoagulação utilizando eletrodos de alumínio

Abstract

Electrocoagulation is an important method of waste removal in liquid effluents, presenting important results in the literature and several advantages, such as low operating cost, production of coagulant in situ, low production of secondary residues, among others. Thus, in this study, the efficiency of the electrocoagulation method was investigated for the removal of residual boron from a synthetic effluent and from a mining effluent. Also tested for a synthetic effluent prepared from a 200 mg L-1boric acid solution and for a real effluent collected from a mining company located in the city of Vitória, different analysis parameters such as electrocoagulation time, current density, pH and supporting electrolyte concentration. The results obtained showed a percentage of boron removal higher than 60% for the synthetic effluent and close to 70% for the mining effluent, when using aluminumelectrodes, pH of7.5, current density of 14.42 mA cm-2and supportingelectrolyte at the concentration of 0.200 mol L-1for the synthetic effluent and of 0.400 mol L-1and 1.000 mol L-1for the mining effluent. In this study, the electrocoagulation method and the conventional method of chemical coagulation were also compared. From the comparison between the two methods, boron removal by electrocoagulation of the mining effluent was56.30%higher than by the chemical coagulation method. As with the removal percentage, the electrocoagulation method was also more advantageous in terms of operational cost, which had a twice as low operating cost when compared to a chemical coagulation method. Thus, electrocoagulation proved to be an efficient method of removing boron from both synthetic effluent and mining effluent, especially when appropriate parameters were applied