Avaliação da eficiência do processo UV/H2O2 no tratamento de efluente kraft e da toxicidade para Daphnia magna

Abstract

The pulp and paper industry has a great potential polluter due not only to the large volume of effluent produced but also its composition as the high concentration of organic carbon e toxic compounds. This study evaluated the efficiency of the UV/H2O2 process in the treatment of Kraft. To this, was carried out two sampling of the Kraft effluent (November, 2012 and March, 2013) and for the first sample was realized a 22 factorial design as variables pH (4.0 and 8.0) and the concentration of hydrogen peroxide (50 and 70 mg / L). Increases in pH from 4 to 8 interfered -10,26% in the removal of apparent color, -32,99% in dissolved organic carbon (DOC) and -18,46% in spectral area. On the other hand, an increase in oxidant concentration contributed 9,64%, 15,87% and 7,36% to decrease this parameters, respectively. Therefore, the best condition of treatment was pH 4 and [H2O2] = 70 mg/L, to which was followed by a more complete characterization before and after the treatment with analysis of apparent and true color, reduction of spectral area, phenolics, lignins compounds, turbidity, DOC and acute toxicity using Daphnia magna. Satisfatory results were achieved for phenolics, lingins compounds and spectral area decrease. However, in the second sample there was an increase in the acute toxicity after the treatment and this could be due the non-seletive attack of hydroxyl radicals to the contaminant’s strucuture, generating by products more toxics.