Tratamento de efluentes da indústria de tintas através da reação de Fenton associado ao processo de sedimentação

Abstract

Due to the growing concern for the environment, several Technologies for treatment of industrial effluents are being developed in order to minimize the impacts on water resources. Amid the various studied technologies, Advanced Oxidations Processes (AOPs) have received attention considerable. Among AOPs, the Fenton reaction, as source of generation hydroxyl radicals, has been outstanding. The Fenton reaction is the catalytic process of decomposition of hydrogen peroxide (H2O2) by ferrous ion (Fe2+) generating hydroxyl radicals, (HO•). The hydroxyl radical has a high oxidizing power, which leads to a partial or total degradation of large number of pollutants compounds. The ferrous ion, in appropriate pH, has the coagulant properties and may contribute to the removal of suspended particles in solution. The efficiency of the Fenton reaction can be enhanced when combined with the settling process. Depending of effluent, the sedimentation may be a slow step that can to reduce the application process on an industrial scale. The use of settler can accelerate the process, allowing the use of the method and also in continuous flow and also the use of iron concentrations higher, increasing the efficiency of treatment. In this study it was evaluated the efficiency of the coagulation processes, Fenton / flocculation, and coagulation followed by Fenton / flocculation in the treatment of effluents from the paints industries. In this study also was projected a lamellar settler to accelerate the sedimentation process. The results confirmed the efficiency of Fenton reaction followed by coagulation / flocculation in the treatment of real effluent of paint industry. The treatment led to a reduction of approximately 95% of COD of effluent, it suitable for disposal. Applying the same technology, using the settler in the sedimentation processes, the efficiency of COD reduction was the same, however, the treatment time was about eight times lower. The application of the Fenton reaction followed by sedimentation trough the lamellar settling led to a reduction of 95% of COD of effluent. The system Fenton / flocculation with lamellar settler was the process more promising, due using of lower concentrations of reactants. The process can be applied in the treatment of industrial effluent, with advantages over conventional methods.