Tratamento de efluente sintético em reator eletrolítico de fluxo contínuo com eletrodos de ferro e alumínio

Abstract

Studies, research and great efforts have been made, over the years, aiming to reduce the damages caused by the industrial sector, especially the textile over water resources, by discarding its highly colored and contaminated effluents due to the high rate of use of elements seen as complex degradation. The focus of this study was to measure the efficiency of the electrocoagulation process applied to the treatment of textile industrial effluent. Thus, a continuous flow electrochemical reactor was used, with iron and aluminum electrodes, achieving maximum efficiency in the degradation of the Direct Red 23 textile dye. The tests were performed using a 2³ factorial design with repetition at the central point and the factors considered (independent variables) pH, spacing between the plates and the hydraulic holding time. To check the efficiency of the process, the parameters pH, turbidity, color and concentration of the dye were analyzed (process dependent variables). For iron electrodes, it was possible to obtain 100.0% and 98.6% efficiency in the removal of dye and color, respectively, on the condition that: initial pH equal to 7.0; spacing between plates of 1.0 cm and detention time of 20.0 min (test 9 of the planning). As for aluminum electrodes, the highest dye and color removal efficiency (in the order of 99.5% and 98.0%, respectively) was obtained in test 7 (pH equal to 9.0; spacing between plates equal 0.5 cm and detention time of 30 min). For turbidity, satisfactory results were not obtained, both for iron and aluminum electrodes. With the use of aluminum electrodes, the greatest removal of this parameter was 37.69%. However, in all tests with iron electrodes there was an increase in turbidity. Nevertheless, it was found that after the settling of the suspended material (flakes) the turbidity value decreased. Through the Pareto diagrams it was possible to verify the statistically significant factors in the electrocoagulation process. Despite the proven high efficiency in the degradation of the dye and the removal of color with both iron and aluminum electrodes, the electrolytic treatment ends up not having the same effectiveness in reducing the turbidity present in the effluent, leaving an inevitable space for future research on the association of electrocoagulation, in continuous flow, with the filtration process to remove suspended solids, thus reducing the turbidity of the final effluent.