Avaliação do efeito da injeção de ar comprimido no tratamento eletroquímico de efluente têxtil sintético

Abstract

Due to the population growth in recent years, the textile industry’s demand has showed an increase of its activities. At the same time it develops, its associated environmental impacts follow the same proportion, and water resources are the most affected. The electroflocculation has gained prominence by being successful in treating wastewater. Thus, it was decided to check whether the injection of compressed air in the system contribute in the efficiency increase of the electroflocculation treatment, collaborating with the flotation of impurities. Aqueous solutions of dye Reactive Blue 5G was used to analyze the effectiveness of electroflocculation treatment and the efficiency of the system with injection of compressed air, both in continuous flow, in addition to the system dynamics for both configurations. The employed hydraulic retention time was of 20 minutes, with the current intensity in the electrodes set at 5 A. Samples were collected at 20, 30 and 40 minutes to analyze the treatment efficiency. For the injection of compressed air, two 4 mm Polyurethane hoses with about 50cm each were included. Small holes were poked into the hoses to cause the air to leak with pressure set at 1.2 bar. As an experimental planning strategy Completely Randomized Design – CRD was used. Six repetitions were performed for each of the two studied treatments. The Analysis of variance – ANOVA and Tukey’s mean comparison test were adopted with a 5% significance level. As a result of ANOVA it became possible to infer that there is a significant difference in between at least two sampling times and after 30 minutes with Tukey’s test the system was at a steady state for the treatment only by electroflocculation. It was possible to verify through the means of the samples that were collected at different times that the results found no significant difference, where the steady state was not reached. Comparing the two systems employed in the study (with and without compressed air) it induced a difference between the results of the treatments, where the injection of compressed air promoted the mixture, were not allowing the mass transfer of dye from the aqueous solution used for the sludge, in other words, it caused the flotation of the system to suffer interference, declining the treatment’s efficiency.