Tratamento de lixiviado de aterro sanitário por meio do processo de eletrocoagulação e filtração

Abstract

The deposition of waste in landfills is one of the possible solutions to solve the problem of urban waste, however, it generates a serious mitigating factor due to its high potential of contamination: the leachate.The purpose of this study was to apply the electrocoagulation process (EC) as a treatment of landfill leachate to: compare its effectiveness by varying pH and time, through the use of iron electrodes; to evaluate the efficiency of the electrocoagulation process, int the removal of turbidity and apparent color parameters, and also in the variation of electric current and electrical conductivity, analyzing the tests before and after filtration; and to evaluate the performance of the electrodes by calculating mass loss and process costs. Eighteen EC tests were performed, varying pH (acid, basic and neutral) and time (40, 60 and 80 min), and then a paper filter was used in each sample in order to verify if there was reduction or variation of the analyzed parameters. It was found that the best efficiency of the parameters apparent color, true color and turbidity occurred mainly in the sample 10, whose pH was 5,83, turbidity of 65,1 uT (42,9 uT post-filtration), apparent color of 262 uH and true color of 262 uH (post-filtration). The best results were mainly for tests whose pH was acid after the use of the filter. However, the lower the pH the higher the wear of the electrode, which results in higher operating costs, which does not reduce the advantage of electrocoagulation in an acid medium, due to the removal values being high. The cost of the sample 10 that presented the best efficiency taking into account all the parameters was of 4,50 R$/m³, which as already mentioned, is high due to the higher wear that occurs when the pH is low. It was verified that the wear of the electrode increases the electrical conductivity of the tests and that the higher the conductivity the lower the resistance to electrical passage, thus increasing the coagulation and flocculation of the leachate and consequently removing larger impurities. The sample, which the greatest wear occurred, was sample 11 with an initial pH of 2,77 using 2,68 mg of electrode, and the one that had the least wear was the test 13 with initial pH of 8.57 and a wear of 0,75 mg, this being a neutral test with a medium color reduction and turbidity. In view of the statements, it can be said that electrocoagulation is efficient in the removal of impurities from effluents, and that the use of the filter (paper) acts as a polishing for this physical-chemical treatment, aiding in the reduction of suspended particles present in excess in the effluent.