Estudo do processo híbrido eletro-Fenton na melhoria da eficiência da remoção de poluentes em efluente de cervejaria

Abstract

The aim of this work was to study the electro-Fenton (EF) hybrid process in the removal of pollutants from brewery wastewater, investigating the operational parameters to improve process efficiency. In order to perform the treatment, the best operating conditions for the Fenton and electrocoagulation (EC) processes were first determined to find the best conditions for the hybridization. For EF, a reactor with 6 iron electrodes was constructed, providing an effective area of 300 cm2 and a useful volume of wastewater of 1.0 L. Complete factorial experimental designs (CFED) were proposed for the Fenton, EC and EF processes. From the proposed experimental designs for Fenton and EC, the concentrations of hydrogen peroxide and iron required to perform the hybridization (9000 mgL-1 and 300 mgL-1, respectively), as well as the electric current density (ECD) necessary to generate the required iron concentration (50 Am-2), were determined. From preliminary tests for the investigation of the consumption of hydrogen peroxide (H2O2) by the process EF, it was verified the necessity to carry out the replacement of this reagent throughout the process, in order to maintain the treatment conditions. Using the treatment time of 30 min and DCE of 50 Am-2, the CFED for EF was performed, with the following parameters being varied: initial pH, intervention time and % of H2O2 replacement. The response to the treatments was interpreted using the analysis of the response surfaces, and it was verified by the analysis of variance (ANOVA) that the mathematical models were well adjusted to the experimental data. From the range where the best dissolved organic carbon (DOC) removal condition obtained by the EF was found, kinetic experiments were performed, and the best treatment condition was finally found, with an initial pH of 3.2, intervention time and a H2O2 replacement of 82.5% over the initial, with a COD removal efficiency of approximately 90% and a considerable reduction in toxicity, evidenced by the LC50 value (71%).