Tratamento de efluente da indústria cafeeira por meio de processos oxidativos avançados

Abstract

The objective of this study was to characterize and evaluate the efficiency of the Fenton, Photo Fenton and Fenton-Like process in the effluent treatment of a coffee industry. Therefore, the characterization of the raw effluent according to the parameters of COD, pH, temperature, settleable solids, suspended solids, alkalinity and volatile acidity was first carried out. The data presented a high concentration of organic matter, with COD of 9,636 mg.L-1, justifying the need to treat the effluent. Aiming for a better design and optimization of the process, preliminary tests were carried out and it was verified that the Fenton process would be the best treatment process for the effluent under study. Thus, the factorial experiment of the 3x4 experiments was used to better suit the Fenton process. In the tests, the best conditions found were those [Fe2+]: 150, 200, 250, 300 mg.L-1; [H2O2]: 8,0; 10,0; 12,0 mol.L-1. It was also verified that the best results were obtained [Fe2+]: 200 mg.L-1 and [H2O2]: 12, 0 mol.L-1, being degraded 53.04% COD and moderate sludge formation. After the treatment of the obtained data, it was observed that the concentrations of H2O2 and the interaction between the concentrations of Fe2+ and H2O2 have significant influence in the process. It was observed that the concentrations of Fe2+ may interfere in the final product due to the great generation of sludge and that when worked with high concentrations of H2O2, the inefficiency in the degradation of the organic matter occurs. Results of COD removal were achieved at approximately 70% and suspended solids 2.0 mL.L-1, characterizing the efficiency of the Fenton process for a primary treatment.