Uso da cavitação hidrodinâmica para degradação do composto melanoidina

Abstract

The food industries and distilleries produce a compound called melanoidin when processing their food. As this compound has recalcitrant properties, its proper disposal has been a great challenge for such industries. Therefore, it is essential to focus on new technologies to remove melanoidin from industrial effluents that are discharged into water bodies. The purpose of this work was to evaluate the hydrodynamic cavitation potential to degrade the melanoidin compound. In this study, the compound was produced synthetically and it was submitted to cavitational experiments in a laboratory scale hydrodynamic cavitation system. In addition, numerical computer simulation was used to identify hydrodynamic parameters of cavitation. Five Venturi devices with different divergent angles, five operating pressures, six initial pH values and four volumes of hydrogen peroxide added at the beginning of the experiments were studied. The results showed that, with an initial compound pH of 2.50, the Venturi device with a divergent angle of 11 degrees and an operating pressure of 600 kPa showed a better efficiency, of approximately 14%. The synergistic use of hydrodynamic cavitation and hydrogen peroxide (15 ml) contributed to increase efficiency to 61%. The cavitation number interval between 0.13 and 0.20 showed high melanoidin compound degradation. The computer numerical simulation showed that the low-pressure region and the pressure recovery rate is influenced by the parameters of operating pressure and divergent angle of the Venturi devices. By improving the degradation of organic compounds and emerging pollutants, it was concluded that the hydrodynamic cavitation can be used as a pre-treatment tool integrating with the biological treatment units that already exist in conventional effluent treatment plants.