Abstract

BACKGROUND Grapes used in the production of juice have high total phenolic content due to the undesirable fermentation process, consequence of the high content of sugar ant fatty acids in grapes, which produce a high amount of ethanol. Therefore, the amount of wastewater with a high concentration of organic matter is an environmental concern related to juice production. We evaluated the potential of the use of these Fenton and photo-Fenton processes in the depuration of organic matter in the juice production wastewater and determined the factors that affect the treatment. RESULTS We obtained different levels of organic matter removal, with a higher level for the experimental conditions, that is, a high concentration of H2O2 and Fe+2 and the use of UV irradiation (photo-Fenton). In this case, COD and polyphenol elimination was 70.2 % and 36.1%, respectively, with juice wastewater under no pretreatment and applying UV irradiation. The most important factor in the removal of COD in juice wastewater was the concentration of Fe+2, followed by H2O2 and the presence of solar UV. The most important factor in the removal of polyphenols is the pretreatment of the juice wastewater, with better results whenthere is no pretreatment. The highest removal of polyphenols was obtained using the water without being pretreated. CONCLUSIONS The specific energy consumption and the electrical energy per order under the photo-Fentonprocess was lower than under the Fenton process, indicating a more efficient energy use. This is because the natural UV irradiation enhances the chemical reaction of the oxidation process, producing a higher difference in the concentration of COD and polyphenols in comparison to the process carried out without UV solar irradiation. (c) 2019 Society of Chemical Industry