Carotenoid Degradation in Annatto Dye Wastewater Using an O3/H2O2 Advanced Oxidation Process

Urucum, also known as annatto, is a plant native to Brazil. However, there is a notable scarcity of scientific studies focusing on the wastewater generated by the annatto natural dye industry. This study seeks to address the existing knowledge gaps by presenting original and substantive data pertaining to this economic sector. This study investigates the degradation of carotenoids in real annatto dye wastewater through the application of an O3/H2O2 oxidation process. A 23 factorial experimental design was utilized to determine the influence of three key variables—pH (2.5–5.5), O3 mass flow rate (8.0–18.0 mg min−1), and initial H2O2 concentration (between 1.572 and 4.716 g L−1)—on both the degradation efficiency and the associated reaction kinetics. The process demonstrated impressive carotenoid removal, achieving degradation efficiencies between 84% and 97% with pseudo-first-order kinetic constants ranging from 0.0310 to 0.0805 min−1. A statistical analysis revealed that the O3 mass flow rate was the most influential factor on the degradation efficiency, while all the operational parameters played significant roles in determining the degradation kinetics. Notably, the process achieved optimal performance without the need for pH adjustment, presenting a cost-efficient solution for industrial applications. These findings offer critical insights into the treatment of high-strength agro-industrial wastewater, thereby advancing the development and implementation of oxidation processes for wastewater management.