Analysis of the Efficiency of <em>Pleurotus </em>Strains and δ-FeOOH Nanoparticles in the Treatment of Sugar Cane Vinasse

Vinasse is a byproduct of the sugarcane ethanol industry, generated at approximately 10 to 15 L per liter of ethanol produced. It is characterized by an acidic pH, intense coloration, high turbidity, and a high organic load, such that its improper disposal represents an environmental and sanitary concern. In this study, the degradation of organic matter in vinasse at concentrations of 25% and 100%, with and without pH adjustment, was evaluated using three strains of the fungus Pleurotus, and the performance of the most efficient strain was further investigated in association with δ-FeOOH nanoparticles, in addition to a phytotoxicity assay using Lactuca sativa. The results showed that all Pleurotus strains exhibited high potential for vinasse discoloration, with emphasis on the HI strain (Pleurotus ostreatus), which achieved approximately 90% removal of turbidity and chemical oxygen demand in the 25% vinasse treatments, while at the 100% concentration, the removal efficiency ranged from 2% to 90%. The addition of δ-FeOOH did not significantly increase removal efficiency in diluted vinasse; however, it conferred magnetic responsiveness to the fungal biomass, facilitating its separation after treatment. Moreover, the treated vinasse showed no toxicity to the germination of Lactuca sativa seeds, indicating reduced environmental and sanitary risks. These results demonstrate that the proposed approach constitutes a promising and sustainable strategy for managing vinasse, contributing to environmental remediation and reducing risks to ecosystems and human health.