Estudo da degradação de microplásticos em água e efluente secundário de estação de tratamento de esgoto por processos baseados em ozônio

The presence of microplastics in water can cause several diseases in humans, such as intestinal inflammation and cancer. Its presence is also associated with reduced efficiency in water and wastewater treatment plants, which can decrease the amount of salts available for each particle in coagulation, cause membrane clogging in the filtration process and inhibit the growth of some bacteria in bioreactors. To remedy the impacts caused by this pollutant, researchers point to advanced oxidative processes (AOPs) as promising treatment technologies. This study, through a factorial experimental design to optimize significant variables in the oxidative process, was dedicated to the use of ozonation (O3 and O3/H2O2), one of the types of AOP, for the degradation of polyethylene microplastic (PE). As a result, the process generated an increase in total organic carbon (TOC), from 0.830mg/L to 1.871mg/L, an increase of 125.36%, using the O3/H2O2 process with 100mg/L of H2O2 and 52 mg/L O3 after 110 minutes. In the Fourier-transform Infrared Spectroscopy (FTIR) analysis, it was possible to observe the carbonyl group at the peak of 1714 cm-1, serving as the main indicator of changes occurred by the oxidative process. In the Scanning Electron Microscopy (SEM) it was also possible to observe changes in the surface of the microplastic after ozonation, demonstrating the degradation capacity in the use of this oxidative process. The FTIR and SEM results also indicate that the use of the O3/H2O2 process, compared to O3, promotes greater importance on the surface of the microplastic, as it promotes a greater concentration of radicals that attack the polymer.