Ficorremediação de 17-alfa etinilestradiol (EE2) pela microalga Chlorella vulgaris imobilizada em cápsulas de alginato

Abstract

Micropollutants of emerging concern are substances found in low concentrations in aquatic matrices (ng/L), but they can cause numerous disruptive effects on exposed organisms, including humans. However, since they are not effectively removed by conventional wastewater treatment technologies, they are increasingly present in domestic effluents. Among these, the synthetic hormone 17α-ethinylestradiol (EE2) stands out, widely used in contraceptives and hormone replacement therapies. The use of selected species of microalgae has been studied and applied in effluent treatment as a potentially effective method for the removal or biodegradation of target contaminants such as hormones. Thus, the present study aimed to evaluate the removal capacity of the microalga Chlorella vulgaris, immobilized in sodium alginate capsules, for the synthetic female hormone 17α-ethinylestradiol (EE2). Initially, the microalga was encapsulated with sodium alginate to assess the ability of the microalga to remain viable and be slowly released into the liquid medium after the encapsulation process. After the encapsulation process, the growth of microalgal cells was monitored over 4 months through cell counting in a Neubauer chamber, and an increase in the number of cells was observed, indicating that the microalga remained viable. In the second stage, a bioassay was conducted, where the encapsulated microalgae were exposed to 50 μg/L of EE2 in mineral water for 96 hours. Parallel control bioassays were conducted with free microalgae in mineral water and with EE2 alone in mineral water. The bioassay was monitored using cell count and EE2 concentration measured by liquid chromatography. Following the results, an ANOVA statistical analysis was conducted with a double replication factor. It was observed that free algae exhibited better performance in terms of reductions during the analyzed periods, achieving a final reduction of 75%. Meanwhile, algae encapsulated in sodium alginate showed a 49% reduction in EE2 concentration after 96 hours of experimentation. Samples of sodium alginate capsules and water (control) also demonstrated hormone removal efficiency. These findings suggest that the encapsulation methodology of this microalgae may be viable for the removal of micropollutants, particularly the hormone EE2.