Removal of Aqueous 17α-Ethinylestradiol by Rhodococcus Species

Pharmaceutical substances such as 17α-ethinylestradiol (EE2), the active component of the contraceptive pill, are often not eliminated during wastewater treatment and are persistent in the environment. Using solid-phase extraction and chromatography methods for analyzing low concentrations of EE2 and metabolites, biodegradability of EE2 was studied using four bacteria grown under aerobic conditions in the absence or presence of a readily available carbon source (2.5 g/L of adipic acid or glucose). Preliminary identification of produced metabolites was also completed. In presence of a cosubstrate, Rhodococcus erythropolis removed EE2 up to 47% of its initial concentration (1.4 and 0.5 mg/L) in 13 h, while it removed only 10% after 75 h without a cosubstrate. In the presence of a cosubstrate, Rhodococcus equi removed EE2 up to 39% of its initial concentration (1.4 mg/L) after 65 h, whereas no significant EE2 removal was observed using Rhodococcus rhodochrous and Rhodococcus zopfii. Preliminary analysis of EE2 transformation products confirmed the presence of phenol and a compound of high molecular weight (331 amu). These results improve our understanding of the effect of common biological wastewater treatment variables such as bacteria strains, acclimation, and presence of cosubstrate, on the removal of EE2.