Photocatalytic removal of 17α-ethinylestradiol (EE2) and levonorgestrel (LNG) from contraceptive pill manufacturing plant wastewater under UVC radiation

Abstract

Photolytic and photocatalytic removals of 17α-ethinylestradiol (EE2) and levonorgestrel (LNG) in pharmaceutical wastewater were investigated under UVC radiation. Wastewater collected from WYETH, St-Laurent, Canada contained high concentrations of EE2 and LNG in suspension and coloring agent tartrazine in solution. Aqueous phase removals of EE2 and LNG were studied as individual contaminants in water and in complex matrices including: co-contaminants in water, in simulated synthetic wastewater and in the wastewater. After 30min of UVC photocatalysis of the individual contaminants, removal efficiencies of EE2 and LNG were 92% and 97%, respectively, while higher photolytic removal was observed for LNG (94%) compared to EE2 (60%). Hydroxyl radicals were shown to contribute significantly to the removal of both compounds in water. In contrast to EE2, photolytic removal of LNG was higher than its photocatalytic removal efficiencies in all complex matrices. Higher photolytic removal of LNG was attributed to the fact that it absorbs UVC radiation considerably more than EE2. Lower photocatalytic removals of LNG in complex matrices compared to its photocatalytic removal as an individual contaminant was due to the presence of EE2 at concentrations up to five times larger than LNG in water, thus leading to increased competition for hydroxyl radicals and retarding LNG removal. In the wastewater matrix photocatalytic removals for EE2 and LNG were similar at 48%, whereas the photolytic removal of LNG (76%) was higher than EE2 (29%). The applicability of UVC processes for reduction of hormone content in similar wastewaters was demonstrated.