Removal efficiencies of natural and synthetic progesterones in hospital wastewater treated by different disinfection processes

Progesterones are ubiquitous in hospital wastewater (HWW) with concentrations much higher than those of estrogens and androgens. To ensure that these water systems are safe to use, disinfection is crucial during HWW treatment by providing “front line” defense against biological contaminations. Here, five disinfection processes, namely, chlorine (Cl 2 ), chlorine dioxide (ClO 2 ), ozone (O 3 ), ultraviolet (UV)), and UV/chlorine (UV/Cl 2 ), were selected to investigate their removal efficiencies for progesterones in primary filtration and secondary biological treatment effluents. There were 61 natural and synthetic progesterones detected in HWW, with the natural progesterones being the main components with a concentration of 845.51 ng/L and contributing to 75.08% of the total progesterones. The primary filtration treatment presented insignificant removal effects on the progesterones, while the secondary biological treatment significantly reduced the progesterone content by biodegradation. The order of removal efficiencies of total progesterones by different disinfection processes was UV/Cl 2 > Cl 2 > O 3 > ClO 2 > UV. UV/Cl 2 showed the highest removal efficiency against progesterones mainly due to the activation of Cl 2 by ultraviolet (UV) photolysis, which helps open the heterocyclic, aromatic, and phenolic rings, thus accelerating progesterone degradation. In addition, the removal efficiencies of natural progesterones in the five disinfection processes were higher than those of synthetic progesterones (progesterone derivatives, 19-nortestosterone derivatives, and 17α-hydroxyprogesterone derivatives).