Natural and synthetic hormone removal using the horseradish peroxidase enzyme: Temperature and pH effects

The primary objective of our research was to establish the technical feasibility of using the horseradish peroxidase (HRP) enzyme for natural and synthetic estrogens–estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethinylestradiol (EE2)–removal. The effects of temperature and pH on enzymatic treatment kinetics were investigated. Residual estrogen concentrations were quantified by liquid chromatography, coupled with mass spectrometry analysis. In a synthetic solution at pH 7 and 25±1 °C, the HRP enzyme-catalyzed process was capable of achieving 92–100% removal of E1, E2, E3, and EE2 within 1 h of treatment with an HRP activity of 0.017 U/ml. The influence of the pH (5–9) and temperature (5–35 °C) on estrogen removal was observed to be significant, with the optimum pH near neutral conditions. The results also showed that wastewater constituents significantly impact the HRP-catalyzed estrogen removal. The experimental research proved that the HRP-catalyzed system is technically feasible for the removal of the main estrogens present in the environment at low concentrations.