A successful attempt to degrade synthetic estrogen 17α-ethynylestradiol (EE2) is demonstrated via combining photocatalysis employing magnesium peroxide (MgO₂)/low-pressure ultraviolet (LP-UV) treatment followed by biological treatment using small bioreactor platform (SBP) capsules. Reusable MgO₂ was synthesized through wet chemical synthesis and extensively characterized by X-ray diffraction (XRD) for phase confirmation, X-ray photoelectron spectroscopy (XPS) for elemental composition, Brunauer-Emmett-Teller (BET) to explain a specific surface area, scanning electron microscopy (SEM) imaging surface morphology, and UV-visible (Vis) spectrophotometry. The degradation mechanism of EE2 by MgO₂/LP-UV consisted of LP-UV photolysis of H₂O₂ in situ (produced by the catalyst under ambient conditions) to generate hydroxyl radicals, and the degradation extent depended on both MgO₂ and UV dose. Moreover, the catalyst was successfully reusable for the removal of EE2. Photocatalytic treatment by MgO₂ alone required 60 min (~1700 mJ/cm²) to remove 99% of the EE2, whereas biodegradation by SBP capsules alone required 24 h to remove 86% of the EE2, and complete removal was not reached. The sequential treatment of photocatalysis and SBP biodegradation to achieve complete removal required only 25 min of UV (~700 mJ/cm²) and 4 h of biodegradation (instead of >24 h). The combination of UV photocatalysis and biodegradation produced a greater level of EE2 degradation at a lower LP-UV dose and at less biodegradation time than either treatment used separately, proving that synergetic photocatalysis and biodegradation are effective treatments for degrading EE2.

Metal hydroxides, owing to their catalytic active sites for the decomposition of O₃ to Reactive Oxygen Species (ROS), have been adapted for catalytic ozonation of micropollutants in wastewater. In this study, commercial Mg (OH)₂ was used for the degradation of cyclophosphamide (CYP) by ozone. The crystal phase was confirmed by X-ray powder Diffraction (XRD). Percent degradation of 10 ppm CYP after 30 min by O₃ and Mg (OH)₂/O₃ was 56 and 93, respectively, suggesting enhanced decomposition of O₃ to ROS by the catalyst. The presence of ROS was further confirmed using pCBA as a probe, which showed that the concentration of ROS was eight times higher in the presence of Mg (OH)₂/O₃ than O₃ alone. Catalytic ozonation experiments in the presence of scavengers showed that OH· radicals play a significant role in the degradation of CYP. The catalyst was found to be reusable for at least three cycles without significant loss in degradation efficiency. To study the compatibility of Mg (OH)₂ for wastewater treatment applications, synthetic effluent was spiked with CYP and subjected to ozonation by Mg(OH)₂/O₃. The TOC of CYP before and after the treatment showed that Mg (OH)₂/O₃ not only degrades CYP but also mineralizes to a certain extent unlike O₃ alone.