ADVANCED OXIDATION PROCESSES IN MICROREACTORS FOR HOSPITAL WASTEWATER TREATMENT

Microreactors have emerged as effective platforms for photocatalytic advanced oxidation processes targeting the removal of persistent emerging contaminants, such as steroid hormones, from hospital wastewater. Steroidal endocrine-disrupting compounds, particularly estrogens and progestins, are commonly present in hospital effluents and are known for their resistance to conventional treatment technologies. Photocatalytic systems based on microreactors offer several advantages over traditional batch photoreactors, including higher surface-area-to-volume ratios, enhanced mass transfer, and reduced diffusion limitations. The continuous microflow facilitates uniform photon distribution and accelerates reaction kinetics. By enabling efficient fluid transport under laminar flow through microchannels, microreactor technology significantly mitigates the mass transfer constraints often associated with catalyst immobilization, owing to the shortened diffusion path from the aqueous phase to the photocatalyst surface. In this study, the degradation efficiency of two representative steroidal hormones, norethindrone and oestrogen, was evaluated using a continuous-flow microreactor system with TiO₂ immobilized and irradiated by UVA-LED light. The key optimized process variables were pH, temperature, hydrogen peroxide concentration, and volumetric flow rate. The reaction system was equipped with piston-driven injection pumps, a Peltier thermal control module, pressure regulation, and online monitoring 1H NMR.

Photocatalytic degradation efficiency was assessed through spectral analysis using 1H NMR, IR, and UV–Vis spectroscopy. The optimal operational conditions for norethindrone degradation (79.3%) were pH 10, 20 °C, 10 mL/min, and 2 ppm H₂O₂. Under the same conditions, oestrogen degradation reached 68%. These results highlight the potential of integrating microreactor-based photocatalysis into hospital wastewater treatment frameworks as a sustainable and efficient solution to eliminate recalcitrant endocrine-disrupting contaminants, thereby contributing to improved environmental and public health protection.