Abstract: The persistence of micropollutants (MPs) in wastewater effluents poses a major environmental challenge, demanding advanced quaternary treatment technologies. Here, we investigate strategies to enhance the simultaneous removal of mixtures of MPs in light-driven advanced oxidation processes (AOPs) through photocatalyst design, radiation source selection, and oxidant addition, aligned with the requirements of Directive (EU) 2024/3019. A TiO2/rGO composite containing 5 wt% GO is synthesised and evaluated for the first time in the FluHelik photoreactor configuration. First, UV-A, UV-C and visible light are tested to degrade venlafaxine (VLX) and diclofenac (DCF) as model MPs (750 µg L-1 each). 150 mg L-1 is the optimal TiO2/rGO dose and UV-C radiation is the most effective irradiation source. Then, the addition of oxidants - hydrogen peroxide (H2O2), hypochlorite (HOCl/OCl-) or persulphate (PS, S2O82-) (0.6 mM each) - further accelerate the reaction rates (9- and 3-fold for VLX and DCF, respectively, regardless the oxidant). Photocatalyst reusability is confirmed over four consecutive cycles. High-performance liquid chromatography is employed to monitor degradation kinetics. The strategies are then evaluated for the quaternary treatment of urban wastewater targeting six MPs (200 µg L-1 each) (atenolol, carbamazepine, diclofenac, diuron, sulfamethoxazole, and venlafaxine). UV-C/H2O2 and UV-C/PS are the best alternatives to treat urban wastewater, achieving > 80 % removal across all MPs. These results highlight the potential of photochemical technologies - applied in the FluHelik photoreactor -, as an effective and scalable solution for advanced wastewater treatment. They also underscore the relevance of integrating complementary technologies to ensure compliance with environmental regulations.

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