Optimizing UV-based advanced oxidation processes for effective TOC removal in wastewater

The growing water demand requires advanced treatment technologies to efficiently remove recalcitrant organic compounds from wastewater for its reuse. This study evaluated and compared the performance of various advanced oxidation processes (AOPs) for total organic carbon (TOC) removal, focusing on UV-based systems. Among the tested methods, UV/PS and UV/TiO2/Persulfate (PS) achieved the highest TOC removal efficiencies of 89.1% and 92.6%, respectively, under optimized conditions. The UV/TiO2/PS process, which combines persulfate activation with TiO2 photocatalysis, demonstrated superior performance under conditions 1 g/L persulfate, 1 g/L TiO2, and 39 W UV output, making it a promising option for wastewater reuse. Non-UV-based AOPs, including US/H2O2 and US/PS, also exhibited high TOC removal efficiencies (87.8% and 81.9%, respectively) due to ultrasonic cavitation. However, their high energy intensity requirements challenges for process scalability. O3/H2O2 achieved moderate efficiency (70.5%), while Fenton-based processes (Fenton and Ultrasound (US)/Fenton) showed lower efficiencies (59.5% and 71.6%) due to their sensitivity to pH conditions. Overall, UV-based systems outperformed others in efficiency and adaptability, with UV/TiO2/PS identified as the most effective for treating recalcitrant pollutants. In the UV/PS and UV/TiO2/PS systems, sulfate ion generation confirmed effective persulfate activation, resulting in sulfate radical formation. Compared to Fenton-based processes, which generate substantial sludge, these systems represent an environmentally favorable alternative.