Effective control disinfection byproducts in municipal wastewater by UV-based advanced oxidation/reduction pre-treatments: Insights from FT-ICR-MS analysis

Disinfection byproducts (DBPs) inevitably form during municipal wastewater disinfection, posing potential threats to human and ecological health. While UV-based advanced oxidation/reduction processes (UV-AOPs/ARPs) show promise in eliminating DBP precursors, their efficacy and mechanisms for controlling both known and unknown DBPs remain unclear. This study systemically investigated dissolved organic matter (DOM) transformation and DBP mitigation during pre-treatments of actual municipal wastewater using UV, UV/Peroxydisulfate (UV/PS), UV/H 2 O 2 , and UV/Sulfite. Combining spectroscopy, chromatography, and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) analyses, the results demonstrated that UV/PS and UV/H 2 O 2 were more effective than UV/Sulfite at degrading aromatic and fluorescent compounds. All pre-treatments significantly reduced total organic chlorine and known DBPs versus direct chlorination, with UV/Sulfite achieving the highest reduction (80.42% and 60.98%). Unknown DBP molecules decreased by 31.54–53.04% (UV < UV/Sulfite < UV/PS < UV/H 2 O 2 ). Specifically, UV/PS and UV/H 2 O 2 preferentially controlled CHOSCl and CHONCl compounds, and 1Cl-DBPs, whereas UV/Sulfite excelled at reducing multi-chlorinated DBPs. Additionally, all pre-treatments reduced the calculated cytotoxicity of known DBPs by 49.89–81.25%, most notably for UV/Sulfite. These findings demonstrate the effectiveness of UV-AOPs/ARPs for comprehensive DBP control and provide practical guidance for selecting an optimal pre-treatment strategy based on target DBP profiles in wastewater applications.