UV Aging Enhances the Formation of Disinfection Byproducts from Tire Wear Particles upon Chlorination

The globally ubiquitous occurrence of tire wear particles (TWPs), formed from friction between tires and road surfaces, is a growing environmental concern. After release, they are exposed to environmental aging such as ultraviolet (UV) radiation and are transported to surface water and wastewater via runoff, raising significant water quality issues, particularly during chlorination treatment. This work investigated the impact of UV aging on the formation of disinfection byproducts (DBPs) from TWPs upon water chlorination. Results demonstrate that UV aging increased total DBP formation by 1.5–2.0 times and markedly altered tire leachate composition. Fluorescence excitation-emission matrix parallel factor analysis revealed a 2–3-fold increase in humic-like, fulvic-like, and protein II-like components, alongside a 3.5-fold increase in electron-donating capacity, indicating oxidative polymer breakdown. Concurrently, a decrease in protein I-like material suggested its degradation or transformation. Crucially, UV aging generated over twice the number of distinct chlorinated byproducts. Notably, the profile shifted from predominantly aliphatic compounds in pristine conditions to include more halogenated aromatic species after UV aging. These findings demonstrate that environmental UV aging enhances the yield and alters the speciation of TWP-derived DBPs, promoting the formation of more diverse and potentially more toxic halogenated compounds.