As an extensively detected pollutant in wastewater, microplastics (MPs) can produce abundant dissolved organic matter (DOM) in wastewater treatment, especially in ultraviolet (UV) disinfection, which may further affect the fate of antibiotics. This study collected the DOM from photoaging of polystyrene, polypropylene and polyethylene terephthalate (MP-DOM), and investigated the effects and mechanisms of MP-DOM on the photodegradation of sulfamethazine (SMT) during UV disinfection. Results showed that three MP-DOM all accelerated photodegradation of SMT, with degradation rates from 0.0057 min⁻¹ in single system to 0.0077–0.0090 min⁻¹ in combined systems. The critical effects were mainly related to the photosensitization of quinone and aromatic structures in MP-DOM, which absorbed UV energy to generate abundant reactive oxygen species (ROS). •OH and ¹O₂ were the key species to enhance photodegradation of SMT, but different producing abilities of ROS by various MP-DOM mainly depended on the components of DOM. Besides, the photodegradation of SMT was enhanced by MP-DOM more significantly in real wastewater due to the synergistic effect of wastewater components and MP-DOM. This study firstly revealed the important role of MP- DOM in the degradation of antibiotics, which will deepen our understanding of the environmental behavior of MPs with the associated products more holistically.

作为废水中广泛检测到的污染物，微塑料 (MPs) 在废水处理中会产生大量溶解性有机物 (DOM)，尤其是在紫外线 (UV) 消毒中，这可能会进一步影响抗生素的命运。本研究收集了聚苯乙烯、聚丙烯和聚对苯二甲酸乙二醇酯 (MP-DOM) 光老化产生的 DOM，并研究了 MP-DOM 在紫外线消毒过程中对磺胺二甲嘧啶 (SMT) 光降解的影响和机制。结果表明，三种MP-DOM均加速了SMT的光降解，降解速率从单一体系的0.0057 min ^-1到0.0077-0.0090 min ^-1在组合系统中。关键效应主要与 MP-DOM 中的醌和芳香结构的光敏化有关，它吸收紫外线能量产生丰富的活性氧 (ROS)。•OH和¹ O ₂是增强SMT光降解的关键物种，但不同MP-DOM产生ROS的能力不同主要取决于DOM的组成。此外，由于废水组分和 MP-DOM 的协同作用，MP-DOM 在实际废水中更显着地增强了 SMT 的光降解。本研究首次揭示了 MP-DOM 在抗生素降解中的重要作用，这将加深我们对 MPs 及其相关产物的环境行为的更全面的理解。