Shen Liang, Chen Wenqi, He Jinyu, Luo Xueru, Mei Yang, Zhang Baoping
Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, the Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen 361005, China.
Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, the Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen 361005, China.
J Hazard Mater. 2025 Mar 15;486:136925. doi: 10.1016/j.jhazmat.2024.136925. Epub 2024 Dec 20.
Managing undesirable biofilms is a persistent challenge in water treatment and distribution systems. Although ultraviolet-light emitting diode (UV-LED) irradiation, an emerging disinfection method with the chemical-free and emission-adjustable merits, has been widely reported effective to inactivate planktonic bacteria, few studies have examined its effects on biofilms. This study aims to fill this gap by exploring the performance and mechanism of UV-LEDs on the prefabricated Escherichia coli (E. coli) biofilms under varying irradiation conditions. The results showed that the wavelength of 275 nm exhibited the best inactivation effect on the biofilm-bound E.coli compared to 268, 312 and 370 nm, achieving 3.2 log inactivation at a fluence of 346.5 mJ/cm and an irradiance of 660 μW/cm. Furthermore, irradiance and irradiation time are proposed for the first time to be a pair of conjugate variables correlated to log inactivation, as a modification of the Bunsen-Roscoe reciprocity law. Additionally, the effect of UV irradiation on extracellular polymeric substances (EPS) in terms of the structure and chemical properties was investigated. The findings support that the oxidative degradation of the polysaccharides and proteins in EPS matrix should be the primary reason for destroying the biofilm framework. Finally, additional hydraulic shear was applied on the irradiated biofilms, suggesting an effective approach for enhancing biofilm removal.
在水处理和配水系统中，控制有害生物膜一直是一项长期挑战。尽管发光二极管（UV-LED）辐照作为一种新兴的消毒方法，具有无化学残留和可调节发射的优点，已被广泛报道对浮游细菌有灭活效果，但很少有研究考察其对生物膜的影响。本研究旨在通过探索不同辐照条件下UV-LED对预制大肠杆菌（E. coli）生物膜的性能和作用机制来填补这一空白。结果表明，与268、312和370 nm相比，275 nm波长对生物膜结合的大肠杆菌表现出最佳的灭活效果，在通量为346.5 mJ/cm²和辐照度为660 μW/cm²时实现了3.2个对数级的灭活。此外，首次提出辐照度和辐照时间是与对数灭活相关的一对共轭变量，作为对本生-罗斯科互易定律的修正。此外，还研究了紫外线辐照对胞外聚合物（EPS）的结构和化学性质的影响。研究结果表明，EPS基质中多糖和蛋白质的氧化降解应该是破坏生物膜框架的主要原因。最后，对辐照后的生物膜施加额外的水力剪切，这表明这是一种增强生物膜去除的有效方法。
