State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, China.
School of Energy and Environment, Southeast University, Nanjing 210096, China.
Water Res. 2023 Sep 1;243:120284. doi: 10.1016/j.watres.2023.120284. Epub 2023 Jun 29.
Ultraviolet light-emitting diode (UV-LED) is a promising option for the traditional low-pressure UV lamp, but the evolutions of DOM composition, the formation of disinfection by-products (DBPs) and their toxicity need further study in raw water during UV-LED/chlorine process. In UV-LED (275 nm)/chlorine process, two-dimensional correlation spectroscopy (2DCOS) analysis on synchronous fluorescence and UV-vis spectra indicated the protein-like fractions responded faster than the humic-like components, the reactive sequence of peaks for DOM followed the order: 340 nm→240 nm→410 nm→205 nm→290 nm. Compared to chlorination for 30 mins, the UV-LED/chlorine process enhanced the degradation efficiency of three fluorescent components (humic-like, tryptophan-like, tyrosine-like) by 5.1%-46.1%, and the formation of carbonaceous DBPs (C-DBPs) significantly reduced by 43.8% while the formation of nitrogenous DBPs (N-DBPs) increased by 27.3%. The concentrations of C-DBPs increased by 17.8% whereas that of N-DBPs reduced by 30.4% in 24 h post-chlorination. The concentrations of brominated DBPs increased by 17.2% during UV-LED/chlorine process, and further increased by 18.5% in 24 h post-chlorination. According to the results of principal component analysis, the non-fluorescent components of DOM might be important precursors in the formation of haloketones, haloacetonitriles and halonitromethanes during UV-LED/chlorine process. Unlike chlorine treatment, the reaction of DOM in UV-LED/chlorine treatment generated fewer unknown DBPs. Compared with chlorination, the cytotoxicity of C-DBPs reduced but the cytotoxicity of both N-DBPs and Br-DBPs increased during UV-LED/chlorine process. Dichloroacetonitrile had the highest cytotoxicity, followed by monobromoacetic acid, bromochloroacetonitrile and trichloroacetic acid during 30 mins of UV-LED/chlorine process. Therefore, besides N-DBPs, the more toxic Br-DBPs formation in bromide-containing water is also not negligible in the practical applications of UV-LED (275 nm)/chlorine process.
紫外线发光二极管 (UV-LED) 是传统低压紫外线灯的一种很有前途的选择，但在 UV-LED/氯工艺中，需要进一步研究原水中 DOM 组成的演变、消毒副产物 (DBPs) 的形成及其毒性。在 UV-LED（275nm）/氯工艺中，同步荧光和紫外-可见光谱的二维相关光谱（2DCOS）分析表明，蛋白质样组分的反应速度快于腐殖质样组分，DOM 的反应峰顺序为：340nm→240nm→410nm→205nm→290nm。与 30 分钟氯化相比，UV-LED/氯工艺提高了三种荧光成分（腐殖质样、色氨酸样、酪氨酸样）的降解效率 5.1%-46.1%，同时显著减少了碳质 DBPs（C-DBPs）的形成，降低了 43.8%，而氮质 DBPs（N-DBPs）的形成增加了 27.3%。氯化 24 小时后，C-DBPs 的浓度增加了 17.8%，而 N-DBPs 的浓度降低了 30.4%。UV-LED/氯工艺过程中溴代 DBPs 的浓度增加了 17.2%，氯化 24 小时后进一步增加了 18.5%。根据主成分分析的结果，DOM 的非荧光成分可能是 UV-LED/氯工艺中形成卤代酮、卤代乙腈和卤代硝基甲烷的重要前体。与氯处理不同，DOM 在 UV-LED/氯处理中的反应生成的未知 DBPs 较少。与氯化相比，UV-LED/氯处理过程中 C-DBPs 的细胞毒性降低，但 N-DBPs 和 Br-DBPs 的细胞毒性增加。二氯乙腈的细胞毒性最高，其次是一溴乙酸、溴氯乙腈和三氯乙酸。因此，在含有溴化物的水的实际应用中，UV-LED（275nm）/氯工艺不仅会形成更多的 N-DBPs，而且形成的更具毒性的 Br-DBPs 也不可忽视。
