Guangdong Key Laboratory of Soil and Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
Guangdong Key Laboratory of Soil and Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; School of Urban Planning and Design, Peking University, Shenzhen, Guangdong 518055, China.
Ecotoxicol Environ Saf. 2023 Oct 15;265:115515. doi: 10.1016/j.ecoenv.2023.115515. Epub 2023 Sep 28.
Sunlight exposure can degrade and transform discharged wastewater effluent organic matter (EfOM) in aquatic systems, potentially enhancing the feasibility of reusing wastewater for drinking purposes. However, there remains a lack of comprehensive understanding regarding the sunlight-induced changes in the molecular-level composition, characteristics, and chlorine reactivity of EfOM. Herein, we investigated the impact of sunlight on the optical properties, chemical composition, and formation of disinfection byproducts of EfOM using multiple spectroscopic analyses, high-resolution mass spectrometry, chlorination experiments, and in vitro bioassays. Upon natural sunlight exposure, we observed significant decreases in ultraviolet-visible absorbance and fluorescence intensity of EfOM, indicating the destruction of chromophores and fluorophores. Photolysis generally yields products with lower molecular weight and aromaticity, and with higher saturation and oxidation levels. Moreover, a shift within the EfOM from condensed aromatic-like compounds to tannin-like components was observed. Furthermore, sunlight exposure reduced the reactivity of EfOM toward the formation of trihalomethanes and haloacetonitriles during chlorination, while there was a slight increase in the specific formation potential of haloketones. Importantly, the disinfection byproducts resulting from chlorination of the irradiated EfOM exhibited reduced microtoxicity. Overall, this study provides new insights into alterations in EfOM under sunlight exposure and aids in predicting the health risks of effluent discharge in water environments.
阳光照射会降解和转化水生系统中排放的废水有机物（EfOM），从而提高废水再用于饮用水的可行性。然而，对于 EfOM 的分子水平组成、特性和氯反应性在阳光照射下的变化，我们仍缺乏全面的了解。在此，我们使用多种光谱分析、高分辨率质谱、氯化实验和体外生物测定，研究了阳光对 EfOM 的光学性质、化学成分和消毒副产物形成的影响。在自然阳光照射下，我们观察到 EfOM 的紫外-可见吸光度和荧光强度显著降低，表明发色团和荧光团被破坏。光解通常会产生分子量和芳香度较低、饱和度和氧化程度较高的产物。此外，EfOM 中的成分从凝聚的类芳香化合物向丹宁类化合物转移。此外，阳光照射会降低 EfOM 在氯化过程中形成三卤甲烷和卤代乙腈的反应性，而卤代酮的特定形成潜能略有增加。重要的是，经辐照 EfOM 氯化生成的消毒副产物的微毒性降低。总的来说，这项研究深入了解了 EfOM 在阳光照射下的变化，有助于预测水环境中污水排放的健康风险。
