State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China.
Sci Total Environ. 2023 Sep 10;890:164248. doi: 10.1016/j.scitotenv.2023.164248. Epub 2023 May 16.
The illicit connection of sewage pipes to stormwater pipes commonly occurs in urban stormwater systems. This brings problems that sewage might be directly discharges into natural water and even drinking water sources without treatment, posing risks to ecological safety. Sewage contains various unknown dissolved organic matter (DOM), which could react with disinfectants and lead to the formation of carcinogenic disinfection byproducts (DBPs). Thus, understanding the impacts of illicit connections on downstream water quality is of significance. This study firstly investigated the characteristics of DOM using fluorescence spectroscopy and the formation of DBPs after chlorination in an urban stormwater drainage system in the case of illicit connections. The results found that the concentrations of dissolved organic carbon and dissolved organic nitrogen ranged from 2.6 to 14.9 mg/L and from 1.8 to 12.6 mg/L, respectively, with the highest levels occurring at the illicit connection points. Concerning DBP precursors, pipe illicit connections introduced considerable precursors of highly toxic haloacetaldehydes and haloacetonitriles into the stormwater pipes. Furthermore, illicit connections introduced more contents of tyrosine-like and tryptophan-like aromatic proteins, which may be related to foods, nutrients, personal care products, etc. in the untreated sewage. This indicated that the urban stormwater drainage system was a significant input source of DOM and DBP precursors to natural water. The results of this study are of great significance for protecting the security of water sources and promoting the sustainability of urban water environment.
污水管与雨水管的非法连接在城市雨水系统中很常见。这带来了污水未经处理直接排入自然水甚至饮用水源的问题，对生态安全构成了威胁。污水中含有各种未知的溶解有机物质（DOM），可能与消毒剂发生反应，导致致癌性消毒副产物（DBP）的形成。因此，了解非法连接对下游水质的影响具有重要意义。本研究首先使用荧光光谱法调查了 DOM 的特征以及在存在非法连接的情况下城市雨水排水系统中氯化后 DBPs 的形成。结果发现，溶解有机碳和溶解有机氮的浓度分别为 2.6 至 14.9 mg/L 和 1.8 至 12.6 mg/L，在非法连接点处浓度最高。关于 DBP 前体，管道非法连接将大量高毒性卤代乙醛酸和卤代乙腈前体引入雨水管道。此外，非法连接引入了更多的酪氨酸样和色氨酸样芳香族蛋白质含量，这可能与未经处理的污水中的食物、营养物质、个人护理产品等有关。这表明城市雨水排水系统是 DOM 和 DBP 前体向自然水的重要输入源。本研究结果对保护水源安全和促进城市水环境可持续性具有重要意义。
