State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, Jiangsu, China.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, Jiangsu, China.
Environ Pollut. 2020 Oct;265(Pt B):114959. doi: 10.1016/j.envpol.2020.114959. Epub 2020 Jun 8.
This study investigated the seasonal characterization of dissolved organic matter (DOM) in reclaimed wastewater (RW) with a special focus on dissolved organic nitrogen (DON) from two full-scale municipal wastewater reclamation plants (WRPs) where the produced RW was used to augment urban rivers. Results showed that the concentrations of DON in RW ranged from 0.32 mg/L to 1.21 mg/L. A higher seasonal mean value of DON in RW from both of the WRPs was observed in winter (p < 0.05, ANOVA). DON chemical characteristics analysis, including ultrahigh-resolution mass spectrometry and ultrafiltration fractionation, showed that DON in RW exhibits more lability during winter than during the other three seasons. This finding was also supported by the results of an algal bioassay experiment, in which DON bioavailabilities were 63.7 ± 3.0%, 53.0 ± 5.3%, 49.5 ± 0.5%, and 49.8 ± 0.2% for WRP-A and were 60.8 ± 2.4%, 43.7 ± 2.2%, 41.2 ± 1.7%, and 43.1 ± 1.1% for WRP-B in winter, spring, summer, and autumn, respectively. Accordingly, DON in RW during winter is more prone to stimulate natural algae and microorganisms, which gives rise to eutrophication in urban rivers. At the molecular level, the seasonal changes in DON are not coupled with those of DOC, which highlights the necessity of DON measurement to obtain a comprehensive understanding of the seasonal characteristics of DOM in RW and its effect on wastewater reuse in urban rivers.
本研究重点探讨了再生废水中溶解有机氮（DON）的季节性特征，所用样本取自两座采用全规模城市污水再生工艺的再生水厂。这两座再生水厂所产再生水均被用于补充城市河流的水量。结果表明，再生水中 DON 的浓度范围为 0.32-1.21mg/L。对两座再生水厂的 DON 季节性均值进行分析，发现无论在哪一座再生水厂，冬季的 DON 浓度均显著高于其他三个季节（p<0.05，ANOVA）。利用超高分辨率质谱和超滤分级等技术对 DON 化学特征进行分析，发现冬季 DON 的可生化性更强。藻类生物测定实验也证实了这一结论，在冬季，A 厂和 B 厂的 DON 生物可利用率分别为 63.7±3.0%、53.0±5.3%、49.5±0.5%和 49.8±0.2%，而在春、夏、秋三季，这一数值分别为 60.8±2.4%、43.7±2.2%、41.2±1.7%和 43.1±1.1%。由此可见，冬季再生水中的 DON 更容易刺激自然藻类和微生物，进而导致城市河流富营养化。从分子水平来看，DON 的季节性变化与 DOC 并无关联，这表明有必要对 DON 进行测量，以便更全面地了解再生水中 DOM 的季节性特征及其对城市河流污水回用的影响。
