Department of Biological Science and Technology, Nanjing University, Nanjing, 210093, PR China.
Department of Biological Science and Technology, Nanjing University, Nanjing, 210093, PR China.
J Environ Manage. 2023 Jan 1;325(Pt A):116398. doi: 10.1016/j.jenvman.2022.116398. Epub 2022 Oct 13.
Wastewater treatment plant (WWTP) effluent is discharged into rivers as supplemental water, which may result in ecological risk. This study compares the element composition and microbial community of WWTP effluent and natural surface water (NSW) and reveals the potential ecological risk of WWTP effluent discharge. Twenty recently upgraded WWTPs and three relatively large reservoirs in Zhengzhou city, China, were selected. The contents of N, P, S, K, Ca, Mg, B, Si, Na, Fe, Mn, Co, Ni and Sn were significantly higher in WWTP effluent than in NSW, while those of Mo, V, Pb and Cd were significantly lower. There was no significant difference between WWTP effluent and NSW in terms of the element imbalance index (IMI) (representing the extent of imbalance of element proportions) relative to the class IV surface water quality standard (the control standard for most Chinese rivers). The macronutrient IMI relative to the Hoagland formula was significantly lower in WWTP effluent than in NSW, and WWTP effluent discharge could significantly lower this index in NSW; this may be an important cause of primary productivity explosion. The microbial diversity was significantly higher in WWTP effluent than in NSW. The predicted relative abundances of mobile genetic elements and oxidative-stress-tolerant phenotypes were significantly higher in WWTP effluent than in NSW, whereas the abundance of gram-negative phenotypes was significantly lower, and that of potential pathogenic phenotypes was slightly lower. The effluent from upgraded WWTPs exhibited a low risk of pathogen diffusion but a high risk of antibiotic resistance gene diffusion. The element composition and microbial community should be considered when evaluating the ecological risk of WWTP effluent discharge.
污水处理厂（WWTP）的出水作为补充水排入河流，可能会带来生态风险。本研究比较了 WWTP 出水和天然地表水（NSW）的元素组成和微生物群落，揭示了 WWTP 出水排放的潜在生态风险。本研究选取了中国郑州市 20 座近期升级的 WWTP 和 3 座较大的水库。WWTP 出水中的 N、P、S、K、Ca、Mg、B、Si、Na、Fe、Mn、Co、Ni 和 Sn 的含量明显高于 NSW，而 Mo、V、Pb 和 Cd 的含量明显低于 NSW。与 IV 类地表水质量标准（中国大多数河流的控制标准）相比，WWTP 出水与 NSW 之间的元素不平衡指数（IMI）（代表元素比例失衡的程度）没有显著差异。与 Hoagland 配方相比，WWTP 出水中的大量营养元素 IMI 明显低于 NSW，WWTP 出水排放可显著降低 NSW 中的这一指数；这可能是初级生产力爆炸的一个重要原因。WWTP 出水中的微生物多样性明显高于 NSW。WWTP 出水中可移动遗传元素和耐氧化应激表型的预测相对丰度明显高于 NSW，而革兰氏阴性表型的丰度明显较低，潜在病原表型的丰度略低。经升级的 WWTP 出水扩散病原体的风险较低，但扩散抗生素耐药基因的风险较高。在评估 WWTP 出水排放的生态风险时，应考虑元素组成和微生物群落。
