Effects of ZnO nanoparticles on high-rate denitrifying granular sludge and the role of phosphate in toxicity attenuation. (August 2019)

• Record Type: Journal Article
• Authors: Cheng, Ya-Fei; Zhang, Zheng-Zhe; Li, Gui-Feng; Zhu, Bing-Qian; Zhang, Qian; Liu, Ying-Yi; Zhu, Wei-Qin; Fan, Nian-Si; Jin, Ren-Cun
• Is Part Of: Environmental pollution. Volume 251(2019)
• Page Start: 166
• Page End: 174
• Publication Date: 2019-08
• Subjects: Denitrifying granular sludge -- ZnO nanoparticles -- Phosphate -- High-throughput sequencing; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2019.04.138
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: The increasing release of engineered nanoparticles (NPs) from consumer products has raised great concerns about their impacts on biological wastewater treatment. In this study, the widely-used ZnO NP was selected as a model NP to investigate its impact on high-rate denitrifying granular sludge in terms of sludge properties and community structure. A hormesis effect was observed during short-term exposure, in which the specific denitrification activity (SDA) was stimulated by 10% at 1 mg L −1 ZnO NPs, but inhibited by 23% at 5.0 mg L −1 ZnO NPs. When continuously exposed to 2.5 mg L −1 ZnO NPs, the nitrogen removal capacity of the denitrification reactor was nearly deprived within 15 days, and the relative abundance of the dominant denitrifying bacterium ( Castellaniella ) was decreased from 51.0 to 8.0%. Meanwhile, the dehydrogenase activity (DHA) and the content of extracellular polymeric substance (EPS) significantly decreased to 22.3 and 61.1%, respectively. Nevertheless, the presence of phosphate substantially weakened the adverse effects of ZnO NPs on the SDA, EPS, DHA and the relative abundance of functional genes even exposed to 6.25 mg L −1 ZnO NPs, which was associated with the fact that the level of Zn(II) released from ZnO NPs was significantly reduced in the presence of phosphate. Therefore, the toxicity of ZnO NPs may be mainly attributed to the release of toxic Zn(II) and could be attenuated in the presence of phosphate. Overall, this study provided further reference and meaningful insights into the impact of engineered NPs on biological wastewater treatment. Graphical abstract: Image 1 Highlights: A hormesis effect was observed during short-term exposure. 2.5 mg L −1 ZnONPs reduced the nitrogen removal capacity by 72.5% within two weeks. 310 mg P L −1 phosphate increased the metabolic activity and abundance of denitrifying bacteria. Based on the PICRUSt, the abundance of genes related to zinc ion assimilation was decreased.