State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
Environ Sci Technol. 2012 Jul 3;46(13):7182-8. doi: 10.1021/es300777b. Epub 2012 Jun 22.
Recently, the potential health and environmental risks of silica nanoparticles (SiO(2) NPs) are attracting great interest. However, little is known about their possible impacts on wastewater biological nitrogen and phosphorus removal. In this study, the acute and chronic effects of SiO(2) NPs on activated sludge viability and biological nutrient removal performance were investigated. It was found that the presence of environmentally relevant concentration (1 mg/L) of SiO(2) NPs caused no adverse acute and chronic effects on sludge viability and wastewater nitrogen and phosphorus removal. However, chronic exposure to 50 mg/L SiO(2) NPs induced the increase of effluent nitrate concentration, and thus depressed the total nitrogen (TN) removal efficiency from 79.6% to 51.6% after 70 days of exposure, which was due to the declined activities of denitrifying enzymes, nitrate reductase and nitrite reductase. Wastewater phosphorus removal was insensitive to 1 and 50 mg/L SiO(2) NPs after either the acute or chronic exposure, because the critical factors closely related to biological phosphorus removal were not significantly changed, such as the activities of exopolyphosphatase and polyphosphate kinase and the intracellular transformations of polyhydroxyalkanoates and glycogen. Denaturing gradient gel electrophoresis (DGGE) analysis revealed that the bacterial community structure was changed after long-term exposure to 50 mg/L SiO(2) NPs, and the quantitative PCR assays indicated that the abundance of denitrifying bacteria was decreased, which was consistent with the declined wastewater nitrogen removal.
最近，二氧化硅纳米颗粒（SiO2NPs）的潜在健康和环境风险引起了极大的关注。然而，对于它们对废水生物脱氮除磷的可能影响知之甚少。在这项研究中，研究了 SiO2NPs 对活性污泥生物活性和生物养分去除性能的急性和慢性影响。结果发现，在环境相关浓度（1mg/L）的 SiO2NPs 存在下，对污泥生物活性和废水氮磷去除没有不利的急性和慢性影响。然而，慢性暴露于 50mg/L SiO2NPs 会导致出水中硝酸盐浓度增加，从而使总氮（TN）去除效率从暴露 70 天后的 79.6%下降到 51.6%，这是由于反硝化酶、硝酸还原酶和亚硝酸还原酶活性下降所致。在急性或慢性暴露后，废水除磷对 1 和 50mg/L SiO2NPs 均不敏感，因为与生物除磷密切相关的关键因素没有明显变化，如外多磷酸盐酶和聚磷酸盐激酶的活性以及多羟基烷酸酯和糖原的细胞内转化。变性梯度凝胶电泳（DGGE）分析表明，长期暴露于 50mg/L SiO2NPs 后细菌群落结构发生了变化，定量 PCR 检测表明反硝化细菌的丰度降低，这与废水脱氮能力下降一致。
