Jeong Emma, Im Wan-Tack, Kim Dong-Hoon, Kim Mi-Sun, Kang Seoktae, Shin Hang-Sik, Chae So-Ryong
a Center for Water Resource Cycle Research, Korea Institute of Science and Technology (KIST) , Seongbuk-gu , Seoul , Republic of Korea.
J Environ Sci Health A Tox Hazard Subst Environ Eng. 2014;49(6):685-93. doi: 10.1080/10934529.2014.865454.
The release of silver (Ag) nanoparticles (NPs) into sewage streams has heightened concerns about potential adverse impacts on wastewater treatment processes. Here, we show that the rate constants of both biological nitrification and organic oxidation decreased exponentially with an increase in the Ag NP concentration, but nitrification was more severely inhibited than the organic oxidation even at low Ag NP concentrations (<1 mg Ag L(-1)) in batch experiments. The long-term exposure effects of Ag NPs on activated sludge bacteria were evaluated in sequencing batch reactors (SBRs) fed with two different substrates favoring heterotrophic and autotrophic bacteria. From a continuous operation for 50 days, it was found that heterotrophic bacteria in the organic removal process have higher tolerance to Ag NPs than do nitrifying bacteria. The effects of Ag NPs on the microbial community in both SBRs were analyzed using 16S ribosomal ribonucleic acid (rRNA) gene sequences obtained from pyrosequencing. The results showed that the level of microbial susceptibility is different for each type of microorganism and that the microbial diversity decreased dramatically after continuous exposure to Ag NPs for 50 days, resulting in a decrease of wastewater treatment efficiency.
银（Ag）纳米颗粒（NPs）排放到污水流中引发了人们对其可能对废水处理过程产生不利影响的担忧。在此，我们表明，在分批实验中，生物硝化和有机氧化的速率常数均随Ag NP浓度的增加呈指数下降，但即使在低Ag NP浓度（<1 mg Ag L⁻¹）下，硝化作用受到的抑制也比有机氧化更为严重。在配备了两种分别有利于异养细菌和自养细菌的不同底物的序批式反应器（SBRs）中，评估了Ag NPs对活性污泥细菌的长期暴露影响。通过连续运行50天发现，有机去除过程中的异养细菌对Ag NPs的耐受性高于硝化细菌。使用从焦磷酸测序获得的16S核糖体核糖核酸（rRNA）基因序列分析了Ag NPs对两个SBRs中微生物群落的影响。结果表明，每种微生物的微生物敏感性水平不同，并且在连续暴露于Ag NPs 50天后，微生物多样性急剧下降，导致废水处理效率降低。
