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Journal of Chemistry
Volume 2016 (2016), Article ID 8608567, 12 pages
http://dx.doi.org/10.1155/2016/8608567
Research Article

Towards a Definition of Harmless Nanoparticles from an Environmental and Safety Perspective

1School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China
2Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, China

Received 15 October 2016; Accepted 2 November 2016

Academic Editor: Henryk Kozlowski

Copyright © 2016 Xueyan Cui et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The rapid development of nanoparticles (NPs), such as silicon nanoparticles (Si NPs) and ferric oxide nanoparticles (Fe2O3 NPs), and their use in myriad commercial applications have raised questions of their potential impacts on wastewater treatment systems. In this study, we investigated the consequences of the presence of Si NPs and Fe2O3 NPs in the denitrification of anoxic sludge. Fe2O3 NPs, at a concentration up to 50 mg/L, had no significant impact on nitrate removal, whereas Si NPs, at concentrations up to 50 mg/L, increased the rate of nitrate removal. We used transmission electron microscopy (TEM) to investigate the effect of Si NPs and Fe2O3 NPs. Si NPs exposure enhanced the abundance of narG-1 gene, which might promote nitrate removal process directly. Finally, we reviewed and identified the specific properties of a variety of NPs responsible for toxicity and found NPs larger than about 100 nm and without ion release in general possible to energy safety and nontoxic or low toxic to environment. Our results provide useful information to understand the response of anoxic sludge to Si NPs and Fe2O3 NPs in complex environmental matrix as well as potent support for wide use of the environmentally friendly NPs.