A Nanoparticle Flaps its Wings

About the author: Dr. Amy Pruden is a professor in the Department of Civil and Environmental Engineering at Virginia Tech and a VTSuN faculty member.

This post was originally published at The Microbiology of the Built Environment Network (microBEnet).

You may have heard the saying that “a butterfly flaps its wings and…” insert your absurd unintended, chaotic, massive consequence here (e.g., a hurricane). We may not have much control over butterflies, but we do make choices as industries, governments, and individuals on which products we produce, regulate, and consume. Examples of such products that we initially thought were wonderful advances for humankind include chlorofluorocarbons (refrigerants), tetraethyl lead (makes engines run smooth), and DDT (curbed malaria epidemics). Unfortunately, the unintended consequences of such substances included a hole in the ozone layer, elevated blood lead, and poisoned ecosystems.

What can we learn from these experiences? Now we are in the midst of another industrial boom: Nanotechnology. It is estimated that thousands of tons of nanomaterials are now being produced each year. Why is there such an interest in nanomaterials? Well, to put it simply- they are “special”. Nanomaterials have unique properties in the size range of 1-100 nanometers that differ from their behavior as larger particles or in dissolved forms. Could these unique properties be a concern to the environment? This is a topic explored by the Virginia Tech Sustainable Nanotechnology (VT SuN) Interdisciplinary Graduate Education Program (IGEP). The aim is to be proactive, and think ahead in terms of what negative consequences our next engineering feats could lead to and nip them in the bud. For example, nanoparticles can be produced with numerous core materials, coatings, and surface modifications- maybe minor tweaks in design now could save the environment later.

In our article to come out in Water Research (Ma et al. 2014 doi.org/10.1016/j.watres.2014.09.008) we sought to determine if commonly produced nanoparticles, made of titanium dioxide, silver, ceria, or iron, might disrupt important water purification processes at wastewater treatment plants when flushed down the drain. We focused in on nitrifying bacteria, which are responsible for removing toxic ammonia, as our canaries in the coal mine. The good news- no observable effects of any of the nanomaterials on nitrifying bacterial activity! However, pyrosequencing of 16S rRNA genes revealed that there were some shifts in the microbial community structure unique to the presence of nanosilver. Future research may explore this further, especially with longer-term dosing, since this study took place in lab-scale simulated wastewater treatment plants over only about 8 weeks. Nonetheless, if there is ultimately good news that nanoparticles can be flushed safely down the drain without environmental impact, well, then that is good news! But, we will not know this for certain unless we test it out- and there are numerous more forms of nanoparticles that need investigating. The earlier we can identify the safest forms of nanoparticles, the better we can guide our “butterflies” in terms of the time and money invested in technological advances and hopefully avoid paying a grave price with unintended environmental consequences.

This post was originally published at The Microbiology of the Built Environment Network (microBEnet).

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