The Effect of TiO2 Nanomaterials on the Bacterial Community in Nitrifying Sequencing Batch Reactors

Abstract

Rapid development and widespread use of nanotechnology has resulted in the increased presence of nanomaterials in wastewater streams. Biological wastewater treatment has the potential to be a crucial technique in capturing and modifying nanomaterials before they enter the environment. However, little is known about the effects of nanomaterials on microbial communities involved in the wastewater treatment process. This project implemented qPCR and RT-qPCR to examine the impact of TiO2 nanoparticles on the bacterial community by measuring the expression of amoA in Nitrosomonas and nsg (a Nitrobacter specific gene) along with the induction of the antibiotic resistance gene, sulI, in a typical nitrifying activated sludge system. Six lab-scale sequencing batch reactors (SBRs) were set up and fed with synthetic wastewater suitable for nitrification. Three test conditions were examined in duplicate reactors: nano-sized TiO2, bulk-TiO2, and no-TiO2 control. Quantification of amoA and nsg levels and expression did not suggest inhibition of the nitrification process as result of nano- or bulk-TiO2 exposure. Quantification of sulI did not suggest induction of sulfonamide resistance. This project provides important genetic information on the effect of TiO2 nanomaterials on the bacterial community in an experimental paradigm that accurately replicates a simulated nitrifying activated sludge system.

Unavailable to the public at the request of the author, 2/9/15. This work, along with some other related work, was published in the journal "Water Research": http://www.sciencedirect.com/science/article/pii/S004313541400637X as "Microbial community response of nitrifying sequencing batch reactors to silver, zero-valent iron, titanium dioxide and cerium dioxide nanomaterials"