Combined impact of TiO2 nanoparticles and antibiotics on the activity and bacterial community of partial nitrification system.

Han Xu,Xiaoyu Cui,Binghua Liu,Wenyu Qi,Jun Liu,Qiang Li,Meng Xu,Guanglei Qiu

doi:10.1371/journal.pone.0259671

Han Xu, Xiaoyu Cui + Show 6 more

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https://doi.org/10.1371/journal.pone.0259671

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Journal: PloS one	Publication Date: Nov 15, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: Linyi University, Shandong University

Abstract

The effects of TiO2 nanoparticles (nano-TiO2) together with antibiotics leaking into wastewater treatment plants (WWTPs), especially the partial nitrification (PN) process remain unclear. To evaluate the combined impact and mechanisms of nano-TiO2 and antibiotics on PN systems, batch experiments were carried out with six bench-scale sequencing batch reactors. Nano-TiO2 at a low level had minimal effects on the PN system. In combination with tetracycline and erythromycin, the acute impact of antibiotics was enhanced. Both steps of nitrification were retarded due to the decrease of bacterial activity and abundance, while nitrite-oxidizing bacteria were more sensitive to the inhibition than ammonia-oxidizing bacteria. Proteobacteria at the phylum level and Nitrosospira at the genus level remained predominant under single and combined impacts. The flow cytometry analysis showed that nano-TiO2 enhanced the toxicity of antibiotics through increasing cell permeability. Our results can help clarify the risks of nano-TiO2 combined with antibiotics to PN systems and explaining the behavior of nanoparticles in WWTPs.

Highlights

In addition to traditional nitrification processes, recent studies have investigated partial nitrification (PN) as a nitrogen removal method [1]
In PN, ammonia is oxidized into nitrite by ammonia-oxidizing bacteria (AOB) without further transformation into nitrate by nitrite-oxidizing bacteria (NOB), resulting in nitrite accumulation
Nitrite accumulated through PN, together with ammonia, can be converted into dinitrogen gas under anoxic conditions by anammox bacteria, such as in the oxygen-limited autotrophic nitrification-denification process [3]

Summary

Introduction

In addition to traditional nitrification processes, recent studies have investigated partial nitrification (PN) as a nitrogen removal method [1]. Nano-TiO2, tetracycline, and erythromycin were added at possible concentrations in WWTPs. Ammonia removal efficiency and nitrite accumulation rate were measured and calculated.

Results

Conclusion