Toxicity and combined effects of antibiotics and nano ZnO on a phosphorus-removing Shewanella strain in wastewater treatment

• Published in: Journal of hazardous materials 2021-08, Vol.416, p.125532-125532, Article 125532
• Main Authors: Yang, Yongkui, Xue, Tongyu, Xiang, Feng, Zhang, Shaoyi, Hanamoto, Seiya, Sun, Peizhe, Zhao, Lin
• Format: Article
• Language: English
• Subjects: Antibiotics; Complexing effect; PAOs; Wastewater; ZnO nanoparticle
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.125532

Antibiotics and nanoparticles, which are emerging contaminants, can occur simultaneously in biological wastewater treatment systems, potentially resulting in complex interactive effects. This study investigated the effects of individual and complex zinc oxide nanoparticles (nZnO) and antibiotics (quinolone and sulfonamide), on the Shewanella strain used to remove phosphorus (PO43-), metabolic processes, as well as its complexing and toxicity mechanisms. The inhibition of PO43- removal increased from 30.7% to 100.0% with increased nZnO concentrations (half maximal effective concentration (EC50) = 1.1 mg Zn/L) by affecting poly-p and glycogen metabolites. The combined exposure to nZnO and ciprofloxacin/norfloxacin (CIP/NOR) had a significant antagonistic effect on the removal of PO43- and on the metabolism of poly-p and glycogen in phosphate-accumulating organisms (PAOs), whereas the complexing of sulfonamide and nZnO had no significant additional effect. Thus, the complexing of nanoparticles and antibiotics exhibited different toxicity effects from the antibiotic structure-based complex reactions. These results can be used to improve wastewater treatment processes and reduce risks associated with wastewater discharge. [Display omitted] •Combined effect and mechanism of antibiotic and nano ZnO on PAOs were evaluated.•nZnO combined with CIP/NOR had a significant antagonistic effect on PO43- removal.•The complex of sulfonamide and nZnO had no significant additional effect.•nZnO complexed on the O atoms of carboxyl group of quinolones.•Complex position between antibiotic and nZnO affected their toxicity on PAO.