Effects of aluminum oxide nanoparticles on the performance, extracellular polymeric substances, microbial community and enzymatic activity of sequencing batch reactor

ABSTRACT

The performance, pollutant removal rate, microbial community and enzymatic activity of a sequencing batch reactor (SBR) were investigated under oxide nanoparticles (Al₂O₃ NPs) stress. Al₂O₃ NPs at 0–50 mg/L showed no evident impact on the COD and NH₄⁺ removals of SBR. The oxygen-uptake rate, nitrifying rate and nitrite-reducing rate slightly diminished with the increase of Al₂O₃ NPs concentration. Compared with 0 mg/L Al₂O₃ NPs, the dehydrogenase activity declined by 23.52% at 50 mg/L Al₂O₃ NPs. The activities of ammonia monooxygenase, nitrite oxidoreductase and nitrite reductase decreased with the increase of Al₂O₃ NPs concentration from 0 to 50 mg/L Al₂O₃ NPs. However, the nitrate reductase (NR) activity slightly increased at 5 and 15 mg/L Al₂O₃ NPs and declined at 30 and 50 mg/L Al₂O₃ NPs. The microbial reactive oxygen species (ROS) production and lactate dehydrogenase (LDH) release merely raised 14.80% and 20.72% at 50 mg/L Al₂O₃ NPs by contrast with 0 mg/L Al₂O₃ NPs, respectively. Al₂O₃ NPs enhanced the production, protein content and polysaccharide content of extracellular polymeric substances owing to preventing the microbes from Al₂O₃ NPs biotoxicity. The existence of Al₂O₃ NPs led to the variations of microbial richness and diversity in the SBR due to their biotoxicity.

GRAPHICAL ABSTRACT

KEYWORDS:

• Aluminum oxide nanoparticles
• nitrifying rate
• denitrifying rate
• enzymatic activity
• microbial richness

Acknowledgements

The work was funded by the Province Key Technologies R & D Program of Shandong (Grants 2007GG10006002).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Key Technologies R & D Program of Shandong Province: [Grant Number 2007GG10006002].