RESUMEN
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 0-50â 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 0â mg/L Al2O3 NPs, the dehydrogenase activity declined by 23.52% at 50â 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 50â mg/L Al2O3 NPs. However, the nitrate reductase (NR) activity slightly increased at 5 and 15â mg/L Al2O3 NPs and declined at 30 and 50â mg/L Al2O3 NPs. The microbial reactive oxygen species (ROS) production and lactate dehydrogenase (LDH) release merely raised 14.80% and 20.72% at 50â mg/L Al2O3 NPs by contrast with 0â 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.