Synergistic analysis of performance, microbial community, and metabolism in aerobic granular sludge under polyacrylonitrile microplastics stress

Aerobic granular sludge (AGS) has proved to be a promising biotechnology for microplastics wastewater treatment. However, polyacrylonitrile microplastics (PAN MPs), the most widely used plastic in textile materials, have not been investigated. Therefore, the effect of the neglected PAN MPs on AGS at different concentrations (1, 10, and 100 mg/L) was evaluated. The results indicated that PAN MPs with 1 and 10 mg/L concentrations had no obvious effect on granular stability and nutrient removal performance, but greatly promoted the secretion of EPS. Remarkably, the granule structure was severely damaged under 100 mg/L PAN MPs. Moreover, microbial community analysis showed that phylum Proteobacteria played a dominant role in resistance to PAN MPs. Metabolic analysis further revealed that genes related to denitrification pathway (nasA, nirK, nirS and norB) and membrane transport were significantly inhibited under PAN MPs stress. This study may provide additional information on the treatment of microplastics wastewater using AGS.

Automated summary

This study evaluated the effect of neglected PAN MPs on AGS at different concentrations. The results showed that 1 and 10 mg/L concentrations of PAN MPs had no significant impact on granular stability and nutrient removal, but greatly increased EPS secretion. However, at 100 mg/L, PAN MPs severely damaged the granule structure. Microbial community analysis revealed the dominance of phylum Proteobacteria in resisting PAN MPs. Metabolic analysis also showed significant inhibition of genes related to denitrification pathway and membrane transport under PAN MPs stress. This study provides additional information on microplastics wastewater treatment using AGS.