[Effect of Differentially Charged Polystyrene Nanoplastics on the Performance of Biological Denitrification in Wastewater Treatment].

Nanoplastics are widely distributed in the environment and can accumulate in organisms. Increasing attention has been paid to the toxic effects of nanoplastics in wastewater biological treatment processes. In this study, polystyrene nanoplastics with different charges were synthesized and used in sequencing batch activated sludge reactors for short-term nanoplastic exposure experiments. Both positively and negatively charged nanoplastics inhibited the nitrogen removal efficiency and gene expressions of nitrification and denitrification-related genes of activated sludge. The inhibiting effect on nitrification of both nanoplastics was enhanced with increasing concentration. The study further evaluated the molecular mechanisms by which differently charged nanoplastics affect denitrification efficiency using the model denitrifying bacterium