The effect and mechanism of polyethylene terephthalate microplastics on anaerobic co-digestion of sewage sludge and food waste.

This research investigated the impact of polyethylene terephthalate (PET) microplastics on the anaerobic co-digestion of sewage sludge and food waste. The performance of anaerobic digester was investigated with different particle sizes (30 µm and 250 µm) PET at concentrations of 0, 0.45, 1.35, and 2.70 mg/g total solid (TS). Results suggested that the CH 4 production at 2.70 mg/g TS level decreased by 21.63% (30 µm) and 15.87% (250 µm) compared with the control group, respectively. PET microplastics exerted negative influence through leaching toxic diisobutyl phthalate (DIBP) and dibutyl phthalate (DBP). Microbial community analysis and redundancy analysis showed that DIBP and DBP reduced the abundances of key hydrolysis bacteria (Bacteroides vadin HA17) and acidification bacteria (Clostridium and Sphaerochaeta). Structural equation model analysis showed that DBP and DIBP were the key factors that reduced the methane production, and they had stronger impact on daily methane production in the 30 µm group compared with the 250 µm group. [Display omitted] • PET microplastics had negative effect on methane production. • PET microplastics-30 µm inhibited the methane production more obviously. • PET microplastics inhibited the hydrolysis and acidification in AD systems. • Leached DBP and DIBP reduced key acidogens and methanogens. [ABSTRACT FROM AUTHOR]