Enhanced semi-continuous hydrogen production by addition of microplastics under mesophilic and thermophilic fermentation

In this study, the influences of polyethylene terephthalate microplastics (PET MPs) on the semi-continuous hydrogen (H-2) production and microbial community under mesophilic and thermophilic fermentation were investigated. Results indicated that PET MPs can enhance the semi-continuous H-2 production performance, and the highest H-2 production rates in mesophilic and thermophilic MPs supplemented groups were 4.85 and 3.6 L L-1 d(-1), which were 21.6% and 63.6% higher than the control groups, respectively. Moreover, it was found that PET MPs could favor the growth of H-2 -producing bacteria and optimize the microbial community structure. In mesophilic MPs supplemented groups, the abundance of genus Lactococcus and Ethanoligenens increased from 20.77% and 6.7% to 38.69% and 10.78%, respectively. The abundance of genus Thermoanaerobacterium became the dominant bacteria in thermophilic fermentation, and its abundance increased from 9.02% to 69.38%. This work provides novel insights into the function of MPs in fermentative H-2 production system.