Synergistic effect of biochar and Phanerochaete chrysosporium regulating biofilm to promote microplastics degradation during composting

This study aimed to explore the impact of sawdust biochar (T2), Phanerochaete chrysosporium (PC, T3), and their mixtures (T4) on the polyethylene microplastics (PE-MPs) degradation and related mechanisms during composting, the treatment without addition was regarded as control (T1). Results showed that compared with the control, adding biochar, PC and their mixture could reduce the PE-MPs abundance from 27,833 to 17,267-22600 items/kg, and the minimum value was observed in T4. Meanwhile, the pronounced surface cracks, highest carbon loss and carbonyl index observed in T4 also confirmed this result. Additionally, adding the mixture of biochar and PC optimized composting environments and selectively enriched bacteria on PE-MPs biofilms, especially NS9_marine_group, main contributor to the PE-MPs degradation with 0-200 μm and 1000-3000 μm. Furthermore, the application of combined amendments enhanced connectivity between PE-MPs and microorganisms, thus benefiting PE-MPs degradation. These findings provide new insights into MPs reduction in compost and a theoretical basis for the safe recycling of organic wastes.