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Unraveling synergistic cascade inhibition of methane production in anaerobic digestion system by polyethylene microplastics and domestic sewage: Physical adsorption, metabolic disruption, and microbial community decoupling
Summary
Researchers systematically explored how the co-presence of polyethylene microplastics and domestic sewage inhibits methane production in anaerobic digestion systems, finding that physical adsorption of microplastics, propionic acid accumulation, and microbial community decoupling identified via multi-omics analysis collectively suppressed cumulative CH4 production by 41.8% compared to controls.
The coexistence of microplastics (MPs) and domestic sewage (DS) poses unprecedented challenges to anaerobic digestion systems. Here, the cascades inhibitory mechanism of polyethylene microplastics (PE-MPs) and DS was systematically explored. Compared with the control group, the cumulative CH production of 289.77 mL/g VS in the WL group (containing DS and PE-MPs) was 41.8 % accompanied by abnormal accumulation of propionic acid (3612 mg/L) and delayed pH recovery. Multi-omics analysis indicated that PE-MPs underwent physical adsorption with reducing substrate availability and impeding nutrient cycling, and biochemical inhibition inducing a 1.9-fold increase in superoxide dismutase and a 91.43 % decrease in acetate kinase. Additionally, ecological process reshaping was characterized by the dominance of Firmicutes with an 119 % increase and the reduction of Methanosarcina with 82 %. Zero model analysis indicated that the stochastic processes (44 %) dominated the community assembly of the WL group, and the network modularization index (0.533) significantly increased. PLS-SEM displayed CH production was a significant negative correlation with alpha diversity (β=-0.24, p < 0.01) and key enzyme activity (β=-0.38, p < 0.01), while volatile fatty acids had a positive correlation with methanogens (β=0.18, p < 0.05). Collectively, these findings displayed DS and PE-MPs significantly reduced nutrient content, induced oxidative stress, and reshaped community composition and assembly.
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