Achieving synergistic enhancement in the anaerobic digestion of corn straw by (CH 4  + CO 2 ) nanobubbles in conjunction with optimized particle sizes.

Nanobubbles (NBs) technology has been proven to promote methane production from anaerobic digestion (AD). In this study, the synergistic effects of (CH ₄  + CO ₂ )-nanobubble water ((CH ₄  + CO ₂ )-NBW) combined with varying particle sizes of corn straw on the AD were investigated. As findings, adding (CH ₄  + CO ₂ )-NBW effectively promoted the methane production from AD of corn straw with different particle sizes. The maximum cumulative methane yield (186.42 mL/ g-volatile solids) was achieved in Group a with the addition of (CH ₄  + CO ₂ )-NBW, representing a 16.89 % increase compared to the control. Furthermore, (CH ₄  + CO ₂ )-NBW could enhance the enzymatic activity. The activities of β-glucosidase and coenzyme F ₄₂₀ were increased by 6.70 % and 11.48 %, respectively. The results of microbial community structure revealed that the addition of (CH ₄  + CO ₂ )-NBW could improve the abundance of dominant bacteria (norank_JS1, norank_Aminicenantales, and Bacteroidetes_vadinHA17) and archaea (Methanomassiliicoccaceae, Methanobacteriaceae, and norank_Bathyarchaeia). This study provides new insights into the application of nanobubbles in the AD of biomass.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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