Achieving synergistic enhancement in the anaerobic digestion of corn straw by (CH4 + CO2) 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 (CH₄ + CO₂)-nanobubble water ((CH₄ + CO₂)-NBW) combined with varying particle sizes of corn straw on the AD were investigated. As findings, adding (CH₄ + CO₂)-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 (CH₄ + CO₂)-NBW, representing a 16.89 % increase compared to the control. Furthermore, (CH₄ + CO₂)-NBW could enhance the enzymatic activity. The activities of β-glucosidase and coenzyme F₄₂₀ were increased by 6.70 % and 11.48 %, respectively. The results of microbial community structure revealed that the addition of (CH₄ + CO₂)-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.