Augmented methanogenic performance in straw-manure co-digestion via micro/nano bubble-enhanced syntrophic metabolism

Yanning Hou; Chao Liu; Jianhong Wei; Wenyan Zhao; Binghua Yan

doi:10.1016/j.biortech.2025.132955

Augmented methanogenic performance in straw-manure co-digestion via micro/nano bubble-enhanced syntrophic metabolism

Bioresour Technol. 2025 Jul 11:132955. doi: 10.1016/j.biortech.2025.132955. Online ahead of print.

Authors

Yanning Hou¹, Chao Liu¹, Jianhong Wei², Wenyan Zhao³, Binghua Yan¹

Affiliations

¹ College of Environment & Ecology, Hunan Agricultural University, Changsha, Hunan 410128, PR China.
² College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan 410128, PR China.
³ College of Environment & Ecology, Hunan Agricultural University, Changsha, Hunan 410128, PR China. Electronic address: zhaowy@hunau.edu.cn.

PMID: 40653119
DOI: 10.1016/j.biortech.2025.132955

Abstract

This study aimed to investigate the enhancement of methane production by comparing air-nanobubble water (air-NBW) and conventional micro-bubble aeration during the anaerobic co-digestion (AcoD) of rice straw and pig manure. Remarkably, the addition of air-NBW (T3-NBW), as the most effective gas supplementation strategy, resulted in the highest cumulative methane yield of 489.49 mL/g·VS with a minimal lag phase of 0.57 days, representing a 59.80 % increase over the control (306.49 mL/g·VS, p < 0.001). This finding aligns with the kinetic fitting data (477.85 ± 5.84 mL/g·VS), wherein the maximum methane production rate for the T3-NBW was 41.89 mL/g‧VS·d^-1. Mechanistic insights revealed that air-NBW dramatically elevated the activity of β-glucosidase (hydrolysis) and coenzyme F₄₂₀ (methanogenesis) by 82.72 % and 133.8 %, respectively, compared to the control. These results suggested that efficient conversion of intermediate products played a critical role in enhancing overall methane yield. Microbial community analysis identified acetotrophic methanogenesis as the dominant pathway, with Methanosaeta abundance reaching 91.66 % in NBW-amended treatments. Additionally, the co-occurrence network analysis showed that the air-NBW system promoted microbial interaction and stabilized the ecological network. Crucially, the NBW treatment exhibited the lowest expression of energy-dependent antioxidant enzyme genes (e.g. superoxide reductase, SOR), suggesting reduced oxidative stress and enhanced energy allocation toward microbial growth and methanogenic activity. By enhancing oxygen dispersion and microbial intracellular redox balance, NBW technology provides a promising approach for improving methane recovery in sustainable waste-to-energy systems.

Keywords: Anaerobic co-digestion; Methane production; Micro/nano-bubble; Rice straw; Swine manure.