Changes in methanogenic performance and microbial community during gradual transition from co-digestion with food waste to mono-digestion of rice straw

Yaqian Liu; Ryoya Watanabe; Qian Li; Yutong Luo; Naohito Tsuzuki; Yu Qin; Yu-You Li

doi:10.1016/j.biortech.2025.132072

Changes in methanogenic performance and microbial community during gradual transition from co-digestion with food waste to mono-digestion of rice straw

Bioresour Technol. 2025 Jan 13:132072. doi: 10.1016/j.biortech.2025.132072. Online ahead of print.

Authors

Yaqian Liu¹, Ryoya Watanabe², Qian Li³, Yutong Luo⁴, Naohito Tsuzuki¹, Yu Qin⁴, Yu-You Li⁵

Affiliations

¹ Department of Frontier Science for Advanced Environment, Graduate School of Environmental Sciences, Tohoku University, 6-6-06 Aoba, Aramaki-Aza, Sendai, Miyagi 980-8579, Japan.
² KUBOTA Corporation, 1-1-1 Hama, Amagasaki, Hyogo 661-8567, Japan.
³ Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University, 6-6-06 Aoba, Aramaki-Aza, Sendai, Miyagi 980-8579, Japan; Key Lab of Environmental Engineering, Shaanxi Province, Xi'an University of Architecture and Technology, No.13 Yanta Road, Xi'an 710055, PR China.
⁴ Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University, 6-6-06 Aoba, Aramaki-Aza, Sendai, Miyagi 980-8579, Japan.
⁵ Department of Frontier Science for Advanced Environment, Graduate School of Environmental Sciences, Tohoku University, 6-6-06 Aoba, Aramaki-Aza, Sendai, Miyagi 980-8579, Japan; Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University, 6-6-06 Aoba, Aramaki-Aza, Sendai, Miyagi 980-8579, Japan. Electronic address: [email protected].

PMID: 39814148
DOI: 10.1016/j.biortech.2025.132072

Abstract

This study investigated the performance and phase-specific characteristics of mesophilic co-digestion of food waste (FW) with rice straw (RS) at different RS proportions (40 %, 60 %, and 80 %), as well as mono-digestion of RS. The system achieved optimal performance at 40 % RS content, with a methane yield of 383.8 mL/g-VS and cellulose removal efficiency exceeding 75 %. When RS content increased beyond 60 %, process performance declined notably. At 80 % RS ratio, an imbalance between acidogenesis and methanogenesis led to volatile fatty acids (VFAs) accumulation (1500 mg-COD/L), compromising both efficiency and stability. Notably, during the transition to mono-digestion, the system maintained stable operation, characterized by increased abundance of functional enzymes associated with cellulosic substance hydrolysis and acidogenesis. This enhanced enzymatic activity may be attributed to the microbial adaptation induced by previous co-digestion with FW. These findings provide valuable insights for optimizing mesophilic RS digestion through strategic co-digestion approaches.

Keywords: Anaerobic digestion; Biogas; Rice straw ratio; Stability; Volatile fatty acids.