Bio-carriers enhance methane production in two-phase anaerobic digestion of low carbon-to-nitrogen ratio food waste solid residues.

Authors

Junwei He, Jing He, Lejun Wang, Jiaying Zhou, Wenhuan Li, Liangyan He, Guanjie Chen, Jinyu Liao, Yinfeng Zhong

Published in

Bioresource technology. Pages 135388. Jul 12, 2026. Epub Jul 12, 2026.

Abstract

Effective anaerobic digestion (AD) of low carbon-to-nitrogen ratio organic solid waste is hindered by persistent ammonia inhibition. This study conducted a systematic comparative evaluation of three mineral-based bio-carriers (zeolite, volcanic rock, and iron-carbon) in a two-phase (LBR-CSTR) system treating food waste solid residues, aiming to elucidate their hierarchical efficacy and the underlying microbial mechanisms. The results demonstrated that zeolite outperformed the other carriers, increasing the cumulative methane yield by 103.03% (to 279.33 mL/g VS_added) compared to the control, far exceeding the improvements achieved by volcanic rock (60.36%) and iron-carbon (60.92%). The key mechanistic insight revealed that zeolite's superiority stemmed from its sustained chemical adsorption of ammonia, which maintained a non-inhibitory NH₄⁺-N microenvironment (<1500 mg/L) in the CSTR. This targeted regulation selectively enriched pivotal syntrophic bacteria (e.g., DMER64) and was associated with a synergistic consortium of versatile methanogens (Methanosarcina, Methanomassiliicoccus, Methanoculleus), correlating with efficient multi-pathway methanogenesis. In contrast, volcanic rock (via physical enrichment) and iron‑carbon (via its electrochemical activity) were unable to mitigate the high‑ammonia stress (>3000 mg/L), which suppressed microbial activity and limited their enhancement. Notably, the iron‑carbon carrier elevated the predicted methanogenic potential, but its actual methane yield was limited by persistent ammonia inhibition, indicating a decoupling of potential from activity. These findings demonstrate the primacy of direct regulation of the chemical microenvironment over merely augmenting physical or electrochemical properties in ammonia-prone systems. This work provides a mechanistic hierarchy for bio-carrier selection and establishes a foundation for designing targeted strategies to optimize the AD of nitrogen-rich wastes.

PMID:
42437577
Bibliographic data and abstract were imported from PubMed on 13 Jul 2026.

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