Rethinking the biochar impact on the anaerobic digestion of food waste in bench-scale digester: Spatial distribution and biogas production

Jing Zhang, He Liu*, Junyao Wu, Chongjun Chen, Yan Ding, Hongbo Liu, Yan Zhou

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

The improvement of biogas production in anaerobic digestion (AD) by biochar introduction has been demonstrated. However, the distribution of biochar in the digester and its effect on AD have been seldom explored. In this study, the distribution of biochar and their impact on AD were investigated in a 30 L semi-continuously operated bench-scale anaerobic digester. The results demonstrated that the biochar significantly increased biogas yields by 23.38 % under an organic loading rate (OLR) of 3.0 g VS/L·d. The stability of the AD under an OLR of 4.0 g VS/L·d was also improved by biochar introduction. The increased stirring speed of the digester enhanced the spatial distribution uniformity of biochar and increased biogas production by 5.89 %. Reducing the particle size of biochar improved its spatial distribution uniformity but did not significantly increase biogas production, likely due to excessive microbial accumulation on the biochar, which have caused substrate competition. Biochar aided AD by boosting microbial genera of Syntrophomonas, Bacteroidota, Cloacimonadot, and Methanosaeta, accelerating volatile fatty acids consumption, and improving microorganisms’ spatial ecological niches. The economic analysis showed that applying residue-based biochar for biogas production presented superior benefits and greater development potential than residue incineration in the food waste AD process. Overall, this study presented a novel and comprehensive understanding of the biochar distribution and impact on food waste AD in digesters.

Original languageEnglish
Article number132115
JournalBioresource Technology
Volume420
DOIs
Publication statusPublished - Mar 2025
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2025

ASJC Scopus Subject Areas

  • Bioengineering
  • Environmental Engineering
  • Renewable Energy, Sustainability and the Environment
  • Waste Management and Disposal

Keywords

  • Anaerobic digestion
  • Biochar
  • Biogas
  • Economic analysis
  • Food waste
  • Spatial distribution

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