Use of biochars in anaerobic digestion

Jan Mumme*, Franziska Srocke, Kathrin Heeg, Maja Werner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


This study investigated the behavior of biochars from pyrolysis (pyrochar) and hydrothermal carbonization (hydrochar) in anaerobic digestion regarding their degradability and their effects on biogas production and ammonia inhibition. A batch fermentation experiment (42°C, 63days) was conducted in 100mL syringes filled with 30g inoculum, 2g biochar and four levels of total ammonium nitrogen (TAN). For pyrochar, no clear effect on biogas production was observed, whereas hydrochar increased the methane yield by 32%. This correlates with the hydrochar's larger fraction of anaerobically degradable carbon (10.4% of total carbon, pyrochar: 0.6%). Kinetic and microbiota analyses revealed that pyrochar can prevent mild ammonia inhibition (2.1gTANkg-1). Stronger inhibitions (3.1-6.6gTANkg-1) were not mitigated, neither by pyrochar nor by hydrochar. Future research should pay attention to biochar-microbe interactions and the effects in continuously-fed anaerobic digesters.

Original languageEnglish
Pages (from-to)189-197
Number of pages9
JournalBioresource technology
Publication statusPublished - 1 Jan 2014


  • Ammonia inhibition
  • Anaerobic digestion
  • Biochar
  • Degradation kinetics
  • Methanogenic microflora


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