Applied Microbiology and Biotechnology

, Volume 43, Issue 3, pp 559–565 | Cite as

Volatile fatty acids as indicators of process imbalance in anaerobic digestors

  • B. K. Ahring
  • M. Sandberg
  • I. Angelidaki
Environmental Biotechnology Original Paper


In continuously stirred tank reactor experiments, with manure as substrate at thermophilic temperatures, the use of volatile fatty acids (VFA) as process indicators was investigated. Changes in VFA level were shown to be a good parameter for indicating process instability. The VFA were evaluated according to their relative changes caused by changes in hydraulic loading, organic loading or temperature. Butyrate and isobutyrate together were found to be particularly good indicators. Butyrate and isobutyrate concentrations increased significantly 1 or 2 days after the imposed perturbation, which makes these acids suitable for process monitoring and important for process control of the anaerobic biological system. In addition it was shown in a batch experiment that VFA at concentrations up to 50 mM did not reduce the overall methane production rate. This showed that VFA accumulation in anaerobic reactors was the result of process imbalance, not the cause of inhibition, thus justifying the use of VFA as process indicators.


Manure Butyrate Anaerobic Digestor Methane Production Volatile Fatty Acid 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • B. K. Ahring
    • 1
  • M. Sandberg
    • 1
  • I. Angelidaki
    • 2
  1. 1.The Anaerobic Microbiology/Biotechnology Research Group, Department of Environmental Science and Engineering, Building 115The Technical University of DenmarkLyngbyDenmark
  2. 2.Department of Biotechnology, Building 223The Technical University of DenmarkLyngbyDenmark

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