Original Paper

World Journal of Microbiology and Biotechnology

, Volume 24, Issue 5, pp 659-665

First online:

The effect of volatile fatty acids on the inactivation of Clostridium perfringens in anaerobic digestion

  • Hamidreza SalsaliAffiliated withDepartment of Civil and Environmental Engineering, Carleton UniversityConestoga-Rovers & Associates Email author 
  • , Wayne J. ParkerAffiliated withDepartment of Civil Engineering, University of Waterloo
  • , Syed A. SattarAffiliated withCentre for Research on Environmental Microbiology (CREM), Faculty of Medicine, University of Ottawa

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The application of sludge digestion systems to remove pathogens has been employed to generate biosolids suitable for reuse in agriculture. Traditionally, temperature is considered the principal agent responsible for pathogen reduction in anaerobic digestion. However, other substances such as volatile fatty acids may also have an antimicrobial effect. The objective of this study was to assess the impact of fatty acid mixtures on the inactivation of C. perfringens over a range of digestion temperatures. An equimolar mixture of acetic acid, propionic acid and butyric acid was applied to digester effluent for a period of 24 h at temperatures of 35 °C, 42 °C, 49 °C and 55 °C. C. perfringens inactivation in digester effluents, when dosed with volatile organic acids, was found to depend on pH, acid concentration and temperature. Temperatures above 55 °C appeared to increase the inhibitory effects of the organic acids at higher concentrations. An interaction between temperature and pH on survival of C. perfringens was observed. The results suggest that high concentrations of organic acids at a pH value of 4.5–5.5 during thermophilic digestion substantially reduce concentrations of C. perfringens in municipal sludge.


Anaerobic digestion C. perfringens Mesophilic Thermophilic Volatile organic acids