The effect of volatile fatty acids on the inactivation of <Emphasis Type="Italic">Clostridium perfringens</Emphasis> in anaerobic digestion |
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Authors: | Hamidreza Salsali Wayne J Parker Syed A Sattar |
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Institution: | (1) Department of Civil and Environmental Engineering, Carleton University, Ottawa, Ontario, Canada;(2) Present address: Conestoga-Rovers & Associates, 651 Colby Drive, Waterloo, Ontario, Canada, N2V 1C2;(3) Department of Civil Engineering, University of Waterloo, Waterloo, Ontario, Canada;(4) Centre for Research on Environmental Microbiology (CREM), Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada |
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Abstract: | 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. |
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Keywords: | Anaerobic digestion C perfringens Mesophilic Thermophilic Volatile organic acids |
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