Abstract

In biogas processes, methane production from acetate proceeds by either aceticlastic methanogenesis or through syntrophic acetate oxidation (SAO). In the present study, the pathway for methane production from acetate was analysed; i) during a gradual increase of the ammonia concentration (final concentration 7 gNH(4)(+) - N/L) in a semi-continuous lab-scale anaerobic digester (4.3 L), operating at mesophilic temperature (37 degrees C) or ii) in diluted enrichment cultures (100 ml) experiencing a gradual increase in ammonia, sodium, potassium and propionic acid. The pathway for methane formation was determined by calculating the (CO2)-C-14/(CH4)-C-14 ratio after incubating samples with C-14-2-acetate. In the anaerobic digester, as well as in the enrichment cultures, the (CO2)-C-14/(CH4)-C-14 ratio clearly increased with increasing ammonium-nitrogen concentration, i. e. as the ammonia concentration increased, a shift from the aceticlastic mechanism to the syntrophic pathway occurred. The shift was very distinct and occurred as the NH4+ - N concentration rose above 3 g/l. No shift in pathway was seen during increasing concentrations of sodium, potassium or propionic acid. The shift to SAO in the biogas digester resulted in a twofold decrease in the specific gas and methane yield.

Keywords

ammonia inhibition; anaerobic digestion; C-14-labelling; mesophilic temperature; syntrophic acetate oxidation

Published in

Water Science and Technology
2008, Volume: 57, number: 5, pages: 735-740
Publisher: I W A PUBLISHING

SLU Authors

• Schnürer, Johan

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences
Other Environmental Engineering


Publication identifier

DOI: https://doi.org/10.2166/wst.2008.097

Permanent link to this page (URI)

https://res.slu.se/id/publ/78176