The effect of incubation temperature on steady-state concentrations of hydrogen and volatile fatty acids during anaerobic degradation in slurries from wetland sediments

Increasing the incubation temperature of two swamp slurries from 2°C to37°C resulted in a 8- to 18-fold increase in the H2 partial pressure. The concentration of volatile fatty acids remained fairly constant except for butyrate, which decreased with increasing temperature. Calculation of Gibbs free energies of syntrophic degradation of butyrate and propionate, and of methanogenesis from acetate and H2 revealed that these reactions were exergonic after the slurries had stabilized at the incubation temperatures. The changes in H2 partial pressure and butyrate concentration with temperature were found important to render the processes exergonic within the tested temperature range.