Modelling methanogenesis during anaerobic conversion of complex organic matter at low temperatures

Abstract

Low temperature consumption of H2/CO2 by microflora of tundra wetland soil and pond silt were simulated using the modified <METHANE> model with consideration of homoacetogens or hydrogen consuming methanogens as hydrogenotrophs. Simulations show that the model with homoacetogens was able to fit the data closely. Under the conditions of high initial hydrogen concentrations acetate was the main precursor of methane. Inhibition of acetoclasic methanogens proved to be significant for tundra soil samples. Methane formation from organic matter contained in the samples of tundra soil was modeled in the wide range of temperature conditions. It was concluded that hydrolysis is the rate-limiting step at 10–28°C, but at 6°C the rate of acetoclastic methanogenesis becomes the rate-limiting stage in methane production. To describe the low temperature methane foonation from organic matter by microflora of pond silt, cattle's and pig's manure the alternative pathways with participation of homoacetogens or hydrogenotrophic methanogens were verified. It was shown that the both pathways fit the measured data comparatively well.