MODELING LOW-TEMPERATURE METHANE PRODUCTION FROM CATTLE MANURE BY AN ACCLIMATED MICROBIAL COMMUNITY

The modified model of anaerobic digestion suggested earlier was used t o describe a low temperature methanogenesis during a batch cattle-manu re digestion by an acclimated microbial community investigated by Kots yurbenko et al. (1993). The model showed that the pH inhibition of ace toclastic methanogens and propionate-consuming syntrophs is significan t in explanation of the long-term constant values of acetate and propi onate concentrations in spire of an appreciable rare of methanogenesis . A low rare of acetate production during acidogenesis as well as prop ionate and butyrate degradation at 6 degrees C is compensated by a low rate of acetate consumption during acetoclastic methanogenesis. The s ystem dynamics was described well by two alternative microbial pathway s with or without participation of homoacetogenic bacteria. The corres ponding kinetic coefficients were evaluated The independent experiment al data during a low-temperature cattle manure digestion without inocu lation were used for the model verification. It was shown that a domin ance of homoacetogenic bacteria over hydrogen-consuming methanogens ne eds to be considered to describe the hydrogen, methane, VFA and pH tim e-profiles. (C) 1998 Elsevier Science Ltd. All rights reserved.