2003 年 26 巻 3 号 p. 167-170
In order to estimate the biological activities of sludge with a very low substrate degradability, to which batch experimental data usually cannot be applied, we developed a new analytical method combined with a mathematical model. During batch tests requiring a long time due to low activity levels, bacteria in the sludge must exponentially grow. The analytical method presented in this study, taking the bacterial growth into account, was applied to seven types of anaerobic digestion sludge to estimate the validity of the proposed method. The specific growth rates of methanogenic bacteria in the sludge, which were obtained by the mathematical model and the methane production data of batch tests, lie in the general range. The measurement results for methane production were significantly consistent with the theoretical simulation results based on the mathematical model with the appropriately calculated specific growth rates. These results indicate that the analytical method proposed here would be useful for determining the very low specific biological activities of sludge.