Experiments using high concentration of the major intermediates of anaerobic digestion were conducted with anaerobic chemostat-type reactors to investigate the temperature characteristics of the methanogenesis process. Temperature ranging from 15°C to 50°C were studied. The optimum temperature was 35°C. The methane production was temperature and loading rate dependent. Bacilli were the predominant microbial species and this predominance was independent of digestion temperature. At the mesophilic range, with increasing temperature the saturation constant (Ks) decreased, while the maximum specific substrate utilization rate (vmax) and growth yield (Yg) increased. Their temperature characteristics were described using exponential expressions. For retention times longer than 8 days, the process progressed normally and satisfactorily even at 25°C, and the substrate removal efficiency was more than 96% which was the same as that at 35°C. At the temperature range of 25°C to 35°C, the simulation model is
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