| Summary: | 碩士 === 國立中央大學 === 環境工程研究所 === 100 === This study investigated the feasibility of solid-state anaerobic digestion for methane production, using simulated municipal solid waste as substrate and sewage sludge as inocula. Unlike the conventional wet anaerobic digestion process, mechanical stirring was not adopted in the digesters of this study. Instead, passive-mixing was achieved by pumping and spraying the liquid residues (i.e., leachate) back to the system, thus gradually rinsing the digesting materials. Initial moisture contents of the feedstock were all below 85%, conforming that the system was always initiated as a solid-state digestion.
The effect of temperature on methane production was examined by performing the digestion process at 35℃and 55℃. Results showed that under thermophilic conditions (i.e., 55℃), 43.32 and 39.42 L/kg VS of maximum methane yields were obtained on Day 28 and 26, respectively. In comparison, mesophilic (35℃) processes only resulted in 35.65 and 38.83 L/kg VS of maximum methane yields, and required a longer period of incubation process (52 and 56 days, respectively). No significant differences in methane production were observed between the circulation rate at 0.38 ml/cm2/min and 0.76 ml/cm2/min. However, when the system was conducted at 0.38 ml/cm2/min circulation rate under mesophilic conditions, production of hydrogen (up to 1.91 L/kg VS) appeared at the early stage of incubation.
These results indicated that using this solid-state anaerobic digestion system to treat municipal solid waste not only can help the degradation of organic substances but can also promote the formation of methane.
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