Liquefaction and Gasification during Anaerobic Digestion of Coffee Waste by Two-Phase Methane Fermentation with Slurry-State Liquefaction

概要

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In order to improve the gas evolution rate during anaerobic digestion of coffee waste by two-phase methane fermentation with slurry-state liquefaction, the liquefaction and gasification processes were separately investigated. In the liquefaction process (including the acidification process), treatment at a pH above 6 had no major effects on the liquefaction and acidification rates. However, the VFA production rates were 880 and 320mg/l・g during mesophilic (37℃) and thermophilic (53℃) liquefaction, respectively. Mesophilic conditions were superior to thermophilic conditions in the liquefaction. With respect to the gasification process, a high TOC volumetric loading rate of 21g/l・d was achieved during thermophilic gasification. However, the mesophilic gasification did not yield stable data, even at a low TOC volumetric loading rate 2g/l・d. The gas yield was 1.7l/g TOC consumed during thermophilic gasification. The thermophilic liquefaction and thermophilic gasification reactors were connected in series and a two-phase experiment was conducted with the reactors at various volumetric ratios. The maximum gas evolution rate of 1.43l/l・d was achieved with a combination of a gasification reactor with a 0.45l working volume and a liquefaction reactor with 2l working volume. This rate was 1.7 times higher than the rate obtained in a previous study.
社団法人日本生物工学会の論文
1994-01-25