Long-Term Assessment of Temperature Management in an Industrial Scale Biogas Plant

Abstract

Temperature management is one of the primary considerations of biogas plant operation, and influences physical and biochemical processes. An increase in the temperature leads to an increase in the hydrolysis rate of the feedstock, while it can inhibit microorganisms taking part in different stages of anaerobic digestion. Because of the complexity of the biochemical processes within the anaerobic digestion process, there is a lack of knowledge about the effects of temperature and temperature change on efficiency. Moreover, the impact of stirring directly affects the temperature distribution in the anaerobic digestion reactors. In this study, the temperature management in an industrial-scale biogas plant was examined, and the effect of small temperature changes (from the operation temperature 42 °C) on the efficiency was studied in a laboratory under two different conditions: with stirring (at 40 and 44 °C) and without stirring (at 40 and 44 °C). The examination results from the biogas plant showed that heat transfer in the reactor was not sufficient at the bottom of the digester. Adaptation of the post-digester samples to the temperature changes was more challenging than that of the digester samples. From digestate samples, higher biomethane generation could be obtained, resulting from sufficient contact between microorganisms, enzymes, and substrates. Overall, differences between these changing conditions (approx. 6 NmL CH4 g VS−1) were not significant and could be adapted by the process.

Analysis Phase of Lean Six Sigma Methodology with Scaled-Down Laboratory Experiments for an Industrial-Scale Biogas Plant

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