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DRY FERMENTATION OF AGRICULTURAL SUBSTRATES
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.orgCitation: Pp. 325-332 in the Ninth International Animal, Agricultural and Food Processing Wastes Proceedings of the 12-15 October 2003 Symposium (Research Triangle Park, North Carolina USA), Publication Date 12 October 2003. 701P1203.(doi:10.13031/2013.15267)
Authors: F. Kaiser, V. Aschmann, M. Effenberger and A. Gronauer
Keywords: Dry anaerobic fermentation, animal waste, silage, batch system
The substrates used in this investigation were grass silage, green forage from landscape care andcattle dung. The production of gas was of 191.38 l/kg of organic dry matter (ODM), 188.64 l/kgODM and 218.48 l/kg ODM respectively. The content of methane in the gas was similar for thedifferent substrates, being an average of 51.89%. Comparing the production of the gas measuredwith the one simulated in wet fermentation, it was found that this investigated system (“Bioferm”) has an efficiency of 32% to 37%. This is consequent with the low degradability thatthe starch presented. These results were related to the use of the anaerobic pre-treatment and ofthe non-uniform percolate spray system.
It can be concluded that the anaerobic pre-treatment should be eliminated from the system. Thepercolate spray system should be improved to ensure that all the substrate is homogeneously wetduring the process. This will insure enough moisture to support an anaerobic microbial flora.
With this investigation it was possible to evaluate the efficiency of the “Bioferm” system of dryfermentation, and to determinate the improvements necessary to optimize the system."/>
It is a challenge to adapt anaerobic fermentation technologies for the direct treatment of organic
waste with solid contents of 20 % and more. While wet anaerobic digestion is well established,
research on dry anaerobic fermentation technology for agricultural substrates has been rather
scarce. Suitable materials are, e.g., grass and maize silage, dung, or green forage. A batch
fermentation system has been proposed where the input is stacked up in a gas-tight container and
left there for fermentation for about 50 days, while being sprayed intermittently with a heated,