How to preserve the energy potential of organic residues during storage? Focus on anaerobic digestion
Résumé
This work presents a set of long-term storage assays at laboratory scale for two different types of catch crops and cattle manures. Comparison between the impact of ensiling and open-air storage techniques on organic matter and energy preservation was performed. Effects of co-ensiling with cattle manure and several additives on silage quality were assessed as well. Aerobic storage led to methane potential losses of more than 80% after 3 months of storage for catch crop assays and around 74% for cattle manure after 4 months. Higher energy recovery rates were obtained after ensiling, strongly depending on the nature of the organic residue used. For both catch crops, at least 96% of methane potential was preserved after 3 months. In contrast, single-handedly cattle manure lost 46% of its methane potential during long-term ensiling. Conservation of cattle manure was successfully enhanced through co-ensiling with fermentation stimulants and inhibitors. The best storage performance was obtained while combining cattle manure with wheat straw and glucose at high concentrations, for which methane potential was fully conserved even after 4 months of co-ensiling. These results highlight a major advantage in using ensiling rather than open-air storage for these organic residues. Moreover, the use of precursors of organic acids as co-substrates improved silage quality of non-adapted biomass for ensiling, such as cattle manure. This work contributes to the optimization of biomass preservation before anaerobic digestion, which will have a major impact on the methane yield of agricultural biogas plants.
Origine : Fichiers produits par l'(les) auteur(s)
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