Characterisation of the biodegradability of post-treated digestates via the chemical accessibility and complexity of organic matter

The stability of digestate organic matter is a key parameter for its use in agriculture. Here, the organic matter stability was compared between 14 post-treated digestates and the relationship between organic matter complexity and biodegradability was highlighted. Respirometric activity and CH4 yields in batch tests showed a positive linear correlation between both types of biodegradability (R2 =0.8). The accessibility and complexity of organic matter were assessed using chemical extractions combined with fluorescence spectroscopy, and biodegradability was mostly anti-correlated with complexity of organic matter. Post-treatments presented a significant effect on the biodegradability and complexity of organic matter. Biodegradability was low for composted digestates which comprised slowly accessible complex molecules. Inversely, solid fractions obtained after phase separation contained a substantial part of remaining biodegradable organic matter with a significant easily accessible fraction comprising simpler molecules. Understanding the effect of post-treatment on the biodegradability of digestates should help to optimize their valorization.

» Author: Géraldine Maynaud, Céline Druilhe, Mylène Daumoin, Julie Jimenez, Dominique Patureau, Michel Torrijos, Anne-Marie Pourcher, Nathalie Wéry

» Reference: Bioresource Technology, Volume 231

» Publication Date: 01/05/2017

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This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement N° 690103