Digestates main characteristics and residual biodegradability: influence of waste origin and management of the digestion plant

Digestates have to be properly valorized as soil improvers or organic fertilisers in order to ensure good environmental and economic performance of the whole anaerobic digestion treatment scheme. Nevertheless, determinants of the digestates quality and digestates residual biodegradability have raised little interest even as they determine their conditions of storage, use or post-processing. The aim of the present study was thus to propose determinants of digestates quality and to assess their residual biodegradability and its impact in terms of further storage or post-treatment.

Five digestion plants were studied: 2 farm plants, 1 agro-waste centralized plant and 2 plants treating mainly urban biowaste. Digestates were sampled 5 times along the year: raw digestate (exit of the digester or post-digester), solid and liquid digestates (after phase separation). Samples were analyzed for chemical and biochemical parameters (C, N, BMP, OUR, etc.) and statistical analysis was performed to find correlation with waste origins, digestion process management, type of phase separation process, etc. Results showed that raw digestates quality is mainly influenced by the origin of the treated waste and by the way to manage the digestion process (dry or liquid) while solid and liquid digestates quality is largely influenced by the phase separation process performance. Residual biodegradability was generally low and depended from the digestion process efficiency. But it could be sufficient for further aerobic post-treatment. Interesting links between biodegradability and characterization of soluble organic matter biochemical fractions have also been proposed through this study.



Copyright: © European Compost Network ECN e.V.
Source: Orbit 2014 (Juni 2014)
Pages: 0
Price: € 0,00
Autor: Anne Trémier

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