State of the art of digestates in France and of their agronomic value

In France, as in several countries worldwide, anaerobic digestion is extensively promoted for the management of organic wastes from various origins like sludge from wastewater treatment plants, food-industry, agriculture (including animal manure and culture residues) and municipal solid waste (including household and green waste). Despite this strong promotion, the status of the digestate remains a problem since it is still considered as a waste by French regulation and can be used only for spreading on land or has to be transformed by composting. Since digestate composition may differ depending on the origin of the methanised substrates and since several different post-processing steps can be used to change its physico-chemical characteristics, we did a review of the different studies realized so far in France concerning anaerobic digestion main waste streams, digestates composition and agronomical value.