NOVELTY - The method comprises introducing (110) volumes of substrates into a strainer, humidifying (120) the volume to hydrolyze organic constituents, injecting (140) a leachate from the humidified volume into an anaerobic digester, sending a portion of the liquid from the digester back into the strainer, where the leachate is injected directly into the digester and beyond a threshold time value, performing aerobic fermentation (181) of the volume of substrates in the strainer, while stopping humidifying the volume of substrates, and performing aerobic maturation (182).    USE - The method is useful for recovering biomass or organic solid substrates (claimed), where the substrates are green wastes, papers and paperboards.    ADVANTAGE - The method is capable of: avoiding the need to handle the substrates in the strainer even during the aerobic maturation thus simplifying industrial exploitation and reducing application and maintenance of the recovery device; and generating less dust and bioaerosols thus improving heath of workers.    DETAILED DESCRIPTION - The method comprises introducing (110) volumes of substrates into a strainer, humidifying (120) the volume to hydrolyze organic constituents, injecting (140) a leachate from the humidified volume into an anaerobic digester, sending a portion of the liquid from the digester back into the strainer, where the leachate is injected directly into the digester and beyond a threshold time value, performing aerobic fermentation (181) of the volume of substrates in the strainer, while stopping humidifying the volume of substrates, performing aerobic maturation (182) by withdrawing the volume of fermented substrates, and positioning the volume in another aerobic place to obtain a stabilized compost whose water content is lower than a maximum value threshold and/or higher than a minimal value threshold. The leachate in the anaerobic digester is mixed with other liquid or pasty organic substrates coming from other sources with potential methanogens. The volumes of substrates include inorganic elements. The volume of fresh substrates is introduced into the strainer whose volume of substrates is withdrawn for the aerobic maturation. A liquid is added to access the organic constituents in the step of humidification. The method further comprises: extracting the liquid output from the digester and oxygenating the extracted liquid; separating the organic and inorganic elements; detecting methane and/or hydrogen sulfide in the strainer at a stage of ventilation of the strainer and at a time of the aerobic fermentation; and performing chemical analysis of the leachate and/or liquid used for the humidification. An INDEPENDENT CLAIM is included for a device for recovering biomass or organic and solid substrates.    DESCRIPTION OF DRAWING(S) - The figure shows a flow diagram of a method for recovering biomass or organic and solid substrates.    Introducing volumes of substrates into a strainer (110)    Humidifying the volume to hydrolyze organic constituents (120)    Injecting a leachate from the humidified volume into an anaerobic digester (140)    Performing aerobic fermentation of the volume of substrates in the strainer (181)    Performing aerobic maturation. (182)