NOVELTY - The method comprises: introducing a partly solid organic matter into a first reaction space (1); performing hydrolysis of a part of the solid organic matter and acidogenesis of the organic matter in a center of the first reaction space; outputting the organic matter from the first reaction space by a first extraction unit (11); introducing the part of the organic matter from the first reaction space into a second reaction space (2); and performing acetogenesis and methanogenesis of the organic matter present within the second reaction space.    USE - The method is useful for methanization of a partly solid organic matter (claimed) for the production of a biogas such as methane.    ADVANTAGE - The method improves the yield of the biogas with good quality.    DETAILED DESCRIPTION - The method comprises: introducing a partly solid organic matter into a first reaction space (1); performing hydrolysis of a part of the solid organic matter and acidogenesis of the organic matter in a center of the first reaction space; outputting the organic matter from the first reaction space by a first extraction unit (11); introducing the part of the organic matter from the first reaction space into a second reaction space (2); performing acetogenesis and methanogenesis of the organic matter present within the second reaction space; and outputting a first digestate of the second reaction space by a second extraction unit. The output of the organic matter of the first reaction space is activated according to a hydrolysis degree of the solid part of the organic matter introduced in the center of the first reaction space. After the organic matter output from the first space of reaction, no solid part of the extracted organic matter is reintroduced into the first reaction space. The step of outputting the organic matter from the first reaction space is followed by a separation step in order to obtain a separate liquid organic matter and a separate solid organic matter. The separation step is followed by an introduction of the separate liquid organic matter into the second reaction space. The acetogenesis and methanogenesis of the separate liquid organic matter are carried out in the second reaction space. The separate solid organic matter is evacuated by an output for separate solid organic matter. The step of outputting the first digestate of the second reaction space is activated according to an abatement rate of the separate liquid organic matter within the second reaction space. The step of evacuation of the separate solid organic matter is followed by the introduction of the separate solid organic matter into a third reaction space. The hydrolysis, acidogenesis, acetogenesis and methanogenesis of the separate solid organic matter are carried out in the third reaction space. A second digestate in the third reaction space is output by a third extraction unit. The step of outputting the second digestate of the third reaction space is activated according to an abatement rate of the separate solid organic matter within the third reaction space. The step of outputting the first digestate of the second reaction space and the step of outputting of the second digestate of the third reaction space are activated independently. The part of the liquid organic matter present within the second reaction space is introduced into the first reaction space. The introduction of the separate liquid organic matter into the first reaction space is controlled in order to maintain within the first reaction space. The part of the separate liquid organic matter is introduced into the first reaction space before its introduction into the second reaction space. The introduction of the separate liquid organic matter into the first reaction space before its introduction into the second reaction space is controlled in order to maintain a pH of lower than 5.5 within the first reaction space. The part of the separate liquid organic matter present within the second reaction space is introduced into the third reaction space. An INDEPENDENT CLAIM is included for an apparatus for methanization of a partly solid organic matter.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of an apparatus for methanization of a partly solid organic matter.    First reaction space (1)    Second reaction space (2)    First extraction unit (11)    Measurement unit (60)    First controller. (70)