TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Device: The methanization apparatus also comprises a separation unit capable of separating an entering organic matter into a separated liquid organic matter and a separated solid organic matter, the separation unit being inserted between the first extraction unit and the second inlet, the entering organic matter originating from the first extraction unit, the separated liquid organic matter feeding the second inlet, and the separated solid organic matter being directed to an outlet for separated solid organic matter. It comprises second controllable extraction unit designed for extracting the digestate from the second space via the second outlet, second measuring unit for measuring a degree of abatement of the separated liquid organic matter contained in the second space, a second controller having a second measuring inlet connected to the second measuring unit and a second control outlet connected to the second extraction unit, the second controller being configured for controlling an activation of the second extraction unit according to a degree of abatement provided by the second measuring unit. It also comprises a third reaction space designed for carrying out a hydrolysis, an acidogenesis, an acetogenesis and also a methanogenesis of separated solid organic matter and comprising a third inlet for organic matter and also a second outlet for a digestate, the third inlet for organic matter being connected to the outlet for separated solid organic matter, the separated solid organic matter originating from the outlet for separated solid organic matter, the separated solid organic matter feeding the third reaction space, third controllable extraction unit designed for extracting the digestate from the third space via the second outlet for a digestate, third measuring unit for measuring a degree of abatement of the separated solid organic matter contained in the third space, a third controller having a third measurement inlet connected to the third measuring unit and a third control outlet connected to the third controllable extraction unit, the third controller being configured for controlling an activation of the third extraction unit according to a degree of abatement provided by the third measuring unit. The second reaction space is a reactor which accepts a load greater than or equal to 5 kg VM/m3.day. The methanization apparatus comprises a first introduction unit for introducing the separated liquid organic matter present within the second reaction space into the first reaction space. It also comprises a second introduction unit for introducing the separated liquid organic matter into the first reaction space; and a third introduction unit for introducing the separated liquid organic matter present within the second reaction space into the third reaction space.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The step of discharge of the organic matter from the first reaction space is followed by a separation step in order to obtain a separated liquid organic matter and a separated solid organic matter, the separation step being followed by introduction of the separated liquid organic matter into the second reaction space, an acetogenesis and a methanogenesis of the separated liquid organic matter is carried out in the second reaction space, and the separated solid organic matter is evacuated via an outlet for separated solid organic matter. The step of discharge of the first digestate from the second reaction space is activated according to a degree of abatement of the separated liquid organic matter within the second reaction space. The step of evacuation of the separated solid organic matter is followed by the introduction of the separated solid organic matter into a third reaction space, a hydrolysis, an acidogenesis, an acetogenesis and a methanogenesis of the separated solid organic matter are carried out in the third reaction space, and a second digestate is discharged from the third reaction space via a third extraction unit. Step of discharge of the second digestate from the third reaction space is activated according to a degree of abatement of the separated solid organic matter within the third reaction space. The step of discharge of the first digestate from the second reaction space and the step of discharge of the second digestate from the third reaction space are activated independently of one another. At least a part of the liquid organic matter present within the second reaction space is introduced into the first reaction space. Introduction of the separated liquid organic matter into the first reaction space is controlled in order to maintain, within the first reaction space, a volatile fatty acid concentration below an acidogenesis inhibition threshold. At least a part of the separated liquid organic matter is introduced into the first reaction space before its introduction into the second reaction space. Introduction of the separated liquid organic matter into the first reaction space before its introduction into the second reaction space is controlled in order to maintain a pH below 5.5 within the first reaction space. At least a part of the separated liquid organic matter present within the second reaction space is introduced into the third reaction space. EXAMPLE - No suitable example given.