Facility for treating organic waste, in order to produce biogas and recover at least one portion of the biogas produced, said facility comprising: - a first tank comprising first separation means extending over a portion of the height of the tank, so as to define a first central compartment, or tube, a first peripheral compartment, or ring, closed in its upper portion, as well as a first compartment for stirring and biochemical exchanges exclusively providing the communication between these two compartments, in the bottom portion of the tank, the first compartment for stirring comprising first stirring means, - a second tank comprising second separation means extending over a portion of the height of the tank, so as to define a second central compartment, or tube, a second peripheral compartment, or ring, closed in its upper portion, as well as a second compartment for stirring and biochemical exchanges exclusively providing the communication between these two compartments, in the bottom portion of the tank, the second compartment for stirring comprising second stirring means, - means (ALIM) for feeding the waste to be treated, into the first ring, - means for transferring the partially treated waste, from the first tube to the second ring, in such a way that the first tube communicates at the upper portion exclusively with the top of the second ring, by a pipe, - means (EVAC) for discharging the treated waste, out of the second tube, - means (43, 44) for circulating the waste by pneumatic forcing, from the first ring to the second tube, these means for circulating comprising: - - a circulation gas line opening into the upper portion of the first ring and making it possible to create a sufficient pressure in the gas blanket of the ring in order to cause to rise in the first tube by pneumatic forcing a volume of substrate corresponding to that of the incoming materials, and - - a circulation gas line opening into the upper portion of the second ring likewise making it possible to proceed by pneumatic forcing in discharging from the second tube a volume of digestates corresponding to that of the incoming materials; where the facility is therefore arranged in such a way that the waste to be treated is transferred in succession from the first volume formed by the first ring, to a second volume formed by the first tube, then to a third volume formed by the second ring, then to a fourth volume formed by the second tube, before being discharged from the second tube by a pipe from the second tank, thanks to a semi-continuous feed with pneumatic forcing. - a first tank comprising first separation means extending over a portion of the height of the tank, so as to define a first central compartment, or tube, a first peripheral compartment, or ring, closed in its upper portion, as well as a first compartment for stirring and biochemical exchanges exclusively providing the communication between these two compartments, in the bottom portion of the tank, the first compartment for stirring comprising first stirring means, - a second tank comprising second separation means extending over a portion of the height of the tank, so as to define a second central compartment, or tube, a second peripheral compartment, or ring, closed in its upper portion, as well as a second compartment for stirring and biochemical exchanges exclusively providing the communication between these two compartments, in the bottom portion of the tank, the second compartment for stirring comprising second stirring means, - means (ALIM) for feeding the waste to be treated, into the first ring, - means for transferring the partially treated waste, from the first tube to the second ring, in such a way that the first tube communicates at the upper portion exclusively with the top of the second ring, by a pipe, - means (EVAC) for discharging the treated waste, out of the second tube, - means (43, 44) for circulating the waste by pneumatic forcing, from the first ring to the second tube, these means for circulating comprising: - - a circulation gas line opening into the upper portion of the first ring and making it possible to create a sufficient pressure in the gas blanket of the ring in order to cause to rise in the first tube by pneumatic forcing a volume of substrate corresponding to that of the incoming materials, and - - a circulation gas line opening into the upper portion of the second ring likewise making it possible to proceed by pneumatic forcing in discharging from the second tube a volume of digestates corresponding to that of the incoming materials; - - a circulation gas line opening into the upper portion of the first ring and making it possible to create a sufficient pressure in the gas blanket of the ring in order to cause to rise in the first tube by pneumatic forcing a volume of substrate corresponding to that of the incoming materials, and - - a circulation gas line opening into the upper portion of the second ring likewise making it possible to proceed by pneumatic forcing in discharging from the second tube a volume of digestates corresponding to that of the incoming materials;