NOVELTY - Apparatus for producing biogas comprises at least one anaerobic reactor provided with a loading section for organic material (M) and reaction chambers (4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b), arranged in line and connected one to each other by deflectors (79) provided with lower and upper alternate passages, for the outflow of organic material through each of chamber, and conveyor to convey the biogas produced within the reaction chambers outside of the reactor. The anaerobic reactor comprises recirculation unit for recirculating organic material between the chambers.    USE - For producing biogas (claimed).    ADVANTAGE - The present apparatus avoids use of a solid sedimentation final compartment, and utilizes solid recirculation unit which directly allows recirculation between the chambers delimited by the deflectors. Such recirculation unit allows the blending and the recirculation of the sludge from the downstream compartments towards the upstream compartments with respect to the direction of the influent flow in order to improve the results in the various biological stages of the anaerobic digestion process and increase the biogas productivity, and reduces the sludge production since sludge is consumed more effectively and with higher yield. Also the present apparatus is structurally simple and achieves reliable biogas production.    DETAILED DESCRIPTION - Apparatus for producing biogas by anaerobic digestion of organic material (M), comprises at least one anaerobic reactor provided with a loading section for organic material and reaction chambers (4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b), arranged in line and connected one to each other by deflectors (79) provided with lower and upper alternate passages, for the outflow of organic material through each of chamber, and conveyor to convey the biogas produced within the reaction chambers outside of the reactor. The anaerobic reactor comprises recirculation unit for recirculating organic material between the chambers. The recirculation unit comprises, outside of the reactor, at least one main line fluidically connecting reaction chambers one to each other, at least one or more inflow/outflow lines (90) for said organic material connected, at a first end (90a), to the main line and at least a second end (90b), to the chambers, at least one recirculation pump for the organic material operating within the main line and/or inflow/outflow lines, and valve for connecting by control the reaction chambers to the main line of fluidic connection. The apparatus comprises at least one pre-treatment tank (13) of the organic material and at least one line (14) for the controlled supply through the loading section of the reactor with the organic material deriving from the pre-treatment tank. An INDEPENDENT CLAIM is included for producing biogas by using the production apparatus involving: loading the reactor with the organic material; carrying out the crossing of reaction chambers by the organic material; and recirculating organic material contained in the reactor, in a controlled way between the chambers.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of the hydraulic circuit of the apparatus for producing biogas.    Reaction chambers (4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b)    Pre-treatment tank (13)    Lagoon (27)    Deflectors (79)    Inflow/outflow lines (90)    First end (90a)    Second end (90b)    Special floating filter (95)    Heating unit (150)    Organic material (M)