NOVELTY - The apparatus such as a flushed anaerobic digester for the treatment of effluent for the production of biogas, comprises two tanks (1, 2) connected with one another, a pipe (3) for the evacuation of sludges connected at bottom of the tanks, a pipe (4) for the evacuation of gas connected at top of the tanks, a recirculation pump (7), an evacuation pump, and a heat exchanger. The tanks comprise a zone for storing gas, a zone for the treatment of effluents with a fixed or movable support for adhering the bacteria, a zone for storing the effluent, and a settling zone.    USE - The apparatus such as a flushed anaerobic digester is useful for the treatment of effluent for the production of biogas.    ADVANTAGE - The apparatus effectively creates and maintains an optimal environment for the development and activity of anaerobic bacteria and controls the thickness of the biofilm thus ensuring a safe and rapid treatment of effluent and efficient production of biogas, and allows better management of sludge by promoting the settling of the effluent and can be easily cleaned by periodically creating the hydrodynamic constraints.    DETAILED DESCRIPTION - The apparatus such as a flushed anaerobic digester for the treatment of effluent for the production of biogas, comprises two tanks (1, 2) connected with one another, a pipe (3) for the evacuation of sludges connected at bottom of the tanks, a pipe (4) for the evacuation of gas connected at top of the tanks, a recirculation pump (7), an evacuation pump, and a heat exchanger. The tanks comprise a zone for storing gas, a zone for the treatment of effluents with a fixed or movable support for adhering the bacteria, a zone for storing the effluent, and a settling zone. The gas storage zone is present above the effluent treatment zone. A connection is provided between the gas storage zone and the tanks, and between the settling zone and the tanks. An insulating gate (5) and a control gate (6) are present in the connection between the settling zone and the tanks. INDEPENDENT CLAIMS are included for:    (1) a process for cleaning an effluent treatment apparatus; and    (2) a process for treating an effluent.    DESCRIPTION OF DRAWING(S) - The figure shows an effluent treatment apparatus for the production of biogas.    Tanks (1, 2)    Sludge evacuation pipe (3)    Gas evacuation pipe (4)    Insulating gate (5)    Control gate (6)    Recirculation pump. (7)