Abstract: A method for biologically treating effluent involves pouring the effluent into a basin in which mobile supports are submerged for developing a biofilm and for carrying out a treatment by fixed fluidized bed, aerating the effluent in the basin with a distribution of air flow, from the bottom of the basin, according to a floor configuration, the aeration supplying air for treating the nutrients, and keeping the supports moving, regulating the aeration to modulate the air flow depending on at least one parameter taken from the following parameters: the residual oxygen concentration, and/or the concentration of oxygen and the concentration of N—NH4, and/or the permitted load; modifying the distribution of the air supply from the floor configuration to a spiral flow configuration when the operating conditions result in an air flow lower than a minimum air flow required to keep the mobile supports moving in the floor configuration.

Abstract: A method for biologically treating effluent involves pouring the effluent into a basin in which mobile supports are submerged for developing a biofilm and for carrying out a treatment by fixed fluidized bed, aerating the effluent in the basin with a distribution of air flow, from the bottom of the basin, according to a floor configuration, the aeration supplying air for treating the nutrients, and keeping the supports moving, regulating the aeration to modulate the air flow depending on at least one parameter taken from the following parameters: the residual oxygen concentration, and/or the concentration of oxygen and the concentration of N—NH4, and/or the permitted load; modifying the distribution of the air supply from the floor configuration to a spiral flow configuration when the operating conditions result in an air flow lower than a minimum air flow required to keep the mobile supports moving in the floor configuration.