Method for treating an industrial effluent charged with aluminium using co2

The invention proposes a method for treating an industrial effluent which is charged with aluminium in order to eliminate all or some of the dissolved aluminium therefrom, comprising the implementation of the following steps: - the effluent to be treated is conveyed to a first zone, which is constituted, for example, by a tank, and in which a pH lower than 9.5 is maintained, and more preferably a pH between 6.5 and 8.5, and even more preferably between 7 and 8, so as to promote the precipitation of the aluminium in the form of aluminium hydroxide and thus make it easier to eliminate it; - a second zone is provided and a portion of the medium which is located in zone 1 is recirculated to zone 2, then the medium is returned from there to zone 1, and gaseous CO2 is injected into the recirculated medium; and - the solid particles which are formed in zone 1 are separated and discharged. The method is characterised in that, taking into account the recirculation of said medium into which CO2 has been injected, the quantity of dissolved CO2 available in zone 1 is 0.5 to 3 times greater, preferably between 1 and 1.5 times greater, than is necessary to precipitate the incoming effluent.