Method for treating an industrial effluent charged with aluminium using CO2

A process for the treatment of an industrial effluent with aluminum for the purpose of removing all or part of the aluminum therefrom, comprising:

• carrying the effluent to be treated to a first zone, where a pH of less than 9.5 is maintained in the first zone, so as to promote precipitation of the aluminum in an aluminum hydroxide form and to thus facilitate its removal;
• providing a second zone, a recirculation of a part of the effluent located in the first zone to the second zone and then, from there, to the first zone, and an injection of gaseous CO2 into the recirculated effluent, are arranged;
• separating and discharging solid particles formed in the first zone;
• wherein, during the injection of gaseous CO2 into the recirculation effluent, the amount of dissolved CO2 available in the first zone is 0.5 to 3 times greater than the requirement necessary for the precipitation of an incoming effluent,
• wherein, during the injection of gaseous CO2 into the recirculation effluent, a sufficient residence time of CO2 is promoted with a pressure between 1.5 bar and 20 bar and a temperature ranging from 5 to 45° C. in the recirculation of the part of the effluent.