A method for treating an aqueous effluent comprising at least one dissolved gaseous compound, by partially separating said compound from said effluent, in order to obtain a treated aqueous phase.In the method, an upflow liquid column of the aqueous effluent is established by injecting and distributing into said column, at the bottom, a gas phase less rich in said compound than the aqueous effluent, for example air or oxygen, said gas phase being distributed in the column in the form of bubbles where the volume increases upward. A mixed liquid/gas stream is obtained at the top. The mixed liquid/gas stream is then separated into a liquid stream constituting the treated aqueous phase, and an offgas stream enriched with said gaseous compound, where the mixed liquid/gas stream is later separated under vacuum by establishing a gas headspace between the liquid stream and the gas stream, and by aspirating the latter.