A device for producing and treating a gas stream is provided that includes an enclosure, of which the lower part is submerged in a liquid supply open at the top and includes at least one liquid intake opening. The submerged lower part of the enclosure contains a volume of this liquid and at least one opening for discharging a gas stream, positioned above the surface of the volume of liquid contained in the enclosure. The device further provides for injecting a gas stream including at least one injection conduit and extends in the upper part inside the enclosure outside the volume of liquid. During operation of the device an incoming gas stream is introduced to create an outgoing gas stream, treated by direct contact with said volume of liquid that is discharged outside the enclosure. A facility inclusive of the device and method of operation are also provided.