Device for injecting fluid into a liquid, method for cleaning said device, and effluent treatment installation

A device for injecting a secondary fluid (F) into a main liquid (L), comprising:

• a first part able to convey the secondary fluid (F) in a substantially longitudinal direction (Z);
• a second part able to eject the secondary fluid (F) from the device, so as to inject said secondary fluid into a main liquid (L), said second part being in fluidic connection with the first part and comprising an open end;
• the device comprising at least a first position, referred to as the low position, and a second position, referred to as the high position, and further comprising a positioning means able to position the device in a position comprised between the first position and the second position, the first and second positions being defined with respect to a distance between the open end of the second part and a reference surface situated in a transverse plane, a minimum distance corresponding to the first position and a maximum distance corresponding to the second position, further comprising a base having a first surface forming the reference surface and situated facing the second part,
• the open end of the second part being configured in such a way as to have at least one point of contact with the base when the device is in the first position (Z1), while still allowing the secondary fluid (F) out.