A static mixer (M) for homogenizing a mixture of at least two liquids, especially after injection of an auxiliary liquid (L1) into a main liquid (L), includes: a closed container (1), with an inflow conduit (3) extending from a first wall of the container, up to the vicinity of the opposite wall, and an outflow conduit (4) which is substantially parallel to the inflow conduit, each conduit being provided with a device (3a, 4a) for connecting to the outside, through the wall of the container.