This facility comprises a support (1) for the substrate, a pressing roll (2), capable of pressing the substrate against said support, a treatment unit positioned downstream of the pressing roll, with reference to the direction of travel of the substrate, said unit comprising injection means (37) for injecting a treatment gas towards said support and means (8) for transforming the surface of the moving substrate. According to the invention, this facility further comprises a containment cover (4) open in the direction of the support, this cover and this support defining an inner volume in which said treatment unit is received, this cover comprising a front wall called the upstream wall (42), facing towards said pressing roll, wherein the smallest distance (d2) between the end edge (42′) of said upstream front wall and the pressing roll, the smallest distance (d3) between said upstream front wall (42) and the treatment unit and the smallest distance (d1) between the upstream end (39) of the treatment unit and the support (1), are such that they define a recirculation volume (VR) for the treatment gas, defined by the end edge of said upstream front wall, the pressing roll, the support and the upstream end of the treatment unit.