The invention relates a device for suction of waste and contaminating substances from the ground of the type used in machines for cleaning roads and similar comprising a suction pipe (2) and a recirculation pipe (3), the device comprising: an inlet aperture (2a) of the suction pipe (2a) and an outlet aperture (3a) of the recirculation pipe (3); the outlet aperture (3a) being a slot surrounding the inlet aperture (2a) near the ground; the device further comprising a system for adjustment (12) of the distance from the ground consisting of an articulated quadrilateral (13), a fluid dynamic cylinder (14) and at least one castor (15) in contact with the ground.