Abstract: A vacuum cleaner wherein a mobile housing contains a tank for a supply of liquid and is connected with a first tube which supplies liquid to a brush serving to scrub and wet a surface to be treated. The brush is further connected with or adjacent to the inlet of a hose which sucks liquid, together with air and solid constituents, into the housing. Coarse solid constituents are segregated by a perforated belt which allows air, liquid and smaller solid particles to enter an upright separating and conveying unit having an air separating device at its lower end, a liquids-solids separating centrifuge in the median portion and a multi-stage compressor at its upper end. Air which is separated from liquid and solid constituents is drawn into the compressor which discharges such air into the atmosphere. The centrifuge has a stator surrounding a hollow rotor which contains a cylinder and a bottom wall defining a compartment which receives clean liquid from above.