Abstract: The filtering column is of the type comprising a perforated hollow metal tubular body (11) around which is disposed a stack (20) of metal rings (27) having deformations forming spacing elements and defining therebetween filtering interstices. The rings (27) have an inside diameter exceeding the outside diameter of the tubular body (11) so as to define between the inner periphery of each ring and the outer periphery of the tubular body a limited radial clearance (26) which does not exceed the elastic limit of each individual ring. The rings (27) constitute a stack (20) retained axially on the hollow body (11) in an undetachable manner with an axial clearance exceeding the aforementioned radial clearance.

Abstract: The apparatus comprises an enclosure divided into two compartments (13 and 14) by a partition wall (15) which has a circular row of apertures (16). Filtering elements (26) of hollow tubular shape are fixed in one (13) of the compartments by an open end on each one of the apertures (16). A rotary tubular arm (20) is mounted in the other compartment (14) and has an end which sweeps along the circle of apertures and coincides with each one of the apertures in turn. The arm has a device (21) at the rotatable end of the arm (20) for closing an aperture (16) of the partition wall (15) and the orifice (51) of the end of the arm and a suction pump (P) for applying a sudden counter-current hydraulic shock through the wall of each filtering element (26) in turn is provided.