Abstract: A compact heat or mass transfer exchange column containing a plurality of vertically spaced-apart sections to define a column space therebetween and at least one integral collector-distributor device in the open space for the collection and distribution in the column of a downwardly flowing liquid. The device comprises a plurality of lateral collection and distribution troughs extending from the central channel or sump to distribute downwardly flowing liquid to a lower section. The lateral trough contains a plurality of removably secured, angled vane elements connected to the upper edges of the lateral troughs, the vanes extending over the open space between the lateral troughs to receive downwardly flowing liquid on the upper surfaces thereof and to direct the downwardly flowing liquid into the lateral troughs, and optionally a wall wiper ring to direct liquid from the internal walls of the column into the collector-distributor device.