Abstract: A liquid treating apparatus in which a vertically disposed tank has a series of longitudinally arrayed volume variable beds of liquid treatment material with fluid permeable partitions between the beds which move longitudinally in response to expansion and contraction of the beds. Forming a part of each partition and moving therewith is a fluid conduit system for collecting and distributing fluids between pairs of beds.

Abstract: The invention provides a method and apparatus for rinsing an object which has been removed from a chromium plating bath, and which has a source of chromium-containing anions thereon, while preventing the delivery of these anions to the environment. In carrying out the invention, chromium-containing anions are removed from the rinse water by an anion-exchange resin. The resin is periodically regenerated by backwashing it, delivering a dilute alkali metal hydroxide solution to the resin, delivering a more concentrated solution of alkali metal hydroxide to the resin, and by rinsing the resin. Effluent from the backwashing and the initial portion of the regeneration procedure is retained and later delivered to the resin. Effluent which contains a higher concentration of chromate ions, displaced from the resin, is delivered to a concentrated chromate solution storage tank.