An apparatus for separating a component from a liquid is disclosed herein. The apparatus includes a plurality of cartridges disposed within a tank, the cartridges being mounted on a support member rotatable about a first axis, and each cartridge being rotatable about a second axis parallel to the first axis. The cartridges include a plurality of holes on an outer periphery thereof, and contain a supply of a granular ion exchange material capable of separating a desired component from the liquid. Means are provided for transferring liquid to be separated into the tank, and to discharge treated liquid from the cartridges to a location outside the tank.