COUNTERCURRENT ION EXCHANGE AND ADSORPTION PROCESSES

In an ion exchange or adsorption process for liquid treatment involving cyclical upflow loading and downflow regeneration stages applied to a compact bed of strong electrolyte ion exchange resin (2) or of polymeric adsorbent resin is cleaned of fines and/or of solid contaminants from the treated liquid and/or segmentally washed without interrupting the cycle of loading and regeneration stages, by transferring part of the resin at or near one or other end of the bed, when in a regenerated state, into a separate container (13) wherein the resin is backwashed and returning the backwashed resin to the top of the bed before, and/or to the bottom of the bed during, the loading stage, resin removed from the bottom of the bed being returned to the bottom of the bed and resin removed from the top of the bed being returned to the top and/or bottom of the bed.