Ion exchange process

Claim 1

A process for the treatment of a fluid, which comprises passing a fluid to be treated through an inlet in a treatment tank in one direction, said tank being substantially filled with ion exchange resin particles to effect ion exchange between the fluid to be treated and said particles, regenerating the ion exchange particles in the same treatment tank on depletion of their ion exchange activity by passing a solution of regenerant in the direction opposite the direction of the fluid to be treated, and removing contaminants which accumulate in and on said resin particles during passage of said fluid or said regenerant by backwashing in a tank separate from said treatment tank by portionwise removal of portions containing up to one-third of all of said resins containing said contaminants through an outlet provided at the end of said treatment tank opposite the end at which said regenerating fluid enters the tank, transporting each removed portion of said resins containing said contaminants into the backwash tank, backwashing the transported resins therein, returning said backwashed resins to said treatment tank through an inlet at the opposite end of said treatment tank from which said resins were removed for backwashing and repeating said transporting and returning of successive portions until all of said resin particles have been backwashed and returned to substantially the same original position in the treatment tank, the resins in the vicinity of said outlet being substantially depleted of their ion exchange activity prior to said backwashing.