Application of ion exchange technology in water treatment

The global population is increasing and because of this, the world may experience great fresh water scarcity. Our water resources are limited and, hence, water treatment and recycling methods are the only alternatives for getting fresh water in the coming decades. Therefore, there is a great need for the development of a suitable, inexpensive and rapid wastewater treatment techniques and reuse or conservation methods in the present century. Ion exchange technology has grown tremendously in the last 100 years. These technologies have found their way into many markets that have made life in America much more comfortable, relative to the ability to resolve water problems that at one time required laborious effort to treat. Once treated, that water could be used to manage domestic households, water livestock, improve milk production for dairies, high-quality feedstock, for power and steam plants and many other applications requiring effective water treatment. The next 100 years will hopefully produce even more advancements, like research currently under way for ion exchange membranes that are electrically regenerated, instead of using salt, which is typical of legacy and current water softeners. Like the early pioneers who helped to establish water treatment, there are new pioneers applying the experience of those who have come before, advancing those technologies to launch the latest ion exchange technology. Most ion-exchange systems contain containers of ion-exchange resin that are operated on a cyclic basis. During the filtration process, water flows through the resin container until the resin is considered exhausted. That happened only when water leaving the exchanger contains more than the desired maximal concentration of the ions being removed. Resin is then regenerated by sequentially backwashing the resin bed to remove accumulated solids, flushing removed ions from the resin with a concentrated solution of replacement ions, and rinsing the flushing solution from the resin. Production of backwash, flushing, and rinsing wastewater during regeneration of ion exchange media limits the usefulness of ion exchange for wastewater treatment. Water softeners are usually regenerated with brine containing 10% sodium chloride. Aside from the soluble chloride salts of divalent cations removed from the softened water, softener regeneration wastewater contains the unused 50 –70% of the sodium chloride regeneration flushing brine required to reverse ion-exchange resin equilibria. Deionizing resin regeneration with sulfuric acid and sodium hydroxide is approximately 20–40% efficient. Neutralized deionizer regeneration wastewater contains all of the removed ions plus 2.5–5 times their equivalent concentration as sodium sulfate. In this study, application of ion exchange technology in water treatment it was discussed.

Keywords:

water treatment , Ion exchange technology , ion exchange membranes , ion-exchange resin