Ion Exchange Technology
The exchange of charged particles called anions and cations is a premier technology used in the purification of water. Hard water containing a lot of calcium ions is treated over beads with negatively charged sodium ions. This results in the replacement of sodium ions by positively charged calcium ions and the water eventually gets softened, though with more sodium ions. Zeloites, made from silicates, are also used in our plants as they can hold plenty of cations. Similarly, there are anion exchange resins that are beds of polymer where cationic groups get attached to the surface.
This technology is primarily used for purifying ground water, leachate and surface water.