Deionizers

Deionizers are ion exchange equipment that consists of cationic bed, anionic bed and a combination of both (mixed bed) to meet the requirement of high purity water for process / utility applications. The equipment separately removes the cations and anions in various units that involve usage of strong acid cation, weak acid cation, weak base anion & strong base anion units. The quality and result of deionization process depends on the characteristics of raw water, ratio of its contents, quality of treatment and the capacity of plant.


Strong acid cations / weak acid cations are employed to treat all types of cations from the raw water (Ca++, Mg++, Na+, K+ etc.). A deionizer unit comprises of a MSRL / FRP vessel that is internally fitted with bottom collecting system and inlet distributor and externally with isolation valve and frontal pipe work. The unit is charged with cation resin that is regenerated with acid (HCl / H2SO4) after its exhaustion, usually engineered for once or twice in a day.

Mixed Bed (MB) units have found to be suitable for polishing of treated water from strong base anion unit or RO plant. The unit produces ultra pure water that is needed for high pressure boiler feed water applications, micro-electronics and semi-conductor industry applications. During this process, the cation and anion resins are mixed in a single vessel and the water is traveled through a resin bed wherein the exchange of ions takes place.

Deionization Process
In the context of water purification, ion-exchange is considered to be a reversible and rapid process wherein the impurity ions present in the hard water are replaced by ions that are released by an ion-exchange resin. The impurity ions are absorbed by the resin, that must be periodically regenerated to restore the earlier ionic form. An ion is an atom or a group of atoms with an electrical charge. Positively-charged ions are known as cations and are usually metals, while the negatively charged ions are known as anions and are usually non-metals. The two most common types of deionization processes are:

• Two-bed deionization
• Mixed-bed deionization

Advantages
Some of the important advantages of modern day deionizers include -

• Easy to use and operate.
• Low cost per gallon of effluent produced.
• Quick and efficient production of usable effluent.
• Superior water purity if the correct resins are used.