Industrial water treatment is a most typical application of ion
exchange resins. Many types of water treatment system are known, and, depending on the
nature of raw water (river water, well water, etc) or on the water quality to be achieved,
an appropriate system design can be selected.
Followings are the basic treatment systems.
System
Softening
Ion-exchange resins
1 tower
softener
raw
water
SK
SK
Strongly acidic cation-exchange resin in Na form
The resin is regenerated with NaCl.
Demineraliation
2 bed
2 tower
raw
water
SK
SA
SK
SA
Strongly acidic cation-
exchange resin in H form.
Strongly basic anion-
exchange resin in OH-form.
Applied in small water treatment systems.
2 bed
3 tower
raw
water
SK
DG
SA
DG
Degasifier: CO2 is removed to reduce anionic load of the
anion-exchange resins.
Most commonly used in industrial applications
4 bed
5 tower
raw
water
WK
SK
DG
WA
SA
WK
WA
Weakly acidic cation-
exchange resin in H-form.
Weakly basic anion-exchange resin in free base form.
Used when hardness or total ion concn is high.
SK and WK resins are regenerated with a strong acid such as hydrochloric acid; SA and WA
resins are regenerated with a strong base such as caustic soda. All resins can be used
repeatedly.
Industrial water treatment
