2. 2
HARD WATER
Water containing calcium (Ca+2) and
magnesium (Mg+2), the hardness
minerals.
HARDNESS can be:
Calcium hardness
Magnesium hardness
Total hardness
3. 3
MEASURMENT OF HARDNESS
Milligrams per liter (mg/L)
Parts per million (ppm)
Grains per Gallon (gpg)
1 mg/L = 1 ppm
1 gpg = 17.1 ppm = 17.1 mg/L
4. 4
DEGREE OF HARDNESS
Soft Less than 1.0 gpg
Slightly Hard 1.0 to 3.5 gpg
Moderately Hard 3.5 to 7.0 gpg
Hard 7.0 to 10.5 gpg
Very Hard 10.5 gpg and above
5. 5
PROBLEMS CAUSED BY HARD
WATER
Decreases the efficiency of the
detergents.
Scaling of pipes, water heaters and
boilers.
6. 6
BENEFITS OF USING SOFT WATER
Soaps and detergents are used more
efficiently.
Materials and surfaces are cleaned better.
Scales in boilers and water heaters are
reduced.
Precipitates are eliminated from the canned
food products.
Softened rinse water does not leave scale.
Fabric washed in soft water lasts longer.
7. Principle
Ion exchange is a water treatment method where
one or more undesirable ionic contaminants are
removed from water by exchange with another
non-objectionable, or less objectionable ionic
substance. Both the contaminant and the exchanged
substance must be dissolved and have the same type
of electrical charge (positive or negative). A typical
example of ion exchange is a process called “water
softening” aiming to reduce calcium and magnesium
content. Nevertheless, ion exchange is also efficient
in removing toxic metals from water.
7
10. 10
RESIN
Plastic beads made of cross linked
polystyrene with functional groups
(sulphonates) that act as ion exchange sites.
The sulphonate group has a negative charge
allowing it to attract and hold (exchange)
positive ions or cations such as H+, Ca+2,
Mg+2, Fe+2, Na+.
12. RESIN BEAD
Cation resin
bead attract
and hold
positively
charged ions.
Those ions
remain on the
bead until the
bead
encounters
other ions for
which it has a
greater affinity.
13. Resin bead
releases Na+
and absorbs
Ca+2 and
Mg+2 ions for
which it has
a greater
attraction.
Ions are not
destroyed or
changed
chemically;
they are simply replaced on the resin bead.
This process is known as ion exchange.
14. ION
EXCHANGE
Resin beads attract Ca+2 and Mg +2 ions and
release Na+
Water has been softened because the Ca+2 and
Mg +2 concentrations, which cause water
hardness have been reduced.
15. After a vast
number of Ca+2
and Mg+2 ions
have become
attached to the
resin beads, and
most of the Na+
ions have been
released, the
resin can no
longer soften
the water.
If no new chemical reaction is set, the incoming
Ca+2 and Mg+2 ions flow untouched through the
unit because there is no room for them on the
resin beads.
16. The reaction can
be reversed by
greatly
increasing the
concentration of
sodium in the
solution.
Reverse process
drive the Ca+2
and Mg+2 ions off
the resin beads
and replace them
with Na+ ions.
This process is
called
REGENERATION.
17. REGENERATION
At appropriate time, the resin beads are
washed with a strong solution, also known
as a BRINE SOLUTION.
Although the resin beads prefer Ca+2 and
Mg+2 ions, the excessive concentration of
Na+ ions overcomes this affinity.
The Ca+2 and Mg+2 are forced off of the resin
beads and are discharged to waste.
The resin beads are ready to remove more
Ca+2 and Mg+2 from the water.
The degree to which the resin is converted is
dependent upon the concentration of sodium
in the brine.
18. The softening reaction is given as:
2RNa+ + Ca+2 RCa+2 + 2Na+
2RNa+ + Mg+2 RMg+2 + 2Na+
The reverse reaction is give as:
2RNa+ + Ca+2 RCa+2 + 2Na+ High Sodium
Concentration
2RNa+ + Mg+2 RMg+2 + 2Na+ High Sodium
Concentration
NOTE: R represents the resin macro-molecule.
19. 19
OPERATIONAL MODES
In practice softeners can be
In service
Exhausted and waiting for regeneration
In regeneration
In standby
Bypassed and out of service
20. 20
BRINING
The resin limited exchange capacity
must be restored periodically through
process known as REGENERATION.
Regeneration can be controlled
manually or automatically.
The frequency of regeneration depends
on time (TIME REGENERATION) or
quantity of produced water (DEMAND
REGENERATION).
21. 21
BRINE MAKING
A brine tank is plastic or fiberglass tank
with a perforated salt platform.
Granular salt is added to a brine tank.
A Brine valve keeps the tank filled with
water to a preset level.
The solid salt is in contact with the
water above the platform and thus
dissolves in the water.
Saturated brine is 26% salt by weight.
22. 22
BRINE DILUTION
Experience has shown that using a 10%
brine solution minimizes salt usage.
To create a 10% brine solution the
brine is mixed with fresh water through
an eductor.
The eductor must be matched to the
softener size to create the right amount
of diluted brine.
23. 23
BRINE APPLICATION
The regeneration reaction is much
slower than normal softening.
Suggested flow rate for the brine is 0.25
to 0.9 gpm/ft3
It requires a significant contact time
between the resin and the brine.
Suggested duration for the brining is 30
to 60 minutes applying 4 to 10 lb of salt
per 1 ft3 resin.
24. 24
TYPES OF WATER SOFTENERS
Manual
Semi-Automatic
Fully Automatic
Demand Initiated Regeneration
25. 25
MANUAL
The owner or the operator initiates
some or all of the steps in the softener
operation.
26. 26
SEMI - AUTOMATIC
The semi-automatic units require only
the regeneration cycle to be initiated by
the operator.
All necessary steps of regeneration and
return to service are handled by the
softener controls.
27. 27
FULLY AUTOMATIC
The fully automatic softener is usually
equipped with a timer, which
automatically initiates the regeneration
cycle and every step in the regeneration
process.
The regeneration is usually done during
the periods of low water usage, such as
hours between midnight and 4 a.m.
29. 29
Ion exchange water softening is an effective
method for reduction of hardness and other
ions in a water supply.
The cost is small in comparison to the benefits
received.
30. 30
BENEFITS
Benefits of using water softener:
Extends the life of water-using appliances,
water heaters and pipes.
Increases savings in detergents, soaps,
shampoos, and other cleaning agents.
Lowers fuel cost. $$$
31. 31
Considered as a luxury item by some, an ion
exchange water softeners are recognized as
a necessity by the millions who use them.
