Ion Exchange process

China Steel Corporation India Private Limited
Demineralized Water supply
System(#400Area)
Name :- Jaypalsinh Boradhara
Emp Code :- Y00550
Dept. :- Water Treatment Operation Section

Water Purification
• Mainly impurities of Dissolved solids like
Ca+2,Mg+2,K+,Na+,Fe+2 and So4-2,No3-2,Cl- ,Co3-2,Hco3-
Are removed by Three methods as following.
• Distillation
• Filtration(Membrane filtration)
• Ion exchange De-mineralition

What is Demineralized Water?
Demineralized water also known as Deionized water, water that has had
its mineral ions removed. Mineral ions such as cations of sodium,
calcium, iron, copper, etc. and anions such as chloride, sulphate, nitrate,
etc are common ions present in water. Deionization is a physical process
which uses specially-manufactured ion exchange resins which provides
ion exchange site for the replacement of the mineral salts in water with
water forming H+ and OH- ions. Because the majority of water
impurities are dissolved salts, deionization produces a high purity water
that is generally similar to distilled water, and this process is quick and
without scale buildup.

DMW Process Flow chart on PLC

Preliminary Treatment of DM Process
Function:-The Activated Carbon filters are
installed to remove organic matter , Chlorine
,Suspended solid, smell and color .
At Plant location

Valve Tag No. Valve Description
ABV-4A01A/B01 Water Sampling Influent Valve
PBV-4A01A/B03 Backwash Inlet Valve (1)
PBV-4A01A/B04 Backwash Outlet Valve (1)
PBV-4A01A/B05 Backwash Inlet Valve (2)
PBV-4A01A/B06 Backwash Outlet Valve (2)
PBV-4A01A/B07 Fast Rinse Discharge Valve
ABV-4A01A/B08 Air Inlet Valve
ACF Valve Tag number and Description

ACF Backwash Procedure on PLC

Activated carbon filter Backwash process
Activated Carbon Filter Backwash is composed of 7 steps.
1.Set aside (60SEC) –– Its main purpose is to separate from water sampling state and enter backwash state.
2. Lower layer water backwash (40CMH) –– Activated carbon layer uses a large amount of water to make
activated carbon bed stir well, and bring away the damaged activated carbon powder and pollutant from
Activated Carbon Filter.
3. Upper layer water discharge (90SEC) –– Its main purpose is to prevent anthracite from being brought out
of the Filter by excessively great air during air backwash of anthracite.
4 Air backwash (3MIN) –– Let a large amount of air enter the upper layer of Activated Carbon Filter to stir
anthracite bed well, and bring the damaged powder and TDS to the upper layer of anthracite bed.
5 Upper layer water backwash (50CMH) –– Its main purpose is to discharge TDS and the damaged anthracite
powder.
6. Set aside (60SEC) –– Its main purpose is to stabilize the anthracite bed layer.
7. Fast Rinse (33CMH) –– Bring away the activated carbon powder and pollutant, which are left after
backwash and stirring at the lower layer of activated carbon bed, from Activated Carbon Filter so as to make
Activated Carbon Filter resume its working performance.

To Produce DM Water Cation exchange resin and Anion exchange resin
is used .
Cation exchange resin reaction
How DM Water is Produced?
• 3R-H(Resin) + Fe+3(Impurity) ---> R3Fe(Resin) + 3H+(Product)
• 2R-H(Resin)+ Ca+2(Impurity) ---> R2Ca(Resin) + 2H+(Product)
• 2R-H(Resin)+ Mg+2(Impurity) ---> R2Mg(Resin) + 2H+(Product)
• R-H(Resin)+ K+(Impurity) ---> RK(Resin) + H+(Product)
• R-H(Resin)+ Na+(Impurity) ---> RNa(Resin) + H+(Product)
• As mention above positive charge dissolved impurity is
exchanged with resin active H+ ions .

Cation exchanger
Function :- Cation exchanger contains Cation
exchange resin(SAC) which removes all positive
charged ions from feed water and releases H+ ions
in feed water.
At Plant Location

Degasifier Tower
Function:- In water demineralization, a Degasifier, or degasser, is often used to remove dissolved carbon
dioxide after Cation exchange. The most common degassers are of the so-called forced
draft or atmospheric type. One is represented below
H+ + HCO3-  Co2 + H2o

Anion exchanger
• Function :- Anion exchanger contains anion exchange resin(WBA&SBA) which removes all negative
charged ions from feed water and releases OH- ions in feed water.

Anion exchange resin reaction
• Anion exchange by WBA
• R-OH(Resin)+Cl-(Impurity) ---> RCL(resin)+ OH-(Product)
• 2R-OH(Resin)+So4-2(Impurity) ---> R2So4(resin)+ 2OH-(Product)
• R-OH(Resin)+No3-(Impurity) ---> RNo3(resin)+ OH-(Product)
• Anion exchange by SBA
• 2R-OH(Resin)+Co3-2(Impurity) ---> R2Co3(resin)+ 2OH-(Product)
• R-OH(Resin)+Hco3-(Impurity) ---> RHco3(resin)+ OH-(Product)
• As mention above negative charged dissolved impurity is exchanged with resin
active OH- ions .
• So, in Demoralization process H+ ions from Cation exchange resin and OH- ions
from Anion exchange resin is exchanged with water impurity. And produce DM
water as beloved.
• H+ + OH- ---> H2O
• Note:- SBA Resin can exchange all anion but feed water is pass through WBA first,
So only carbonate and bicarbonate will be exchange by SBA Resin.

• CA+2,Mg+2,K+,N
a+,Fe+2,Cl-,No3-,So4-
2,Sio2,Co3-2,Hc03-
CA+2,Mg+2,
K+,Na+,Fe+2
,Cl-,No3-
,So4-
2,Sio2,Co3-
2,Hc03-
H+,Cl-,No3-
,So4-
2,Sio2,Co3-
2,Hc03-
H+, Cl-,
No3-, So4-2,
Sio2, Co3-2,
Hc03-
H+,Cl-,No3-,So4-
2,Sio2,Co3-2 Flow
go into Anion
exchanger.
SBA
Co3-2
WBA
Cl-,No3-,So4-2
H+ + OH- = H2o
DMW
Sio2 leakage
Cation exchanger
Degasifier
Anion exchanger
Feed water
Product water
SCHEMATIC DIAGRAM OF DEMINRALITATION WATER
SYSTEM

Lets watch a small video of Ion exchange process

Types of Resin and application
• 1. Strong acid Cation resin (SAC)
(R-SO3-)SAC can exchange All positive charged Cation
like,Na+,K+,Ca+2,Mg+2,Fe+2,Fe+3
• 2. Weak acid Cation resin (WAC)
(R-COO-)WAC can exchange only Ca+2 associated with temporary
hardness like ca(hco3)2 and Na+,K+,Fe+2,Fe+3 is leakage
• 3. Strong base anion resin (SBA)
(R-N+ (CH3)3) ; (R-N + (CH3)2 CH3CH2OH) SBA can exchange
Co32(Carbonate),Hco3-(Bicarbonate)
• 4. Weak base anion resin (WBA)
(R-N (CH3)2) WBA can exchange only Cl-(Chloride),So4-2(Sulphate),
No3-(Nitrate)(Mineral acid)

How resin volume is decided?
• Raw water analysis
• Minerals concentration in mg/l
• Meq/l of minerals = [Concentration in mg/l ] /
[50mg/meq ]
• Ionic load (Cycle M3 * Total Cation or Anion meq/l)
• Resin volume (ionic load/resin operating capacity)

CSCI Raw water quality and DM Plant Design .

Meq/l of minerals as caco3 of Cation.
Ionic load : 4.100 meq/l * 599.6 (Cycle volume) : 2458 eq
Resin volume require : 2458 eq (Ionic load) / 1.64(Resin
operating capacity eq/l) : 1498 liter .

Meq/l of minerals as caco3 of WBA.
WBA Ionic load : 1.300 meq/l * 599.6 (Cycle volume) :
779.48 eq
Resin volume require : 779.48 eq (Ionic load) / 0.55(Resin
operating capacity eq/l) : 1417.23 liter .

Meq/l of minerals as caco3 of SBA.
• (4.1 meq/l ) Total anion – (2.8 meq/l ) Hco3- - (1.3 meq/l )
FMA + (.25 meq/l )Co2 + (.34 meq/l ) Sio2
• SBA Ionic load : .59 meq/l * 599.6 (Cycle volume) : 353.76
eq
• Resin volume require : 353.76 eq (Ionic load) / 0.55(Resin
operating capacity eq/l) : 643.20 liter .
Total Anion Resin volume : (1417.23 liter)WBA Resin volume
+(643.20 liter) SBA Resin volume = 2060 liter

Cation exchanger Valve Tag number and Description
Valve Tag No. Valve Description
ABV-4A02A/B01 Water Sampling Inlet Valve
ABV-4A02A/B02 Water Sampling Outlet Flow Control Valve
PBV-4A02A/B03 Dosing Inlet
PBV-4A02A/B04 Chemical Discharge Valve
ABV-4A02A/B05 Fast Rinse Valve
PDV-4A02A/B06 Water Sampling Valve
PDV-4A08A01 Diluted HCl Inlet Valve
PDV-4A08A02 HCl Dosing Outlet Valve
PDV-4A08A03 HCl Supplement Valve

Regeneration Details of Cation exchanger

Resin regeneration
• In process of Demineralization when resin is completely exhaust
then regeneration is require to achieve resin in active state .
• Cation exchange resin is achieved in active H+ state .
• Anion exchange resin is achieved in active OH- state.
• Cation exchanger resin regeneration
• R2Ca(exhaust resin)+ 2Hcl ---> 2RH(active resin)+ Cacl2(Calcium
chloride)(waste impurity)
• R2Mg(exhaust resin)+ 2Hcl ---> 2RH+ Mgcl2(Magnecium
• RNa(exhaust resin)+ HCl ---> RH+ Nacl(Sodium chloride)(waste
impurity)
• R2Fe(exhaust resin)+ 2Hcl ---> 2RH(active resin)+ Fecl2(Ferrous

Cation exchanger Regeneration Procedure on PLC

Cation exchanger Regeneration process
Cation Exchanger Regeneration is composed of 5 steps.
1. Set aside –– Its main purpose is to separate from water sampling state and
enter Regeneration state, and meanwhile, release pressure from the tank.
2 Dosing –– 32% of HCl is pumped by ejector of gauge tank to mix with dilution water to form
5% HCl. It enters Cation Tower to exchange for saturated cation resin. High-concentration HCl
replaces the Fe2+, Ca2+, Mg2+ and Na+ cations on resin and discharges them from the tank.
3. Slow Rinse –– Use dilution water to discharge superfluous chemical and the replaced cations.
Control the slow rinse time at a set value of 80 min.
4. Fast Rinse 1 –– Use a large amount of filter water for cleaning. It will reduce the small amount
of chemical left on resin layer. Control the fast rinse time at a set value of 5 min.
5. Fast Rinse 2 –– Carry out fast rinse together with Anion Tower until the
requirement of water quality of Anion Tower (conductivity <3 μs/cm) is met.

Anion exchanger Valve Tag number and Description
Valve Tag No. Description
ABV-4A04A/B01 Water Sampling Inlet Valve
ABV-4A04A/B02 Water Sampling Outlet Valve
PBV-4A04A/B03 Dosing Inlet Valve
PBV-4A04A/B04 Chemical Discharge Valve
ABV-4A04A/B05 Fast Rinse Valve
ABV-4A04A/B06 Fast Rinse Recycle Valve
ABV-4A04A/B07 Backflow Valve
PDV-4A04A/B08 Water Sampling Valve (1)
PDV-4A04A/B09 Water Sampling Valve (2)
PDV-4A10A01 Diluted NaOH Inlet Valve
PDV-4A10A02 NaOH Dosing Outlet Valve
PDV-4A10A03 NaOH Supplement Valve

Regeneration Details of Anion
excanger

Anion regeneration
• Anion exchange resin is achieved in active OH- state.
• Rcl(exhaust resin) + NaOH ---> ROH( regenerated resin) +
Nacl(Sodium chloride)(waste impurity)
• R2So4(exhaust resin) + 2NaoH ---> 2ROH( regenerated
resin) + Na2so4(Sodium sulphate)(waste impurity)
• RNo3(exhaust resin) + NaOH ---> ROH( regenerated resin) +
NaNo3(Sodium nitrate)(waste impurity)
• R2Co3(exhaust resin) + 2NaoH ---> 2ROH( regenerated
resin) + Na2Co3(Sodium carbonate)(waste impurity)

Anion exchanger Regeneration Procedure on PLC

Anion exchanger Regeneration process
Anion Exchanger Regeneration is composed of 6 steps.
1. Set aside –– Its main purpose is to separate from water sampling state and enter
Regeneration state, and meanwhile, release pressure from the tank.
2. Dosing 1 –– 45% of NaOH is pumped by ejector of gauge tank to mix with dilution water to
form 0.5~1.5% NaOH. It enters Anion Tower to exchange with saturated anion resin. 0.5~1.5%
NaOH replaces the SiO2,HCO3- and CL- anions on resin and discharges them from the tank.
3. Dosing 2 –– NaOH is pumped by ejector of gauge tank to mix with dilution water to form
3~4% NaOH. It enters Anion Tower to discharge the residual SiO2,HCO3- anions on resin from
the tank.
4. Slow Rinse –– Use dilution water to discharge the superfluous chemical and the replaced
anions. Control the conductivity of slow rinse water discharged to Chemical Discharge Outlet at
a set value (usually <500 μs/cm).
5. Fast Rinse 1 –– Use a large amount of Decationized water to wash the small amount of
chemical residual towards the outlet, and reduce the conductivity to that of the recycled water
(usually <500μs/cm).
6. Fast Rinse 2 –– Use Decationized water to wash chemical towards the outlet, and reduce the
conductivity to that of the water sample (usually<3μs/cm). Transfer the water produced in this
step to VC-3A01 for reuse.

Anion/Cation Resin Back wash V-4A06A
After service has been undergone for a period of time ,
Resin cracks for the reasons expansion, contraction and
pressure . Therefore , After a period of time, cation
exchange resin or anion exchange resin should be pumped
out of exchanger water wash and air wash the exchanger
to wash away the cracked resin and supplement new
resin .
This operation has to be carried out completely manually

Example of backwash of row A Cation exchanger
Step 1 : Resin transfer
First of all , transfer cation resin from the tower to anion / Cation resin backwash V-
4A06A . Since the tower uses a partition to separate from strong cation resin , a
description on strong cation resin is made below.
Steps :
Use metal hose to connect cation exchanger AC-02/04 with transfer pipe BW-11 the
join of the tower is the nozzle at lower part . Make sure that the pipe is connected well
; otherwise, a large amount of resin will be lost.
Open the Pneumatic valve PBV-4A02A03 of V-4A02A , manual valve Ac-02 , manual
valves BW-10 and BW-11 of V-4A06A , and manual valves BW-15 , BW-16 and BW-17
in dosing Area .Start the backwash regeneration pump P-4A05A/B . Due to pressure ,
resin is transfer from tower to backwash tank during this time, take sample from V-
4A06A , and send it to resin company to take lab taste .
After resin transfer is completed , close all the running pumps pneumatic valves and
manual valves.

Step 2 : Lower water level
Its purpose is to prevent resin from overflowing and avoid loss of resin
if water level is to high during air backwash .
Step :
Open manual valves BW-06 and BW-08 of anion /cation resins
backwash V-4A06A .
Discharge water to second window( Counting from top to the bottom)
close the manual valves BW-06 and BW-08
Note: Resin cannot be wash away if water level is not high enough ( it
should be at least 10 cm high in resin bed).

Step 3 : Air Backwash
Use air to remove pollutant on resin surface via friction and let the
damaged resin float on resin surface for easier water backwash
Step : Open the manual valve BW-01 and BW-05 to let air go into
backwash tank for washing .
The backwash time is around 5 min .
After the time is up, close all the open manual valves.
Set aside for 5 min sedimentation of resin bed

Step 4 : Water backwash
Inject water to the tank at the bottom to backwash the damaged resin out of the resin bed .
Steps : Open the manual valves BW-02 ,BW-03 and BW-05 start the backwash regeneration
pump P-4A05A/B .
Making use of upper water force lighter and damaged resin flows out with water through the
overflow pipe.
Adjust water flow by BW-02 to ensure the height of resin bed the height of resin bed cannot
exceed the potion at half of the top window of backwash tank otherwise resin will be
discharged.
The backwash time is around 30min the length of time is base on the quantity of damaged resin
being Overflown and discharge if there is still a large amount of damaged resin backwash time
should be lengthened .
after completion of backwash let resin sediment for around 10 min and close all the valves

Step 5 : Cleaning Resin transfer
After completion of Backwash resins is transfer back to exchanger by Backwash tank
this step use the ejector at the lower part of Backwash Tank to transfer resin via water
force .
Step: Dismantle the metal hose connected previously and seal the nozzle at the lower
part connect the dismantle hose with the nozzle at the upper part install AC-01,03
and check whether it is well connected so as to prevent loss of resin
Open the manual valves AC-01,03 of V-4A02A . Open the manual valves BW-07,BW-09
and BW-11 backwash tank open the pneumatic valves ABV-4-A02A05 of V-4A02A start
the backwash recycle pump P-4A06A/B .
Use slide glass to see whether transfer of resin is completed .
Close all the valves and stop the backwash Regeneration Pump.

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Ion Exchange process

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