2

TABLE OF CONTENT

Chapter 1 .......................................................................................................................................................... 1

Process Description ..................................................................................................................................... 1

Chapter 2 .......................................................................................................................................................... 3

Operation of the Downflow unit .................................................................................................................. 3

Chapter 3 .......................................................................................................................................................... 6

Operation of Upflow unit ............................................................................................................................. 6

Chapter 4 .......................................................................................................................................................... 8

Quality of water from each Unit ................................................................................................................... 8

Chapter 5 .........................................................................................................................................................10

Water analysis .............................................................................................................................................10

Chapter 6 .........................................................................................................................................................17

Troubleshooting ..........................................................................................................................................17

1

Chapter 1

Process Description

1.0 Demineralizer Demineralization or deionization is the process of removing dissolved salts from water by

using Ion Exchange Resin . Basically Ion exchange demineralization is a two step process

with both Cation and Anion resin . The raw water called influent water is first passed

through the Cation resin bed containing SAC Resin in H + form . Ca , Mg & Na are

removed and the salts are converted to their respective acids .The corresponding acid

containing anions like Cl , SO4 , NO3 are removed by passing the cation effluent through

Anion column containing Anion resin in Hydroxyl Form. The hydrogen ion from cation

neutralizes the hydroxyl ion and produces pure water.

Ion exchange is an equilibrium reaction which is reversible . In the hydrogen cation Resin

, Cations like Ca , Mg are exchanged for H ions. After some period The resin is not able

to exchange any more ions. The bed is exhausted . The Resin has to be brought back to

its original form . This is done by the regenerating the resin with strong acid and the

process of restoring the resin back to its original condition is called

Regeneration. Similarly the Anion resin is restored back after exhaustion by regenerating

it with Alkali.

CaCl2 Ca HCl

R SO3 H + MgSO4 R Mg +

NaCl Na H2 SO4

Ca CaCl2

R Mg + HCl R H + MgCl2

Na NaCl

Similarly For Anion Resin

HCl Cl

R OH + H2 SO4 R SO4 + H2 O

H2CO3 CO3

Cl Cl

R SO4 + NaOH R OH + Na SO4

CO3 CO3

It is more economical to remove CO2 by mechanical means i.e. by degasser .

2

Technical Data Sheet

Type Up flow / down flow

Parameters unit SAC WBA SBA DGT DGWT

Diameter

mm 1000

Diameter

M

Area

M2

Bed depth

M

Height (HOS)

M

Resin Type

Liters

Resin Volume

Chemicals required

as 100%

Acid

Caustic

Kgs

OBR

M3

Min treatment flow

M3/ Hr

Max treatment flow

M3/ Hr

Service cycle

M3/ Hr

Normal flow

M3/ Hr

Regeneration Flow

M3/ Hr

Backwash flow

M3/ Hr

Slow rinse flow

M3/ Hr

Fast rinse flow

M3/ Hr

Maximum pressure

Kg/cm2

Minimum Pressure

Kg/cm2

3

Chapter 2

Operation of the Downflow unit

2.1 Service start up

SAC

Open Main inlet valveV1 & Air Release ValveV6 once water starts coming from V6,

Close V6.

Open rinse outlet valve V5 and rinse the unit for 5 to 10 minutes and take a sample

of water.

Test for FMA and Hardness and if okay close V5 and open the outlet valve V2

Degasser

Start degasser blower before opening the cation outlet valve. Let the degasser sump get

filled.

SBA

Once the degasser sump is filled open SBA main inlet valve V1 & Air Release Valve

V6. Once Water starts coming from V6, Close V6

Open SBA drain inlet valve V10. The unit is Rinsed till the specified conductivity is

obtained. Then close Rinse outlet valve V10 and open SBA Outlet Valve V2

Now the entire System is in Service

V1 INLET VALVE

V2 OUTLET VALVE

V3 BACKWASH INLET VALVE

V4 BACKWASH OUTLET VALVE

V5 RINSE OUTLET (DRAIN OUTLET)

V6 AIR RELEASE

V7 POWER WATER INLET VALVE

V8 SUCTION VALVE

V1 V4

V3 V2

V5

V6

V1 V4

V3 V2

V5

V7

V8

SAC

DGT

DGWT

SBA

4

After the DM plant has given Specified quantity of Treated Water Or When the

conductivity Of SBA outlet water increases the plant is stopped and both the cation &

Anion units are put into regeneration . The Regeneration steps are as follows .

2.2 Regeneration After the unit has given specified quantity of treated water , it has to be regenerated.

Backwash

Open V3 & V4 . After 10 minutes close V3 & V4. Once should be careful with this

operation because resin can escape if flow rate is very high.

Injection

Required quantity of chemical is taken in chemical measuring tank and water is added to

make the chemical of required concentration.

1) Open power water valveV7 and open drain valve V5

2) Slowly open suction valve V8 and the brine should be injected in 20- 40 minutes

3) Close V8 and all water to pass trough for some time to flush out the pipeline.

4) Close V7 & V5

Final Rinse

Open V1 and Valve V5 and after 20 minutes start checking the quality of water and if

satisfactory close valve V5 and open V2 to take the unit into service.

5

INLET TO ION EXCHANGE UNIT

Chemical

Tank

ION

EXCHANGE

V1 V4

V3 V2

V5

Outlet

V7

V8

6

Chapter 3

Operation of Upflow unit

3.1 Service start up

SAC

Open main inlet valveV1 and final rinse valveV4 and rinse the unit for 5 to 10 minutes

and take a sample of water.

Test for FMA and Hardness and if okay close V4 and open the outlet valve V2

Degasser

Start degasser blower before opening the cation outlet valve. Let the degasser sump get

filled.

SBA

Once the degasser sump is filled open SBA main inlet valve V1 and final rinse valveV4

and rinse the unit till the specified conductivity is obtained. Then close rinse outlet valve

V4 and open SBA outlet Valve V2. Now the entire system is in Service

3.2 Regeneration In upflow system the regeneration is always counter current i.e. the regeneration flow is in

the opposite direction of service flow.

Injection

Open power water Valve V5 and Drain Valve V3

Open Chemical injection valve V6 in such a way that the Chemical is injected in 20—

40minutes

Slow Rinse After the chemical (acid/caustic) has been injected close chemical suction Valve V6.

After 20—40minutes Close V5 & V3

Final rinse

a) Open V1 and V4

b) Check the quality of water from the unit at the outlet of V4.

c) If satisfactory close V4

d) If the unit has to be taken for service open V2 or close the pump

7

Regeneration line

Ion exchange

unit

V1 V3

V4

V2

V5

V6

chemical

Tank

8

Chapter 4

Quality of water from each Unit

4.1 Strong Acid cation 1. It will contain free mineral acidity (FMA ) nearly equal to equivalent Mineral

acidity (EMA) in the feed water.

2. It also contains free CO2 generated by the alkaline salts present in raw water.

3. Hardness of cation effluent will be nil.

4. The only cation from the feed that is present in the effluent is the sodium ion that has

slipped through column .

5. The difference between the EMA in the feed and the FMA in the effluent gives the

sodium slip from the cation unit .

6. The sodium slip from cation unit is a function of Regeneration level, the sodium

content of the raw water and the EMA of water .

7. Therefore For a given water & Regeneration level the sodium slip is fixed. This is

the average value of the sodium slip over a cycle .

8. The actual slip characteristics shows high slip at the start of a run and thendrops to

a constant value for a major portion of the run and then rises again near exhaustion .

9. This pattern of slip is true for Co – flow units .

10. The slip for countercurrent unit is constant throughout the run .

11. The FMA in the effluent drops at exhaustion and the pH rises indicating that

exchanger should be removed from service .

4.2 Degasser 1. The function of degasser is to remove CO2

2. The residual CO2 in degassed water corresponds to the solubility of CO2 in water

at that temperature . The analysis of degassed water will be same as that of cation

effluent but the CO2 content will be about 5 ppm, depending

upon the actual ambient condition .

4.3 Strong Base Anion 1. All Anions including silica are absorbed by Strong base Anion exchanger .

2. The effluent is demineralized water having trace cation & Anion .

3. The SBA effluent will Not contain chloride and sulphate.

4. At normal regeneration level , the silica of SBA outlet water will be less than 0.5

ppm as SiO2.

5. Silica leakage is a function of regeneration level, temperature of regenerant SiO2/ TA

ratio and the sodium slip from the cation unit .

6. There will be some amount of P Alkalinity which will be depend upon the sodium

slip from the preceding cation unit.

7. P Alkalinity directly reflects the sodium slip from the cation unit . A slip of ppm

sodium gives P value of 1 ppm.

8. Conductivity and pH are also dependent on sodium slip . One ppm of sodium slip

will give a conductivity rise of 5 to 6 Micro siemens / cm2 and a pH of 8 to 9

9

9. The functioning of anion unit is largely depend upon the functioning of the preceding

cation unit.

10. A conductivity of 30 micro mhos and pH of 8- 9 is considered satisfactory for a

two bed system.

11. A rise in conductivity at anion outlet will indicate exhaustion of either cation or

anion unit .

12. Rise in conductivity with a drop in pH of anion effluent indicate exhaustion of anion

unit .

13. Rise in both conductivity and pH indicates exhaustion of cation unit .

14. If silica is considered for determining the breakthrough point of anion bed than

actual silica determination must be done at regular intervals .

15. Basic titration equipment are necessary for smooth operation of DM plant .

10

Chapter 5

Water analysis

5.0 Introduction The following water analyses are done for smooth operation of Demineralizing

plant.

a) Hardness

b) Chloride

c) Sulphate

5.1 Methods of testing hardness 5.1.1 Hardness

Hardness is defined as a soap consuming capacity of water. Hardness is mainly due to

presence of calcium and magnesium salts. There are two kinds of hardness – Temporary

and Permanent. Temporary hardness also called carbonate hardness is due to presence of

carbonates and bicarbonates. Permanent hardness is mostly due to chloride, sulphate and

nitrates.

5.1.2 Method EDTA forms a chelated soluble complex when added to a solution of certain metal ions if

EBT(Erichrome Black T) is added to water containing hardness the colour of the solution

turns wine red. This solution when titrated with EDTA will complex all the calcium and

magnesium and when this happens the colour turns blue from Red wine. The point at

which colour change takes place is known as END POINT.

5.1.3 Reagents

1. Ammonia buffer solution .

2. 0.01M solution of EDTA

3. Erichrome Black t Indicator

5.1.4 Apparatus Required

1. Burette

2. Graduated cylinder

3. Conical flask (Erlenmeyer Flask)

4. Wash bottle

5. Distilled water

5.1.5 Procedure

Step -1 : Take 50ml of sample in an Erlenmeyer

Step -2 : Add 2ml of Ammonia buffer solution.

Step -3: Add 3 to 5 drops or ½ tablet of Erichrome black T indicator.

Step -4: The color becomes wine red

Step -5: Immediately titrate against EDTA solution.

11

Step -6: Carry on titration till the end point is reached i.e. when the color changes to

blue.

5.1.6 Calculation Volume of 0.01 EDTA Solution

Total Hardness as CaCO3 = ------------------------------------------------- X 1000

(mg/liter) Ml of sample

The permanent hardness is found by boiling the water. IT is cooled and then above

procedure repeated. Temporary hardness is given by the difference of two readings.

5.1.7 Interference If bicarbonate exceeds 250 PPM it is advisable to add 1ml of 2N HCL before adding the

buffer solution. Any other metal ions chelating with EDTA can interfere with the result

provided they are in excess then mentioned below

Al++

> 20ppm, Cu++

> 20ppm, iron (Fe++

or Fe+++

) > 10 PPM PO3 >

25ppm.

5.2 Calcium Hardness The water sample is titrated against EDTA solution using MUREXIDE INDICATOR

(Ammonium purpurate) in highly alkaline medium.

5.2.1 Reagents

1. 1N Sodium Hydroxide Solution

2. 0.01M Standard EDTA Solution

3. Murexide Indicator

5.2.2 Apparatus Required

1. Porcelain dishes 100ml capacity.

2. Burette 25 to 50ml

3. Pipettes

4. Stirring rods (Glass)

5. Graduated cylinder.

5.2.3 Procedure

Step -1 : Prepare standard solution as described in chapter.

Step -2 : Prepare a color comparison blank in a porcelain dish. The dish should be of

white color 2.0ml of 1N NaOH and 0.2g (4 to 6 drops of indicator) solid indicator is

added to 50ml of distilled water with constant stirring 0.05 to 0.1ml of EDTA titrant is

added to produce unchanging purple color.

Step -3 : 50ml of sample solution is pipetted into similar white dish.

Step -4 : Add few drops of 0.02 N HCL to neutralize the alkalinity.

Step -5 : Boil for 2 to 3 minutes to expel CO2 and then cool to room temperature.

12

Step -6 : Add 20ml of 1N NaOH or volume sufficient to produce pH of 12 – 13 and

mix.

Step -7 : Add 0.2gm of powdered indicator or 4 to 6 drops of solution.

Step -8 : Stirring constantly titrate with EDTA solution to the colour of comparison

blank.

Step -9: Add 1 to 2 drops of titrant in excess to be sure that no further deepening of

colour takes place.

5.2.4 Calculation

(A-B) X C X 1000

Calcium as ppm CaCO3 = -----------------------------

Ml of sample

Where A = ml of EDTA required for titration of sample.

B .= ml of EDTA required for titration of blank.

C = mg of CaCO3 equivalent to 1.0 ml of EDTA.

5.2.5 Magnessium Hardness The difference between Total Hardness and Calcium Hardness is magnesium Hardness

Caution

Laboratory Testing should be done by qualified personnel only. The person should

verify the method before testing.

13

5.3 Determination of Chloride 5.3.1 Method

Chloride is determined in neutral water or in slightly alkaline solution by titration with

standard silver nitrate solution and potassium dichromate as indicator. Silver chloride is

precipitated and at the end point red silver chromate is formed.

5.3.2 Reagents

1. Silver nitrate standard solution.

Dissolve 4.791 gram silver nitrate in distilled water and dilute to 1 litre.

Store in brown glass bottle .( 1 ml = 1 ml Cl-).

2. Sodium chloride standard solution

Dissolve 1. 648gram dried sodium chloride NaCl in about 200 ml of distilled water

in a beaker . Rinse the beaker twice with distilled water and pour the rinsing into

volumetric flask. Make up to the mark with distilled water. .( 1 ml = 1 ml Cl-).

3. Potassium chromate indicator .

Dissolve 5 gram Potassium chromate K2 CrO4 in 100 ml of distilled water . Add

silver nitrate solution drop by drop to produce a slight red precipitate of

Silver chromate , and filter .

5.3.3 Procedure

1. Take 100 ml sample in an Erlenmeyer flask.

2. Add 5 drops of phenolphatlein indicator .If the sample turns pink add 2 drops of .02

N HNO3 . If acidic add a small amount of AR grade calcium carbonate.

3. Add 1 drop of potassium chromate indicator solution and stir. The solution will turn

red .

4. Titrate with standard silver nitrate solution with constant stirring until only the

slightest perceptible reddish colouration persists . If more than 25 ml is required take

50 ml of sample and dilute it 100 ml .

5. Repeat the procedure with 100 ml distilled water blank to allow for the presence

Of chloride in any of the reagents and for the solubility of silver chromate.

5.3.4 calculation

1000 (V1 - V2)

Chloride as Cl - = ------------------------------ mg/ litre

Volume of sample

V1 = Volume of silver nitrate required by sample (ml)

V2 = Volume of silver nitrate required by the blank (ml)

5.3.5 Interference If sample is highly coloured add aluminum hydroxide and let it settle and then filter. This

is possible only for raw water .

If sulfide , sulfite or thiosulfate is present , add 1 ml of H2O2 and stir for 1 minute.For

Bromide , iodide and cyanide register as equivalent chloride concentration.

Conductivity And pH are measured online .

14

5.4 Silica

The silica content of natural waters will vary to a considerable extent depending on the

locality. The presence of silica is particularly objectionable in water used for boiler feed

purposes as it may lead to the formation of hard dense scales. In addition, a very serious

problem encountered in high pressure operation, is the deposition of siliceous materials on

turbine blades and super heaters.

The gravimetric method is the standard applicable above 20mg./litre SiO2 content. This

method is followed for standardization of standard silicate solution used in colorimetric

methods. The heteropoly blue colorimetric method is adaptable for the range of 0 to 2

mg./litre. Blank reagent should always be used in all the three methods.

Method A (Gravimetric Method)

5.4.1 Procedure

Take a sample to contain at least 10mg.of Sio2. If necessary, clarify by filtration. Acidity

with 2 to 3 ml. of conc.HCl and evaporate to dryness in a platinum dish on a water bath.

At regular intervals add 2 or more portions of 2 to 3ml.conc.HCl warm and add

50ml.distilled water. Loosen the clinging residue from the sides and bottom of the dish

and filter collecting the filtrate. Wash the dish and residue with hot 1:50 HCl and finally

with distilled water until the washings are free from chloride. Return the filtrate and

washings to the platinum dish and again evaporate to dryness.

Repeat as previously, collecting the residue in another filter paper. Dry the two filter

papers with residue, burn, ignite at 1000-1200 0

C in a platinum crucible and weigh.

Moisten the residue with a few drops of distilled water, add 2 drops of H2SO4 and

10ml.48%HF. Cautiously evaporate to dryness on a steam bath in a fume cupboard.

Again ignite at 1000-1200 0

C, cool and weigh. Carry out a blank.

5.4.2 Calculation

(A-B) – (C – D) X 1000

SiO2 ,mg./litre = -------------------------------

Ml. of Sample

Where:

A = Weight of crucible and sample residue in mg. after first ignition.

B = Weight of crucible and sample residue in mg. After HF treatment and second

ignition. C = Weight of crucible and blank residue, in mg. after HF treatment and second

ignition.

Method B

5.4.3 Colorimetric estimation of Silica Ammonium molybdate as approximately pH 1.2 reacts with silica and any phosphate

present to produce heteropoly acids. Oxalic acid is added to destroy the molybdosilicic

acid but not the molybdosilicic acid. Even if phosphate is known to be absent, the

addition of oxalic acid/highly – is desirable and is a mandatory step. The intensity of the

yellow colour is proportional to the concentration of molybdate-reactive silica. The

yellow molybdosilicic acid is reduced by means of 1-amino-2-napthol-4-sulphuric acid to

heteropolyblue. The blue colour is more intense than the yellow colour and provides

increased sensitivity. In at least on of its forms, silica does not react with molybdaet even

15

though it is capable of passing through filter paper and is not noticeably turbid. The

presence of such a molybdate unreactive silica is undesirable in raw water. It will not be

removed in the water treatment plant and will find its way to high pressure steam system

where it will be converted to ‗molybdate-reactive‘ silica. Such increase in silica content

will give rise to scale problem. Chromate and large amounts of Fe,Po4 ,sulfide, tannin,

colour and turbidity are potential interference. Inorganic sulfide can be removed by

boiling an acidified sample. The addition of 1ml.of 1% EDTA solution after molybdate

reagent overcomes high Fe and Ca concentrations.

5.4.4 Colorimetric estimation of silica-0-20ppm SiO2

Reagents

1. Ammonium molybdate solution

2. 2 N. Sulphuric acid.

3. 10% Oxalic acid.

4. Lovibond comparator with standard silica disc.

5.4.5 Procedure

1. Fill one Nessler tube to 50ml.mark with sample and place in the left hand

compartment of Lovibond comparator.

2. Fill the other Nessler tube with 50ml. Of sample, at 25-300

C. Add 2ml. Of acidified

ammonium molybdate solution. Mix thoroughly, add 4ml. Of oxalic acid again mix

thoroughly. Place in the right hand compartment and allow to stand for 10 minutes.

3. Stand the comparator facing a uniform source of light, and compare the colour of the

sample with the colours in the disc. Rotate the disc until the colours are matched.

5.4.6 Calculation SiO2 in mg./litre =Disc reading X 20

Note

1 Should the colour in the test solution be deeper than the deepest standard, a fresh test

should be carried out using a smaller quantity of sample, and diluting to 50 ml. With

distilled water before adding the reagents.

2 Silica free water

Distilled water from an all-metal ―still‖ or water which has been passed successively

through a mixed bed deionization unit and strongly basic anion exchanger such as

Tulsion A-27 MP unit regenerated with a regeneration level of 320gm. Per litre NaOH

has been found to be suitable.

Prepare and store in a polyethylene bottle a large batch of water containing not more than

0.005 SiO2,

Determine the silica content of the water by treating it as sample. This water is used to

prepare reagents and standards, and to dilute samples when necessary.

16

5.4.7 Colourimetric estimation of silica –0-2ppm SiO2

Reagents

1 Acidified ammonium molybdate solution.

2 10 % Oxalic acid.

3 Amino-napthol reducing agent.

4 Lovibond comparator with standard silica disc or spectrophotometer suitable for

measurement at 815 mu wave length.

5.4.8 Procedure 1. Fill one of Nessler tube to the 50ml.mark with sample, and place in the left

compartment of Lovibond comparator.

2. Fill the other Nessler tube with 50ml. Of sample, at 25 –300

C. Add 2ml. If acidified

ammonium molybdate solution. Mix thoroughly, stand for 5 minutes. Add 4ml. Of

oxalic acid and mix well. Then 2ml. Of reducing agent, mix well and wait for 10

minutes. The blue colour of the sample is compared with that of a blank comprising

the same water without reagents, using a spectrophotometer (wavelength 815mu).

Compute the silica content from the standard graph prepared from the standard silica

solution.

Method C

5.4.8 Determination of Total silica (Molybdate reactive and unreactive silica)

1 1 Sodium bicarbonate

2 1N sulphuric acid.

3 Other reagents as per previous method.

5.4.9 Procedure Take 100ml. Of sample or lesser quantity(20-100 mu.SiO2) but made upto 100ml. With

distilled water in a platinum dish. Add 200mg. Silica free sodium bicarbonate and digest

on a steam bath for one hour. Cool and add slowly, with stirring, 2.4ml. sulphuric acid

(1N). Do not interrupt the analysis but proceed at once with remaining steps. Transfer

quantitatively into a plastic container. For development of colour and calculation refer the

previous procedure.

17

Chapter 6

Troubleshooting

6.1 Cation Exchanger

Problem Cause Action Loss of Capacity Improper regeneration Carry regeneration as per

specification

Change in raw water

characteristics, Increase in

Na/TC.

Increase acid quantity

Over exhaustion of unit Normal acid will not restore

capacity increase acid quantity.

Channeling Remove resin fines Replace

broken strainer or laterals

Faulty distribution system-

check and rectify.

Loss of Resin Inspect resin bed depth

Control Backwash flow

Resin fouling 1.Get Resin analyse

2.Clean with acid

3.Replace if analyse too much

decross linking and broken

beads.

Poor Quality of treated water Valve leakage

Higher flow greater than

normal design range increases

leakage

Increase Na/TC has more

profound effect on leakage

from increased flow rate

Low flow rate The flow rate should be

maintained above 0.5 GPM/ft3

of resin.

Temperature Does not have much effect

except for very low

temperature

Increased TDS Increased leakage (Analyze

and correct).Add resin if

required.

Hardness in Raw water Valve leakage, High flow rate,

change in Raw water

composition . Inefficient

regeneration

High sodium slip in treated

water

Over exhaustion (Double

injection)

Improper regeneration

(Correct)

18

6.2 Weak Base anion

Problem Cause Action Loss of capacity Increase in EMA in raw water Add more Resin, Increase

regenerant chemical for plant

in use.

Rinsing time increases Resin oxidized to weak acid

(Retains Na), Replace resin,

Try regeneration by Ammonia,

Recycle rinse water.

Silica Fouling Problem normally occurs when

WBA / SBA combination is

used. Clean with hot caustic,

In thorough fare regeneration

of WBA/SBA drain 1/3 of

spent of caustic before feeding

it to WBA.

Flow rates Operate at specified flow rate

Precipitation by Ca, Mg etc Use decationised or

deminieralised water for

dilution of regenerant. Check

cation unit functioning.

Improper working of cation

leads to anion problem.

Poor treated water quality

Chloride in treated water Check cation, Analyse

regenerant for chloride,

Regenerant valve leaking

(Check). Chloride leaking to

sodium leakage normal.

High pH Cation not operating properly.

Leaking valve (normally the

regenerant valve).

Low pH, High conductivity Backwash valve leaking

Treated water contains

hardness

Check cation, check degasser

(especially water treatment

plants suited near cement

plant.) Hardness in regenerant

and Regenerant dilution water

High sodium content in treated

water

Resin escapes from cation unit

to WBA unit due to Broken

laterals. Check, give more

rinse.

Ion leakage Valve leaks, channeling, High

or low flow etc.

Fouling Chemically clean, carryout

pretreatment

19

6.3 Strong Base anion

Problem Cause Action Loss of capacity Increase in Ionic load Put more resin, use more

regenerant. check for Degasser

functioning

Long Rinsing time Cation not working,

Organically fouled resin. Give

brine treatment.

Increase in Alkalinity Check. Add resin or reduce

output

Fouled Resin Chemically clean with hot

caustic for silica & brine

treatment for organic fouling

Precipitation by Ca, Mg Check Regenerant for Ca/Mg

etc. Check cation if

regenerated by H2SO4. Use

Decationised or DM water for

dilution.

Resin ageing Use specified concentration of

NaOH

Bacterial contamination Unit idle. Do not keep unit

idle. Very important where

high purity water required.

Heavy metal fouling Iron in regenerant or through

leakage from cation. Damaged

Rubber lining.

Poor treated water quality High pH, high conductivity Check cation. Do more

Rinsing Check conductivity

meter

Low pH, High conductivity Check anion. Regeneration

not carried. properly. Organic

fouling, check pH meter

High silica Resin organically fouled.

(Clean chemically). Carry

regeneration as per

specification. Regenerant

temperature low (carry

regeneration by hot caustic).

High service water

temperature, check.

Chloride leakage Valve leakage, chloride in

regenerant WBA not working

silica precipitation in WBA.

Rectify.

Hardness Check cation. Use cation or

DM water for dilution and

rinsing.

Sodium leakage Check raw water for sodium,

check cation for sodium slip,

Na slip give rise conductivity.

20

DEGASSER SYSTEM

Problem Cause Action

High residual CO2 from

Degasser.

Choked suction filter Check and Clean

Improper air flow to Degasser Check damper, blower speed

discharge pressure.

Degasser blower not Switched

on during service run

Check and operate blower.

Broken air seal. Air seal not

fit. Results in Short circuiting

Check and replace fitting

provide air seal.

Flooding in Degasser Very high flow rate Reduce flow

Packed tower choked due to

director broken packing

material

Open and check, Replace

broken packing

First layer of packing Not

arranged properly

Arrange as per instructions.

Dirt/Dust in air(Normally in

Cement and Allied Industries

Degasser sucks dust and dirt

into water This can lead to

clogging of Anion unit.

Chokes suction filter

Install air filter Periodic

cleaning of suction filter.