This document provides an overview of water treatment for corrosion, including pretreatment of water, corrosion mechanisms, factors affecting the rate of corrosion, protection against corrosion, water treatment at corrosion sites, water chemistry, and calculations. It discusses pretreatment methods like clarification and sedimentation. It also examines corrosion mechanisms, objectives of water treatment to minimize corrosion and other issues, and factors influencing the corrosion rate like pH, dissolved gases, temperature, velocity, and microbial growth. Additionally, it covers alkalinity, how chemical corrosion inhibitors work, recommended treatment chemicals, blowdown and makeup water calculations, biocides, cooling tower calculations, clarifier data, process water data, and makeup and reverse osmosis water data.

1. CCoooolliinngg wwaatteerr ttrreeaattmmeenntt ((CCoorrrroossiioonn))
DDeeppaarrttmmeenntt:: CChheemmiissttrryy
MMSS IInndduussttrriiaall cchheemmiissttrryy 22001144
MM..KKaammrraann uull hhaassssaann
SS..ZZuullffiiqqaarr AAllii
KKaappiill DDeevv
FFaabbiihhaa iirrffaann
NNiiddaa nnaazz
FFaaiizzaa iifftteekkhhaarr

2. WWaatteerr ttrreeaattmmeenntt ::
Pretreatment of water.
Corrosion mechanism
Factor effecting rate of corrosion
Protection of corrosion
Water treatment for corrosion site
Water chemistry
Calculations
Customer Training WT200C Page 2

3. PPrree--ttrreeaattmmeenntt ooff wwaatteerr
Clarification:
A process used to improve water
by separating and removing
suspended solids from water.
Sedimentation :When solid settle
out of liquid.

4. PPrree--ttrreeaattmmeenntt ooff wwaatteerr iinntteerrnnaall
ssttrruuccttuurree ooff ccllaarriiffiieerr::

5. PPrree--ttrreeaattmmeenntt ooff wwaatteerr oovveerrvviieeww
ooff ccllaarriiffiieerr::

6. PPrree--ttrreeaattmmeenntt ooff wwaatteerr wweeiirr ffllooww::

7. PPrree--ttrreeaattmmeenntt ooff wwaatteerr::
Customer Training WT200C Page 7

8. PPrree--ttrreeaattmmeenntt ooff wwaatteerr::
Customer Training WT200C Page 8

9. PPrree--ttrreeaattmmeenntt ooff wwaatteerr
Detention Time (DT):
The time it takes for a drop of water to
travel from inlet to outlet.
Typical Design Value 2-3 hrs

10. PPrree--ttrreeaattmmeenntt ooff wwaatteerr
If the incoming flow rate is too high, then the
water will spend less time in the tank (the
detention time will be low) and all of the floc
may not be removed.
If the incoming flow rate is low, the amount
of time the water will spend more time in the
tank (detention time will be high) and the
water treatment plant may not be operating at
its optimum capacity

11. CCoorrrroossiioonn
Destruction of plant
increased maintenance costs
Fouling
loss of efficiency due to increased pumping
costs
loss of heat transfer efficiency
Increased Biological Nutrients
fouling and health implications

12. CCoorrrroossiioonn rreeaaccttiioonn::
2Fe + O2 + 2H20 → 2Fe+ + + 4OH-Anode
reaction:
2Fe → 2Fe+ + 2e
Cathode Reaction:
O2 + 2H20 + 2e → 4OH-

13. CCoorrrroossiioonn mmeecchhaanniissmm
Customer Training WT200C Page 13

14. OObbjjeeccttiivveess ooff WWaatteerr TTrreeaattmmeenntt
MINIMISE SCALE
MINIMISE CORROSION
MINIMISE FOULING
MINIMISE BIOFOULING
MAXIMUM EFFICIENCY

15. PPRROOBBLLEEMMSS OOFF WWAATTEERR
Effect of conductivity

16. HHooww ppHH ddooeess aaffffeecctt tthhee
ssyysstteemm??
Acidic and slightly alkaline water can dissolve metal and
the protective oxide film on metal surfaces. More alkaline
water favors the formation of the protective oxide layer.

17. HHooww OOxxyyggeenn ddooeess aaffffeecctt
tthhee ssyysstteemm??
• Temperature increases diffusion of
oxygen to metal surface also increases
Promote corrosion.

18. HHooww TTuurrbbiiddiittyy ddooeess aaffffeecctt
tthhee ssyysstteemm??

19. HHooww ppHH ddooeess aaffffeecctt tthhee
ssyysstteemm??
In general, when pH is below
recommended ranges, the chances for
corrosion increase and when pH is
above recommended ranges, the chances
for scale formation increase. The
effectiveness of many biocides also
depends on pH; therefore high or low pHs
may alleviate the growth of
microbiological problems

20. HHooww ppHH ddooeess aaffffeecctt tthhee
ssyysstteemm??
Corrosive Water Scale-forming Water
low pH high pH
soft or with primarily noncarbonate
hardness( Chloride Sulphate)
hard with primarily carbonate
hardness(Carbonates ,Bicabonates 7
Hydroxide)
low alkalinity high alkalinity
Soft: 0 to75 mg/L as CaCO3 Hard: 150 to 300 mg/L as CaCO3
Moderate: 75 to 150 mg/L as
Very Hard: Above 300 mg/L as
CaCO3
CaCO3

21. FFaaccttoorrss tthhaatt aaffffeecctt tthhee
ccoorrrroossiioonn::
P H:
Acidic and slightly alkaline water can
dissolve metal and the protective oxide
film on metal surfaces. More alkaline
water favors the formation of the
protective oxide layer.
Dissolve gassaes: Oxygen dissolved in
water is essential for the cathodic reaction
to take place.

22. FFaaccttoorrss tthhaatt aaffffeecctt tthhee
ccoorrrroossiioonn::
Temperature:
Temperature increases diffusion of
oxygen to metal surface also increases
Promote corrosion.

23. FFaaccttoorrss tthhaatt aaffffeecctt tthhee
ccoorrrroossiioonn::
Velocity:
High velocity water increases corrosion
by transporting oxygen to the metal and
carrying away the products of corrosion
at a faster rate.
When water velocity is low, deposition of
suspended solids can establish localized
corrosion cells, thereby increasing
corrosion rates

24. FFaaccttoorrss tthhaatt aaffffeecctt tthhee
ccoorrrroossiioonn::
Microbial growths
Microbial growths promote the
formation of corrosion cells in addition;
the by products of some organisms,
such as hydrogen sulphide from
anaerobic corrosive bacteria are
corrosive.

25. AAllkkaalliinniittyy::
In cooling water two forms of
alkalinity play a key role. These are
carbonate (CO3) alkalinity and
bicarbonate (HCO3) alkalinity.
Bicarbonate alkalinity is by far the
most common. Alkalinity and pH are
related because increase in pH
indicates increases in alkalinity and
vice versa.

26. AAllkkaalliinniittyy::
When OH- CO3 HCO3
P=O 0 0 T
2PT 0 2P T-2P
2P=T 0 2P 0
2PT 2P-T 2(T-P) 0

27. HHooww ddooeess AAllkkaalliinniittyy aaffffeecctt
tthhee ssyysstteemm??
When water with carbonate or bicarbonate
alkalinity is heated, the alkalinity is broken
down to carbon dioxide. The carbon
dioxide released, combines with the water
to give carbonic acid, which can cause
corrosion of iron or steel equipment. The
corrosion products react further with
alkalinity and the deposits can build up in
the same manner as calcium carbonate
scale.

28. HHooww ddoo cchheemmiiccaall ccoorrrroossiioonn
iinnhhiibbiittoorrss wwoorrkk??
Anodic inhibitors :
Form a protective film on the anod.
All oxidizers and promote passivation by
increasing electrical potential of iron.
Customer Training WT200C Page 28

29. HHooww ddoo cchheemmiiccaall ccoorrrroossiioonn
iinnhhiibbiittoorrss wwoorrkk??
Cathodic inhibitors:
form insoluble precipitate that coat of
protective surface on the cathode.
At cathode of corrosion cell is elevated due to
generation of hydroxide ion..
Customer Training WT200C Page 29

30. HHooww ddoo cchheemmiiccaall ccoorrrroossiioonn
iinnhhiibbiittoorrss wwoorrkk??
Cathodic inhibitors:
Calcium orthophosphate also cathodic
inhibitors.
Orthophosphonate dual mechanism anodic
inhibitor cathodic precipator.
Customer Training WT200C Page 30

31. HHooww ddoo cchheemmiiccaall ccoorrrroossiioonn
iinnhhiibbiittoorrss wwoorrkk??
Cathodic inhibitors:
Orthophosphonate dual mechanism anodic
inhibitor cathodic precipator.
HDPE +Fe == Fe Phosphonate (At anod)
HDPE +Ca == Ca Phosphonate(cathode)
Customer Training WT200C Page 31

32. HHooww ddoo cchheemmiiccaall ccoorrrroossiioonn
iinnhhiibbiittoorrss wwoorrkk??
Mainly anodic:
Chromates, (in absence of oxygen)
Nitrites, (in absence of oxygen)
Orthophosphates Molybdate (in presence of oxygen)
Mainly cathodic:( Precipitator) p H 7-9
Bicarbonates/ carbonate ( Calcium cabonates)
Metal cations, Zn hydroxide
Polyphosphates (Ca –phospate)
Customer Training WT200C Page 32

33. HHooww ddoo cchheemmiiccaall ccoorrrroossiioonn
iinnhhiibbiittoorrss wwoorrkk??
Most closed-loop water systems use a
sodium nitrite based inhibitor for
corrosion control and a biocide to
prevent biological contamination. These
inhibitors will protect both the ferrous
and non- ferrous materials in your
piping system...
Customer Training WT200C Page 33

34. HHooww ddoo cchheemmiiccaall ccoorrrroossiioonn
iinnhhiibbiittoorrss wwoorrkk??
The major advantages of using nitrite based corrosion
inhibitor are as follows:-
Removes dissolved oxygen by converting the nitrite
to nitrate.
Negligible loss of metal or corrosion.
Excellent heat transferability and flow rate.
Long and extended life of Water without fouling
Customer Training WT200C Page 34

35. WWaatteerr ttrreeaattmmeenntt CChheemmiiccaallss
ffoorr cclloossee lloooopp ssyysstteemm::
Customer Training WT200C Page 35

36. RReeccoommmmeennddeedd EEssttiimmaattiioonn
DDoossaaggee ooff cchheemmiiccaallss::
Chemicals Purpose Concetration Consumption kg / day
Scal Trol PDC 9325
Cathodic corrosion
inhibitors 1ppm 68
Spectrus NX1104 Non Oxidizing Bioside 60 ppm 178/shock
BetzDearborn AP1120 P Anionic polymer 0.3 ppm 22
Caustic p H Alkalinity control p H 7.5-8.5 1500-2500
CorrShield NT 4201
Anodic corrosion
inhibitors 500-1000 ppm 2.5kg/m3
Customer Training WT200C Page 36

37. BBlloowwddoowwnn mmaakkee uupp
wwaatteerr ccaallccuullaattiioonn::
Customer Training WT200C Page 37

38. CCoonnttrrooll ooff CCoonncceennttrraattiioonn
The number of times the solids build in
the system water is termed the
concentration factor (CF).
CF is controlled by bleed
to increase CF - decrease bleed
to decrease CF - increase bleed
Customer Training WT200C Page 38

39. BBlleeeedd CCoonnttrrooll
Effect of too much or too little bleed:
Too much bleed :-
low concentration factor
waste of water
waste of treatment
Too little bleed:-
high concentration factor
danger of scale and fouling
increased nutrient in system
danger of biofouling
Customer Training WT200C Page 39

40. x While increasing concentration factor
reduces water use, it also increases
nutrients in the system water,
encouraging growth of bacteria and
slimes. Therefore, we normally run
most cooling systems between 2 and 5
x x
x
x
x
1 2 3 4 5 6
Concentration Factor
Water
Use
Customer Training WT200C Page 40

41. NNoonn OOxxiiddiissiinngg BBiioocciiddeess
• Screen water
• Select alternating biocide to prevent resistant strains from
developing
• Effective against SRB’s
• Can protect system long after dosing.
• Contain biodispersant
• Higher dosage for kill possible
• Environmentally some have rapid breakdown e.g.
DBNPA
Customer Training WT200C Page 41

42. NNoonn OOxxiiddiissiinngg BBiioocciiddeess
• Screen water
• Select alternating biocide to prevent resistant strains from
developing
• Effective against SRB’s
• Can protect system long after dosing.
• Contain biodispersant
• Higher dosage for kill possible
• Environmentally some have rapid breakdown e.g.
DBNPA
Customer Training WT200C Page 42

43. NNoonn OOxxiiddiissiinngg BBiioocciiddeess
• Screen water
• Select alternating biocide to prevent resistant strains from
developing
• Effective against SRB’s
• Can protect system long after dosing.
• Contain biodispersant
• Higher dosage for kill possible
• Environmentally some have rapid breakdown e.g.
DBNPA
Customer Training WT200C Page 43

44. CCoooolliinngg ttoowweerr CCaallccuullaattiioonn::
Parameters Symbol /derivation values
RR RRM3/hrs 2834
System volume Vm3 2967
Hot water temp C 63
cold water temp C 31
Delta -T ΔT 32
Evaporation rate Ev 127
Cycles of concentration Nc =Ev+BD/BD 3
Blowdown rate BD=E/Nc-1 63
Make up rate MU=E+BD 190
Metallurgy MS
Customer Training WT200C Page 44

45. CCllaarriiffiieerr ddaattaa::
Parametrs Values
Clarifier Feed flow 3052m3/hrs
Clarifier Feed inlet temp 73 C
SS OF Feed water 3170ppm
System volume 10732m3
Customer Training WT200C Page 45

46. PPrroocceessss wwaatteerr ddaattaa::
Parametrs Values
P H 7-8
TDS 100 PPM
Ca H 35PPM
Total Iron 0.3
T.Aerobic bacteria 10000 cfu/cm
M.Alkalinity 50 ppm
Chloride 25ppm
Customer Training WT200C Page 46

47. MMaakkee uupp wwaatteerr RR OO ddaattaa::
Parametrs Make up water R O WATER
P H 7-8 7-8
Conductivity 650 50
Ca H 80 3PPM
Mg H 55 N/A
Total Iron 0.12 N/A
SS 6 N/A
M.Alkalinity 80 ppm 10 ppm
Chloride 90 ppm 15ppm
Customer Training WT200C Page 47

48. PPrroo.. WWaatteerr MMCCWW ddaattaa::
Parametrs Process water Machinery C.W
P H 7-8 8.5-10.5
Conductivity 200 -250 3500
Ca H 35 N/A
Total Iron 0.3 0.3
Total aerobic bacteria 10000 CFU/CM Nil
M.Alkalinity 50 N/A
Chloride 25 ppm N/A
Customer Training WT200C Page 48

49. The Ryznar Stability Index
formula:
RI Indication (Ryznar 1942)
RI5,5 Heavy scale will form
5,5 RI 6,2 Scale will form
6,2 RI 6,8 No difficulties
6,8 RI 8,5 Water is aggressive
RI 8,5 Water is very aggressive
is:
Customer Training WT200C Page 49

50. The Ryznar Stability Index
formula:
pH
Conductivity in TDS
[Ca2+]
[HCO3
-]
Water temperature
RI
is:
Customer Training WT200C Page 50

51. BBllooww ddoowwnn mmaakkee uupp
wwaatteerr ccaallccuullaattiioonn::
Customer Training WT200C Page 51

52. CCoooolliinngg ttoowweerr eeffffiicciieennccyy::
Approach = Cold Water Temperature – Wet Bulb Temperature
Range = Hot Water Temperature – Cold Water Temperature
Cooling Tower Efficiency
=
Range/
(Range + Approach) X
100
32/35*100= 91.43%
Customer Training WT200C Page 52

53. WWhhaatt iiss iinn yyoouurr mmiinndd aasskk??
Customer Training WT200C Page 53

54. Customer Training WT200C Page 54