Reveres Osmosis system

Plant Chemistry
Reveres Osmosis System
Prepared By : -
Umar Farooq
Senior Chemist NOMAC
MSC ( Chemistry ) MBA ( Marketing )
umar7325@yahoo.com umarfarouq@nomac.com
SIWEP Shuaibah Jeddah
Saudi Arabia
1

Reveres Osmosis System
 Part 1
 Water Chemistry
 Sea water impurities
 Simulation of Reveres Osmosis system
 Anatomy of Spiral Wound Element
 Principle of Reveres Osmosis
 Part 2
 Chemical Handling and safety
 Corrosion phenomena
 Membrane Fouling
 Membrane Scaling

4
At the end of the respective training course, the participants will
be able to:
• Identify the chemical Hazards & how to handle chemical material safely.
• now the foundations of Water Quality Control to avoid the scale corrosion
and biological growth in the reveres osmosis system, and to operate the
mentioned at max performance.
• Understand the troubleshooting events to the plant chemistry system.
Vision
• Water Quality Control will lead all to understand the limitations and
international standards as well as increasing the plant availability.
• Occupational health will maintain within high standards, zero incident.
• Operational process will maintain highly performance due to plant chemistry
troubleshooting.
Umar Farooq Senior Chemist
SIWEP NOMAC
Main Objective

Water Chemistry
 Water is an excellent solvent and dissolve to varying
degree. any thing it comes into contact with it.
Water born impurities
 Water contains some impurities which are
Dissolved inorganic compound
Bi Carbonate, Carbonates, Sulphate , nitrates , Chlorides of
calcium , magnesium ,sodium and potassium , inorganic
Suspended materials, like clay, silt ,sand , soil and metal
oxides, These can not be remove by filtration.
SIWEP NOMAC 5

Dissolve Organic Compound
Humic acid , fulvic acid , tannine , insoluble matter
such as dead bacteria and other biological
products
Dissolve gasses
 Such as oxygen , nitrogen , carbon di oxide ,
sulpher dioxide , ammonia , and hydrogen
sulphide absorbed from atmosphere and solid
surface
Micro Organism
 Such as bacteria algae and fungi
SIWEP NOMAC 6

Why Water is Unique
 Water is only substance that exist in form of solid , liquid
and steam
 Specific heat = 1calorie/gram
 It expand = 1600 time
 Three Isotopes = H , D2O , T2O
 Heat of fusion = 144Btu / Lbs
 Heat of vaporization = 980 Btu / Lbs
 Freezing Expand = 1/9
 Depending upon pressure ,its boil with in the
temperature = 35-704F*
SIWEP NOMAC 7

Properties of Water
 It is chemical compound expressed by the formula H2O.
 It is formed by two item of hydrogen and one atom of
oxygen
 Due to different electro negativities of hydrogen and
oxygen.H20 Molecule is electrically charged .
 When the other molecule combine with it then will be
formed hydrogen bonding
 Water is the best solvent .
It dissolved different substance
In it and the process of dissolving
Is desolation
Model of hydrogen bonds
Between modules of water
SIWEP NOMAC 8

Sea Water
 It is store house of impurities
 It contain 3.6% by weight of solids.
 Normally 75% impurities of sea water are Br, I , So4 ,
and Ca ,Mg , K , etc.
 Cat ion and Anion Salts in Sea water
Cations Anions
Calcium Ca++ Bicarbonate (HCO3
-),
Magnesium Mg+ + Carbonate (CO3
2-),
Sodium Na+ Sulfate SO4
2-
Iron Fe2+ (ferrous) Chloride Cl -
Aluminum AI3+ Nitrate NO3
-
Potassium K+ Fluoride F-
SIWEP NOMAC
9

RELATIVE SETTLING VELOCITIES OF SAND
and SILT PARTICLES IN STILL WATER
Particle Diameter, mm Order of Magnitude Time Required to Settle 1 Foot
10.0 Gravel 0.3 Seconds
1.0 Coarse Sand 3 Seconds
0.1 Fine Sand 38 Seconds
0.01 Silt 33 Minutes
0.001 Bacteria 35 Hours
0.0001 Clay Particles 230 Days
0.00001 Colloidal Particles 63 Years
SIWEP NOMAC 10

Shuaibah RO-Expansion Plant
Media filters (32)
Cartridge filters
(9+1)
1st Pass RO
(10)
Permeate Tanks (2)
Seawater pumps (2+1)
Shock chlorination
H2So4
FeCl3
Polymer
SBS
Antiscalant
1st pass HP
Pump (10)
2nd Pass RO (10)
NaOH
Antiscalant
Potabilization
Plant
•Nominal Capacity : 150,000 m³/hr.
•1st Pass Recovery : 41.5 %.
•2nd Pass Recovery : 90%.
•1st RO Permeate = 168000 m3/day.
•Feed Water TDS=37000-44000 mg/l.
•Feed Water Silt Density Index: < 5(100%),<4 (95%)
5-Permeate Transfer Pump
SWCC Tank
11
SIWEP NOMAC

Seawater supply Pump
D M F
Cartridge
filter
H P Pump
Booster Pump
1st pass R O
E R D
2 nd pass R O
2 nd pass
Feed pump
Permeate
Transfer pump
Potabilisation
Backwash water
Tank
Out fall
To SWCC Shuaibah II
Storage Tank
S MBS
Anti scalant
Anti Scalant
Caustic sodaAcid
Coagulant
Polymer
Back wash
12
SIWEP NOMAC

Training Module # 2 RO System
SIWEP NOMAC 13

What is Desalination
 Reverse osmosis is a membrane process
where salty source water is supplied under
pressure to a semi-permeable membrane
resulting in the passage of fresh
water through the membrane while the
membrane prevents the passage of the
dissolved minerals leaving them in the
concentrated brine.
SIWEP NOMAC 14

Definitions
 SWRO – means Seawater Reverse Osmosis
unit also called 1st PASS RO.
 BWRO – means Brackish Water Reverse
Osmosis unit also called 2nd Pass RO
 ERD – means Energy Recovery Device.
 PERMEATE – means the purified water passing
through the RO membranes. Also called product
water.
SIWEP NOMAC 16

Reverse Osmosis Membrane
Feed Water
FE-SEM Photograph
of RO Membrane
(UHR -FE-SEM) x Product Water
SIWEP NOMAC
0.5um
Ultra -thin Salt Rejection Layer Cross
linked Fully Aromatic Polyamide 0.2um
Supporting layer poly
sulfon 45um
Base Fabric Non- Woven
Fabric polyester 100 um
17

The RO Membrane
 The membrane layer which makes the separation is
extremely thin (approximately 200 nanometer)
 It is supported on a porous polysulphone backing
layer which gives the membrane layer some strength
(approximately 45 micron thick)
 The polysulphone is itself supported on a non-woven
polyester backing fabric (approximately 100 micron
thick)
SIWEP NOMAC 18

The RO Membrane
 Most RO membranes are made of cellulose
acetate or polyamide composites
cast into a thin film as a sheet (or sometimes as
fine hollow fibers)
 For potable water
applications the membrane type typically
selected are thin film sheets
made from polysulphone with an ultra-thin (3
micron) polyamide salt rejecting
layer
SIWEP NOMAC 19

The Spiral Wound Element
20
SIWEP NOMAC

Anatomy of a spiral wound element
 The pressurized feed water flows in an axial direction
through the feed /brine spacer mesh.
 The pressure forces some of the feed water through the
membrane layer, leaving the majority of the dissolved
salt on the feed side of the membrane .The water
crossing the membrane is called permeate.
 The permeate is collected in the permeate spacer
material.
 The permeate spacer material is located between 2
sheets of membrane .The 2 sheets of membrane plus
the permeate spacer is collectively called a leaf.
SIWEP NOMAC 21

Spiral Wound Membrane Cutaway
22
SIWEP NOMAC

Osmosis and Reverse Osmosis Phenomenon
 The reverse osmosis process can be used
to purify water by removing dissolved
minerals, and virtually 100% of colloidal
and suspended matter to produce high
quality water of improved color, taste and
other properties at low cost compared
to other purification processes.
SIWEP NOMAC 23

Particle Size and Separation Process
SIWEP NOMAC 25

Temperature Effect
Increasing Water Permeability Salt Rejection
Feed Temperature
Water permeability will increase about 3% per 1degC
•Highest water temperature must be considered for warranty exposure
•Highest operating pressure should be checked at lowest operating
temperature.
SIWEP NOMAC 26

Salinity Effect
Feed Salinity
•Salt rejection decreases at lower feed salinity (<400mg/l
as NaCl) due to RO membrane negative charge effect.
SIWEP NOMAC 27

pH Effect
Feed pH Almost same
•Salt rejection is rather constant over a broad pH range.
•Salt rejection will decrease at extremely high and low feed
pH
SIWEP NOMAC 28

What is Boron (1)
 Predominant reason for limiting Boron in water.
1)For Human
 Reproductive dander ( represent )
 Teratogenic properties ( suspected )
 WHO preliminary limit < 0.5mg/l
 EU guideline <1.0mg/l
2) Damage to Plant Crops
 Leaf damage ( Citrus tree is very sensitive)
 Reduce fruit yield
 Induce premature ripening
 Boron Concentration in sea water: 4.5-5.5mg/l
 Sea water distillation water by RO membrane does not meet
requested Boron revel.
SIWEP NOMAC 29

Boron Removing Process (1)
 High pH RO Operation –SWRO Permeate is treated again with
high pH
Anti Scalant NaOH Permeate
Low Boron Concentration
<0.5
Feed
SWRO Permeate
Concentrate
Borate will be change to ionized Boric
H3BO3 + H20 H4BO4 - +H + Pka =9.2
Borate ( H3BO3) Boric ( H4BO4 )
SIWEP NOMAC
pH 9.8 – 10.5
30

Boron Removing Process (2)
 Boron will be change to ionized Boric
H3BO3 + H2O H4BO4 - +H + pKa=9.2
B(OH)3+OH - B(OH) 4 - pKa=4.8
Difference of removal performance ( TM720 )
SIWEP NOMAC
H3BO3 : 70% H4BO4 - : 99.5%
31

Suspected Problem during High pH operation
Scaling problem is caused by excessive high pH operation ,
too low anti-Scalant dosing or too high recovery operation.
Scaling substance : CaCO3, Mg(OH)2
pH control, anti-Scalant dosing and correct recovery operation
are very important.
- Correct pH measurement,
- Good and enough pH meter calibration
- Correct anti-Scalant dosing
- Check anti-Scalant dosing rate and
consumption very frequently.
- 2nd pass brine pH & conductivity checking
SIWEP NOMAC 32

Pressure Vessel Probing(1)
 A flexible tube is inserted through the permeate port of a
vessel to measure the permeate concentration at known
intervals through the vessel.
 Performed on vessels identified by the Pressure
Vessel Profile.
 Locates the elements or o-rings which are the source
of high salt passage.
SIWEP NOMAC 33

Pressure Vessel Probing (2)
SIWEP NOMAC 34

Membrane De lamination
SIWEP NOMAC 35

Membrane Oxidation
 If composite polyamide RO membrane element are exposed to the
oxidizing chemical such as free chlorine ,chloramines, bromine,
ozone, or other oxidizing chemicals, irreparable damage is
happened to the membrane ,normally evinced by decrees of salt
rejection.
 Lead and element are typically more effected than the other in case
of oxidizing chemical present in RO feed water.
 If several specific condition are assembled, chlorine generating
problem might be occurred.
 Dissolved Oxygen.
 NaHSO3 (SBS)
 Heavy Metal ion
( Cu, Co, Mn, etc. Low concentration ,ppb order ,is enough)
 High Salinity chlorine ion
SIWEP NOMAC 36

Chlorine Generation Mechanism under existing of
Heavy Metal
 Even if RO feed water does not contain Chlorine,
Chlorine will be generated
 Following substances are required to generate chlorine.
1. Dissolved Oxygen, 2. NaHSO3 (SBS)
3. Chloride Ion 4. Heavy Metal Ion(Cu, Co, Mn. etc.)
 Following chemical reactions in the process of
generating chlorine (ex. with Copper).
SO3 2- + Cu 2+ SO3- + Cu + *1
SO3 - + O2 SO5- *1
SO5- + SO3 2- SO5 2- + SO3- *1
SO5 2- + Cl - ClO - +SO4 2- *1
(ClO - :Chlorine, Cl2 )
Reference
*1 : C. H. Barron and H. A. O’Hern, Chemical Eng. Sci.397-404
SIWEP NOMAC 37

RO System Normalization
These changes make difficult to know the real RO
membranes performance
Normalization is necessary to know real RO membranes
performance at specific operating conditions(=reference data)
Required pressure and/or permeate quality change
(at fixed permeate flow operation) (feed pressure, permeate TDS)
What is normalization ?
RO feed water condition change
(Temperature, TDS, pH)
RO operating condition change
(Flow rate, Recovery)
SIWEP NOMAC 38

Water Analysis Details
- Conductivity - Sodium Bisulphite (feed and brine)
(every shift only)
- TDS (by 180degC)
(once a week)
- SDI
(every shift only)
- Chlorine (after SBS dosing)
- ORP (Redox) - Turbidity (NTU)
- Chloride – Sulphate
- Bicarbonate - Silica
-Nitrate – Fluoride
- Boron - Iron
Feed Water Analysis should include the following ions :
Red color : Mandatory items of Shuaibah III warranty condition
- Temperature - pH
- Sodium - Potassium
- Calcium – Magnesium
- Barium - Strontium
SIWEP NOMAC 39

High Permeate TDS
Poor permeate quality can be caused by
the following:
 Changes in operating conditions
 Damage to membrane (oxidants,
hydrolysis, etc..)
 Fouling
 Mechanical Leakage
SIWEP NOMAC 40

Causes of Mechanical Leakage
 O-ring leak
 Interconnector or Permeate Tube crack
 Glue Line failure
 Membrane de lamination
 Membrane fracture
 Membrane mechanical abrasion
 Membrane degradation through chemical
exposure
SIWEP NOMAC 41

Reverse Osmosis Element
 A reverse osmosis element can take several forms
 Flat sheet, in a plate and frame device
 Tubular
 Spiral wound
 Hollow Fine Fiber
 Our discussion is limited to the Spiral Wound
configuration.
 This is the most commonly used configuration for large
scale water and waste water reclamation purposes
SIWEP NOMAC 42

PERMEATE FLOW
% RECOVERY = X 100
FEED FLOW
FEED TDS - PERMEATE TDS
% REJECTION = X 100
FEED TDS
PERMEATE TDS
% PASSAGE = X 100
FEED TDS
Calculation of Production
43
SIWEP NOMAC

GLOSSARY USED IN R.O. PLANT
• Anti Scalant - A chemical agent added to water to inhibit the precipitation
or crystallization of salt compounds.
• Bio fouling - Blockage or obstruction due to dead or living animal or plant
matter
• Brackish water - Water with TDS of 1000 - 10000 ppm
• Brine - A saline solution with a concentration of dissolved solids
exceeding that of sea water.
• Colloid - Particulate matter usually <1 mm in size which does not settle
out rapidly and not filtered easily.
• Concentrate - The reject stream from RO unit
44
SIWEP NOMAC

GLOSSARY USED IN R.O. PLANT (Cont..)
• End use - The ultimate use of permeate water
• Feed water - The input water to the RO system
• Flux - The RO membrane throughput, usually expressed as gallons per
square foot of membrane per day.
• Foulant - Any substance that causes fouling
• Fouling - The act of depositing suspended solids on the membrane
surface or in the feed channel which impeeds the proper functioning of the
RO unit.
• Langellier Index - A means of expressing the degree of calcium carbonate
saturation in the solution
• LSI = pH(Sol) - pH(Ca)
where pH (sol) = pH of the solution
pH (Ca) = pH at which CaSO4 saturation starts
LSI should be negative
45
SIWEP NOMAC

Module - The combination of membrane elements and their pressure tube.
Osmosis - The tendency of water to pass through a semi permeable
membrane into a solution of higher concentration so as to equalize the
concentration on either side of the membrane
Osmotic pressure - The pressure that is exerted by the salt solution
separated from another aqueous solution by a semi permeable membrane
tending to draw water across the membrane to equalize concentration on
either side of the membrane.
Oxidation - A chemical reaction in which the atoms in an element lose
electron and the elements valence is correspondingly increased.
Permeability - The passage or diffusion of gas, vapour, liquid, or solid
through a barrier (membrane) without physically or chemically affecting it.
Recovery - Ratio of permeate flow to feed flow, usually expressed as
percentage
46
SIWEP NOMAC

Rejection - The process where certain materials are not allowed to pass
through (i.e. are rejected) a semi permeable membrane.
Salt rejection - The amount of salt in the feed water that is rejected by the
reverse osmosis membrane, expressed as percentage.
• Saturation - The state where all of the solute (salts) that can normally be
dissolved at a given temperature have been dissolved.
• Scale - A coating which forms on working surfaces of a system due to
precipitation or crystallization of salt compounds or solids.
• Semi permeable - The ability to allow some molecules in a mixture to pass
through but not all
• Silt - Sedimentary material consisting of fine mineral particles intermediate in
size between sand and clay.
• Silt Density Index (SDI) - A field test used to determine the fouling potential
of reverse osmosis feed water.
47
SIWEP NOMAC

SDI = 100(1-t1/t2)/ T
where,
t1 = Time required to pass 500 ml in the beginning, in seconds
t2 = Time required to pass 500 ml at the end, in seconds
T = Time between t1 and t2, in minutes
BASED ON DEGREE OF FILTERATION
• - REVERSE OSMOSIS MEMBRANES (96-99 % rejection of salts)
• - NANOFILTERATION MEMBRANES (85-90% rejection of salts)
• - ULTRAFILTAERATION MEMBRANES ( Colloidal &
macromolecules separation)
BASED ON MATERIAL OF CONSTRUCTION
• - CELLULOSE ACETATE MEMBRANES
• - THIN FILM POLYAMIDE MEMBRANES
48
SIWEP NOMAC

ADVANTAGES OF REVERSE OSMOSIS
 ECONOMY :
Low energy and operating cost especially when de-mineralising brackish
water with TDS above 500 ppm.
 REGENERATION FREE :
Continuous operation requires no regeneration.
 POLLUTION FREE :
Environmental friendly because NO REGENERATION effluent generated
like in Ion Exchange Process.
 EXCELLENT PRODUCT WATER QUALITY :
More than 97% - 98% rejection of Dissolved Solids and more than 99%
rejection of un dissolved organic substances like Bacteria, Viruses,
Colloidal particles and other organic impurities.
49
SIWEP NOMAC

APPLICATIONS OF R.O.
• DRINKING WATER - HOUSING, HOTELS, INDUSTRIES, OFFSHORE
RIGS, RURAL AREAS ETC.
• BOILER FEED WATER
• ULTRA PURE WATER - PHARMACEUTICALS, MEDICAL APPLICATIONS
• ULTRA HIGH PURITY WATER - ELECTRONICS AND SEMI
CONDUCTORS
• WASTE WATER RECYCLING - REUSE OF EFFLUENT OR SEWAGE
WATER
• SPECIAL APPLICATIONS - JUICE CONCENTRATION, METAL
RECOVERY ETC.

PARAMETERS RES PONSIBLE FOR SCALING & FOULING ON RO
MEMBRANES
SEA WATER ANALYSIS
Physical ChemicalBiological
SS,
O & G,
Colour,
Odour
Micro org.
Algae
Planktons
Inorganics Organics
COD
BOD
Cations
Calcium, Magnesium
Sodium, Potassium
Anions
Chloride, Sulphate,
Nitrate, Alkalinity, Silica
51
SIWEP NOMAC

OPTIMIZING RO PERMEATE RECOVERY
1. The recovery of large RO System is commonly chosen based on the
potential for scale formation. The higher the recoveries, the greater the
concentration of salts will be in the downstream membrane stages, thus
the higher the potential for scale formation
2. Because of the need to ensure adequate turbulence within the RO
elements, achieving higher recoveries is more difficult than just reducing
the RO concentrate flow.
52
SIWEP NOMAC

Sr.
No.
R.O PLANT D. M. PLANT
1 Continuous operation.
No. need for regeneration
Regeneration is required
every day.
2 Easy operation. Cumbersome operation.
3 Excellent Silica rejection. Good silica rejection.
4 Very less space required. More Space required.
5 No effect of even it TDS or
raw water quality changes
over a period of time.
Increase in TDS or Raw
Water quality over time
reduces operating hours,
increase operating costs &
outlet water quality
deteriorates.
6 Latest technology Old technology
7 Compact skid mounted
minimal civil work.
Large space and civil works
required.
R.O PLANT Vs D. M. PLANT
53
SIWEP NOMAC

R.O PLANT Vs D. M. PLANT
Sr.
No.
R .O. PLANT D. M. PLANT
8 Modular designed
expansion possible.
No expansion feasible.
9 Execution faster High execution time
10 Can handle wide range of
TDS i.e. 500 to 60000 ppm
Only effective within range
of 100 to 1000 ppm
11 Very low operating cost.
Payback period of capital
cost differential could be
12-15 months & net saving
after that depending on Sea
/Raw water TDS.
High operation cost.
12 Technology upgradation
possible.
Upgradation not possible.
54
SIWEP NOMAC

MYTHS AND FACTS OF R.O
MYTHS
• R.O. SYSTEM IS COSTLY
• DIFFICULT TO OPERATE
OPERATION COSTLY
• HIGH TECH
TECHNOLOGY FOR HIGH
TECH PEOPLE
• USED ONLY FOR SEA
WATER TREATMENT
• VIABLE ONLY FOR HIGH
CAPACITY
• MEMBRANE LIFE 1-2
YEARS (C.A.)
FACTS
• R.O. SYSTEM IS
ECONOMICAL
• USER FRIENDLY AND
OPERATION ECONOMICAL
• USABLE BY ALL LEVEL OF
PEOPLE
• USED FOR BRACKISH AND
SEA WATER
• VIABLE FOR ALL CAPACITIES
• MEMBRANE LIFE 3-5 YEARS
(P.A.)

56
Chemical Handling
SIWEP NOMAC
Exposure

Exposure
Route of Exposure
• The route (site) of exposure is an important
determinant of the ultimate dose—different
routes may result in different rates of
absorption.
 Dermal (skin)
 Inhalation (lung)
 Oral ingestion (Gastrointestinal)
 Injection
• The route of exposure may be important if
there are tissue-specific toxic responses.
• Toxic effects may be local or systemic
57
SIWEP NOMAC

Exposure
Time of Exposure
• How long an organism is
exposed to a chemical is
important
Duration and frequency
contribute to dose. Both may
alter toxic effects.
 Acute Exposure = usually entails a
single exposure
 Chronic Exposures = multiple
exposures over time (frequency)
58
SIWEP NOMAC

Father of Modern Toxicology
Paracelsus—1564
―All things are poisonous, only the dose makes it non-
poisonous.”
Dose alone determines toxicity
All chemicals—synthetic or natural—have the capacity
to be toxic
Dose
THE KEY CONCEPT in Toxicology
59
SIWEP NOMAC

―No employer may allow the use, handling
or storage of a Controlled Product
in a workplace unless the product carries
a label and a material safety data sheet
which meet the requirements of this Act
and the regulations and unless the
worker has received the training and
information required to carry out the
work entrusted to him safely‖
- Article 62.1, An Act respecting occupational health and
safety R.S.Q., S-2.1
60
SIWEP NOMAC

Personal Protective Equipment
SIWEP NOMAC 61

Anti Scalant Perm quest 0010E
Care should be taken
that the Anti Scalant is
not affected by
chlorine or other
oxidizing agent.
Anti Scalant retard the
growth of crystalline salt
structure in RO feed
and concentrate stream.
Anti Scalant, in
conjunction with acid,
can be used to control
calcium carbonate
scaling.
SIWEP NOMAC 62

Safety and handling of Anti
Scalant
 Ingestion of the anti Scalant may cause a
jelly-like mass inside the intestine and may
result in intestinal obstruction.
 If in contact with skin, the affected area
should be washed off with plenty of water.
SIWEP NOMAC 63

Caustic Soda Usage at RO Plant
 Caustic soda is used in the second pass
feed water to increase the pH to around
8-9.
 The solubility limit of silica is higher pH
particularly above 9.
 Boron rejection is higher at higher pH.
H3BO3 + H2O H4BO4 - +H + pKa=9.2
SIWEP NOMAC 64

Caustic soda Usage at CO2
Plant
 Caustic soda is used in the carbon dioxide plant for SO2
removal from the flue gas
 Flue gas generated from the burner contains sulphur
oxides that are formed due to sulphur content in the fuel
oil
 These gases are very harmful for the plant as they can
cause corrosion of the plant.
 They are removed in the scrubber where sodas ash 10%
solution is circulated through a packed column.
 The pH is maintained between 7 to 8.
SIWEP NOMAC 65

Safety and handling of Caustic
Soda
 It is incompatible with a wide variety of
chemicals including many metals, ammonium
compounds, cyanides, acids, nitro compounds,
phenols, and combustible organics.
 Heat of solution is very high and may lead to a
dangerously hot solution if small amounts of
water are used
 Caustic soda absorbs carbon dioxide from the
air
SIWEP NOMAC 66

Safety and handling of Caustic Soda
 It is very corrosive.
 It can cause severe burns.
 It may cause serious permanent eye damage
and is very harmful if ingested.
 It is harmful by skin contact or by inhalation of
dust.
 It may cause severe irritation of the respiratory
tract, inflammation of lungs, difficulty breathing if
inhaled
 It may cause pulmonary edema
SIWEP NOMAC 67

Monoethanol amine (MEA) Usage
 Monoethanol amine is used for CO2 absorption
in the carbon dioxide generation plant.
 Flue gas containing CO2 is passed from the
absorber.
 MEA solution is circulated in a packed column
where CO2 is absorbed in MEA solution.
 The temperature of the MEA is maintained at
around 35-40 degrees centigrade for better
absorption of the CO2 where around 99% of the
CO2 is absorbed.
SIWEP NOMAC 68

Safety and handling of MEA
 Monoethanol amine is highly corrosive
chemical.
 It can cause eye and skin burns.
 It can be harmful or fatal if swallowed.
 It can cause dizziness and drowsiness if
inhaled.
 Monoethanol amine can cause respiratory
tract infection and can damage liver,
kidney if swallowed.
SIWEP NOMAC 69

 Repeated skin contact may cause a
persistent irritation or dermatitis.
 Immediately flush eyes with large amounts
of running water for at least 15 minutes.
 Immediately remove contaminated
clothing and shoes.
 If the person is conscious and can
swallow, immediately give two glasses of
water but do not induce vomiting.
SIWEP NOMAC 70

Potassium permanganate solution
 Potassium permanganate is used for NO2,
MEA, and acetaldehydes removal from the
carbon dioxide gas.
 . When CO2 gas enters the PPM
scrubber, nitrogen dioxide, MEA particles
and acetaldehydes are washed with
potassium permanganate solution that is
being circulated in the PPM scrubber.
SIWEP NOMAC 71

Safety, and handling of KMno4
 Heat, shock, friction, or contact with other
materials may cause fire or explosion.
 Potassium permanganate is harmful if
swallowed.
 Breathing of vapor or dust of potassium
permanganate should be avoided.
 Acute exposure can cause irritation or corrosive
to body tissue on contact.
 Chronic exposure may lead to lung irritation and
central nervous system disorders.
SIWEP NOMAC 72

Chlorine dioxide plant
 Chlorine dioxide is generated according to the following
reaction.
 Sodium Chlorite (31%) + Hydrochloric acid (33%) =
Chlorine dioxide + Sodium Chloride + Water
5NaClO2 + 4HCl = 4ClO2 + 5NaCl + 2H2O
 Therefore, to generate 1 kg of chlorine dioxide, 5.7 kg of
sodium chlorite, 5.7 kg of Hydrochloric acid and 1 m3 of
water is needed.
 This reaction takes place in water and therefore we have
a very diluted solution of around 2000 ppm of Chlorine
dioxide.
SIWEP NOMAC 73

Chlorine di oxide
 5Naclo2 + 4Hcl 4Clo2 +5Nacl +2H20
 Chlorine di oxide use for potable water
disinfection
 To protect drinking water from disease causing
organisms, or pathogens
 Chlorine has been hailed as the savior against
cholera (an acute infectious disease of the small intestine),and various other
water-borne diseases
Chlorine dioxide
SIWEP NOMAC 74

Potable water disinfection
 The bactericidal efficiency is relatively unaffected by pH
values between 4 and 10
 Chlorine dioxide is clearly superior to chlorine in the
destruction of spores, bacteria's, viruses and other
pathogen organisms on an equal residual base
 Chlorine dioxide has better solubility
 No corrosion associated with high chlorine
concentrations. Reduces long term maintenance costs
 ClO2 destroys phenols and has no distinct smell
SIWEP NOMAC 75

Chlorine Health Effects Table
Bulletin work safe Alberta CH 067-Chemical Hazards
Chlorine Concentration ppm Health Effect
0.03-0.04 Range of odour theshold
1-3 Mid irritation of the eyes, nose and throat
3-6
Stinging or burring in the eyes, nose and throat,
headache, watering eyes, sneezing, coughing,
breathing difficulty, bloody nose.
5-10
Severe irritation of the eyes, nose and respiratory
tract
10
Immediately dangerous to life and health ( IDLH )
Concentration
10-25 May be fatal after 30 minutes of exposure.
>25
Immediate breathing difficulty, build up of fluid in
the lungs ( pulmonary edema)possibly causing
suffocation and death. Pulmonary edema may be
immediate or delayed
>1000 Fatal after a few breaths
SIWEP NOMAC 76

Chlorine Effect On Respiratory System
External Effect
1. Directly attack to cilia
2. Na & K pump damage
3. Surfactant damage
Internal Effect
1. GHS activate nephritic factor
2. Capillary damage
3. Sensory nerve
4. Interstitium
Abbreviation
Alveoli
ASC Ascorbate
Surfactant defensive system to
prevent shrinking
X Secondary Intermediate
IL8 To digest to kill
SIWEP NOMAC 77

Immediately Dangerous To Life or Health Concentrations (IDLHs)
National Institute for Occupational Safety and Health ( NIOSH )
Substance
Original IDLH Value
ppm
Revised IDLH Value
ppm
Carbon Mono Oxide 1500 1200
Chlorine ( IWPP ) 30 10
Chlorine dioxide ( IWEP ) 10 05
Chloroform 1000 500
Hydrazine 80 50
Iodine 10 2
Ammonia 500 300
Bromine 10 3
Nitrogen dioxide
50 20
SIWEP NOMAC 78

Materials Causing Immediate and
Serious Toxic Effects
Characteristics
May cause immediate
death or serious injury if
inhaled, swallowed, or
absorbed through the skin
SIWEP NOMAC

Hydrochloric acid HCL
It will be used
as a
disinfectant
for potable
water.
SIWEP NOMAC 80

Safety and handling of HCL
 Hydrochloric acid is very hazardous in case of
skin contact, eye contact, and ingestion.
 It can cause corrosion, irritation, and ingestion.
 It is slightly hazardous in case of inhalation.
 Liquid or spray mist may produce tissue damage
particularly on mucous membranes of eyes,
mouth and respiratory tract.
 Severe over-exposure can result in death.
 Inflammation of the eye is characterized by
redness, watering, and itching.
SIWEP NOMAC 81

Sodium Chlorite Naclo2
 Sodium chlorite is required for the
generation of chlorine dioxide.
 It will be used as a disinfectant for potable
water.
 Ideally, 5.7 kg of sodium chlorite is
required per kg of chlorine dioxide
generation.
SIWEP NOMAC 82

Safety and handling of Naclo2
 It is not a combustible substance but gives
toxic fumes in case of fire.
 Exposure to skin or eyes may induce
redness and pain.
 Inhalation may cause abdominal pain and
vomiting.
SIWEP NOMAC 83

84
1) Alert someone else immediately
2) Evacuate and barricade the area
3) If a chemical spilled on the body:
Rinse the affected area with running
water for at least 15 minutes, remove contaminated clothing
and shoes while rinsing. Call for medical help.
4) Wear personal protective equipment: apron, gloves,
safety glasses, face shield or respirator, according to
the type of the chemical and the amount spilled.
5) Absorb the spill using absorbent sleeves and wipes
SIWEP NOMAC

BREAK
SIWEP NOMAC 85

Corrosion
 The destruction of metal
by chemical or
electrochemical with its
Environment is called
corrosion
SIWEP NOMAC 86

Battery Analogy
 Anode
 Cathode
 Electrical Circuit
 Metal lost at anode
Corrosion
e -
Electrolyte
Anode
Cathode
SIWEP NOMAC 87

Factors Influencing Corrosion
SIWEP NOMAC 88
pH
Temperature
Dissolved
Solids
System
Deposits
Water Velocity
Microbiological
Growth

Types of Corrosion
 Biological corrosion
 Cold end corrosion
 Cavitations
 Dezincification corrosion
 Fatigue corrosion
 Petting Corrosion ( localized corrosion )
 General corrosion ( Uniform Corrosion )
SIWEP NOMAC 89

Types of Corrosion
 Galvanic corrosion
 High temperature corrosion
 Hydrogen attack corrosion
 Inter granular corrosion
 Stress Corrosion
 Under deposit corrosion
SIWEP NOMAC 90

Different Types of Corrosion attack
General attack
 When the corrosion is uniformly distributed over the
metal surface.
 The conceder amount of iron oxide produced by
generalized attack contribute to fouling problem
Localized or pitting attack
 Exist when only small areas of metal surface corrode.
 Pitting is the most serious form of the corrosion because
action is concentrated in small area
 Pitting may perforate the metal in a short time.
SIWEP NOMAC 91

Base Metal
Localized Pitting Attack
Water
Original
Thickness
Pitting Corrosion
 Metal removed at
same rate but from
a much smaller area
 Anode very small
 Often occurs under
deposits or weak
points
 Leads to rapid
metal failure
SIWEP NOMAC 92

Different Types of Corrosion attack
Galvanic attack
 When two different metals are in contact.
 The more active metal corroded rapidly.
Common example in water system are
 Steel & brass , Zinc & brass , Aluminum &
steel , Zinc & steel ,
 If galvanic attack occurs the metal named
first will corrode
SIWEP NOMAC 93

To Prevent Corrosion
SIWEP NOMAC 94

Methods To Control Corrosion
 Use corrosion resistant alloys: $
 Adjust (increase) system pH: Scale
 Apply protective coatings: Integrity
 Use ―sacrificial anodes‖: Zn/Mg
 Apply chemical corrosion
inhibitors
 Cathodic Protection
SIWEP NOMAC 95

Cathodic Protection
 Galvanic Sacrificial Anode
Pieces of active metal such as magnesium
or Zinc placed in contact with the corrosive
environment and are electrically
connected to the structure to be protected.
Example: Condenser, Desalination( MSF )
SIWEP NOMAC 96

The Galvanic Series
ZINC - Anode
STEEL - Cathode
This arrangement of metals
determines what metal will
be the anode and cathode
when the two are put in a
electrolytic cell
(arrangement
dependent on salt water as
electrolyte).
SIWEP NOMAC 97

Fouling
FOULING is the accumulation of solid
material, other than scale, in a way that
hampers the operation of equipment or
contributes to its deterioration
SIWEP NOMAC 98

Fouling
The deposition of suspended particles on the membrane
surface.
o Foul ant on the membrane surface increases the
resistance to
the flow of water through the membrane.
o Fouling causes lower productivity at constant net
pressure or
higher net pressure at constant productivity.
o Sometimes higher salt passage will be caused by
fouling.
SIWEP NOMAC 99

Membrane fouling is caused by
 Improper pretreatment system
 pretreatment condition upset
 Chemical dosing system upset
 Improper material selection (piping, valve, pump, etc.)
 Improper flushing after shutdown
 Scaling by excess recovery ratio
 Biological contamination in feed water
 Feed water chemistry change
SIWEP NOMAC 100

Typical fouling materials
 Suspended Solid, Colloid, silt, clay
 Hydrates of metal oxides (Iron, manganese,
copper, aluminum, etc.)
 Pretreatment coagulant
 Scale (Silica, calcium carbonate, calcium sulfate,
etc.)
 Organic chemicals (antiscalant, cationic
polymer, nonionic polymer, etc.)
 Biological contamination and its growth
SIWEP NOMAC 101

Membrane Fouling
Cause of Trouble : Fouling (Suspended Solid, Coagulant )
 ( SS leakage from pretreatment )
 Fouling Amount : 62.4g Ash Ratio : 75.9%
(Dry weight) (SiO2:32%, Al:9.7%, Fe:4.8%)
SIWEP NOMAC 102

Type's of Membrane Fouling
Microbiological Fouling Silica Fouling
SIWEP NOMAC 103

Type's of Membrane Fouling
Membrane Degradation Iron Fouling
SIWEP NOMAC 104

RO Troubleshooting Matrix ( 1 )
Possible
cause
Possible
Location
Pressure
Drop
Feed
Pressure
Salt
Passage
Metal Oxide Fouling
( e.g Fe,Mn,Cu,Ni,Zn)
1st stage
Lead Membrane
Rapid Increase Rapid Increase Rapid Increase
Colloidal Fouling
(Organic & Inorganic Complex )
1st Stage
Lead Membrane
Gradual Increase Gradual Increase Slightly Increase
Mineral Scaling
( Ca, Mg, Ba, Sr)
Last Stage
Tail Membrane
Moderate Increase Slightly Increase Marked Increase
Polymerized Silica Last Stage
Tail Membrane
Normal to Increased Increased Normal to Increase
Biological Fouling Any Stage, Usually
lead element
Marked Increase Marked Increase Normal to Increase
Organic Fouling
( dissolved NOM)
All Stage Gradual Increase Increased Decreased
Anti Scalant Fouling 2nd Stage
Most severe
Normal to Increased Increased Normal to Increase
SIWEP NOMAC 105

RO Troubleshooting Matrix ( 2 )
Possible
cause
Possible
Location
Pressure
Drop
Feed
Pressure
Salt
Passage
Oxidant damage
(Cl2,ozone,KMnO4)
1st stage
Most severe
Normal to decreased Decreased Increased
Hydrolysis damage
(Out of range pH)
All Stage Normal to decreased Decreased Increased
Abrasion damage
(Carbon fines , etc)
1st stage
Most severe
Normal to decreased Decreased Increased
O-ring leaks
(at interconnectors or
adapters)
Random
(typically at feed
adapter)
Normal to decreased Normal to decreased Increased
Glue line leaks
(due to permeate
back pressure in
service or standby )
1st stage
Most severe
Normal to decreased Normal to decreased Increased
Glue line leaks
(due to closed
permeate valve while
cleaning or flushing )
Tail element of a
stage
Increased
( based on prior
fouling & high delta
P)
Increased
( based on prior
fouling & high delta
P)
Increased
SIWEP NOMAC 106

Fouling
 Factors which influence fouling are:
 Water Characteristics
 Water Temperature
 Water Flow Velocity
 Microbiological Growth
 Corrosion
 Process Contamination
 Environmental (i.e. atmospheric pollutants)
SIWEP NOMAC 107

Differential Pressure increase
Problem of High Differential Pressure (1)
 Fouling will be accelerated
 RO element mechanical trouble thrust force
 Getting difficult to remove by cleaning
SIWEP NOMAC 108

Differential Pressure increase (2)
Problem of High Differential Pressure (2)
 Fouling will be accelerated
 RO elements mechanical trouble by thrust force
 Getting difficult to remove by cleaning
SIWEP NOMAC 109

Typical causes of DP increase
Upstream
 Suspended solids, colloid, bacteria, silt,
clay, iron corrosion and pretreatment
coagulant in the feed water
Downstream : scaling
 Any stage mainly lead position : Biological
fouling
SIWEP NOMAC 110

Bio Fouling Control
 General Methods for Bio
Fouling Control
 Prevent contact with direct sunlight
wherever possible
 Disinfect make-up water
 Regularly maintain and disinfect filters
 Application of Biocides
SIWEP NOMAC 111

Economic Impact of Fouling
 Decreased plant efficiency
 Reduction in productivity
 Production schedule delays
 Increased downtime for maintenance
 Cost of equipment repair or replacement
 Reduced effectiveness of
chemical inhibitors
SIWEP NOMAC 112

Scaling
The deposition of sparingly soluble salts
onto the membrane
surface and/or the feed channel material.
o Scaling occurs primarily in the
downstream elements because of
the higher concentrations existing
in this portion of the RO system.
o Common Scalant include
• calcium sulfate,
• calcium carbonate.
• Silica
o Less common Scalant include
• Calcium Phosphate
• Calcium Fluoride
• Barium sulfate
Mineral Scale
SIWEP NOMAC 113

Scaling caused by
 Too much high
recovery
 Higher pH operation
 Lower antiscalant
dosing
 Water chemistry
change
SIWEP NOMAC 114

Single Element Test on site
Single Element
Performance Test on site
Single element
weight checking
Single element
performance
checking
SIWEP NOMAC
Membrane
Spacers
Opened
Membrane
Separator mash
is pulled out
115

Single Element Performance
Test on site
 RO element outside visual checking
 Single element weight checking
 Single element performance checking
 Measuring RO element weight after 30 min vertical
standing
water drain.
 New element weight : around 15 -16kg
(depend on water drain condition)
 Weight checking will help to know fouling tendency in the
pressure vessel.
SIWEP NOMAC 116

RO element outside visual
checking
 Single RO element performance measuring
equipment on site is very helpful
 To check RO membrane performance more
reliably.
 To check RO membrane performance before /
after cleaning.
 To carry out pre-cleaning test (if single element
cleaning test is available)
SIWEP NOMAC 117

SIWEP NOMAC
0.54
0.59
0.70
0.58
0.70
0.63
0.50
CL 0.61
0.25
0.35
0.45
0.55
0.65
0.75
0.85
0.95
J-10-1 J-10-2 J-10-3 NEW J-10-4 J-10-5 J-10-6 J-10-7
PermeateFlow(m3/hrs)
SWRO # 2 Membrane Performance 09.07.2012
Permeate Flow ( m3/hrs)
118

Membrane Inspection
SIWEP NOMAC 119

SIWEP NOMAC 120

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