RO Pretreatment System Chemistry

Plant Chemistry
RO Pretreatment System
Umar Farooq
Senior Chemist
NOMAC SIWEP Shuaibah
Jeddah Saudi Arabia 1

RO Pre Treatments System
 Water Chemistry
 Pretreatment System
 Coagulation Flocculation & Sedimentation
 Chemical Handling and safety precaution
 Biology and Chemistry for Filtration
 Microbiological growth causes
 Corrosion phenomena
 Bio fouling
Umar Farooq Senior Chemist
NOMAC SIWEP Shuaibah Jeddah 2

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 pretreatment 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.
NOMAC SIWEP Shuaibah Jeddah
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.

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

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*

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

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-

Types of Hardness
Temporary Hardness ( Alkaline Hardness )
 It is due to presence of bicarbonates of calcium
and magnesium in water , also called carbonate
hardness. It can be removed by boiling and
pretreatment process
Permanent Hardness(Non Alkaline Hardness )
 It is due to presence of chlorides , sulphate and
nitrate of calcium and magnesium , it can be
remove by ion exchange and desalination
process

Types of water
Raw water
 Water taken from any natural source which is untreated
Hard water
 If salt of calcium Ca++and magnesium Mg+ +dissolve in
water called hard water
Soft water
 If calcium Ca++and magnesium Mg+ + salt not present in
water is called soft water
Dami water
 Water having no ion no mineral salt remove by ion
exchange method are called demi water.

Types of water
Pretreatment water
 Water having no turbidity no color and suspended particle is called
pretreatment water
Reverse osmosis water
 Pure water by forcing saline or impure water through a semi
permeable membrane across which salts or impurities cannot pass.
Heavy water
 Water having deuterium isotope of hydrogen is known as heavy
water
Pure water
 Water having no impurities and having pH =7

RO Process flow diagram

Pretreatment System
In this module we will learn about the Pretreatment process
and the individual steps that make up the process;
COAGULATION, FLOCCULATION and
SEDIMENTATION.
We will learn about the various types of equipment and
systems available to effect Pretreatment of water, their
expected performance and limitations.
We will learn about operating procedures and practices to
make the Pretreatment process work.
We will also learn about monitoring and control practices
available to determine how well it is working, as well as
troubleshooting the process when it is not performing
well.

Water Pretreatment is the removal of
suspended solids (microorganisms, dirt,
silt, etc.) by settling from a water stream.
Pretreatment is a mechanical/physical
process which requires chemical
conditioning to enhance pretreatment
performance

CONTAMINANTS PRESENT IN WATER
 Turbidity ..... This is normally in the category of
suspended material, but with particle sizes so
small as to have an infinite settling rate.
 Color ..... Particle size again falling into the
colloidal or sub colloidal range. Color can also be
present in a true solution.
 Iron and Manganese ..... Only very small amounts
found in surface waters, but sometimes large
quantities are found in well waters.
 Oil and Grease ..... Usually expressed as oil or
extractable matter (Freon or Hexane)

CONTAMINANTS PRESENT IN SEA WATER
 Hardness ..... Calcium and magnesium salts expressed as
CaCO3.
 Alkalinity ..... Bicarbonates, carbonates and hydroxides.
 Acidity ..... Free mineral acids such as H2SO4 or HCl.
 Dissolved Solids ..... Primarily chlorides, sulfates and silica.
 Organic matter ..... Expressed as COD or TOC.

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

Definitions
• Coagulation - The electrochemical
process of neutralization of surface
charges (usually negative) to allow
small colloidal particles to collide and
form larger masses capable of settling
or withstanding pressure.
• Flocculation - The physical process of
the formation of larger masses, often
enhanced by the addition of long-chain
polymeric compounds

COAGULATION
 Coagulation is a process of charge
neutralization of finely divided colloidal
impurities in water into masses that will settle
rapidly and filtered out of this process.
 Coagulation involves neutralizing the negative
charge particle to adhere.
 For this purpose mixing can be accomplished
by in-line static mixers

Coagulation
•Destabilization of
colloids by
neutralizing the
forces that keep
them apart

Definition
 Dissolved Solids – Organic or inorganic compounds dissolved in
water, e.g. salt. Water is a nearly universal solvent. (TDS)
 Suspended Solids – The amount of suspended particulate matter
measured milligrams per liter (mg/l = ppm) (TSS)
 Alkalinity – The acid neutralizing capacity of water, mainly sum of
HCO3
-,CO3
=, and OH- concentrations
 Apparent Color – The color in water caused by light absorption at
different wavelengths due to the dissolved and suspended material
 True Color – The residual color in water remaining after any
suspended material has been removed
 Turbidity - a measure of the clarity of the water in FTU, JTU, or NTU.
It is an expression of the optical property that causes light to be
scattered or absorbed rather than transmitted as straight lines
through water
 Aquatic humic substances - heterogeneous, yellow to black, organic
materials that include most of the naturally occurring dissolved
organic mater

Rapid Mix
 Static mixer
 No moving parts
 Creates velocity gradient for mixing
 Rapid dispersion of treatment chemicals
 Mixing for sweep flocculation
 Hydroxide formation 1- 7 seconds (1-2 seconds warm water)
 G - 300 - 16000 sec-1, who knows
23

Flocculation
•The
agglomeration, or
building up of
smaller particles.
•To form a bigger
particle or flock can
settle

FLOCCULATION
 Gentle mixing is required to bring the small
particles together permitting them to increase
in size and settle more rapidly
 Coagulant are chemicals used to neutralize the fine
particles of suspended mater in water form flock that
will settle and can be filter out .
 Coagulant aid are that chemicals which added along
with the coagulants help in larger and better flock
formation.eg poly acryl amide.
Poly acryl amide formula

Many factors influence Coagulation and
Flocculation;
• Mixing
• Time
• Amount of Solids in the system
• Velocity Gradient (size vs. shear
resistance)
• Temperature

Chemicals Used In Water Treatment
 Aluminum Sulfate (Alum) Al2 ( So4)2
 Poly aluminum Chloride (PAC)
 Ferric Chloride Fecl3
 Organic Polymers Poly Acryl Amide
 Inorganic/Organic Polymer Blends
Structural Formula of PAC

Chemical reaction of pretreatment system
 Al2(SO4)3 + 6NaHCO3 3NaSO4 + 2Al(OH)3+6CO2
 Fe2(SO4)3 + 6NaHCO3 3NaSO4 + 2Fe(OH)3+6CO2
 2FeCl3+ 3Ca(OH)2 2Fe ( OH )3 + 3CaCl2
 Reaction takes place in two steps
 FeSO4 + Ca(OH)2 3NaSO4 + Fe ( OH )2 +CaSO4
 Fe ( OH )2 + O2 + 2H2O Fe ( OH )3

Chemical reaction of pretreatment system
 FeCl3+ H2O Fe(OH)3 + 3 HCl
 FeCl3 + CuCl FeCl2 + CuCl2
 2FeCl3+ 3Ca(HCO3)2 2Fe(OH)3 + 3CaCl2 +7CO2
 2FeCl3+3Ca(OH)2 2Fe(OH)3 + 3CaCl
 Different coagulants and Coagulant aid chemicals which are available in
market for pretreatment process
 Coagulants
1) Ammonium alum Al2 ( SO4)2.
2) Poly aluminum chloride [Al2(OH)nCl6-n]m
3) Aluminum Sulphate Al2 (SO4)3
4) Ferric Chloride FeCl3
5) Ferric Sulphate Fe 2( SO4 )3
6) Sodium Aluminates Na2 Al2 SO4

Ferric Hydrolysis Reactions*
 FeCl3 +3H2O Fe(OH)3 + 3HCl
 Fe+++ + H2O FeOH+++ H+
 FeOH++ + H2O Fe(OH)2
+ + H+
 Fe(OH)2
+ + H2O Fe(OH)3 + H+
 Fe(OH)3 + H2O Fe(OH)4
- + H+
 2Fe++++ 2H2O Fe2(OH)2
+++++ 2H+
 3Fe++++ 4H2O Fe3(OH)4
++++++ 4H+
 Alkalinity neutralization
H+ + HCO3 H2O + CO2
From Water Quality and Treatment, 4nd Edition, American Water Works Association

Chemical for Pretreatment
 Coagulant aid
1) Poly acryl amide
2) Magnesium chloride Mg Cl2
3) Magnesium Sulphate Mg So4
4) Bentonite ( clay )
5) Magnesia

 JAR TESTING
 Gang stirrer used to simulate plant’s
 Flash mix time and intensity
 Flocculation time and intensity (slow mix)
 Settle for 10-15 minutes
 Coagulants added at start of flash mix time
 Flocculants added as start of slow mix time
 pH adjustment if needed before coagulant for
turbidity removal and after coagulant for color
removal

RO Pretreatment Goals
 R. O. Pretreatment
Goals
 Reduce SDI < 3.0
• Difficulties with very
clean water
• Consistent Operation
 Do not contribute
fouling agents
 How to maintain the
System

DMF Monitoring
3.12
4.40
2.77
3.46
3.79
3.10
3.24
3.98
2.58
4.20
3.89
3.97
3.84
3.96
4.40
3.80
4.51
4.35
4.42
4.48
4.60
4.26
3.97
4.12
3.85
4.24
3.93
4.104.05
4.154.10
CL 3.92
2.25
2.75
3.25
3.75
4.25
4.75
5.25
14 5 17 11 9 23 24 32 26 3 1 30 6 31 4 7 28 8 22 27 13 10 29 19 12 2 18 16 21 15 25
SDIFirsttimeDMFModificationafter1hrsservictime
DMF SDI Monitoring 12 Oct 2010 To 4 March 2012
Cycle 1
34

Sea water monitoring

pH
 pH - The log of the inverse of the hydrogen ion
(H-) concentration. The acidity or basicity of
water is determined by the amount of H- present.
0 7 14
Acid BaseNeutral
Rain Water
5 7.5 8.5
Drinking Water
6
Range for Ferric Coagulation

pH range of different products

Water Biology &
Chemistry for
Filtration
38

Source Conditions
 Possibly Anoxic or Anaerobic at lower levels –
reducing conditions
 Very high TDS, possible color
 pH high but varied
 Very low turbidity
 Limited inorganic suspended solids
 High temperature
 Subject to biological growth

Source Components
 Biological material
 Algae
 Bacteria
 Protozoa
 Viruses
 Color
 Colloidal solids -
--
--
-
-
-
-
- - -

Inorganic Colloids
 Clay, Silt and
Precipitates
 Characteristics
 Surface charge
 Electrical
attraction
 Double boundary
layer
 Effects of pH

Coagulation
 Stable Colloidal
Suspension
 Mechanisms of
Destabilization
 Double - layer compression
 Electrostatic attraction
 Enmeshment
 Interparticle bridging
 Effects of pH
 Restabilization
 Coagulation with Ferric
Chloride

Coagulation
 Charge
neutralization
 Formation of
―microflocs‖
 Attraction to
charged particles
- -
-
--
-
-
--
--
-
-
-
-
-
- -
-
-
-
-
-
-
-
-
-
--
-
--
-
- -
Fe(OH)3

Flocculation
 Charge neutralization
Fe(OH)3

Flocculation
 Sweep flocculation

Flocculation
 Bridging
- -
-
--
-
--
-
--
--
-
-
-
-
-
-
-- --
-
--
--
-
--
-
-
-
-
--
- -
-
-
-
- -
-
-
- -

Coagulant Aids - Polymers
 Cationic
 Primary coagulant
 Coagulant aid
 Nonionic
 Improved floc retention
 Filter aid
 Anionic
 Coagulant aid
 Sludge thickening
 Not expected to be used – info just for knowledge

Chemical Feed Calculations
 Conversions
 Water
• 1 meter3 = 1000 liters
• 1 Kilogram per Liter
 Specific Gravity (S. G.) = weight of liquid / weight of water
 Parts Per Million (PPM) = units / million units
• grams / million grams
• the same as milligrams per liter (mg/l)
 Chemical Feed Rates
 Liquid
 Dry

Filtration
 Surface Straining
 Depth
 Adsorption
 Adhesion
 Coagulation
 Flocculation
 Sedimentation
 Hydraulic shear

Filtration
 Media aging
 Effect on attachment
of particles
 Time and means of
development
 Effects of media
growth
 Effects of overgrowth

Filter Operation
 Solids accumulation
 Increased resistance to
flow
 Higher shear development
 Turbidity breakthrough
 Service run length
 Accumulated time
 Potential for biological
growth
 Headloss
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12 14 16 18 20 22 24
Turbidity
Headloss

Filter Backwash
 Cleaning action
 Interparticle collision
 Hydraulic shear
 Backwash
 Water only wash
 Water with auxiliary
wash
 Rates
 Temperature effects
 Bed expansion

Filter Backwash
 Factors effecting
particle movement
 Shape
 Size
 Specific gravity
 Changes with time
 Changes with solids
 Rate selection
 Temperature effects
 Bed expansion

My Rules
 Feed only as much chemical as necessary to achieve
the quality goals
 Feed enough chemicals to achieve the quality goals
 Constantly review the chemistry
 Allow plenty of time after any change for equilibrium to
be achieved
 Turbidity values can be misleading
 Check as necessary to make sure no biological fouling is
developing
 Never be in a hurry in a water plant.
 Always refill from the bottom
 Observe at least one filter backwash per day

55
Safe Chemical Handling

Exposure
• In order for a chemical to produce a biological effect, it must first reach a
target individual (exposure pathway).
• Then the chemical must reach a target site within the body
(toxicokinetics).
• Toxicity is a function of the effective dose (how much) of a foreign
chemical (xenobiotic) at its target site, integrated over time (how long).
• Individual factors such as body weight will influence the dose at the
target site
X =
56

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

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

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

The emerging field of
―Pharmacogenomics‖ or
―Toxicogenomics‖ offers
the potential to identify and protect
subsets of people predisposed to
toxicity from chemicals or drugs
Typical Population
Identify People with “normal” responses
More
Sensitive
Less
Sensitive
60

Acids – A corrosive chemical that proteinizes upon contact with body
tissue and causes immediate pain.
Bases – A corrosive chemical that does not proteinize upon contact with
body tissue and does not cause Immediate pain.
Carcinogens - Substances which under favorable conditions through
direct or indirect action, either externally or internally, act on healthy
cells to cause a metamorphosis and bring about a rapid proliferation of
cellular elements and the development of structure abnormalities.
Chemical – Means any element, chemical compound or mixture of
elements
and/or compounds

Compressed Gas – Non Flammable materials which have a PSIA
greater
than 40 at 70*F, or a PSIA greater than 104 at
104*F, or those Flammable materials which have a
PSIA greater than 40 at 100*F.
Those with sufficiently high toxicity are class “A” poisons and
receive a Poison gas label.
All flammable gas, liquefied or non-liquefied and dissolved have flash
points below room temperature. It’s impossible to avoid forming a
flammable mixture if any leaks into the air.
Container – Means any bag, barrel, bottle, box, can, cylinder, drum
Reaction vessel, storage tank or the like that contains
hazardous chemical.

Explosive – Substances under which certain conditions of
shock, temperature
or chemical reaction decompose with violent rapidity, usually releasing large
quantities of gasses and heat.
Exposure/Exposed – Contact with a hazardous chemical in the course of
employment through any route of entry (inhalation, ingestion, skin contact or
absorption, etc.) and includes potential (e. g., accidental or possible)
exposure.
Flammable Liquids – A liquid whose vapor can form an ignitable mixture
with air. The liquid is the fuel, the surrounding atmosphere is the oxidizer.
For the mixture to burn an ignition source must be present.

64
Are there portions in your workplace that
are hazardous?

COMMON BASES (pH 8-14)
 Sodium hydroxide (lye)
 Sodium Hypochlorite (Bleach)
 Aqueous ammonia
 Potassium hydroxide (Potash)
 Ammonium hydroxide
CRITERIA FOR STORING CORROSIVE LIQUIDS
 Inspect before placing in storage
 Separate acids from bases
 Separate acids & bases from other materials
 Use drip pans under containers
 Use personal protective equipments (PPE)
 Use correct dilution sequences
 Use approve storage containers
65

Corrosive Material
Precautions
Store acids and bases in
separate areas
Avoid inhaling these
materials
Avoid contact with skin
and eyes
Wear the recommended
protective equipment and
clothing

HANDLING CORROSIVE LIQUIDS
 pH – The pH of a liquid is the numerical measure of its
relative acidity or alkalinity. The range is from 0 – 14 with a
neutral level expressed as a pH of 7.0
 Above 7.0 – The liquid is more alkaline or basic.
 Below 7.0 – The liquid is more acidic
COMMON ACIDS
 Hydrochloric acid
 Hydrofluoric acid
 Nitric acid
 Phosphoric acid
 Chromic acid
67

Corrosive Material
Characteristics
´Will burn eyes and skin on
contact
´Will burn tissues of
respiratory tract if inhaled
7

CRITERIA FOR HANDLING HIGHLY TOXIC LIQUIDS
 Can be extremely toxic to humans
 Preplanning is critical when using these materials
 Know the adverse health effects
 Restrict access to these materials
 Carefully review storage requirements
 Ensure sufficient training levels achieved
 Use adequate personal protective equipments
 Use Approve storage containers.
CRITERIA FOR STORAGE STRONG HIGHLY TOXIC LIQUIDS
 Inspect containers before placing in storage
 Separate for incompatibles
 Use Personal protective equipments
 Use approved storage containers
69

Materials Causing Other Toxic Effects
Precautions
Avoid inhaling gas or vapours
Avoid skin and eye contact
clothing
Do not eat, drink or smoke
near these materials
Wash hands after handling

HANDLING REACTIVE LIQUIDS
 Know the adverse health effects
 Know the reactive nature of the material
 Separate from incompatibles
 Restrict access to these materials
 Carefully review storage requirements
 Ensure sufficient training level achieved
 Use adequate personal protective equipment(PPE)
 Use approved storage containers.
STORAGE CRITERIA FOR STRONG REACTIVE LIQUIDS
 Follow established procedures
 Inspect before placing in storage
 Separate from incompatibles
 Use adequate personal protective equipment (PPE)
 Use approved storage containers.
71

Dangerously Reactive
Material
Characteristics
Store away from heat
Avoid shock and friction
clothing

STORAGE CRITERIA FOR STRONG
SOLID MATERIALS
 Inspect containers before placing in storage
 Separate from incompatibles
 Use mechanical devices to lift heavy bags
 Use personal protective equipments
 Protect from contamination in storage
 Use exhaust ventilation
 Empty bags have residual product inside
 Use approved storage containers.
73

MANAGEMENT OF HANDLING AND
DISPOSAL OF EMPTY CONTAINERS:
 Inspect containers for product residual
 Do not use empty containers as trash cans
 Check with environmental management
 Triple rinse reusable containers
 Remember _ Residual Product is hazardous too
 Follow local procedures
 Check with supervisor If policy is unclear.
74

75
Eye Protection
Safety Glasses /
Goggles
Face
Shield
Respiratory System Protection
Dust mask
Respirator with Charcoal
Filter
General Purpose
Respirator
SCBA
Skin Protection
Apron
Closed Shoes / Boots
Chemical Gloves
Impermeable Suite

76

77
YOUR GUIDE TO CHEMICAL SAFETY

78
1. Product Information
2. Composition/Information on Ingredients
3. Hazards Identification
4. First Aid Measures
5. Fire Fighting Measures
6. Accidental Release Measures
7. Handling and Storage
8. Exposure Controls/Personal Protection
9. Physical and Chemical Properties
10. Stability and Reactivity
11. Toxicological Information
12. Ecological Information
13. Disposal Consideration
14. Transport Information
15. Regulatory Information
16. Other Information
Material Safety Data Sheets (MSDS)

Sodium Hypochlorite Usage
 Sodium Hypochlorite is use for disinfection
1. This is also used for disinfection of dual
media filters during the process of backwashing
2.Residual chlorine of 0.3-0.5 ppm is to be
maintained in the system just before the dosing
of SBS
3.Chlorine existing in water as hypochlorus
and hypochlorus acid ion ( Hypochlorite ) define
as free available chlorine.

Chlorination
 HOCl <7 8> H + OCl
Hypochlorous Acid
 At the higher pH range as the ratio of Ocl
increase as the sterilization effect of chlorine
compound decrease.
 It is practically observed that the sterilization
force of Ocl is approximately 20 time less as that
of HOCl
 HOCl has significantly higher effect than Ocl

Chlorine compound
 Chlorine compound used for sterilization of
microorganism
 Chlorine gas Cl2
 Calcium hypochlorite Ca ( Ocl )2
 Sodium hypochlorite Naocl
 Cl2 + H2O HOCl +HCL
 Ca (Ocl )2+ H2O HOCl +Ca ( OH )2
 NaOcl + H2O HOCl + NaOH

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
Umar Farooq Senior Chemist NOMAC
SIWEP Shuaibah Jeddah 82

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

Disinfection and oxidation
 History of disinfection
 Chlorine
 Reactions
• Gas - Cl2 + H2O ↔ HOCl + HCl (^ pH 4)
• Liquid - NaOCl + H2O ↔ HOCl + NaOH
• (^ pH 6.0) HOCl ↔ OCl- + H+ (^ pH 7.5)
 Mode of action / problems
 Shock chlorination – biological growth
 Dechlorination

Chlorine Health Effects Table
Bulletin work safe Alberta CH 067-Chemical Hazards
Chlorine Concentration ppm Health Effect
0.03-0.04 Range of odor threshold
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

Safety Precaution of Chlorine
 It is a very corrosive chemical
 It causes burns to skin and eyes
 It is harmful if ingested, inhaled
 it may cause skin irritation
 If it comes in contact with skin, immediately
wash the skin with plenty of water
 Flush the eyes if it comes in contact with the
eyes

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

 If inhaled, the person should be
immediately removed to fresh air and
medical attention should be sought if signs
of suffocation
 Eyes should be protected
 Chlorine is corrosive to metallic material
 To avoid corrosion should be maintain
proper dosing

Acute Effects of Chlorine
 Tickling of the nose at 0.014 to 0.054(ppm);
 Tickling of the throat at 0.04 to 0.097 ppm;
 Tching of the nose and cough, stinging, or
dryness of the nose and throat at 0.06 to 0.3
ppm;
 Burning of the conjunctiva and pain after 15
minutes at 0.35 to 0.72 ppm;
 Discomfort ranging from ocular and respiratory
irritation to coughing, shortness of breath, and
headaches above 1.0 ppm.

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

Chlorine Advantages
 Economical
 Traditional technology
 Chlorine kill microorganism by destroying
cell wall of the microorganism with there
oxidizing forces

Chlorine Disadvantages
 Slower kill at high pH
 Consumed by ammonia, sulfides, iron, manganese, &
hydrocarbons
 Volatile and easily stripped, thus high usage rates
 High feed rates and residuals can cause higher
corrosion rates
 Poor control (or slug treatment) leads to degradation of
water treatment compounds -- e.g. organic phosphate
and tolyltriazole
 Chlorinated organics, e.g., THM’s, are toxic, regulated,
and persistent in the environment

93
REACTIVE – burns, explodes or releases toxic
vapors if exposed to other chemicals, heat, air or
water.

Sodium Bi Sulphite Na2S2O5
 Used as a reducing agent for free chorine
 Almost zero for compliance of the membrane
tolerance limit
 The most common and economical chlorine
reducing agent is Sodium bi sulphite.
 When dissolved in water, sodium bisulfite (SBS) is
formed from SMBS
Na2S2O5 + H2O → 2 NaHSO3
 SBS then reduces hypochlorous acid according to
2NaHSO3 + 2HOCl → H2SO4 + 2HCl + Na2SO4

 In theory, 1.34 mg of sodium metabisulfite will remove
1.0 mg of free chlorine. In practice,
 however, 3.0 mg of sodium metabisulfite is normally
used to remove 1.0 mg of chlorine.
 In aqueous solutions, however, sodium bisulfite can oxidize readily
when exposed to air. A typical solution life can vary with
concentration as follows:
Concentration (wt %) Solution life
10 1 week
20 1 month
30 6 months

 When RO membranes are fouled with heavy metals
such as Co and Cu, residual SBS (up to 30 ppm)
partially converts to oxidants under the presence of
excessive oxygen.
 SBS dosing amount control must be optimized
and oxidation conditions of the concentrate must be
monitored by an oxidation-reduction
potential (ORP) meter

Safety and handling OF SBS
 It is a fine white granular product with a pungent
smell of sulphur dioxide.
 It may irritate the skin and may cause irritation
and burns to the eyes.
 It reacts with acids to form toxic and irritating
sulphur dioxide gas.
 Immediately wash with plenty of water if sodium
bisulphite comes in contact with skin
 Flush the eyes if it comes in contact with the
eyes

Sulphuric acid H2SO4
1.Sulphuric acid is feed at RO
Pretreatment in the feed water
stream to lower the pH to avoid
the calcium scaling in the
system.
2.Calcium carbonate solubility
increases with decrease in pH
3.Calcium carbonate solubility
decreases with
increase in temperature

Safety and handling of H2SO4
 It is very hazardous in case of skin contact
 It is very hazardous in case of eye contact of
ingestion
 Liquid or spray mist may produce tissue damage
particularly on mucous membranes of eyes,
mouth and respiratory tract
 Skin contact may produce burns

LAYERS OF THE SKIN
BURNS & SCALDS
TYPES OF BURN
100

Ferric chloride Fecl3
 Ferric chloride is used as a coagulant in
Reverse Osmosis plant to aid effective
filtration in the dual media filter
 The use of ferric chloride increases the
settling velocity of the suspended solids by
flocks formational media filters.
 Ferric chloride is effective in a wide range
of pH

Safety and handling of Fecl3
 Ferric chloride is very hazardous in case of skin contact, eye
contact, and ingestion.
 Ingestion may cause damage to the liver. gastric irritation,
abdominal pain and diarrhea. Moderately toxic by ingestion.
 Liquid and spray mist may cause tissue damage particularly on
mucous membranes of eye, mouth and respiratory tract.
 Severe irritant and corrosive to moist or wet skin
 Inhalation of the spray mist may cause severe irritation of the
respiratory tract
 characterized by coughing, choking, or shortness of breath.
 In case of eye contact, immediately flush eyes with plenty of water
for at least 15 minutes.

67
Careless handling can cause real
problems…

104
CORROSIVE
FLAMMABLE
POISON
DANGEROUS
WHEN WET
SPECIAL SYMBOLS – helps you recognize the kind of hazard
the chemical could present if not properly handled. These are found on labels
of containers that have been shipped by truck, rail, or air.

105

106
DEGREE OF HAZARD
0 – minimal hazard
1 – slight hazard
2 – moderate hazard
3 – serious hazard
4 – severe hazard
HEALTH
FLAMMABILITY
REACTIVITY,INSTABILITY
SPECIAL

Health Hazards
 Corrosives/Oxidizers
* Injuries to tissue or skin
 Toxics/Flammables/Compressed gasses
* Damage to Respiratory System
 Explosives
* Over Pressure * Flying Objects
Radioactive
* Radiation Sickness * Cancer
Carcinogens
* Cancer

Container Label Information
 Safe Handling/storage Procedures
 Health/Physical Hazard(s)
 Primary Hazard(s)
 First aid treatment
 Manufacturer
 Identity

109
Make sure every container you use has a label.
Report missing, dirty, or illegible labels so they can be replaced.
Be sure to put labels on portable containers for all hazardous chemical.
Read labels before handling containers- and follow their warnings.
Ask your supervisor about any label information you don’t understand.

110
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

111
6) Collect all materials into polyethylene
Disposal bags. Collect any broken glass with
a dustpan and brush and place in a labeled carton
7) Rinse the area and ventilate well until dangerous
levels are no longer in the air
8) Remove personal protective equipment and place any
disposable items in a polyethylene disposal bag
9) Place waste in appropriate, labeled containers
10) Replace any equipment that was used
Investigate the incident with your supervisor including
recommended preventative actions

Materials Causing Toxic Effects
Characteristics
´May cause death or permanent
injury following repeated or long-
term exposure
´May irritate eyes, skin and
breathing passages: may lead to
chronic lung problems and skin
sensitivity
´May cause liver or kidney
damage, cancer, birth defects or
sterility

113
A) Flammable Gas / Toxic Gas:
Evacuate the Area
Remove sources of ignition and materials that can burn
Put on SCBA and protective clothing as necessary
Close the cylinder valve. If possible, without risking
yourself
If you can’t - stay in a safe distance, cool cylinders with
water spray to prevent ignition, until all gas is released.

114
B) Fire in gas storage area:
Evacuate the area
Call the fire department immediately
Put on full protective gear
Cool cylinders with water spray continuously to
prevent explosion of the cylinders
Try to prevent the spread of the fire and wait for help

INVESTIGATE AND
ANALYSE
EVERY ACCIDENT
115

WHAT ARE UNSAFE
CONDITIONS???
116

UNSAFE CONDITIONS:
 Unsafe construction
 Lack of machine guards
 Inadequate guarding
 Defective working conditions
 Poor layout
 Overcrowding in workplace
 No personal protective equipment
 Unsafe lighting
 Storage of hazardous substance
117

BASIC CAUSES OF ACCIDENTS:
PERSONAL FACTORS:
 LACK OF KNOWLEDGE OR SKILL
 MENTAL OR PHYSICAL DEFECTS
 IMPROPER ATTITUDE
118

BASIC CAUSES OF ACCIDENTS:
JOB FACTORS:
 UNSAFE CONDITIONS
 POOR WORK STANDARDS
119

SHORT BREAK
120

BIOLOGICAL GROWTH
CROSSION CAUSES
121

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

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

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

Factors Effecting Corrosion
 Water Chemistry eg Cl;NH3;S;O2
 Ammonia increases the corrosion of copper and alloys of
copper by complexing the copper present in the protective layer
of copper oxide or copper carbonate
 pH - Optimum pH 6.0 - 9.0
 Water Velocity
Erosion Impingement Cavitation
 Stress Corrosion Cracking
 De alloying
 Pitting (Under Deposit; H2S; Cl)

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

100
10
0
5 6 7 8 9 10
CorrosionRate,RelativeUnits
pH
Corrosion Vs. pH

Corrosion Vs. Temperature
Corrosion Rate
Temperature
In general, for every 18 F in
water temperature, chemical
reaction rates double.

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

Erosion Corrosion
Corrosion

Corrosion
4Fe  4Fe2+ + 8e-
2O2
Anode
8OH-
8e- + 2O2 + 4H2O  8OH-
4H2O
Cathode
4Fe2+ + 8OH-  4Fe(OH)2
O2 + 4Fe(OH)2  2Fe2O3 + 4H2O
O2

Corrosion
FACTORS PROMOTING CORROSION
 Impurities/inclusion in the metal
 Localized stress
 Discontinuities in metal surface
 Low pH conditions
 Low flow velocities
 Differences in
 Temperature
 Oxygen
 Salt Concentration (Significantly Effected by Water
Borne Deposits)

MICROBIOLOGICAL
GROWTH

Microbiological Growth
 Water treatment is
about managing three
fouling processes...
 Corrosion
 Scale
 Microbio
The microbial fouling
process is...
 The most complex
 The least understood
 The hardest to measure
and monitor
 Controlled using the least
desirable, most
expensive, & potentially
hazardous products

Bacteria
Sears
Tower
 Bacteria extremely small
 Compared to a
human, a bacteria is
like a grain of sand to
the Sears Tower
 Size allows many
(millions) to fit into a
small volume of
water...

Types of Bacteria
4. Nitrifying 5. Denitrifying
3. Iron
Depositing
2.
Anaerobic
Corrosive
1. Slime
Forming

Bacteria
Slime Formers
Iron DepositingAnaerobic
Typical Rods

MicrobiologyThe most
prevalent
problems
in
Pre-
treatment
water
systems
are related
to
microbiolo
gy
Proteins
Phospholipids Hydrophilic groups
Hydrophobic groups
Phospholipid molecules
Glycocalyx
Outer Membrane
DNA
Periplasmic
Space
Flagellum
Cell Membrane
Cytoplasm
Proteins

Biohazardous Infectious Material
Characteristics
Contact with microbiological
agents (e.g., bacteria,
viruses, fungi and their
toxins) may cause illness or
death

Biohazardous Infectious Material
Precautions
clothing
Work with these materials
in designated areas
Disinfect area after
handling
Wash hands after
handling

Basic Growth Requirements
Inorganic
Nutrients
Food Source
Gaseous
Element
Temperature
pH
Interaction with
other
Microorganisms
Bio Fouling

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
142

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

Bio Fouling
 Types of Microorganisms
 BACTERIA - need/ do not need Oxygen
• Aerobic - Slime and Spore former
• Anaerobic - SRB, Clostridia, etc.
• Iron bacteria - Gallionella
• Nitrification - Nitrosomas, Nitrobacter
 ALGAE - need light, food source
 FUNGI - destroys wood, reinforces deposits
 PROTOZOA - feed on bacteria/algae

Slime and there prevention
 Slime occurs to gather with corrosion and
scale
 Slime is caused by the adhesion and
accumulation of soft muddy material.
 It formed by mixing micro Organism like
bacteria , fungi , algae .
 It grow by utilizing the dissolved nutrient in
water with inorganic mater like mud , sand,
and dirt Umar Farooq Senior Chemist

Slime
Slime
146

Microbiologically induced Under Deposit
Corrosion
1. Bioactivity generates CO2 and/or H2S which lowers the pH
underneath the Deposit
2. Iron Corrodes and tubercle grows as pitting corrosion develops
1 2
Bio Fouling

To Prevent Corrosion

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

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

Preventing Fouling
Prevention
 Good control of makeup Pretreatment
 Good control of corrosion, scale, & microbiology growth
Reduction
 Increase backwashing frequency
 Side stream filter
Ongoing Control
 Back flushing, Air rumbling
 Chemical treatment

Charge Reinforcement Mechanism
Slightly anionic
suspended
particle
Suspended Solid
which has adsorbed
highly anionic
chemical
Highly
Anionic
Chemical
 Anionic polymers increase strength of charge
already present on suspended solids
 Keep particles small enough so they do not
settle out

Fouling Control
Charge Reinforcement Dispersants:
adsorb onto particles, creating very highly charged
surfaces, which repel each other because of like
charges.
+
+Fe(OH)2
+
Fe(OH)2
+
Fe(OH)3
o
+
+
+
Fe(OH)2
+
Fe(OH)3
o
Fe(OH)2
+
Fouling

OXIDIZING BIOCIDES

Oxidizing Biocides
 Penetrate microorganism’s cell wall and
burn-up the internals of the organism
 Effective against all types of bacteria
 No microorganism resistant to oxidizers
 Kill everything given sufficient
concentration levels & contact time

Oxidizing Biocides
 Broad-spectrum
effectiveness
makes oxidizers
primary biocide in
large cooling water
applications
Oxidizers
 Gas Chlorine
 Bleach
 Acti-Brom
 BCDMH
 Stabilized Bromine

Oxidizing Biocides
 Biocide effectiveness
pH dependent
 Cl2  HOCl & OCl-
 Br  HOBr & OBr-
 HOCl/HOBr Biocidal
 @ pH=8.0
HOCl: 22%
HOBr: 83%
 Bromine more
biocidal
HOClorHOBr
0
10
20
30
40
50
60
70
80
90
100
4 5 6 7 8 9 10 11 12
pH
0
10
20
30
40
50
60
70
100
OCl-orOBr-
HOCl
HOBr
80
90

Before Biodispersant
After Biodispersant
Biodispersants
Do not kill -- Penetrate deposits and increase the
effectiveness of oxidizing & non-oxidizing biocides.

Monitoring & Control
Free
or
Total
Pillow
Sample
DPD DR5000
Spectrophotometer
or
Color
Wheel
ppm
Oxidant
Residual
(as Cl2)
Oxidant Determination Test
Diethyl Phenylenediamine (DPD)
Bio Fouling Monitoring

 BENEFITS
 Rapid Program Adjustment To
Maintain Optimum Performance
 Determine The Most Effective
Biocide Program
 Maximize Cost-Performance
 Maximize Technical Results
 Minimize Environmental Impact
COST
PERFORMANCE
ENVIRONMENT
TRA-CIDE
Bio Fouling Monitoring

161
Any QUESTION
Thanks 4ur Attention

Shuaibah IWEP III RO EXPANSION
Shuaibah IWEP III RO EXPANSION
Name & ID____________________
Written Check Plant Chemistry (RO Pretreatment System)
Date: 12-11-2012
Time: 20 min
Marks: 20
Note: 1) General portion of the paper has to be attempted by all trainees.
General Chemistry
Q 1) Select the appropriate answer. (15 marks)
i. How many chemical used in pretreatment system.
H2S04
Fecl3
Polydactyl amide
All of the above
ii. The neutral pH of water represent by
10
5
7
None of the above
iii. Danger range of chlorine is
5 ppm
18 ppm
25 ppm
i. Water is only substance that exist in three state
------------------------------------
------------------------------------
------------------------------------
ii. How many types of hardness write name
--------------------------------------------
--------------------------------------------
iii. sources of water write any five name of
--------------------------------------------
--------------------------------------------
--------------------------------------------
--------------------------------------------
-------------------------------------------
iv. Coagulation is the process of pretreatment system true / falls
v. Pretreatment process three step process true / falls
vi. is the symbol of hazards true / falls
vii. is the symbol of corrosive true / falls
Q 1) Pick up the correct answer: (5 marks)
i. Hypochlorite use for __________ ( Disinfection , Infection )
ii. The MSDS Stand for _____________(Material safety data sheet , material safely
demand sheet)
iii. PPE Stand for ________ (Personal power equipment , Personal protective
equipment )
iv. For neutralization of chlorine used________(Sodium meta bi sulphite , Antiscalent )
v. H2SO4 Skin contact may produce _________ ( burn , smell )
i. Water contains some impurities which are
Dissolved inorganic compound
Dissolve Organic Compound
Dissolve gasses
Micro Organism
All of the above
ii. Settling time of bacteria in the water is
30 minutes
1 hrs
12 hrs
35 hrs
iii. Ferric chloride ( Fecl3 ) used for pretreatment process as a
Coagulant aid
Coagulant
Cationic Coagulant
All of above
iv. Factor infusing corrosion
pH
Temperature
Dissolved Solids
Microbiological Growth
All of above
v. The destruction of metal by mechanical is called
Corrosion
Erosion
Pitting Corrosion
Non of above

RO Pretreatment System Chemistry

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