WATER SUPPLY

Roslinda@Sem 1 2016/2017
3.1 Water and Health

• 80% of sickness in the world is caused by

inadequate water supply or sanitation
• 40% of the world population does not have
access to safe drinking water
• It is estimated that water-borne diseases
kill 25,000 people per day
• In many populated areas of the world,
water-borne diseases represent the
leading cause of death
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Engineered water system

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3.2 Palatable and Potable
 The goal of municipal water treatment is to
provide water that is both palatable and potable
• Palatable • Potable
– aesthetically pleasing – safe to drink
– considers the presence of – not necessarily aesthetically pleasing
chemicals that do not pose – potability affected by
a threat to human health • microbials (e.g. Giardia,
– palatability affected by Cryptosporidium)
chloride, color, corrosivity, • organic chemicals (e.g., alachor,
iron, manganese, taste and chlordane, cis-1,2-
odor, total dissolved solids, dichloroethylene, disinfection by-
turbidity products)
• inorganic chemicals (e.g.,
cadmium, copper, lead, mercury)
• radionuclides

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3.3 Water Sources

There are two water sources used

regularly as shown below
Groundwater Surface water
(shallow wells, deep wells) (rivers, lake, reservoir)

 constant composition  variable composition

 high mineral content  low mineral content
 low turbidity  high turbidity
 low color  colored
 low or no D.O.  D.O. present
 high hardness  low hardness
 high Fe, Mn  taste and odor
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Roslinda@Sem 1 2016/2017 6
3.4 Surface Water Treatment

• Primary objectives are to

1. Remove suspended material (turbidity) and color
2. Eliminate pathogenic organisms
• Treatment technologies largely based on coagulation and flocculation
(--- compulsory)

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Loji Rawatan Air Semenyih, Selangor

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Rapid Mix - From the aerators, the water flows into the rapid mix tank
/chemical pre-treatment. The purpose of the rapid mix tank is to provide a
complete mix, allowing the lime/alum to come in contact with the dissolved
minerals. Motor-driven paddles keep the mixture moving and prevent
settling in the mix tanks. Alum is a polymers, acts like a "glue,” holding
together the particles and allowing them to grow even larger.

Flocculation.- During mixing and flocculation, the particles attach to one

another to form larger solids that will be settled by gravity and removed
during another stage of treatment. As slow proceeds through each tank
the force and speed of the mixing is gradually reduced, allowing the
particles to grow as large and heavy as possible.

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Settling - Next, the water flows to settling/sedimentation tanks, or clarifies,
where floc settle to the bottom as lime sludge/alum sludge. The retention
time is two to three hours to allow the flow settle by gravity. Part of this
sludge is returned to the mixing tank to assist in coagulation; the
remainder is drawn off continuously to holding ponds or lagoons for final
disposal.
Filtration –This step id particularly for the removal of the very fine particle
which is not settle by gravity.
Chlorination - To ensure bacteriological safety of the water supply a
calculated dose of chlorine will be added. The chlorine disinfects the
water and protects against microbial contamination after the water leaves
the treatment plant. Dose of chlorine will also protect treated water from
growth of algae if exposed to direct sun.
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Roslinda@Sem 1 2016/2017 11
3.5 Raw water intake
• Raw water intakes withdraw water from a river, lake, or reservoir over a
predetermined range of pool levels.
• Intake can be correctly positioned using a number of techniques including
suspending the inlet from a float, securing the inlet in a rigid structure such as
bucket or crib ( Figure 3.3), using rigid pipe work ( Figure 3.4) , or in freezing
condition.

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Intake Site Selection
The following are the characteristics
for intake site selection
a) Intake velocity
• Water quality • High velocities – head loss, entrain suspended

Intake Design Consideration

• Water depth matter, trap fish, and other aquatic animals.
• Velocity below 8 cm/s allows aquatic animal to
• Stream or current velocities
escape, and minimize the suspended matter.
• Foundation stability
• Access
• Power availability b) Intake-port location- Water quality in each stratum
• Proximity to water may vary. To achieve, multiple intake ports set at
treatment plant various levels are generally provided

• Environmental impact • Top intake – less than 2 m below normal level.

• Bottom intake – least 1 m above the bottom
• Hazard to navigate

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3.6 Screening
• It is a unit operation that removes suspended matter from water.
• Screens may be classified as coarse, fine, or micro strainer,
depending on the size of material removed
Coarse screen or trash rack
• To prevent large object from entering
the conveyance system
• Consists of vertical flat bars, or, in
some cases, round pipes spaced with
5 to 8 cm of clear opening.
fixed
• Installed outside of any sluice gate.
• The velocity through the coarse
rotary
screen is generally less than 8 cm/s.

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Fine screen
• To remove smaller objects that may
damage pumps or other equipment.
• Screens consists of heavy wire mesh
with 0.5 cm square opening
• The typical design velocity through
the effective area is in the range
of 0.4 to 0.8 m/s.
• There are two types: Traveling
screens and passive screen
installation

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3.7 Aeration

 Aeration involves bringing air or other gases in contact with water.

 The purpose of aeration are
1. Reduce the concentrations of taste and odor causing substance
by volatilization
2. To oxidize iron and manganese, rendering them insoluble.
3. To dissolve oxygen in water to make it taste better
4. To remove compounds for better water treatment (H2S removal
before chlorination and CO2 removal before softening)

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Types of aerator

1) Cascade -Water is sent down

gravitically, and oxygenated as it
come into contact with the air
bubbles caused by turbulent flow

2) Diffused air -Water is

enriched with oxygen as it
come into contact with the air
bubbles.

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3.8 Coagulation and Flocculation

Surface water contains organic and inorganic particles.

such as clay and colloids remain in are charged negatively

suspension without aggregating for long and stable in nature
periods of time. Therefore, particle cannot be (stable = existing in
removed by sedimentation. ionized form).

How to destabilise the particle/colloid to

make it able to settle down in sedimentation
tank?

ANSWER:
By adding the COAGULANT ( charged positively)!!!

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Roslinda@Sem 1 2016/2017 19
JAR test is a laboratory works to illustrate the coagulation and flocculation concepts
associated to nature water. From this experiment the optimal pH, coagulant dose ,and
coagulant aid could be determined.

Therefore, coagulation and flocculation designed to remove

• Microorganisms and colloids that caused turbidity
• Toxic compounds that are absorbed to particles
• Inorganic materials

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Rapid mixing varieties

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3.8.2 Coagulation
 Coagulant is a process utilizes chemical coagulant. The coagulant is mixed
thoroughly with the water (in rapid mix process). The various species of the
positively charged particle (from coagulant) adsorb to the negatively
charged colloids (color, clay, turbidity) and negatively charged particles.
 Once the charge is neutralized, the small suspended particles are capable
of sticking together. The slightly larger particles formed through this process
and called microflocs, are not visible to the naked eye.
 The water surrounding the newly formed microflocs should be clear. If it is
not, all the particles' charges have not been neutralized, and coagulation
has not been carried to completion. More coagulant may need to be added.
 Microfloc itself is not yet settleable, and then flocculation process takes
place.

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3.8.3 Flocculation
 is the process in which the destabilised particles are
bound together by hydrogen bonding of Van der Waal’s
forces to form larger particle flocs
 High molecular weight
polymers, called coagulant aids,
may be added during this step
to help bridge, bind, and
strengthen the floc, add weight,
and increase settling rate. Once
the floc has reached it optimum
size and strength, the water is
ready for the sedimentation
process.

 Figure shows the flocculation

basin, in which no motor or
paddle used to assist the
mixing.

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Coagulant  Types of coagulant
 is the substance (chemical) that is - Alum: Al2(SO4)3.14H2O
added to the water to destabilize - Ferric chloride: FeCl3
particles and accomplish coagulation. - Ferric sulfate: FeSO4
 Properties of coagulant - Polyelectrolytes
 Non-toxic and relatively inexpensive
 Insoluble in neutral pH range - do not
want high concentrations of metals
left in treated water
 Cation: trivalent cation is lesser
dosage ( compared to Ca2+ and Na+)

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• Why trivalent cations
considered as good
coagulant ?

ANSWER:
Cations such as Fe3+
and Al3+ has a higher
molecular weight, easy
to settle. Therefore, it
removes turbidity
effectively even a small
dose was used.

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Coagulant type Examples

Inorganic metallic Aluminium sulfate (Al2(SO4)3•14H2O, sodium aluminate,

coagulant aluminium chloride, ferric sulfate and ferric chloride

Prehydrolyzed metal Made from alum and iron salts and hydroxide under
salts controlled condition; polyaluminium chloride (PAC)

Organic polymers Cationic polymers, anionic polymers, and nonionic polymers

Natural plant-based Opuntia spp. And MoringaOleifera (used in many parts of

materials the world esp. developing country.

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How does alum works?
In sufficient alkalinity in the water Alum sludge=alum floc =dry sludge
(without water, H2O=Al(OH)3), settle in the flocculation tank

1Al2(SO4)3•14H2O + 6HCO3- ↔ 2Al(OH)3(s) + 6CO2 +14H2O + 3SO42-

1 mole of alum added uses 6 moles of alkalinity and produces 6 moles of CO2

The above reaction shifts the carbonate equilibrium and decreases the pH
However, as long as sufficient alkalinity is present and CO2 (g) is allowed to
evolve, the pH is not drastically reduced and is generally not an operational
problem
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Example 3.1
Calculate the amount of alum sludge produced and alkalinity (HCO3- ) consumed when 1 mg/L alum
was used.
Solution

1) Chemical reaction

Al2(SO4)3.14H2O + 6HCO3- ↔ 2Al(OH)3(s) + 6CO2 + 8 H2O + 3SO42- + 14H2O

2) Equivalent weight (EW)

EW alum = 594 g/mole

EW alkalinity = 61 g/mole
EW alum sludge = 78 g/mole

3) Solid removed when 1 mg/L alum was used,

1 mg/L = 1.684 x 10-6 mole/L

(594 g/mole)(1000 mg/g)
4) Known that 1 mole/L alum yield 2 mole/L of alum sludge, therefore

Solid removed = 2 (1.684 x 10-6 mole/L) (78 g/mole)

= 2.63 x 10-4 g/L = 0.26 mg/L

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5) Alkalinity consumed when 1 mg/L alum was used,

Known that 1 mole/L alum yield 6 mole/L of alkalinity, therefore

Alkalinity removed = 6 (1.684 x 10-6 mole/L) (61 g/mole)
= 6.16 x 10-4 g/ L
= 0.62 mg/L HCO3-

Expressed in CaCO3
= 0.62 mg/L HCO3- x EW CaCO3 / EW HCO3-
= 0.62 mg/L HCO3- x 50 g/eq /61 g/eq
= 0.51 mg/L HCO3- as CaCO3

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3.9 Sedimentation Tank/
Settling Tank/ Clarifier

• Following flocculation, the water then flows into the settling basins as
shown below (left) . The plan view of clarifier shown below (right)
• Water in clarifier/settling/sedimentation tank is nearly quiescent – low
flow with little turbulence and resides for at least 3 hrs and the flocs
settle out and collect at the bottom ( mechanically removed
periodically).

Sedimentation basins are either rectangular or

circular, normally 1 unit sedimentation system
comprises of 2 tanks

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 Rectangular basin
Upflow clarifier

Over flow – settle water outlet Over flow – settle water outlet

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The key parameters and typical values in the design of settling tank are:
- surface over flow rate – 20 - 35 m3/day/m2
- detention times – 2- 8 h
- weir overflow rate – 150 – 300 m3 /day/m

to remove the settled

water from the basin
without carrying away any
of the floc particles.
to evenly
distribute the flow
and suspended
particles across
the section of the depends upon the method of
settling zone cleaning, the frequency of
cleaning and the quantity of
sludge estimated to be
produced.

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Example 3.2
Calculate the diameter and depth of a circular clarifier for a design flow of 3800 m3/d and an
overflow rate of 0.00024 m/s and a detention time of 3 h. Calculate the weir loading rate by
assuming the total effluent weir is 20 m.

Solution

1) Volume , V = Qt
= (3800 m3/d) ( 3/24)
= 475 m3

2) Q = 3800 m3/d = 0.044 m3/s

3) Surface overflow rate = Q/A

0.00024 m/s = (0.044 m3/s ) / (A m2)
So , Area, A = 183.3 m2

4) Depth, D =V/A
= 475 m3/183.3 m2 = 2.59 m

5) Diameter = 15.3 m

6) Weir loading rate = Q/ Lw

= (3800 m3/d )/(20 m) = 190 m3/day.m (OK!, refer to slide 32)

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Example 3.3

Determine the surface area Solution

of a sedimentation tank.
The design flow is 0.044
m3 /s. Use a design 1) First change the flow rate to
overflow rate of 20 m / day. compatible units.
Find the depth of the
sedimentation for the (0.044 m3/ s)(86,400 s / day) = 3801.6 m3
given overflow rate and day
detention time. 2) surface area.

surface area is = 3801.6 m3 /day

20 m/ day
= 190.m2

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3) Length to width dimension

Common length-to-width , L: W ratios

( 2:1< L:W < 5:1 , and lengths seldom exceed 100 m)

A minimum of two tanks is always provided.

Use two (2) tanks, each with a width of 5 m, a total surface area of 190 m2

Length = 190 m2 /(2 tanks)(5 m wide) = 19 m

length-to-width ratio of 3.8: 1 (OK!)

4) Find the tank depth.

Rule of thumb that the detention time should be 2-8 h.
Assumed the detention time of 120 min
Q = V/t
V=Qt
V = (1900.8 m3/d )(120 min)( d/1440 min) = 158 m3

Depth = 158 m3/ 95 m2 =1.684 m,= 1.7 m

The final design would then be two tanks, each having the following
dimensions:

5 m wide x 19 m long x 1.7 m deep plus sludge storage depth.

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 Example
Types Description Water Wastewater
Treatment Treatment
-Settling as discrete particles at a constant 1.Pre-sedimentation 1.Grit chamber
settling velocity 2.In filter bed after
-No flocculation during backwashing
I Sedimentation
- Apply Stokes’ Law

-Particles that aggregated or flocculate during Sedimentation after alum 1.Primary sedimentation
sedimentation or iron coagulation 2.In settling tanks after trickling
filtration
II
3.In upper portions of
secondary clarifiers after activated
sludge treatment
-Particles settle as a zone or blanket Settling in lime soda ash 1.Activated sludge sedimentation
-Usually have a clear interface between the settling sedimentation 2.Sludge thickeners
III
sludge and the clarified effluent

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Roslinda@Sem 1 2016/2017 37
Ideal sedimentation basins (Type 1) - UPFLOW CLARIFIER
The concept of an upward-flow sedimentation tank is shown in Figure.
Two important terms in sedimentation zone design are:

1)settling velocity, vs : velocity of the particle

to be removed

2) overflow rate / hydraulic surface loading, vo :

velocity of water decreases as the water flows upward

Note that the velocity of the particle remains

unchanged. Therefore,

If vsvo, then 100% of particles remain in

tank
If vs<vo, then 0% of particles remain in tank

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Example 3.4

If a settling velocity of a particle is 2.8 mm/s and the overflow rate of a

upflow clarifier is 0.56 cm/s, what percentage of particles are retained in
upflow clarifier?

Solution

vs = 2.8 mm/s = 0.28 cm/s

v0 = 0.56 cm/s,

Note that

vs< vo, then 0% of particles remain in tank

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Ideal sedimentation basins (Type 1)- REGTANGULAR BASIN
Particle removal is dependent on the overflow rate, v0.
In order for particle to be removed settling velocity, vs must be sufficient so that it
reaches the bottom during the time the water resides in the tank (td).

vs= v0 , 100 % particles removed

vs> v0 , 100 % particles should be easily removed
vs< v0 , some fraction of the particles will be
removed , P = 100 Vs/V0
The concept of a horizontal flow sedimentation
tank is shown on Figure

In a horizontal flow sedimentation tank:

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Example 3.5

If a settling velocity of a particle is 0.7 cm/s and the overflow rate of a

horizontal flow clarifier is 0.8 cm/s, what percentage of particles are
retained in clarifier?

Solution

Vs = 0.7 cm/s
v0 = 0.8 cm/s,
Note that

vs < v0 , P = 100 vs / vo= 100 ( 0.7)/(0.8) = 87.50 or 88 %

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Example 3.6

A water treatment plant has a horizontal –flow sedimentation tank with an

overflow rate of 17 m3/d. m2 and wishes to remove particles that have
settling velocities of 0.1 mm/s. What percentage of removal should be
expected for each particle in an ideal sedimentation tank?

Solution

Vs = 0.1 mm/s
v0 = 17 m3/d. m2 =? mm/s, ( do the conversion so, v0= 0.2 mm/s)

Note that
vs < v0 , P = 100 vs / vo= 100 ( 0.1)/(0.2) = 50%

Recalculate by considering v0 are 0.2 mm/s and 1 mm/s respectively.

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3.10 Filtration
 The water leaving the sedimentation tank (settled water) still contains floc
particles, remaining the turbidity in the range from 1 to 10 NTU. These
levels of turbidity interfere with the subsequent disinfection processes, so
the turbidity must be reduced. EPA (Environmental Protection Agency)
requires the turbidity of treated water at least at 0.3 NTU.
 In order to reduce turbidity to less than 0.3 NTU, the filtration process is
normally used.
 The most common filtration used is granular filtration. Granular filtration is
a process for separating suspended or colloidal impurities from water by
passage through a porous medium.
 Porous medium usually a bed of sand or other medium; coal, garnet,
granular activated carbon (GAC), or ilmenite.
 Basically water fills the pores between the sand particles, and the
impurities are left behind either clogged in the open spaces or attached to
the sand itself.

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Several methods of classifying filter accordingly to;

A) the type of medium used B) Allowable loading rate, va

i) Sand i) slow sand filters ( SSF)

ii) coal ( anthracite) ii) rapid sand filters (RSF)
iii) dual media ( coal + sand) iii) high-rate sand filters
iv) mixed media
( coal, sand + garnet) Note: va = Q / As

va = face velocity ,
Q = flow rate onto filter surface, m3/d
As = surface area of filter, m2

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 Comparison between granular filtration

Process Slow Sand Filtration Rapid Filtration

Characteristics
Filtration rate 0.05-0.20 m/h 5-15 m/h
Media diameter 0.30-0.45 mm 0.5-1.2 mm
Bed depth 0.9-1.5 m 0.6-1.8m
Required head 0.9-1.5 m 1.8-3.0 m
Run length 1- 6 months 1- 4 days
Regeneration method Scraping Backwashing
Maximum raw-water turbidity 10-50 NTU Unlimited with proper
pretreatment

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3.10.1 Rapid Sand Filtration

 Also known as depth filtration.

 Rapid sand filters (Figure 3.23) are the most common type of filter used
in water treatment.
 The filters are cleaned by backwashing;
- Agitating the bed either mechanically or with compressed air and
washing water upwards through the bed to the surface.
- The ‘backwash’ water is then wasted or return to the beginning of
the plant to treatment.
 Normally a minimum of two filters are constructed to ensure
redundancy.
 For a larger plant (> 0.5 m3/s), a minimum of four filters is suggested.
 The surface area of the filter tank is generally restricted in size to about
100m2, except for very large plants

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Example

For a flow of 0.8 m3/s, how many rapid sand filter of dimensions 10 m x 20 m are needed
for a loading rate of 300 m3/d.m2?

Solution

1) Determine Q in m3/d

Q = (0.8 m3/s)( 86400 s/d) = 69120 m3/d

2) Determine total area required

A = 69120 m3/d = 230.4 m2

300 m3/d.m2
3) Number of filters ( must round to next highest integer)

No = 230.4 m2 = 1.152 or 2 filters

(10 m) (20m)
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3.10.2 Slow sand filtration
Maintenance

Slow sand filters slowly lose their performance as the Schmutzdecke grows and thereby reduces the rate of
flow through the filter.

The top few millimetres of fine sand is scraped off to expose a new layer of clean sand. Water is then
decanted back into the filter and re-circulated for a few hours to allow a new Schmutzdecke to develop. The
filter is then filled to full depth and brought back into service.
at a loading rate
of 2.9 to 7.6
m3/d.m2 by
gravity feed

formed in the first 10–

20 days of operation
and consists of
bacteria, fungi,
protozoa, rotifera and
good quality range of aquatic
with 90-99% organisms
bacterial
reduction. provides the effective
purification in potable
water treatment,

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3.11 Disinfection
 Disinfection is used in water treatment to
reduce pathogens (disease –producing
microorganism) to an acceptable level.
 Disinfection is not the same as sterilization.
Sterilization implies the destruction of all living
Vibrio cholera
organisms. Drinking water need not be sterile.
 Human enteric pathogens that must be Giardia
destroyed by disinfection included bacteria (E.
coli O157, Vibrio cholera), Viruses, Protozoa,
(Cryptosporidium spp., Giardia) and Amebic
cysts.

E.coli
Roslinda@Sem 1 2016/2017 49
 Others disinfectant
1. Ozone (O3)
5. Chloramines (NH2Cl, NHCl2, NCl3)
– very powerful oxidant – kills cysts
– longer contact time if primary disinfectant
– no taste and odor problems
– used in combination with other disinfectants
– widely used in Europe
6. Chlorine dioxide (ClO2)
– no residual
– very effective
– more expensive than chlorine (produced on-site)
– must be produced on site
2. Ultraviolet radiation
– effective bactericide and viricide
– water must be free of turbidity and lamps free of slime
and precipitates
– no residual protection
3. Hypochlorite salts: NaOCl and Ca(OCl)2
– more expensive to purchase
– easier to handle
– more common for small supplies
Roslinda@Sem 1 2016/2017 50
Disinfectant

 Cheaper,
 Tends to decrease pH
 Each mg/L of chlorine
added reduced the
alkalinity by up to 1.4 mg/L
as CaCO3

 Always contain alkali to

enhance stability
 More expensive
 Tend to raise pH
 safer

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Typical mixers for the addition of chlorine

Roslinda@Sem 1 2016/2017 52
3.11.3 Chlorine Reaction in Water

 When chlorine is added to water, a mixture of hypochlorous acid (HOCl) and hydrochloric acid
(HCl) is formed:

Cl2 (g) + H20  HOCl + H+ + Cl-

 This reaction is pH dependent and essentially complete within a very few milliseconds. The pH
dependence may be summarized as follows:
- In dilute solution and at pH levels above 1.0, the equilibrium (above equation) is displaced to the
right and very little Cl2 exists in solution.
- Below pH 1.0, depending on the chloride concentration, the HOCl reverts back to Cl2 (above
equation)
- HOCl is a weak acid and dissociates poorly at levels of pH below about 6.
- Between pH 6.0 and 8.5 there occurs a very sharp change from undissociated HOCl to almost
complete dissociation:

HOCl = H+ + OCl-

- Chlorine exists predominantly as HOCl at pH levels between 4.0 -6.0

- (At 20oC, above pH 7.5), and (at 00C, above pH 7.8), hypochlorite ions (OCl-) predominate.
- Hypochlorite ions exist almost exclusively at levels of pH around 9 and above.

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To be of practical service, such water disinfectants must possess the following properties:

1. They must destroy the kinds and numbers of pathogens that may be introduced into water
within a practicable period of time over an expected range in water temperature.
2. They must meet possible fluctuations in composition, concentration and condition of the
waters to be treated
3. The must be neither toxic to human and domestic animals nor unpalatable or otherwise
objectionable in required concentrations.
4. The must be dispensable at reasonable cost and safe and easy to store, transport, handle
and apply.
5. Their strength or concentration in the treated water must be determined easily, quickly and
(preferable) automatically.
6. They must (residual chlorine) persist within disinfected water in a sufficient concentration to
provide reasonable residual protection against its possible recontamination before use.

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Residual Chlorine

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3.14 Water Distribution System

 Typically, distribution systems

are designed to satisfy
domestic, commercial and
industrial water needs and
fire fighting purposes.

 The water distribution system

is the essential link between
the water supply source and
the consumer

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Roslinda@Sem 1 2016/2017 57
Roslinda@Sem 1 2016/2017 58
 In large town or cities, the
distribution system is usually
arranged into pressure zone
controlled from specific
service reservoir (Figure). This
allow for better leakage control
and metering of water usage
in each district. Such zones
are often interconnected by
zone boundary valves to allow
for the transfer of water
between zones if the need
arises.

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Distribution method had categorized to three as follows:
a) Gravity distribution
Possible only when the source of supply is located substantially above
the level of the city.
b) Pumping Without Storage
Least desirable method of distribution, since it provides no reserve flow
in the event of power failure and pressure will fluctuate substantially with
variations in flow.
c) Pumping With Storage
Water is pumped at a more or less uniform rate, with flow in excess of
consumption being stored in elevated storage tank distributed throughout
the system.

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dead ends" that prevent supply water to any point from at type most commonly used.
water from being circulated least two directions
throughout the system It can incorporate loop
permits any broken pipe sections feeders, which distribute
water tends to stagnate in to be isolated for repair without the flow to an area from
dead-end patterns, making disrupting service several directions.
them more susceptible to
taste and odor problems Street patterns, topography,
development, and
requires frequent flushing, treatment and storage
so hydrants should be facilities dictate a
placed at the extreme end of distribution system in
these lines design

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3.14.1 Distribution System Components
 A water distribution network (Figure 3.30) is a collection of links
connected together at their endpoint called nodes.
 Nodes may be points of water withdrawal (demand nodes), locations
where water is introduce to the network (source nodes), or locations
of tanks or reservoirs (storage nodes).
 Valves are links in pipelines that are used to regulate flow or
pressure. Pumps are used to increase the hydraulic head (pressure)
of water.

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