Water treatment involves processes that remove contaminants and make water potable for human consumption and industrial use. It generally involves screening, coagulation, flocculation, sedimentation, filtration and disinfection. The objectives are to produce water that is safe, aesthetically appealing and at a reasonable cost. Different water sources like surface water and groundwater require different treatment methods depending on the contaminants present. Standards exist for raw water quality and treated drinking water quality.

1. by: Ma. Teresa P. Francisco
DT Student
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2.  Water treatment is the process of making
water suitable or acceptable for an end-use.
 It removes existing water contaminants and so
reduces their concentration that the water becomes fit
for its desired application.
 Why Water Treatment?
 Natural waters are rarely of satisfactory quality for human
consumption or industrial use and nearly always needed to
be treated.
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3.  In the United States and the United Kingdom,
by far the most common sources of raw freshwater
are rivers and lakes, though in recent decades, more
sources of groundwater are being utilized.
 Some groundwater sources are so pure that no
treatment is necessary although when used for public
supplies, local water authorities tend to apply a
disinfection process, but this is primarily for
disinfection purposes of the distribution network.
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4.  The objectives of water treatment are to produce:
Water that is safe for human consumption
Water that is appealing aesthetically to the consumer
Water at a reasonable cost
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5.  Advanced water treatment processes are often
required by industry, e.g. the beverage or
pharmaceutical industries. Such industries
may have higher standards than those for
potable supplies.
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6.  Public water supplies normally service
the requirements of:
Domestic households
Fire fighting
Industrial
Commercial
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7. Source: UN Development Program 2006 7

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9. Development of New Water Sources:
 Angat Dam - the only present source of water supply for the MWSS
service area serving a total of 13 million population out of the total
service population of 15 million, or only 87% total service coverage.
 Angat Dam provides a supply volume of 4,000 million liters per day
(4,000 mld) out of the present demand of 4,395 mld, or a deficit of
395 mld.
 By 2015, the projected demand is expected to reach 5,054 mld, thus
requiring the development of supplementary sources of water to
address the increasing demand.
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10.  In discussing water quality, two sets of
standards exist:
 The quality of raw water
 The quality of the treated potable water
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11.  Organoleptic Parameters
 Physicochemical Parameters
 Parameters Concerning Substances
Undesirable in Excessive Amounts
 Parameters Concerning Toxic Substances
 Microbiological Parameters
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12. Organoleptic parameters
■ Turbidity
■ Colour
■ Odour
■ Taste
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13. Turbidity
Turbidity refers to how clear the water is
The greater the amount of total
suspended solids in the water, the
murkier it appears and the higher the
measured turbidity
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14. Materials that cause water to be turbid
include
 Clay
 Silt
 Plankton
 Microscopic organisms
 Soluble colored organic compound
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15. COLOUR
Colour is an optical parameter consisting
in absorbing of a part of spectrum of
visible radiation by substances dissolved
in water, and suspension particles present
in water or sewage.
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16. Colour in water may appear as the result of
different sources activity:
type of vegetation
decay of plant matter
algae growth
plankton
minerals (iron, manganese and copper)
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17. TASTE AND ODOUR
are usually inter-related.
Compounds in water that are perceived
as giving it a taste are generally inorganic
substances present in concentrations such
higher than those of organic pollutants
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18. TASTE AND ODOUR
Inorganic chemicals that can affect taste
but not cause any odour are salt, minerals,
metals.
A few inorganic chemicals can cause
both taste and odour problems. These are
ammonia, chlorine, hydrogen sulphide.
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19. TASTE AND ODOUR
Organic chemicals usually affect both
taste and odour: the compounds
concerned include hydrophilic acids,
carboxylic acids, amino acids,
carbohydrates, hydrocarbons, biological
decay products, petroleum products and
pesticides.
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20. Physico-chemical parameters
 Temperature and pH
 Conductivity (salinity)
 Chlorides
 Sulphates
 Silica
 Calcium
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21. Physico-chemical parameters
 Magnesium
 Sodium
 Potassium
 Aluminum
 Total hardness
 Dry residues
 CO2
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22. Parameters Concerning Substances
Undesirable in Excessive Amount
 Inorganic Compounds: nitrates, nitrites,
ammonium, phosphorus, fluoride, metals
(Iron, Manganese, Copper)
 Organic conontaminants: THM’s, phenols,
surfactants
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23. Parameters Concerning Toxic Substances
 Arsenic
 Cadmium
 Cyanide
 Chromium
 Lead
 Mercury
 Nickel
 Etc 23

24. Microbiological Parameters
 Bacteria
 Viruses
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25.  Water for treatment and subsequent public
consumption is normally sourced from:
Rivers: upland and lowland
Lakes and reservoirs
Groundwater aquifers
 The selection of the source is governed by many
factors, including proximity to the consumers,
economics, long-term adequacy of supply and raw
water quality.
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26. Each source presents its own problems
 Surface water has elevated levels of soil particles and algae,
making the water turbid
 may contain pathogens
 Groundwater has higher levels of dissolved organic matter (yellow color)
and minerals such as iron
 Both sources may have high levels of calcium and magnesium (hardness)
 both can be contaminated by toxic chemicals
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27.  Four classes of water treatment:
Class Description Source
A No treatment Some borehole
water
B Disinfection only Occasional upland
water, some
borehole water
C Standard water treatment Lowland rivers and
reservoirs
D Special Water Treatment Some rural supplies
(Fe and Mn)
Color removal
Industrial water
Algae removal
Organics removal
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28. Screening
Coagulation
Flocculation
sludge
Sedimentation
Filtration
Disinfection
Storage
Distribution
Raw water
Alum
Polymers Cl2
sludge
sludge
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29.  Removes large solids
logs
branches
rags
fish
 Simple process
may incorporate a mechanized trash removal system
 Protects pumps and pipes in Water Treatment Plants

30.  Small particles are not
removed efficiently because
they settle too slowly
 they may also pass through
filters
 easier to remove if they are
clumped together
 Coagulated to form larger
particles, but they don't
because they have a negative
charge
 repel each other (like two
north poles of a magnet)
 In coagulation
 we add a chemical such as alum
which produces positive charges
to neutralize the negative charges
on the particles
 particles can stick together
 forming larger particles
 more easily removed
 process involves addition of
chemical (e.g. alum)
 rapid mixing to dissolve the
chemical
 distribute it evenly throughout
water
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31.  Aluminum Sulfate Al2(SO4)3
 Ferrous Sulfate FeSO4
 Ferric Sulfate Fe2(SO4)3
 Ferric Chloride FeCl3
 Lime Ca(OH)2
Aluminum salts are cheaper but
iron salts are more effective over
wider pH range
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32.  Now the particles have a neutral
charge
 They can an stick together
 The water flows into a tank with
paddles that provide slow mixing
 bring the small particles together to
form larger particles called flocs
 Mixing is done quite slowly and
gently in the flocculation step
 If the mixing is too fast, the flocs
will break apart into small particles
that are difficult to remove by
sedimentation or filtration.
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 Water flows to a tank called a
sedimentation basin
 Gravity causes the flocs to settle to the
bottom
 Large particles settle more rapidly
than small particles
 It would take a very long time for all
particles to settle out and that would
mean we would need a very large
sedimentation basin.
 So the clarified water, with most of
the particles removed, moves on to the
filtration step where the finer particles
are removed

34.  The filtration apparatus is a concrete box which contains sand
(which does the filtering), gravel (which keeps the sand from
getting out) and underdrain (where the filtered water exits)
 After the filter is operated for a while, the sand becomes
clogged with particles and must be backwashed
 Flow through the filter is reversed and the sand and particles are
suspended
 The particles are lighter than the sand, so they rise up and are
flushed from the system. When backwashing is complete, the
sand settles down onto the gravel, flow is reversed and the
process begins again
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35.  With particles removed, it
only remains to
provide disinfection, so that
no pathogens remain in the
water
 Protozoan pathogens are
large in size and have been
removed with other particles
 Bacteria and viruses are
now destroyed by addition
of a disinfectant
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36. Chlorination
 Enough chlorine is
added so that some
remains to go out in the
water distribution
system, protecting the
public once the water
leaves the plant
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37.  Pumping of the clean
water produced at the
treatment plant to the
community is
called distribution
 This can be done directly
or by first pumping the
water to reservoirs or
water storage tanks
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38.  Water fluoridation is the controlled addition
of fluoride to a public water supply to
reduce tooth decay. Fluoridated water has
fluoride at a level that is effective for
preventing cavities; this can occur naturally or
by adding fluoride.
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39.  Ground waters are more likely to have a
higher fluoride content.
 Most surface water have negligible amount.
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41.  Purposes:
To take a water treated by standard processes and to
improve it to exceptionally high quality as often
required by particular industries.
To treat a water containing specific chemical or
microbiological contaminants to an acceptable standard,
i.e removal of iron and manganese, the removal of blue-green
algae, the removal of specific organics
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44.  Techniques Used:
Iron and manganese removal - iron is removed by
pressure filters while manganese is removed by gravity
sand filters
Ion Exchange and inorganic absorption - water
softening by exchanging undesirable calcium and
magnesium cations with sodium. Also used to remove
undesirable cations including barium, strontium and
radium and undesirable anions including fluoride,
nitrates, silicates and chromates
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45.  Techniques Used:
Adsorption of organics – undesirable contaminants are
adsorbed on to solid adsorbents.
Membrane processes – uses microfiltration,
ultrafiltration, reverse osmosis, electrodialysis
Oxidation including chemical oxidation – two or more
chemical species are added with the purpose of
increasing the oxidation state of one.
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The Angat River is the largest and
most important source of water for our
region.

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