Water treatment introduction

ADVANCED WATER
TREATMENT TECHNOLOGY
MODULE-1
Presented By:
MELROY CASTALINO
1st Year Mtech (ENV)
B.I.E.T, Davangere.
Under the Guidance of:
Dr. H B ARAVINDA
HOD Civil Engineering Department
B.I.E.T, Davangere.

CONTENTS
• INTRODUCTION
• OBJECTIVES FOR TREATMENT OF WATER
• SOURCES OF WATER
• MICRO-ORGANISMS IN NATURAL WATER AND PURIFICATION
• DRINKING WATER QUALITY AS PER BIS
• SOURCES OF WATER POLLUTION, DISEASES AND CONTROL
• FLOW DIAGRAM ON WATER SUPPLY PROJECT
• INTAKE STRUCTURES AND TYPES
• REFERENCE 1

INTRODUCTION
• Water is the most abundant compound in the nature
• It covers 75% of the earth surface
• About 97.3% of water in the Oceans is saline and 2.14% is held in ice-caps.
• Barely the remaining 0.56% found on earth which is useful for general livelihood.
• Water quality typically falls within 3 categories i.e., physical, chemical and
microbiological. Physical parameters include colour, turbidity, total suspended
solids etc.,
• Chemical parameters include heavy metals, acidity or basicity etc.,
• Microbiological parameters include bacteria, viruses and protozoan parasites.
• The water treatment aims at removing all the above parameters and make the
water potable and palatable for human use.
2

OBJECTIVES
1) The principal objective of water treatment is to provide water free from physical,
chemical and microbiological parameters.
2) To make water potable for humans.
3) To remove pathogenic organisms.
4) To improve the quality of water.
5) To remove corrosion causing agents.
6) To maintain better sanitation and beautiful surroundings.
3

Sources of Water and their Characteristics
• The source of water commonly determines the nature of the collection,
purification, transmission and distribution works.
• Sources are classified as:
1. Surface sources:
i. Rainwater
ii. Rivers
iii. Lakes and ponds
2. Sub-surface sources:
i. Infiltration Galleries
ii. Wells
iii. Springs
4

Rainwater
• The evaporated water from the surface rise-up into the atmosphere were it
condenses in clouds and falls back to earth in the form of rain.
• Rate of precipitation can be measured in mm/hr using rain gauges
• Light rain <2.5mm per hour, medium rain 2.5mm to 7.6mm per hour and heavy
rain >7.6 mm per hour
• Types of rainfall
i. Relief rainfall: when air has been blown over the sea and is the forced up over
an area of high land.
ii. Frontal rainfall: when warm air is forced to rise over cold air. The moisture in
the warm air condenses as it cools which causes clouds and rain.
iii. Convectional rainfall: when hot air rises and cools condenses in cloud forming
rain. Occurs mostly in tropics where it is hot. 5

Rivers
• Rivers are the main source of surface water.
• Rivers are further classified into Perennial and Non-perennial rivers.
• Perennial rivers have water throughout the year therefore they do not require any
arrangements to hold the water.
• But the Non-perennial rivers dry up wholly or partially in summer.
• In summer the quality of river water is better than monsoon because the run-off
water also carries clay, slit etc which make the water turbid. So, river water require
special treatments.
• Mostly all the cities are situated near the rivers which usually discharges sewage
in the rivers.
• Therefore, much care should be taken while drawing water from the river.
7

Lakes and Ponds
• Inland bodies with sufficiently large surface areas are called lakes
• Inland bodies with small surface areas are called ponds
• Lakes and ponds may be artificially constructed or naturally occurring
• The water from these sources may be better in quality than the river water and can
be used for domestic purpose without much treatment.
• The quality of water in the natural ponds lakes depends upon the basin’s capacity,
catchment area, annual rainfall etc.,
9

Infiltration Galleries
• A horizontal tunnel which is constructed through water bearing strata for trapping
underground water near rivers, lakes or streams are called “Infiltration galleries”
• The yield from the galleries may be as much as 1.5 × 104
lt/day/m length of
infiltration gallery.
• Infiltration galleries may be constructed with masonry or concrete.
Fig: infiltration galleries
11

Wells
• A well is defined as an artificial hole or pit made in the ground for the purpose of
trapping water.
• In India 17- 85% of Indian population has to depend on wells for its water supply.
There are different types of wells,
1. Shallow wells
2. Deep wells
3. Tube wells
4. Artesian wells
12

Shallow wells
• Shallow wells are constructed in the uppermost layer of the earth’s surface.
• The diameter of well varies from 2-3 m and a maximum depth of 7m.
Deep wells
• The deep wells obtain their water from an aquifer below the impervious layer.
• The water from the outcrop travels to the site of deep well.
• The outcrop is the place where aquifer is exposed to the atmosphere.
• The rain water entered at outcrop and get thoroughly purified when it reaches to
the site of deep well.
13

Fig 5: Shallow and Deep well
14

Springs
• Sometimes ground water reappears at the ground surface in the form of springs.
• Springs generally supply small quantity of water and hence suitable for the hill
towns.
• Some springs discharge hot water due to presence of sulphur and useful only for
cure of certain skin disease.
• Types of springs:
1. Gravity springs
2. Surface springs
3. Artesian springs
15

Gravity springs
• When the ground water table rises high and water overflows through the sides of
natural valley or a depression, the spring formed is known as a gravity spring.
Surface springs
• Sometimes an impervious obstruction supporting the underground storages
becomes inclined causing the water table to go up and get exposed to the ground
surface. This type of spring is called surface spring.
Artesian springs
• When the ground water rises through a fissure in the upper impervious stratum,
the spring formed is artesian spring.
16

Fig 6: Gravity, Surface and Artesian Spring
17

Comparison of Surface and sub-surface sources
SURFACE WATER
• Quantity: The quantity available for
surface water depends upon rainfall.
• Since the rainfall is not uniform,
storage reservoirs are constructed
which provide good means of storing
and utilizing rainwater.
• Quality: The quality of water
obtained from the rivers is generally
not reliable as it contains large amount
of untreated sewage, industrial waste
etc., which discharged.
• A lot of treatment will required before
supply.
SUB-SURFACE WATER
• Quantity: The quantity of ground
water is generally less than that of
surface water.
• They depends upon the underground
storage and the geological formation
of the area.
• Quality: Ground water generally
contain lesser suspended matter.
• As the water passes through the
porous earth strata water undergoes
natural filtration.
• This water require less treatment.
18

MICRO-ORGANISMS PURIFY WATER
1. Ciliate protozoa: they play an very important role in the purification process.
Bacteria are eaten by small Ciliate protozoa which in turn eaten by metazoa.
Fig 7: Ciliate protozoa
19

2. Nitrifying Bacteria: these are aerobic bacteria which can convert nitrogenous
waste into nitrates, such as ammonia which is highly toxic. The main types of
nitrifying bacteria are Nitrosomonas and Nitrobacter.
Fig 8: Nitrosomonas and Nitrobacter.
20

3. Methanogens: they can deliver methane gas, by breaking down the
organic materials or use H2 and CO2 to make methane.
Although methane emissions have negative environmental impacts, the
use of methanogens can be use in reducing wastewater and the pollution
of water systems across the world.
Fig 9: Filamentous methanogen.
21

4. Rotifers: these microscopic complex organisms are filter feeders removing fine
particulate matter from water. They occur naturally in aerobic lagoons, activated
sludge process, in trickling filters and in final settlement tanks.
Fig 10: Rotifers
22

5. Saprophytic Bacteria and Fungi: they can convert organic matter into living
cell mass, carbon-di-oxide, water and a range of metabolic by-products.
Fig 11: Saprophytic Bacteria and Fungi
23

DRINKING WATER QUALITY AS PER BIS
Sl.
No.
Characteristics Acceptable
limits
Permissible
limit
1 pH 6.5-8.5 No
Relaxation
2 Taste and odour agreeable agreeable
3 Colour (in forel ule
scale)
5 15
4 Turbidity (NTU Scale) 1 5
5 Total dissolved solids
in ppm
500 2000
6 Total hardness in mg/l 200 600
7 Total alkalinity as
CaCO3 mg/l
200 600
8 Chlorides in mg/l 200 1000
9 Fluorides in mg/l 1 1.5
10 Sulphates in mg/l 200 400
11 Iron in mg/l 0.3 No relaxation
24

Sl.
No.
Characteristics Acceptable
limits
Permissible
limit
12 Lead in mg/l 0.01 No relaxation
13 Magnesium as Mg in mg/l 30 100
14 Calcium as Ca in mg/l 75 200
15 Total alkalinity as 𝐶𝑎𝐶𝑂3
mg/l
200 600
16 Manganese as Mn mg/l 0.1 0.3
17 Copper as Cu in mg/l 0.05 1.5
18 Zinc as Zn in mg/l 5 15
19 Nitrate in mg/l 45 No relaxation
20 Silver as Ag in mg/l 0.1 No relaxation
21 Sulphide in mg/l 0.05 No relaxation
22 Free residual chlorine in mg/l 0.2 1
23 Boron as B in mg/l 0.5 1.0

SOURCES OF WATER POLLUTION
• Water pollution is an major problem which lead the world on a path of destruction.
• Water is an easy solvent enabling most pollutants to dissolve in it easily and
contaminate it.
• The following are the sources of water pollution:
1) Industrial waste
2) Sewage and waste water
3) Marine dumping
4) Radioactive waste
5) Leakage from landfills
25

WATER-BORNE DISEASES
• Water pollution involves the pollution of surface waters and/or groundwater,
which may cause a series of diseases referred to as water pollution diseases.
• Diseases like:
1. Typhoid
2. Cholera
3. Diarrhea
4. Jaundice
5. Amoebiasis
6. Vomiting
7. Stomach cramps
8. Respiratory infections
9. Thyroid system disorders
26

Control Measures of Water Pollution
1. Administration of water pollution control should be in the hands of
state or central government.
2. Public awareness must be initiated regarding adverse effects of
water pollution using the media.
3. Basic and applied research in public health engineering should be
encouraged.
4. Qualified and experienced people must be consulted from time to
time for effective control of water pollution.
5. Laws, standards and practices should be established to prevent water
pollution.
6. Industrial plants should be based on recycling operations as it helps
prevent disposal of wastes into natural waters. 27

Control measures contd..,
7. Water supplies must be disinfected, checked thoroughly then sent to
public. This applies to water supply scheme and open wells etc.
8. More precautions needed during heavy rain, floods and repair works
on road.
28

FLOW DIAGRAM ON WATER SUPPLY
PROJECT
29

Unit diagram of water supply project
Aeration
30

Unit diagram of water supply In Rural Areas

Unit diagram of water supply from Reservoir.

INTAKE STRUCTURES AND TYPES OF INTAKE
STRUCTURE
• Definition of intake structures:
Intake structures are used for collecting water from the surface
sources such as river, lake, and reservoir and conveying it further to the
water treatment plant.
• These structures are masonry or concrete structures and provides
relatively clean water, free from pollution, sand and objectionable
floating material.
31

Site selection for intake structures
1. The site should be so selected that it may admit water even under worst
condition of flow.
2. Generally, it is preferred that intake should be sufficiently below the shore
line.
3. Site should be very close to treatment plant as possible.
4. It should be so located that it is free from the pollution. It is better to
provide intake at upper stream of city so that water is not contaminated.
5. It should not interfere with river traffic.
6. It should be located where good foundation conditions are available.
7. The site should be protected from rapid currents which may damage the
intake structure.
8. The site of the work should be easily approachable without any
obstruction. 32

Design Considerations
1. Sufficient factor of safety against external forces such as heavy
currents, floating materials, submerged bodies, ice pressure, etc.
2. Should have sufficient self weight so that it does not float by up-
thrust of water.
33

Types of intake structures
1. Simple Submerged intakes:
i. Submerged intake structures
ii. Rock filled timber intake
2. Intake towers:
i. Wet intake towers
ii. Dry intake towers
3. River intake structures
i. Twin well type
ii. Single well type
4. Canal intake
5. Reservoir intake
34

Simple submerged intake
1. Intake structures are constructed by simple concrete block or rock filled timber
crib.
2. These are constructed near lakes, where slit tends to settle down.
3. The opening is generally kept at about 2 to 2.5 m above the lake bed level to
avoid entry of silt.
4. They are cheap in construction and are constructed entirely under water does
the name submerged intake.
5. They are widely used for small water supply projects.
6. Limitation is that they are not accessible for cleaning and repairing.
35

Fig 12 :Simple submerged intake
36

Fig 13:Rock filled timber intake 37

Intake towers
• They are widely used on large water supply projects, for drawing
water from rivers or reservoirs having large change in water level.
• They are located near the river bank.
• There are two major types:
i. Wet intake towers
ii. Dry intake towers
38

Wet intake towers
• It consists of a concrete circular shell filled with water up to the
reservoir level.
• Has a vertical shaft inside which is connected to withdrawal pipe.
• The withdrawal pipe may lie over the bed of the river or may be in the
form of tunnels.
• Gates are placed on the shaft, so as to control the flow of water into
the shaft.
• The water coming out of the withdrawal pipe may be taken to pump
house for lift.
39

Dry intake towers
• The water is directly drawn into the withdrawal conduit through the
gated entry ports.
• It has no water inside the tower if its gates are closed.
• When the entry ports are closed, a dry intake tower will be subjected
to additional buoyant forces.
• Hence it must be of heavier construction than wet intake tower.
• They are used as water can be withdrawn from any selected level of
the reservoir by opening the port at the level.
41

River intake structures
• They are generally constructed for withdrawing water from almost all
rivers.
• It is a type of intake which may either located sufficiently inside the
river so that demands of water are met with in all the seasons of the
year.
• Or they may be located near the river bank where a sufficient depth of
water is available.
• They can be classified as:
i. Twin well type of intake structure
ii. Single well type of intake structure
43

Twin well type of intake structure
• They are constructed on almost all types of rivers, where the river
water hugs the river bank.
• It consists of 3 components:
An inlet well: inlet well is usually circular in C/s, made of masonry or
concrete.
 An inlet pipe: inlet pipe connects inlet well with jack well. It has a
minimum dia of 45 cm, laid at slope of 1 in 200. flow velocity through
it <1.2 m/s. water entering jack well is lifted by pumps and fed into the
rising main.
 Jack well: jack well should be founded on hard strata having bearing
capacity ≥ 450 KN/m2
.
44

Fig 16:Twin well type of intake
45

Single well type of intake structure
• Intake structures will not have inlet wells and inlet pipe in this type of
river intake.
• Opening or ports fitted with bar screens are provided in the jack well
itself.
• The silt entering the jack well will partly settle down in the bottom silt
zone of jack well.
• The jack well can be periodically cleaned manually by stopping the
water entry in to the well.
46

Fig 17:Single well type of intake
47

Canal intake
• In some cases, source of water supply to small town may be an
irrigation canal passing through the town, canal intake are constructed.
• Generally it consists of masonry or concrete intake chamber of
rectangular shape, admitting water through a coarse screen.
• A fine screen is provided over the bell mouth entry of the outlet pipe.
• The intake chamber may be constructed inside the canal bank if it
does not offer any appreciable resistance to normal flow in the canal.
48

Reservoir intake
• When the flow in the river is not guaranteed throughout the year, a
dam is constructed across it to store water in the reservoir so formed.
• These are similar to river intake, except that these are located near the
upstream face of the dam where maximum depth of water is available.
• Design of intake may vary based on the type of dam.
50

REFERENCE
1) Clifford, D. A. (1990) “Water Quality & Treatment: A Handbook of Community
Water Supplies”, 4th Ed. New York: McGraw-Hill.
2) Conlon, W. J. and S. A. McClellan. (1989). “A water treatment process”. Journal
of the American Water Works Association 81(11):47.
3) EPA (U.S. Environmental Protection Agency). (1985). National Primary
Drinking Water Regulations: Fluoride. Federal Register 50:220.
4) H. David Stensel and Franklin L. Burton “Textbook for: Wastewater engineering
treatment and reuse” Metcalf and Eddy fourth edition.
5) Issam Najm and R. Rhodes Trussell, “New and Emerging Drinking Water
Treatment Technologies”

Water treatment introduction

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