powerpoint presentation for microsoft office ppt 2010

3. WATER
RESOURCES

4. A. Surface sources such as:
1. Ponds and Lakes
2. Streams and Rivers
3. Storage resources ( Dams )
B. Subsurface or Underground sources
such as:
1. Springs
2. Wells ( Open and Tube- wells )

5. LAKE
A lake is a body of relatively still fresh or
salt water of considerable size, localized in a
basin, that is surrounded by land apart from a
river, stream, or other form of moving water that
serves to feed or drain the lake. Lakes are inland
and not part of the ocean and therefore are
distinct from lagoons, and are larger and deeper
than ponds. Lakes can be contrasted with rivers
or streams, which are usually flowing. However
most lakes are fed and drained by rivers and
streams.

6. Natural lakes are generally found in
mountainous areas, rift zones, and areas with
ongoing glaciations. Other lakes are found in
endorheic basins or along the courses of mature
rivers. In some parts of the world there are many
lakes because of chaotic drainage patterns left
over from the last Ice Age. All lakes are
temporary over geologic time scales, as they will
slowly fill in with sediments or spill out of the
basin containing them.

7. LAKE

8. POND
A pond is a body of standing water, either
natural or man-made, that is usually smaller
than a lake. They may arise naturally in
floodplains as part of a river system, or they may
be somewhat isolated depressions (examples
include vernal pools and prairie potholes).
Usually they contain shallow water with marsh
and aquatic plants and animals. A few animals
also make ponds, including both alligators and
beavers. The type of life in a pond is generally
determined by a combination of factors including
water level regime (particularly depth and
duration of flooding) and nutrient levels, but
other factors may also be important, including
presence or absence of shading by trees, presence
or absence of streams, effects of grazing
animals, and salinity.

9. Humans also make ponds. A wide variety of
man-made bodies of water are classified as
ponds. Some ponds are created specifically for
habitat restoration, including water treatment.
Others, like water gardens, water features and
koi ponds are designed for aesthetic
ornamentation as landscape or architectural
features. Fish ponds are designed for commercial
fish breeding, and solar ponds designed to store
thermal energy.
Standing bodies of water such as puddles,
ponds, and lakes are often categorized separately
from flowing water courses, such as a brook,
creek, or stream.

10. POND

11. STREAM
A stream is a body of water with a current, confined
within a bed and stream banks. Depending on its locale
or certain characteristics, a stream may be referred to
as a branch, brook, beck, burn, creek, "crick", gill
(occasionally
ghyll), kill, lick, rill, river, syke, bayou, rivulet, streamag
e, wash, run or runnel.
Streams are important as conduits in the water
cycle, instruments in groundwater recharge, and corridors
for fish and wildlife migration. The biological habitat in the
immediate vicinity of a stream is called a riparian zone.
Given the status of the ongoing Holocene
extinction, streams play an important corridor role in
connecting fragmented habitats and thus in conserving
biodiversity. The study of streams and waterways in
general is known as surface hydrology and is a core element
of environmental geography.

12. These are bodies of flowing water moving in one
direction. Streams and rivers can be found everywhere—
they get their starts at headwaters, which may be springs,
snowmelt or even lakes, and then travel all the way to their
mouths, usually another water channel or the ocean. The
characteristics of a river or stream change during the
journey from the source to the mouth. The temperature is
cooler at the source than it is at the mouth. The water is
also clearer, has higher oxygen levels, and freshwater fish
such as trout and heterotrophs can be found there.
Towards the middle part of the stream/river, the width
increases, as does species diversity—numerous aquatic
green plants and algae can be found. Toward the mouth of
the river/stream, the water becomes murky from all the
sediments that it has picked up upstream, decreasing the
amount of light that can penetrate through the water.
Since there is less light, there is less diversity of flora, and
because of the lower oxygen levels, fish that require less
oxygen, such as catfish and carp, can be found.

13. STREAM

14. RIVER
A river is a natural watercourse, usually
freshwater, flowing towards an ocean, a lake, a sea, or
another river. In a few cases, a river simply flows into
the ground or dries up completely before reaching
another body of water. Small rivers may also be called
by several other names, including
stream, creek, brook, rivulet, run, tributary and rill.
There are no official definitions for generic
terms, such as river, as applied to geographic
features, although in some countries or communities
a stream may be defined by its size. Many names for
small rivers are specific to geographic location; one
example is "burn" in Scotland and northeast England.
Sometimes a river is said to be larger than a
creek, but this is not always the case, because of
vagueness in the language.

15. Rivers are part of the hydrological cycle.
Water within a river is generally collected from
precipitation through a drainage basin from
surface runoff and other sources such as
groundwater recharge, springs, and the release of
stored water in natural ice and snowpacks (e.g.,
from glaciers). Potamology is the scientific study
of rivers.

16. RIVER

17. DAM
A dam is a barrier that impounds water or
underground streams. Dams generally serve the
primary purpose of retaining water, while other
structures such as floodgates or levees (also
known as dikes) are used to manage or prevent
water flow into specific land regions. Hydropower
and pumped-storage hydroelectricity are often
used in conjunction with dams to generate
electricity. A dam can also be used to collect water
or for storage of water which can be evenly
distributed between locations.

18. DAM

19. SPRING (HYDROLOGY)
A spring—also known as a rising or
resurgence—is a component of the hydrosphere.
Specifically, it is any natural situation where
water flows to the surface of the earth from
underground. Thus, a spring is a site where the
aquifer surface meets the ground surface.

20. SPRING (HYDROLOGY)

21. WATER WELL
A water well is an excavation or structure
created in the ground by digging, driving, boring or
drilling to access groundwater in underground
aquifers. The well water is drawn by an electric
submersible pump, a trash pump, a vertical turbine
pump, a handpump or a mechanical pump (e.g.
from a water-pumping windmill). It can also be
drawn up using containers, such as buckets, that
are raised mechanically or by hand.
Wells can vary greatly in depth, water volume
and water quality. Well water typically contains
more minerals in solution than surface water and
may require treatment to soften the water by
removing minerals such as arsenic, iron and
manganese.

22. WATER WELL

24.  SURFACE SOURCES refers to water
occurring in lakes, rivers, ponds, streams,
or other fresh water sources used for
drinking water supplies. It is naturally
replenished by precipitation and
naturally lost through discharge to the
oceans, evaporation, evapotranspiration
and sub-surface seepage.

25.  These also pertains to the sources in
which the water flows over the surface of
the earth and is directly available as raw
water like what is mentioned in the
previous slide.

26.  The surface water that goes deeper into
the earth enhances the groundwater
safe deposits , though on the other hand
it contains more salt and energy is
required to take it out.

27. Image of the entire surface water flow of the Alapaha River near
Jennings, Florida going into a sinkhole leading to the Floridan
Aquifer groundwater

31. Potrerillos Dam
Trinity Dam

32. Grand Coulee Dam
Arch Dam
Trinity Dam

33. Thomson Dam
Evretou Dam
Trinity Dam

34. Water resources are sources of water that are useful
or potentially useful. Uses of water include
agricultural, industrial, household, recreational and
environmental activities. Virtually all of these human uses
require fresh water.

35. WATER RESOURCES
97% of the water on the Earth is salt water.
However, only three percent is fresh water; slightly
over two thirds of this is frozen in glaciers and polar ice
caps. The remaining unfrozen freshwater is found
mainly as groundwater, with only a small fraction
present above ground or in the air.

36. WATER RESOURCES
The sources of  Surface Sources
water which  Ponds and Lakes
can be  Streams and Rivers
harnessed  Storage Resources ( Dams)
economically
can be divided  Subsurface or Underground
into the Sources
following two  Springs
categories:  Wells

37. Surface Water
Surface water is water in a river, lake or fresh water
wetland. Surface water is naturally replenished by
precipitation and naturally lost through discharge to
the oceans, evaporation, evapotranspiration and sub-
surface seepage.

38. Ponds
 A pond is a body of water shallow enough to support
rooted plants. Many times plants grow all the way
across a shallow pond.
 Water temperature is fairly even from top to bottom
and changes with air temperature. There is little wave
action and the bottom is usually covered with mud.
Plants can, and often do, grow along the pond edge.
The amount of dissolved oxygen may vary greatly
during a day. In really cold places, the entire pond can
freeze solid.

39. Ponds

40. Lakes
 A lake is bigger than a pond, and is too deep to support rooted
plants except near the shore. Some lakes are big enough for
waves to be produced.
 Water temperatures in lakes during summer months is not
uniform from top to bottom. Three distinct layers develop: The
top layer stays warm at around 65–75 degrees F (18.8–24.5
degrees C). The middle layer drops dramatically, usually to 45–65
degrees F (7.4–18.8 degrees C). The bottom layer is the
coldest, staying at around 39–45 degrees F (4.0–7.4 degrees C).
Since light does not penetrate to the bottom, photosynthesis is
limited to the top layer. Because of the warmer waters and more
plentiful food supply, almost all creatures spend the summer
months in the upper layer.

41. Lakes
 During spring and fall the lake temperature is more
uniform. Fish and other animals are found throughout the
layers of the lake.
 Even in cold climates, most lakes are large enough so that
they don't freeze solid, unlike ponds. During the winter
months some creatures hibernate in the bottom mud.
Some fish continue to feed, but less actively. A layer of ice
can develop on the top of lakes during winter. The ice
blocks out sunlight and can prevent photosynthesis.
Without photosynthesis, oxygen levels drop and some
plants and animals may die. This is called "winterkill."

42. Lakes

43. Streams and Rivers
 Rivers come in lots of different shapes and sizes, but they
all have some things in common. All rivers and streams
start at some high point. The high point can be a mountain,
hill or other elevated area. Water from some source like a
spring, snow melt or a lake starts at this high point and
begins to flow down to lower points. As the water flows
down, it may pick up more water from other small streams,
springs or or from rain or snow melt. These streams may
slowly join together to form a larger stream or river. Small
rivers and streams may join together to become larger
rivers. Eventually all this water from rivers and streams will
run into the ocean or an inland body of water like a lake.

44. Streams and Rivers
 Although river water makes up only about 0.2 percent
of all the fresh water on Earth, it plays a very important
role. Rivers are like roads. They carry water, organisms
and important gases and nutrients to many areas.
They also help drain rainwater and provide habitats for
many species of plants and animals. As they make
their way to the sea, rivers help shape the features of
the Earth. Rivers are travel routes for people and
provide the power for hydroelectric plants.

45. Streams and Rivers

46. Storage Resources ( Dams)
 A dam is a barrier that impounds water or
underground streams. Dams generally serve the
primary purpose of retaining water, while other
structures such as floodgates or levees (also known as
dikes) are used to manage or prevent water flow into
specific land regions. Hydropower and pumped-
storage hydroelectricity are often used in conjunction
with dams to generate electricity. A dam can also be
used to collect water or for storage of water which can
be evenly distributed between locations.

47. Storage Resources ( Dams)

48. Subsurface or Underground Sources
 Sub-surface water, or groundwater, is fresh
water located in the pore space of soil and
rocks. It is also water that is flowing within
aquifers below the water table. Sometimes it
is useful to make a distinction between sub-
surface water that is closely associated with
surface water and deep sub-surface water in
an aquifer (sometimes called "fossil water").

49. Springs
 A spring is also known as a rising or
resurgence. It is a component of the
hydrosphere. Specifically, it is any natural
situation where water flows to the surface of
the earth from underground. Thus, a spring
is a site where the aquifer surface meets the
ground surface.

50. Springs

51. Wells
 A water well is an excavation or structure created in the
ground by digging, driving, boring or drilling to access
groundwater in underground aquifers. The well water is
drawn by an electric submersible pump, a trash pump, a
vertical turbine pump, a handpump or a mechanical pump
(e.g. from a water-pumping windmill[1]). It can also be
drawn up using containers, such as buckets, that are raised
mechanically or by hand.
 Wells can vary greatly in depth, water volume and water
quality. Well water typically contains more minerals in
solution than surface water and may require treatment to
soften the water by removing minerals such as arsenic, iron
and manganese.

52. Wells

53. Water Supply Schemes

54. scheme
• means a system to draw water from
suitable source, treat it and then supply it
to the consumers

55. The underground water is generally pure (from
suspended impurities point of view because
of natural filtration) but contains more dissolved
salts.
The lifting of water (pumping out from wells) also
requires energy (electricity) whereas the filtration
of surface water is a costly affair.
So the environmental engineers in the public health
engineering departments (water works) make
schemes(plans) to supply potable (fit for drinking
from all points of view, i.e. clarity, dissolved
salts, and free from bacteria etc.) water to the
consumers

56. Types of Water Supply Schemes
• rural water • Urban water supply
supply schemes schemes

57. Aspects to be Considered
• surety of availability of water
• quality of water
• cost of treatment
• cost of supply

58. Traditional Source scheme
• traditional source of the water supply already
existing in the village like an open well or the pond
is electrified and pumping machinery is installed
• The pumped water is distributed to the villager’s
byte existing small tanks near the wells.
After commissioning the scheme it was handed
over to the villagers to run at their own cost
• But the schemes were not run by them
successfully due to lack of interest and money.

59. Pump and Tank Schemes
• In these schemes the government public
health departments develop a source in the
village itself. It may be an open well or a
tube-well generally. One ground level
reservoir (G.L.R.) is constructed and the
pump installed on the source fills water in this
tank. Public stand posts (P.S.Ps) are
constructed by the sides of this GLR and
public is allowed to fetch water from here free
of cost-free but no hose connections are
given.

60. Pump and Tank Schemes

61. Regional Water Supply Schemes
• this is a combined scheme of many villages
• Pipe lines have to be laid to carry water from
the source to the benefited villages. So it is a
costlier option.
• Some times connections to individual houses
are also given depending upon the population
and the paying capacity and willingness of
the consumers. There are some regional
water supply schemes which cater the needs
of hundreds of villages along with the urban
towns

62. Regional Water Supply Schemes

63. Piped Water Supply Schemes
• These are generally for towns or big villages
(urban areas).
• In these schemes house connections are
given and the consumption is charged. The
source may be in the locality or a distance
source.
• Overhead tanks known as elevated service
reservoirs (E.S.R) are constructed for the
distribution of water through the distribution
mains.

64. Piped Water Supply Schemes

65. • First of all the raw water is treated by all
means including disinfection (most
important).Then pumped to ESRs and
then distributed either for the whole day or
at certain fixed time.
• The consumption is generally metered and
charged on monthly basis. After some
years the existing water supply schemes
are reframed and executed.
• Such schemes are known as Reorganized
Water Supply Schemes.

66. Urban Water Supply Schemes
• These are the schemes implemented for
the urban areas.
• The main difference in design of rural and
urban water supply scheme is the rate of
water supply.
• . The other main difference is the house
connections.

67. • In most of the rural water supply schemes
water is supplied at a common point and
people have to fetch it from this common
place also known as public stand post.
• In urban water supply schemes every
house is given a metered or flat rate
service connection through which water is
generally supplied intermittently.

68. • The water obtained from a surface or
ground source is treated and lifted in an
elevated service reservoir. Then it is
distributed through properly designed and
maintained distribution system. Though
some of it is wasted in leakages but the
loss should not be more than 10%. The
water is also supplied for industrial and
commercial purposes. Some of the water
is always stored for fire fighting.

69. Urban Water Supply Schemes

74. PHYSICAL AND
CHEMICAL
STANDARDS OF
WATER

75. Safe drinking water
• Free from pathogenic organisms
• Clear
• Not saline
• Free from offensive taste or smell
• Free from compounds that may have
adverse effect on human health
• Free from chemicals that cause corrosion
of water supply systems

76. PHYSICAL STANDARDS OF
WATER
Parameters Desirable Permissible
limit limit
Colour Hazen unit 5 25
Turbidity-NTU 5 10
pH 6.5-8.5 6.5-8.5
Hardness (as 0.3 1
CaCO3)mg/l
TDS 500 2000

77. CHEMICAL STANDARDS OF POTABLE
WATER
Parameters Desirable Permissible
limit limit
Nitrate mg/l 45 45
Chloride mg/l 250 1000
Flouride mg/l 1 1.5
Arsenic mg/l 0.05 0.05
Aluminium mg/l 0.03 0.2

78. Bacteriological Standards

79. Water entering the
distribution system

80. Coliform (bacteria, as the indicator
organism) count in any sample of 100mL
should be zero
Sample of water that does not conform to
this standard calls for an immediate
investigation into both the efficacy of the
purification process and the method of
sampling.

81. Criteria of water in the
distribution system
• E. Coli(Escherichia Coli, bacteria found in the
colon of human beings as natural habitant) count
in 100ml of any sample should be zero
• Coliform organisms, not more than 10 per 100ml
shall be present in any amount
• Coliform organisms should not be detectable in
100ml of any two consecutive sample or more
than 55 of the samples collected per year

82. Individual or
small community supplies
• E. Coli count should be zero in any sample of
100mL and coliform organisms should not be
more than 3 per 100ml.
• If it exceeds the said amount, the supply shoul
be disinfected

83. Virological Standards
0.5 mg/L of free chlorine residual for an hour
• Sufficient to inactivate virus even in water that
was originally polluted
• Insisted in all disinfected supplies in areas
suspected of infectious hepatitis Jaundice
• Other areas insists of 0.2mg/L of this free residual
for half an hour

84. 9. What are the toxicological
materials found in water?

85. •Total coliform bacteria
Total coliform bacteria are commonly
found in the environment (e.g., soil or
vegetation) and are generally harmless. If
only total coliform bacteria are detected in
drinking water, the source is probably
environmental. Fecal contamination is not
likely. However, if environmental
contamination can enter the system, there
may also be a way for pathogens to enter the
system. Therefore, it is important to find the
source and resolve the problem.

86. • E. Coli
E. coli is a type of fecal coliform
bacteria commonly found in the
intestines of animals and humans. E.
coli is short for Escherichia coli. The
presence of E. coli in water is a strong
indication of recent sewage or animal
waste contamination. Sewage may
contain many types of disease-causing
organisms.

87. • Fecal coliform bacteria
Fecal coliform bacteria are a sub-group
of total coliform bacteria. They appear in
great quantities in the intestines and feces of
people and animals. The presence of fecal
coliform in a drinking water sample often
indicates recent fecal
contamination, meaning that there is a
greater risk that pathogens are present than
if only total coliform bacteria is detected.

88. PHYSICAL
CHARACTERISTICS OF
WATER
Temperature
It can be measured by a
thermometer. The temperature
should be suitable for human beings
depending on climatic and weather
conditions. An average temperature is
15 degree Celsius.

89. Turbidity
The muddy or cloudy appearance of such
particles that presents hindrances on path of
light. The turbidity is measured by a turbidity
rod or a turbidity meter with physical
observations and is expressed as the
suspended matter in mg/I or ppm (part per
million). The standard unit of turbidity is that
which is produced by 1 mg of finely divided
silica in one litre of distilled water.

90. Colour
It is imparted by dissolved organic
matters from decaying vegetation or some
inorganic materials. The presence of algae or
other aquatic plants in water may impart
colour changes. The standard unit of colour
is that which produced by one milligram of
platinum cobalt dissolved in one litre of
distilled water. It is measured by lab`s by
Nessler`s tubes by comparing the sample
with the known intensities. The instrument
used is TINTOMETER.

91. Taste and odour
The dissolved inorganic salts or organic matter or the
dissolved gases may impart taste and odour to the water.
The water must not contain any undesirable or
objectionable taste or odour. The extent of taste or odour
is measured by the term called odour intensity which is
related with the threshold odour, which represents the
dilution ratio at which the odour is hardly detectible.
The water to be tasted is gradually diluted with odour
free water and the mixture at which the detection of taste
and odour is just lost is determined. The number of times
the sample is diluted is known as the threshold number.
Thus if 20 ml of water is made 100ml (until it just losses
its odour and tastes) then the threshold number is 5. For
domestic water supplies the water should be free from
any taste and odour so the threshold number should be 1
and not to exceed to 3.

92. Specific conductivity of water
It is determined by means of a portable
diionic water tester and is expressed as
micro ohms per cm at 25 degree Celsius.
Mho is the unit of conductivity and is
equal to 1 ampere / 1 volt . The specific
conductivity is multiplied by a co-efficient
(generally 0.65) so a to directly obtain the
dissolved salt content in ppm.

93. Chemical Characteristics of
water

94. • Since water is such a good solvent, it is not
surprising to find many different chemical
substances present in it. Water, on reaching a
river, will contain inorganic and organic
compounds which were dissolved as rainwater
percolated through the soil and rocks. In
addition, some gases will dissolve in rainwater
during its passage through the air.
• Analysis of water is done to determine this
chemical characteristics.

95. Total solids and Suspended solids
• The total amount of solids can be determined
by evaporating a measured sample of water
and weighing the dry residue left.
• The suspended solids can be determined by
filtering the water sample and weighing the
residue left on the filter paper.
• The difference between the total solids and
the suspended solids will be the dissolved
solids.

96. pH of Water
• pH is equal to the negative logarithm of
hydrogen ion. The higher value of pH means
lower value hydrogen ion concentrations and
thus represent alkaline water and vice versa.
• The neutral water has the same number of H+
and OH- ions.
• If an acid is added to neutral water the number of
hydrogen ion and thus reduces pH. Similarly, if an
alkali is added the number of hydroxyl ion
increases thus reducing hydrogen ion and the pH
increases.

97. • Hence, if the pH of water is more than 7 it is
alkaline and if it’s less than 7 it is acidic.
• Generally, the alkalinity of water is caused by
the presence of bicarbonates of calcium &
magnesium, or by the carbonates, or the
hydroxides of Na, K, Ca, and Mg.
• Acidity is caused by the presence of mineral
acids, free CO2 sulfates of Fe and Al etc.

98. • For municipal water supplies the pH should be
close to 7 as possible. The lower pH may
damage the pipelines etc. by reacting with
them. The alkaline water may produce
sedimentation in pipes, difficulties in
chlorination and adverse effect on human
physiological system.

99. Hardness of Water
• Hardness in water prevents the formation of
sufficient foam when used with soap.
• Hardness in water is mainly due to the presence
of ions of the metals calcium (Ca2+), magnesium
(Mg2+), and iron (Fe2+). Rivers and lakes fed by
water that has run from chalky areas and
limestone (CaCO3) contain an abundance of
calcium. Calcium and magnesium account for at
least 70% of the total cations in water.

100. • Hardness is measured by titration method and
is expressed in ppm or mg/l. Generally the
underground water is harder as it dissolves
the salts in its journey form surface to the
ground water table. For boiler feed waters and
for efficient washing of clothes the water must
be soft, i.e. hardness should be less than
75ppm.

101. Chlorides
• Chlorides are generally present in water in the
form of sodium chloride and their
concentration above 250mg/l produces a salty
taste in drinking water. The chlorides can be
measured in water by titrating the water with
standard silver nitrate solution using
potassium chormate as indicator.

102. Nitrogen Content
• Nitrogen in water may occur in one or more of
the following:
– Free Ammonia
• Indicates a very fast stage of decomposition of organic
matter.
– Albuminoid Nitrogen
• Represents the quantity of nitrogen present in water
before the decomposition of organic matter has
started.

103. Metals
• Various metals in minerals may be present in
water like Fe, Mn, Cu, Pb, Cd, As, Se, etc. The
allowable limits

104. Dissolved Gasses
• Various gases like CO2, O2, N2, H2S and CH4 etc.
may be present in dissolved form in water.
• H2S even in small concentration gives bad taste and
odor.
• CO2 indicates biological activity.
• O2 is generally absorbed by water from the atmosphere
• Organic matter may be present in water due
to the disposal of waste water in it.
• Organic matter has the tendency to become inorganic
matter known as decomposition of organic matter and
the process is bio-chemical

105. Bio Chemical Oxygen Demand(BOD)
– Demand of oxygen imposed by the aerobic
bacteria
– This reduces the dissolved oxygen content of
water. So if the dissolved oxygen of water is found
to be less than the concentration it indicates
water pollution.
• The BOD of water should be zero.

106. Treatment
of
Water

107. The available raw water has to be treated to make
it fit, i.e. potable, means safe for human consumption. It
should satisfy the physical, chemical, and bacteriological
standards. The various methods of water purification are:
Screening
 Plain sedimentation
Sedimentation aided with coagulation
Filtration
Disinfection
Aeration
SofteningMiscellaneous treatments like
defluoridation, recarbonation, desalination, etc.

108. S creening
Screens are provided before the intake works so as
to prevent the entry of big objects like debris, branches of
trees, parts of animals etc. Screens may be of two
types, coarse screen and fine screens. Coarse screen are
parallel iron rods placed vertically or at a slope at about 2.5
cm to 10 cm apart. The fine screens are made up of fine
wire or perforated metal with small openings less than 1 cm
in size. Finer is the screen more are the chances of clogging
so generally only coarse screens are used. The screens may
be manually cleaned or mechanically cleaned depending
upon the requirement i.e. the size of the treatment plant.

109. P S lain edimentation
Sedimentation is done to remove the impurities which
have specific gravity more than that of the water and are
settleable. When water is moving these impurities remain in
suspension due to the turbulence and as the velocity is reduced
they settle down. It is not necessary to stop the motion of water
completely as it will require more volume of the sedimentation
tanks. As per the theory of sedimentation the settlement of a
particle depend upon the velocity of flow, the velocity of water,
the size shape and specific gravity of particle. The settling
velocity of a spherical particle is expressed by Stroke’s law.

110. S edimentation aided with C oagulation
The fine suspended particles like mud particles and the
colloidal matter present in the water cannot settle down by plain
sedimentation with ordinary (lesser) detention periods. Some of
the colloidal impurities will not settle even if the water is detained
for long periods in the sedimentation tanks as the same charge on
the clay particles repel each other and do not allow them to settle
down. So the sedimentation is aided with coagulation. Coagulation
is a process in which some chemical like alum or ferrous sulfate is
mixed in water resulting in particle destabilization. Operationally
this is achieved by the addition of appropriate chemical like alum
and intense mixing for achieving uniform dispersion of the
chemical. These chemicals are more effective when the water is
slightly alkaline .

111. Sometimes sodium carbonate or lime is to be added to
achieve the suitable pH of water. Flocculation is the stage of
the formation of settleable particles (or flocs) from
destabilized (neutral) colloidal particles and is achieved by
gentle (slow) mixing. So in flocculation the alum is first
mixed rapidly for dispersion and then slow mixing produces
flocs. Both these stages of flocculation are greatly influenced
by physical and chemical forces such as electrical charge on
particles, exchange capacity, particle size and
concentration, pH, water temperature, and electrolyte
concentration.

112. F iltration
Filtration is the physical and chemical process for
separating suspended and colloidal impurities from water
by passage through a porous bed made up of gravel and
sand etc. Actually the sedimentation even aided with
coagulation and flocculation cannot remove all the
suspended and colloidal impurities and to make water
(specifically surface water) fit for drinking, thus filtration is
a must. The theory of filtration includes the following
actions:

113. 1.) M echanical S training
The suspended particles present in water that are bigger
in size than the voids in the sand layers are retained their and the
water becomes free of them. The sand layer may get choked
after some time and then it is to be cleaned for further action by
washing it back.
2.) S edimentation
The small voids in the sand act as tiny sedimentation
tanks and the colloidal matter arrested in these voids is a
gelatinous mass and thus attracts other finer particles. These
finer particles are thus removed by sedimentation.

114. 3.) Biological Metabolism
Certain microorganisms are present in the sand voids.
They decompose the organic matter like the algae etc. and thus
remove some of the impurity.
4.) E lectrolyte C hange
According to the theory of ionization, a filter helps in
purifying the water by changing the chemical characteristics of
water. The sand grains of the filter media and the impurities in
water carry electrical charge of opposite nature which
neutralizes each other and forces the particles to settle now by
gravity.

115. D isinfection
The filtration of water removes the suspended
impurities and removes a large percentage of bacteria
but still some remain there in the filtered water. These
bacteria may be harmful (pathogenic bacteria). The
process of killing these bacteria is known as
disinfection. There are many diseases like cholera,
gastro entities, infectious hepatitis, typhoid etc., the
bacteria or virus of which transmits through water. It is
necessary to make water free from any micro-organism
before human consumption.

116. Contamination (mixing of pathogenic micro-organism) may
take place in the water supply at any time (because of leakage etc.)
so proper measures must be taken to stop it at all levels. Generally
the disinfection is done by adding chlorine to water. There should be
a residual amount of chlorine after the disinfection to fight with any
probable contamination in the route of water to the consumer.
S M ome ethods of D isinfection:
•Boiling of water
•Treatment with excess lime
•Use of ozone
•Treatment with ultraviolet rays
•Use of potassium permanganate
•Treatment with silver
•Use of bromine, iodine and chlorine

117. Criteria for a Good Disinfectant
•It should be capable of destroying the pathogenic organisms
present, within the contact time
•Available and not unduly influenced by the range of physical and
chemical properties of water encountered particularly
temperature, pH and mineral constituents.
•It should not leave products of reaction which render the water
toxic or impart colour or otherwise make it unpotable.
•It should have ready and dependable availability at reasonable cost
permitting convenient, safe and accurate application to
water.
•It should possess the property of leaving residual concentrations to
deal with small possible recontamination.
•It should be amenable to detection by practical, rapid and simple
analytical techniques in the small concentration ranges to
permit the control of efficiency of the disinfection process.

118. F actors A ffecting E fficiency of D isinfection
•Type, condition and concentration of organisms to be destroyed
•Type and concentration of disinfectant
•Contact time and concentration of disinfectants in water and
•Chemical and physical characteristics of water to be treated
particularly the temperature, ph and mineral constituents.
Potable water should always have some amount of
residual chlorine, as there are all chances of contamination at all
levels. This may be 0.2 ppm. to 0.3 ppm. Depending upon the
requirement (rainy season or enhance chances, more CL2
required). To make sure the presence of chlorine some tests are
done out of which Orthotolodine test is the most common one.

119. O rthotoIodine T est:
In this test 10 ml of chlorinated sample of water is taken
after the required contact period (say half an hour) in a glass
tube. 0.1 ml of orthotoIodine solution is added to it. The color
formed is noted after 5 minutes and compare with the standard
colored glasses. Darker is the yellow color formed more is the
residual chlorine. The test is very simple and even a semi-skilled
employee can perform it satisfactorily and it can be done at the
site itself and accordingly corrective measures can be taken. For
example if there is a complaint from a hostel mess. Test is
performed for the tank water and if no residual chlorine is found,
bleaching powder (a good source of chlorine) is mixed with
some water and added to the tank water is paste form and stirred.
The test is again performed after half an hour till it shows the
required residual chlorine.

120. A eration
Taste and odor, both are undesirable in water. Aeration is
done to remove taste and odor. Aeration is done to promote the
exchange of gases between the water and the atmosphere.
P urpose:
•To add oxygen to water for imparting freshness, for example
water from underground sources may have lesser oxygen.
•For expulsion of carbon dioxide, hydrogen sulfide and other
volatile substances causing taste and odor.
•To precipitate impurities like iron and manganese especially
from underground water.

121. In aeration gases are dissolved in or liberated from
water until the concentration of the gas in the water has
reached its saturation value. The concentration of gases in
the liquid generally obeys Henery’s law which states that
the concentration of each gas in water is directly
proportional to the partial pressure (product of the volume
percentage of the gas and the total pressure of the
atmosphere.) or concentration of gas in the atmosphere in
contact with water. The saturation concentration of a gas
decreases with temperature and dissolved salt in water.
Aeration accelerates the exchange of gas.

122. To ensure proper aeration, it is necessary to:
•Increase the area of water in contact with the air. The smaller are
the droplets produced, the larger will be the area available.
•Keep the surface of the liquid constantly agitated so as to reduce
the thickness of the liquid film which would govern the
resistance offered to the rate of exchange of the gas.
•Increase the time of contact of water droplets with the air or
increase the time of flow which can be achieved by
increasing the height of jet in spray aerators and increasing
the height of the tower in case of packed media.
Where oxygen is to be dissolved in water, the concentration
or partial pressure of the oxygen may be increased by increasing the
total pressure of the gas in contact with water. For this purpose air
injected into a main under pressure is a reasonably efficient method
of increasing the amount of dissolved oxygen.

123. W S ater oftening
The reduction or removal of hardness from water is called
water softening. For domestic water supplies, the softening is
done to reduce the soap consumption, to ensure longer life to
washed fabric, to lower the cost of maintaining plumbing fixtures
and to improve the taste of food preparations and improve
palatability. For industrial supplies, softening is one for reducing
scale problems in boilers and the interference in the working of
dyeing systems. Usually a total hardness of 75 to 100 mg/L
would meet these requirements. The magnesium hardness should
not exceed 40 mg/L to minimize the possibility of magnesium
hydroxide scale in domestic water heaters.

124. Calcium and magnesium associated with
bicarbonates are responsible for carbonates hardness and
that with the sulfates, chlorides and nitrates contribute to
non carbonate hardness. Normally the alkalinity measures
the carbonate hardness unless it contains sodium alkalinity.
The non carbonate hardness is measured by the difference
between the total hardness and the carbonate hardness.
Carbonate and bicarbonates of sodium are described as
negative non carbonate hardness.

129. Water Softening Processes

130. • The reduction or removal of hardness from
water is called as water softening. For the
domestic water supplies the softening is
done to reduce the soap consumption, to
ensure longer life, to wash fabric, to lower
the cost of maintaining plumbing fixtures and
to improve the taste of food preparation and
improve the palatability (good taste). For
industrial supplies, softening is done for
reducing scaling problems in boilers and the
interference in the working of dyeing
systems.

131. Origin of water "hardness"
1. Carbon dioxide reacts with water to form carbonic acid which
at ordinary environmental pH exists mostly as bicarbonate ion
2. Microscopic marine organisms take this up as carbonate to
form calcite skeletons which, over millions of years, have built
up extensive limestone deposits. Groundwaters, made slightly
acidic by CO2 (both that absorbed from the air and from the
respiration of soil bacteria) dissolve the limestone .
3. Thereby acquiring calcium and bicarbonate ions and becoming
"hard". If the HCO3– concentration is sufficiently great, the
combination of processes and
4. causes calcium carbonate ("lime scale") to precipitate out on
surfaces such as the insides of pipes. (Calcium bicarbonate
itself does not form a solid, but always precipitates as CaCO3.)

132. Processes
Conventional water softening
Most conventional water-softening devicesdepend on a process
known as ion-exchange in which "hardness" ions trade places
with sodium and chloride ions that are loosely bound to an ion-
exchange resin or a zeolite (many zeolite minerals occur in
nature, but specialized ones are often made artificially.)
Magnetic water softening and scale control
There is a long history of the promotion of magnets to alleviate the
"hardness" of mineral-containing waters, and particularly to
control the deposition of scale in teapots, plumbing systems,
evaporators, and boilers. There are now a large variety of
devices on the market that claim to reduce scale deposition, and
some claim to "soften" the water as well. The earlier devices
mostly employed permanent magnets, but many now use
alternating magnetic or electrostatic fields. The magnetic field
surrounds the pipe at some point and penetrates it from all
sides. This obviously limits its use to non-ferrous pipes such as
copper or plastic.

133. Catalysts cannot soften water
Many groundwaters are supersaturated in hardness ions, and it is
conceivable that a suitable catalyst could cause this escess
material to precipitate out. But even if the solid carbonates were
filtered out, the remaining water would be saturated and
capable of forming scale on heat exchanger surfaces and leaving
evaporative deposits in teakettles and on surfaces. It would also
react with soaps to produce scums in laundry and bathtubs.

134. Question # 16
What is the requirement of
pressure of water to be supplied
to the residences?

135. Landscape requirements
• A requirement of the design process is to produce a
landscape survey of the proposed area of construction
to assess the effect of the project on shrubs and trees.
Trees to be retained should be identified, marked and
methods of protection determined. Vegetation such as
mature trees and other natural habitat for fauna shall
not be removed unnecessarily.
• Backfilling of trenches shall be arranged to provide
topsoil at the surface of the trench, and shall be such
that no depressions are left along pipe alignments after
settlement of the soil. Special care is required in
restoration of highly visible sites and existing
pavements.

136. Pipe deflection
• Deviation of a pipeline around an obstruction can
be achieved by deflection at pipe joints or in
combination with bends or connectors. The
deflection angle permitted at a flexible joint shall
be in accordance with the manufacturer's
recommendation. For laying PVC or PE pipes on
curves, minimum radii are to be as per
manufacturer's recommendations. If deflection of
joints does not provide the necessary deviation,
bends and other fittings shall be employed.

137. Pipelines in easements
• Water mains that are located
anywhere other than in the road
reserve of a dedicated public road
shall be located within an
appropriately sized water supply
easement subject to ACTEW's
approval.

138. Locating buried mains
• Tracer wire shall be used for all non-metallic water
mains for the purpose of locating buried mains (by
passing a signal through the wire, which can then
be picked up by the detector). PVC coated copper
wire (1mm) shall be taped to the non-metallic main
in a continuous length. At every hydrant, sufficient
slack shall be left to enable the wire to be brought
up to the surface within each hydrant
surround, wound three times around, and taped to
the hydrant immediately below the hydrant head.
• Marking tape to AS 2648 shall be laid in a
continuous length on top of the pipe embedment
material, 150mm above all water mains.

139. Water supply master plan
• The design of the water reticulation network
including pipe layout and sizes, fire risk
categories, zone boundaries, and valving to
meet breakdown requirements shall be shown
on a Water Supply Master Plan

140. System reliability
• All elements of ACTEW's water supply system should be
planned and detailed to ensure as high a level of reliability
as is reasonable. Features incorporated into a system layout
to enhance reliability include the following:
• for critical mechanical equipment, a standby capacity
sufficient enough to maintain full capacity with any one
element out of service;
• for distribution systems downstream of reservoirs, a
'looped' rather than 'branched' layout is generally used to
provide more than one supply route on distribution
systems. Valving is arranged as described in Clause 5.4.
These valving arrangements help to limit the area needing
to be shut down when isolating and repairing any section of
main;

141. • for all reservoirs, either duplicate tanks or pressure
regulated bypass arrangements to maintain a rate of
supply to the distribution system equivalent to at
least the design bulk supply rate (if the reservoir is
out of service);
• emergency storage in reservoirs, which in addition to
providing a reserve for fire fighting, can be used to
maintain a distribution supply for limited periods
during bulk supply interruptions. Inter-zone
connections or other arrangements can usually be
made to maintain some supply. In some extreme
cases, it may be necessary to contact consumers and
request sparing the use of water until repairs can be
completed. The limited periods referred to above, for
maintaining supply, range from a few hours during
prolonged high demand (in summer) to a few days
during low demands in winter.

142. Pressure requirements
• Maximum pressures
• Pressure zoning is arranged wherever possible to limit the maximum static
pressure at any point to 75 metres head. In special cases this is relaxed to 90
metres head.
• There are two areas within the ACT where maximum static heads over 100
metres currently exist:
• the Woden town centre area below contour 587 metres AHD could experience
a maximum static head in excess of 100 metres up to 107 metres;
• the North Canberra area, which comprises the
City, Acton, Braddon, Turner, Reid, Lyneham, Dickson and Downer below
contour 575 metres AHD, could experience a maximum static head in excess of
100 metres and up to 115 metres.
• All pipework shall be designed for the field test pressure as defined in Clause
3.5.4, for the following reasons:
• to allow for the use of inter-zone connections during emergencies;
• to allow for waterhammer;
• to allow for standardisation of equipment and flexibility of use.

143. • for domestic development exceeding two stories and
for shopping, commercial and industrial: the equivalent
of 30 metres head over the highest point on the block.
• For very large blocks such as institutional campuses, an
extra allowance of 5 metres head for every 1000
metres distance, between the main and the most
critical point on the block (with regard to either
elevation or distance from the main), is permitted.
• Stated residuals are to be achieved with service
reservoirs at half capacity and an allowance for
reservoir outlet losses of 1.5 metres. The system
should be checked to ensure that the same residuals
can be achieved at 50% peak hour demands with any
one element out of service.

144. Pipe roughness
• Reticulation mains are to be sized to provide
the minimum heads (specified above) using
the Colebrook-White equation. A pipe
roughness value (k) of 0.3mm averaged over
the life of the main is to be used when no
allowance is made for valves and fittings. A
pipe roughness value (k) of 0.15mm should be
used if specific allowances have been made
for valves and fittings.

145. Design velocity
• Ideally, the velocity in water mains should range
between 0.5m/s and 2.0m/s. However, under
extreme conditions (e.g. fire flows in high fire risk
areas) velocities up to 5m/s are acceptable. Very
low velocities in pipes cause water quality
problems due to long detention times and should
be avoided if possible. Minimum diameters and
lengths of main should be constructed consistent
with meeting the required demands on the
network. Generally, dead end mains with tapered
diameters below DN100 should be used in cul-de-
sacs.

146. General detailing requirements for
pipelines
• As mentioned in the introduction, there is a
demonstrated need to construct systems in a standard
configuration using tried and proven methods and
materials. Within the ACT, any deviation from normal
practice has the propensity to increase stock holdings for
spare parts, and create additional maintenance costs by
way of labour charges. Any deviation from standard
practice will require the specific approval of ACTEW. A
submission detailing the proposals, in full, must be made
to include an economic and long term benefit
analysis, and the covering life cycle costs. The costs of
burst mains can quickly erode cost differentials of the
initial costs in pipe networks. Unless otherwise noted, the
current version ofAustralian Standards shall apply.

147. Valve size
• The nominal size of a valve may be reduced
below the nominal size of a pipe line providing
the reduction in size does not significantly
reduce the hydraulic capacity of the main.
Such intentions must be identified at
the Design Submission stage of the works.

148. Scour outlets
• On water mains without hydrants (e.g. generally bulk
supply mains), scour (or drain) outlets, with isolating valve
control, shall be provided at all low points. Wherever
possible, on water mains with hydrants (e.g. reticulation), a
hydrant should be located at or near all low points.
• Scour outlets should also be provided on bulk supply mains
to assist in the draining of each section of main between
sectioning valves.
• For larger mains, the size of the scour should be
determined after considering (1) the length of time
available for draining the pipe section, and (2) the facilities
available to dispose of the flow.

149. Water supply services
• For new leases and in the redevelopment of
existing leases water supply services shall be
installed by developers of municipal works.
The service shall terminate just inside the
front property boundary.

151. 
Aeration is used to treat tastes and odors, to help remove
minerals such as iron and manganese from water, and to
remove carbon dioxide from the water.
In general, aeration is more commonly used when treatin
groundwater than when treating surface water. Surface
water has typically run through creeks and rivers, aeratin
the water before it reaches the treatment plant.

152. How Does Aeration Work?

Aeration is the intimate exposure of water and air. It is a
way of thoroughly mixing the air and water so that
various reactions can occur between the components of
the air and the components of the water.

153. 
Fig. 1 –The Process of Aeration

154. Two methods of aeration

1. Scrubbing action
2. Oxidation

155. Why aeration is done?
The goal of an

aerator is to increase the
surface area of water coming in contact with
air
so that more air can react with the water. As
air or water is broken up into smaller
drops/bubbles or into thin sheets, the same
volume of either substance has a larger
surface area.

157. Water softening is the reduction of the concentration of
calcium, magnesium, and certain other metal cations in
hard water. These "hardness ions" can cause a variety of
undesired effects including interfering with the action of
soaps, the build up of limescale, which can foul plumbing,
and galvanic corrosion.[1] Conventional water-softening
appliances intended for household use depend on an ion-
exchange resin in which hardness ions are exchanged for
sodium ions. Water softening may be desirable where the
source of water is hard.[2] However, hard water also conveys
some benefits to health by reducing the solubility of
potentially toxic metal ions such as lead and copper.

158. Water softening methods mainly rely on the
removal of Ca2+ and Mg2+ from a solution or the
sequestration of these ions, i.e. binding them to a
molecule that removes their ability to form scale or
interfere with soaps. Removal is achieved by ion
exchange and by precipitation methods. Sequestration
entails the addition of chemical compounds called
sequestration (or chelating) agents.
Since Ca2+ and Mg2+ exist as nonvolatile salts, they
can be removed by distilling the water, but distillation
is too expensive in most cases (rainwater is soft
because it is, in effect, distilled.)

159. Effects of sodium
For people on a low-sodium diet, the increase in
sodium levels (for systems releasinwater. For
example:
A person who drinks two litres (2L) of
softened, extremely hard water (assume 30 gpg)
will consume about 480 mg more sodium (2L x
30 gpg x 8 mg/L/gpg = 480 mg), than if
unsoftened water is consumed.
This amount is significant.
g sodium) in the water can be
significant, especially when treating very hard

160. This amount is significant. The American Heart
Association (AHA) suggests that the 3 percent of the
population who must follow a severe, salt-restricted diet
should not consume more than 400 mg of sodium a day.
AHA suggests that no more than 10 percent of this sodium
intake should come from water. The EPA’s draft guideline of
20 mg/L for water protects people who are most
susceptible. Most people who are concerned with the added
sodium in water generally have one tap in the house that
bypasses the softener, or have a reverse osmosis unit
installed for the drinking water and cooking water, which
was designed for desalinisation of sea water. Potassium
chloride can also be used instead of sodium
chloride, which would have the added benefit of helping to
lower blood pressure, although costly. However, elevated
potassium levels are dangerous for people with impaired
kidney function: it can lead to complications such as
cardiac arrhythmia.

162. Various Methods of Water
Softening
 Ion exchange water softener
 Softening water through magnets
Water softening is a process in which a plant reduces
magnesium, calcium and ion concentration from the hard
water. On an average, hard water contains about 90 pounds of
dissolved rocks. It can pose hazards to human health.
Hardness of water can damage hair in a man and makes
water less safe for drinking.
The rocks which get dissolved in water mixes magnesium
and calcium ions in pipes and heats the surface of
dishwashers and washing machines. Water hardness also
makes soap less effective.

163. Ion Exchange Water Softener
 Ion exchange water softener depends on
two tanks- the brine and resin tanks.
 This process removes magnesium and
calcium ions.
 Potentially hard water will pass through
the resin beads in resin tank.
 When the beads become saturated with
magnesium and calcium ions, the ion
exchange softener goes offline.
 Brine tank is again filled with new
sodium ions which are ready for
exchange, it flushes the resin tank and
then it becomes online again.
 This method is suitable for all appliances
which uses a lot of water. This method
can also increase the life span of dishes
and clothes.
 This method is not ideal for drinking
purposes because of the sodium intake.

164. Softening Water through Magnets
 It is a new method for water softening and this is the safest
method for drinking purposes.
 This is non-chemical based water softening method.
 The process involves magnets placed outside or inside the
water pipe and water flows through a magnetic field.
 Water is stripped of its hardness and impurities because of
the magnetic field’s strength.
 It is also advised to put the magnet bars close to the water
source.

167. What do you understand by
wastewater management?

168. The wastewater management system
should aim at the following achievement:
 Proper collection of wastewater
discharged by the community.
 Adequate treatment of wastewater to
achieve the desired effluent standards.
 Safe and efficient operations and as far as
possible self supporting.
 Sound financial management.

169. The wastewater management has
the main components as collection,
conveyance, treatment and disposal
of wastewater.

171. Describe the Method of Design of Sewer
Line along with the Hydraulics of Sewer

172. What is sewer?
Sewer is an artificial conduit or system of conduits
used to remove sewage and to provide drainage.
Sewage is the mainly liquid waste containing
some solids produced by humans which typically
consists of
-washing water
-faeces
-urine
-laundry waste
-other material from household and industry

173. The objective of sewage treatment is to make the sewage
harmless before it is disposed.
The disposal means final laying of sewage on the land or
leaving it on land to flow and mix in some body of water like
the river or a pond.
The sewage has many characteristics like temperature,
hydrogen ion concentration (pH), color and odor,
solids, nitrogen, phosphorous, chlorides, bio-chemical oxygen
demand (BOD), chemical oxygen demand (COD), and toxic
metals etc. Though all of them are important for
determination of disposal criteria, BOD is the most important
one.
The Bio-chemical oxygen demand (BOD) of sewage or
polluted water is the amount of oxygen required for the
biological decomposition of biodegradable organic matter
under aerobic conditions.

174. The general temperature of sewage is 20 degree celsius so it is
termed as BOD5 at 20 degree C as the standard BOD. The BOD
satisfaction equation is as follows,
Yt = L (1-10Kd t)
Where Yt = BOD at any time t
L = initial BOD at time t = 0
Kd = deoxygenation co-efficient
(function of temperature)
KdT = Kd20 × 1.047 T–20
T = temperature of the reaction
Kd20 = 0.1 per day (for normal sewage).
So the BOD5 determines the strength of the sewage. Higher is the
BOD5 stronger is the sewage. The average value of domestic
sewage is 300 parts per million (ppm) or mg/liter.

175. In the 20th century developed world, Sewers
are usually pipelines that begin with
connecting pipes from buildings to one or
more levels of larger underground horizontal
mains, which terminate at sewage treatment
facilities. Vertical pipes, called
manhole, connect the mains to the surface.
Sewers are generally gravity powered, though
pump may be used if necessary

176. Most drains have a single large exit at their
point of discharge (often covered by a
grating to prevent access by humans and
exit by debris) into either a
canal, river, lake, reservoir, ocean and
spread out into
smaller branches as they move up into
their catchment area.

177.  Sanitary sewer is a type of underground
carriage system for transporting sewage
from houses or industry to treatment or
disposal.
 Sanitary lines generally consist of laterals,
mains, and manholes (or other various
forms of traps).

178. ‰SEPARATESEWER SYSTEM
‰COMBINED SEWER SYSTEM

179. A combined sewer is a type of sewer
system which provides partially
separated channels for sanitary sewage
and Storm water runoff. This allows the
sanitary sewer system to provide
backup capacity for the runoff sewer
when runoff volumes are unusually
high, but it is an antiquated system that
is vulnerable to sanitary sewer overflow
during peak rainfall events.

180. A separate sewer system is a type
of sewer system which one pipe system
carries wastewater and another
separate pipe system carries storm
water.

183. BIO-CHEMICAL OXYGEN
DEMAND
Bio-Chemical Oxygen demand (BOD) of
sewage or polluted water is the amount of
oxygen required for the biological
decomposition of biodegradable organic
matter under aerobic conditions.

184. • Readily decomposable organic matter
like food items, human excreta, urine,
etc. is known as the putrescible
matter.
• The decomposition of organic matter
is done by the bacteria. There are
mainly two types of bacteria:
1. aerobic bacteria which work in
presence of oxygen.
2. anaerobic bacteria which work
in absence of oxygen.

185. CHEMICAL OXYGEN
DEMAND
The chemical oxygen demand of
the biodegradable and non-
biodegradable organic matter.

186. • The COD can be readily(3-4hrs)
measured in the laboratory where as
the BOD5 determination takes 5 days
in the laboratory.
• The COD/BOD ratio varies
generally from 2.0 – 2.5.
• The BOD of the waste decides its
foulness or offensiveness.

187. • When wastewater is disposed in the
river, it consumes the dissolved oxygen
of the river water for the satisfaction
of its BOD. This reduces the Dissolved
Oxygen(D.O) of the river water.
• If the D.O goes below 4 p.p.m., almost
all the fish and aquatic life shall be
destroyed.
• The died fish will become organic
matter that will further decompose and
the whole of the D.O of the fresh body of
water shall be exhausted and it will
convert into a polluted and useless body
of water.

189.  The Water Treatments are the process to remove
the different impurities present in the raw water, to
render the water safe and clean and to ensure the
water treatment process and treated water quality
meets the drinking water standards. The type of
water treatment required depends on the
characteristics of the raw water. The characteristics
of the raw water is assessed by taking sample of
water from the source during different seasons of
the year and analyzing for physical, chemical and
bacteriological quality parameters.

190.  Water treatment involves removal of undesirable
constituents from water and then disposal of them
in easiest and safest manner. To achieve these
goals, a variety of water treatment operation and
processes are utilized, which exploit various
physical and chemical phenomena to remove or
reduce the undesirable constituents from the
water. Those operations used in the treatment of
water in which change is brought about by means
of or through application of physical forces are
known as Water Treatment Process unit
operations . Those Process used for the Water
Treatment in which is brought about by means of
chemical reaction are known Unit Process.

191. Chemical precipitation :Enhancement of removal of
suspended solids by chemical addition.
• Coagulation in Water Treatment Process - Coagulation
is the addition and rapid mixing of coagulant resulting in
destabilization of the colloidal particles and formation of
micro flocs.
• Ion exchange in Water Treatment Process - The cations
and anions in water are selectively removed when water is
percolated through beds containing cation and anion
exchange resins.
• Aeration or Gas transfer in Water Treatment Process -
Addition or removal of gases from liquid phase.
• Disinfection in Water Treatment Process - Selective
destruction of disease-causing organisms present in water.

192.  Screening – it is a unit operation that removes
floating and suspended larger material from water.
 Aeration- Aeration is the unit water treatment
process for the exchange of gases between water
and atmosphere. Aeration or gas transfer involves
either bringing air or other gases in contact with
water or to transfer volatile substances from the
liquid to the gaseous phase.
 Coagulation and Flocculation- the unit
processes to convert the stable colloidal particles
into settle able flocs by destabilizing the charge on
the colloids so as to remove turbidity from the
water. Water with little or no turbidity will be clear.
In addition to removing turbidity from the

193.  Sedimentation – it is a unit operation to settle out the
suspended particles in water by gravitational force. This is
achieved by lowering the flow velocity of the water below
the suspension velocity in a basin to settle out suspended
particles by gravity. The process is also known as settling or
clarification.
 Filtration - is the unit operation in Water Treatment.
Filtration using a filter media to separate the suspended
particles mechanically from water to render water free from
turbidity.
 Disinfection - is the unit process employed to inactivate
the disease producing bacteria present in water by addition
of certain chemicals in order to render the water safe for
consumption. Common disinfectant is chlorine and the
process of addition of chlorine is known as chlorination.
 Demineralization -is the process of removing dissolved
minerals and mineral salts, present in the form of mineral
ions in water. This process strips out all chemical
impurities present in water.

194. Wastewater Treatment

195. • The treatment of wastewater is a general term that applies to any
operation/process that can reduce the objectionable properties of
wastewater and make it less objectionable. Wastewater treatment is a
combination of physical, chemical and biological processes.
• Unit Operations are the methods of treatment in which the application of
physical forces predominate while unit processes are those in which the
chemical and biological activities are involved. The aim of wastewater
treatment works is to produce an acceptable effluent through the available
unit operations. Generally the wastewater treatment processes bring about
changes in concentration of a specific substance by moving it either into or
out of the wastewater itself. This is known as the phase transfer. The main
phase transfers are as follows,

196. • Gas transfer : aeration • Centrifuging
• Chemical conditioning
• Ion transfer
• Biological floatation
• Chemical coagulation
• Vacuum filtration
• Chemical precipitation
• Sludge digestion
• Ion exchange
• Incineration
• Adsorption
• Wet combustion
• Solute stabilization
• Chlorination
• Liming
• Recarbonation
• Break point and super chlorination
• Solid transfer
• Straining
• Sedimentation
• Floatation
• Filtration
• Nutrient transfer
• Solid concentration and
stabilization
• Thickening

197. Operation Application
1. Screening Removal of floating water
2. Comminution Grinding and shredding of big objects
3. Equalization Equalization of flow and BOD loading
4. Mixing Mixing of chemical and gases in wastewater and
keeping solids in suspension
5. Flocculation Enlarging small particle
6. Sedimentation Removal of settleable solids
7. Floatation Thickening of biological sludge
8. Filtration Removal of fine material after biological or chemical
treatment
9. Micro screening Removal of algae from stabilization ponds, oxidation
ponds effluent

198. Process Application
1. Chemical precipitation Removal of phosphorus and enhancement of
suspended solids removal in sedimentation
2. Gas Transfer Addition and removal of gases
3. Adsorption Removal of organics
4. Disinfection Killing of disease causing organisms
5. Dechlorination Removal of chlorine residuals
6. Miscellaneous Specific wastewater treatments

199. Biological unit processes are those processes in which the removal of
objectionable matter is done by biological activity. In this process the objectives
are to coagulate and remove the dissolved or nonsettleable colloidal solids.
Biological processes are differentiated by the oxygen dependence of
the microorganisms responsible for the wastewater treatment as follows,
1. Aerobic processes: The processes occur in presence of oxygen by the
aerobic bacteria. The aerobic process include the following,
1. Trickling filter (attached growth process)
2. Activated sludge process with its modifications (suspended growth process)
3. Aerobic Stabilization ponds (oxidation ponds)
4. Aerated lagoons
2. Anaerobic processes: The anaerobic processes occur in absence of
oxygen by the anaerobic bacteria. The anaerobic bacteria processes include
the following,
1. Anaerobic sludge digestion
2. Anaerobic contact process
3. Anaerobic filters
4. Anaerobic lagoons or ponds
5. Septic tanks and imhoff tanks
3. Facultative process: the facultative bacteria can act in presence as well
as in absence of oxygen.

202. WASTE WATER TREATMENT
 Physical unit operation
 Chemical unit operation
 Biological unit operation

203. FOUR LEVELS OF WASTE WATER
TREATMENT
 PRELIMINARY TREATMENT
 PRIMARY TREATMENT
 SECONDARY TREATMENT
 TERTIARY/ ADVANCED TREATMENT

216. The treatment of wastewater is a general term that includes any
unit operation or process that can reduce the objectionable
properties sewage to make it less offensive (bad, foul). The
treatment includes:
1. Removal of floating and suspended solid matter
2. Treatment of biodegradable organic matter
3. Disinfection (elimination of pathogenic organisms)

217. The various operations and processes for the treatment of sewage give
effluent (treated wastewater) and the sludge (solids separated in
semi solid form). The effluent may be directly disposed either in the
receiving waters (rivers, ponds) or on land. The sludge is generally
first of all treated and then disposed. The aim of processing sludge is
to extract water (reduce high volumes) and dispose the dewatered
residue through a combination of physical, chemical and biological
operations. The after dewatering chemical conditioning and
thickening the sludge is treated biologically, generally by anaerobic
treatment.

218. SUSPENDED SOLID MATTER
Small particles of solid pollutants that float on the surface of, or
are suspended in sewage or other liquids. They resist removal by
conventional means.
BIODEGRADABLE
The ability to break down or decompose rapidly under natural
conditions and processes.
DISINFECTANT
A chemical or physical process that kills pathogenic organisms in
water. Chlorine is often used to disinfect sewage treatment
effluent, water supplies, wells, and swimming pools.

219. ORGANIC MATTER
Carbonaceous waste contained in plant or animal matter and
originating from industrial sources.
DISINFECTION
treatment to destroy harmful microorganisms
PATHOGENS
Microorganism that can cause disease in other organisms or in
humans, animals and plants. They may be bacteria, viruses, or
parasites and are found in sewage. Fish and shellfish contaminated by
pathogens, or the contaminated water itself, can cause serious
illnesses.

223. ANAEROBIC
DIGESTION
AND
BIOGAS

224. ANAEROBIC DIGESTION
ANAEROBIC DIGESTION IS A
SERIES OF PROCESSES IN
WHICH MICROORGANISMS BREAK
D OW N B I O D E G R A DA B L E M AT E R I A L I N
T H E A B S E N C E O F OX YG E N. I T I S U S E D
FOR INDUSTRIAL OR DOMESTIC
P U R P O S E S T O M A N A G E WA S T E A N D / O R
T O R E L E A S E E N E R G Y.

225. ANAEROBIC DIGESTER
ANAEROBIC DIGESTER
I S A N A I R T I G H T, O X Y G E N - F R E E
CONTAINER THAT IS FED AN ORGANIC
MATERIAL, SUCH AS ANIMAL MANURE
OR F OOD S C RA P S. A B I OL OG I C A L
PROCESS OCCURS TO THIS MIXTURE TO
P ROD U C E M E T H A N E G A S, C OM M ON LY
K N OW N A S B I O G A S, A L O N G W I T H A N
O D O R - R E D U C E D E F F L U E N T. M I C R O B E S
B R E A K D OW N M A N U R E I N T O B I O G A S
A N D A N U T R I E N T - R I C H E F F L U E N T.

226. THERE ARE FOUR KEY BIOLOGICAL
A N D C H E M I C A L S TAG E S O F A N A E RO B I C
DIGESTION:
HYDROLYSIS
ACIDOGENESIS
ACETOGENESIS
METHANOGENESIS

227. T H E K E Y P RO C E S S S TAG E S O F
ANAEROBIC DIGESTION

228. BIOGAS
BIOGAS TYPICALLY REFERS TO
A GAS PRODUCED BY THE BIOLOGICAL
B R E A K D OW N O F O RG A N I C M AT T E R I N
T H E A B S E N C E O F OX YG E N. O RG A N I C
WA S T E S U C H A S D E A D P L A N T A N D
ANIMAL MATERIAL, ANIMAL FECES, AND
K I T C H E N WA S T E C A N B E C O N V E R T E D
I N T O A G A S E OU S F U E L C A L L E D B I OG A S.

229. TYPICAL COMPOSITION OF BIOGAS
Compound Chem %
Methane CH4 50–75
Carbon dioxide CO2 25–50
Nitrogen N2 0–10
Hydrogen H2 0–1

230. THE END

232. Disposal into Water Bodies

233. Disposal of Wastewater
in a River

234. Disposal of Wastewater
in a River

235. Disposal of Wastewater
in an Ocean

236. Disposal of Wastewater
in an Ocean

237. Disposal of Wastewater
in an Ocean

238. WASTEWATER
DISPOSAL ON LAND-
LAND APPLICATION

239. Wet Land Treatment
The process in which wastewater is
distributed evenly distributed over the
ground surface which acts as a low rate
filter. Suspended particles are strained out
colloids and organic matter are absorbed by
the soil particles. Nutrients are utilized by
vegetation and more complex organic
materials are decomposed to simpler
inorganic compounds by soil bacteria.

240. 1. Natural Wetland
Wetlands are areas that are
permanently or periodically inundated or
saturated by surface or groundwater and
support the growth of aquatic vegetation.
Wetlands are defined as land where the
water surface is near the ground surface
long enough each year to maintain
saturated soil conditions, along with the
related vegetation. Natural wetlands
include saturated wetlands and
freshwater wetlands.

241. Wetland plants can be classified into two
(2) functional types:
a. Rooted Plants
* emergent macrophytes- roots in the sediment
and emergent stems and leaves
* submerged macrophytes- stems and leaves
submerged
* floating leafed macrophytes- stem
submerged and leaves floating
b. Floating Plants- they have surface leaves
and roots which hang down into the water

242. 2. Constructed Wetlands
Constructed wetland is defined as a
wetland specifically constructed for the
purpose of pollution control and waste
management, at a location other than
naturally existing wetland. Constructed
wetlands are used to improved the quality of
point and non-point sources of water
pollutants and are also used to treat
petroleum refinery waste, compost and
landfill leachates, fishpond discharges and
pre- treated industrial wastewater.

243. Two (2) basic types of constructed
wetland:
a. Free Water Surface Wetland- consist of a
basin or channels w/ some type of barriers
to prevent seepage, soil to support the root
of the emergent vegetation and water at a
relatively shallow depth flowing through the
system.
b. Subsurface Flow Wetland- consists of a
basin or channels with barriers.

244. Principal mechanism in wastewater
treatment:
a. sedimentation
b. bacterial action
c. filtration
d. absorption
e. precipitation
f. nutrient uptake
g. vegetation system

245. Advantages of Constructed Wetlands:
• Wetlands can be less expensive to build
than other treatment options.
• Operation and maintenance expenses
(energy and supplies) are low.
• Operation and maintenance require only
periodic, rather than continuous, on site
labor.
• Wetlands are able to tolerate fluctuations in
flow.

246. • They facilitate water reuse and recycling.
• They provide habitat for many wetland
organisms.
• They can be built to fit harmoniously into the
landscape.
• They provide numerous benefits in addition
to water quality improvement.
• They are an environmentally sensitive
approach that is viewed with favour by the
general publice

247. Disadvantages of Constructed Wetlands:
• There are no standardized designs that can
be routinely applied to universal
applications. Each system of constructed
wetlands must be custom- designed and
site- specific. This limitation is not
necessarily detrimental because it allows
each system to be designed on wastewater
flow, soil characteristics, and geochemical
processes particular to each system’s
needs.

248. • Constructed wetlands traditionally have
poorer performance in colder weather. The
biological processes slow down in lower
temperatures. This severely limits winter
use of the system.
• Depending on the design, they may require
a relatively large land area compared to a
conventional facility.
• The design and operating criteria for this
new science are yet precise.

249. • The biological and hydrological processes
within a constructed wetland are not yet
well understood.
• There may be possible problems with
pests.

250. Effluent Disposal on Land
1. Spraying Method- a process leads to
removal waste load through filtration during
percolation and removes most of the
suspended solids. A combination of
processes such as evaporation,
transpiration, percolation and runoff work for
the disposal of wastewater by spraying.

251. 2. Drip Method- drip systems utilize pressure
compensated drip tubing to slowly and
evenly dispense the wastewater just below
the soil surface, but still within the root zone
of the vegetation.
3. Ponding Method- used where evaporation
losses are much greater. This method is
preferred in there areas where land
availability is not an issue and rainfall is not
widespread and heavy.

252. Domestic Waste Disposal: Septic tank
The septic tank is the most widely
used method of disposal of domestic waste
disposal. Septic tank was one of the most
earliest treatment devices developed. It
works simply by acting as a settling tank for
the household sewage.
Components of septic tank:
a. Influent tank c. Dosing tank
b. Settling tank d. Adsorption field

253. Some common methods:
1. Spreading on land or soil- wet digested
sludge may be disposed of by spreading
over farmlands and plowing under after it
has died. The humus in the sludge
conditions the soil, improving its moisture
relativeness.
2. Lagooning- another popular method
because it is simple and economical if the
treatment plant is in remote location. A
lagoon is an earth basin into which raw or
digested sludge is deposited.

254. 3. Dumping- a suitable disposal method only
for sludge that are stabilized so that no
decomposition or nuisance conditions will
result. Digested sludge clean grit and
incinerator can be disposed off safely by
this method.
4. Landfill- a sanitary landfill can be used for
disposal of sludge, grease and grit whether
it is stabilized or not if a suitable site is
convenient. The sanitary landfill method is
most suitable if it is also used for disposal of
the refuse and other solid waste in the
community.

255. In a true sanitary landfill, the wastes are
deposited in a designed area, compacted in
place with a tractor or roller, and covered
with 30cm layer of clean soil.

256. Digested Sludge in Different Application
on Land:
1. Cropland- sludges are applied to cropland
either by surface spreading, or by
subsurface injection sludge is usually
applied once a year to a given area.
2. Marginal Land- sludges has been applied
to marginal land for reclamation in
Pennsylvania and in other states
successfully. This is usually a one- time
process and a continual supply of land
must be provided for future applications.

257. 3. Forest Land- it is determined by sludge
characteristics, tree maturity, species, soil,
etc. application to a specific site is often
done only at multi- year intervals.

259. Septic Tank
& Soak Pits

260. SEPTIC TANK

261. SEPTIC TANK
• It is a combination of sedimentation
and digestion tanks where the
sewage is held for 24 hours. During
this period the sattleable suspended
solids settle down to the bottom.

262. SEPTIC TANK
• The direct outflow
of the sewage is
restricted by the
provision of two
baffle walls. The
baffle walls divide it
in three components
and the sewage entering
at any time gets exit after
24 hours.

263. SEPTIC TANK
• The tank is organic matter and thus
reduces BOD. This results in the
reduction of in the volume of sludge
and release of gases like carbon
dioxide , methane and hydrogen
sulfide. The hydrogen sulfide is an
obnoxious gas and smells like rotten
eggs so the problem of foul gases is
always there and so it is called as a
septic tank.

264. Soak Pits

265. SOAK PITS
• Preferable when water table is low
and the soil is porous.
• It is easy to construct and cheap.
• Circular fit with a dry masonry lining.
• It has a size of 3.0m diameter and
3.0m depth which is sufficient for a
moderate family of 5 persons for a
cleaning period of 7 years in porous
soil.

266. SOAK PITS
• It can accommodate the whole
sewage of the house and nothing
comes out of it so there is no
problem of treatment and disposal.
• It is planned and constructed in
such a way that the water of sewage
is soaked in the soil and penetrates
deep under ground.
•

267. SOAK PITS
• The only consideration is the:
GROUND WATER TABLE
It should be deep so that either the percolating
sewage does not mixes with it or it gets purified in
its journey through the soil layers before it mixes
with the ground water. After all if it mixes with the
ground water the pathogenic bacteria present in it
shall contaminate the ground water and one has to
treat the tube-well before direct consumption.