Diploma. ii es unit 3.1 environment water pollution

Environmental pollution
Environmental Science
Unit:3.1

Definition
• Any undesirable change in the physical, Chemical or
biological characteristics of any components of the
environment (air, water, soil) which can cause harmful
effects of various forms of life or property.
• Pollution is the introduction of contaminants
into the natural environment that cause adverse
change

There are various types of pollution :
• Air pollution
• Water pollution
• Noise pollution
• Land pollution
• Thermal pollution

Causes of Environmental pollution
(1) Natural(volcanic eruption, forest fire)
(2) Man Made
Causes of man made environmental pollution are:
• Rapid industrialization
• Population growth
• Unplanned urbanization

Water pollution
• Water pollution can be defined as alteration in physical,
chemical or biological characteristics of water through natural
or human activities making it unsuitable for it’s designated use.
• It can be also defined as the presence in water, of some foreign
substances or impurities (organic, inorganic, biological
Radiological) in such quantity so as to constitute a health hazard
by lowering the
water quality and making it unfit
for use.
2

Signs of polluted water
• Bad taste of drinking water
• Offensive odours of rivers, lakes and oceans
• Decrease in numbers of fish in fresh water and
sea water
• Oil and grease floating on the surface
• Unchecked growth of aquatic weeds

Sources of water pollution
• Sources of water pollution can be Classified as
(a) Point sources:
the source which can be identified as a single location are called point sources
Examples are as follows
• Industrial effluent
• Power plants
• Sewage discharge etc.
It is possible to minimize the water pollution from the point sources if the waste
water is collected and is given some treatment before it is discharged into a
water body.

(B) Non point sources
• Non point sources also called as Area or diffuse sources :
The discharge from this sources is not at any particular site, rather
this sources are scattered, which individually or collectively
pollute the water.
Examples are as follows:
• Surface runoff from agricultural fields
• Overflowing small drains
• Rain water sweeping roads and fields
• Atmospheric deposition etc.

Point and Nonpoint Sources
NONPOINT SOURCES
Urban streets
Suburban
developmen
t
Wastewater
treatment
plant
Rural homes
Cropland
Factory
Animal feedlot
POINT
SOURCE
S
Fig. 22-4 p. 494
3

Major sources of surface water pollution are
• Sewage: discharge of sewers and drains.
• industrial effluents from different industries
• Synthetics detergents used for washing and cleaning
• Agro chemical like fertilizers containing nitrates and phosphate and pesticides used in
the agricultural fields which comes in the runoff from the agricultural land
• Oil spillage during drilling and shipment
• Waste heat from industrial discharge increases the temperature of the waste bodies.
Major sources of ground water pollution are
• Septic tank
• Deep well injection of industrial effluents
• Mines etc

Classification of water pollutants
It can be classified into the following categories
a. Suspended matter
b. Natural organic pollutants (sewage and effluent from some industries
like dairy, food processing etc.). They are also called as oxygen
demanding waste
c. Synthetic organic compounds (Detergents, fertilizers, Pesticides)
d. Pathogens (Bacterias,viruses, protozoa, worms)
e. Inorganic pollutants (acids ,alkali ,metals)
f. Thermal pollutants or thermal discharge
g. Radioactive pollutants
h. Sediments

Water pollutants can also be classified in general on the
basis of physical nature as:
Suspended particles :
• This particles have diameter of more than 1 micrometer and are the largest in polluted
water.
• They are large enough to settle out of water quickly and may be retained on the filter
Examples :leaves ,soil particles, oil and grease etc.
Colloidal particles :
• These particles are so small that their settling rate is insignificant.
• They cannot be removed by plain sedimentation
• They are charged particles, charged can be negative or positive but mostly in water
colloidal particles are of negative charge
Dissolved matter :
• This pollutants gets dissolved in the water and does make water turbid, such matter does
not settled out or nor can be removed by filter
• It can be organic or inorganic

Effects of water pollutants
Effects of various types of water pollutants are as follows :
Oxygen demanding waste (biodegradable organic waste )
• Organic matter which reaches the water bodies is decomposed by microorganisms present
in water.
• For this oxygen dissolved in water is used.
ORGANIC MATTER + DO (O2) + BACTERIA CO2 + H2O
Biochemical oxygen demand (BOD)
• It is used to as a measure to find out the amount of biodegradable matter in the water.
• It is defined as amount of oxygen required by the bacteria to decompose the biodegradable
organic matter under aerobic condition.
• The saturate value of DO in water is in the order of 8-15 mg/l .
• Optimum Do required for healthy fish and other aquatic life is about 5-8 mg/l.
•Due to degradation of waste DO level gets reduced
• If DO drops below 4mg/l fish and other aquatic life is threatened and in extreme cases
killed.

• Many waste water especially sewage contains many pathogenic micro organism which
are usually contained if faeces and urine of the infected persons
• Water borne diseases like cholera, dysentery, typhoid, bacillary dysentery are caused
due to pathogen present in water.
Pathogens
Nitrogen and phosphorus Compounds( Nutrients)
• Addition of compounds containing nitrogen and phosphorus helps in growth of algae
and other plants.
• These compounds are nutrients for growth of algae and other plants.
• When there concentration is high it causes rapid growth causing algal bloom.
• It covers up the water surface and prevent entry of sunlight into water bodies
Aquatic plants along with algae thus die; the bacteria present in water now decompose
all these dead plants
• The decayed organic matter adds unwanted color, odor and taste to water
It also reduced DO of water and leads to death of fish and other aquatic animals
This process of nutrients enrichment is known as Eutrophication

Toxic Compounds
 pollutants such as heavy metals, pesticides, cyanides and many other organic and
inorganic compounds are harmful to aquatic organisms
 some of the substances like pesticides, methyl mercury etc move in to the bodies of
organisms from medium in which these organism live.
 Substance like DDT are not water soluble and have affinity for body lipid.
These substance tend to accumulate in organisms body .This process is called bio
accumulation.
 The concentration of these toxic substances builds up at successive levels of food
chain. These process is called Biomagnifications.
 Minamata Disease occurs due to consumption of methyl mercury contaminated fish.
 Nitrate more than 45mg/l causes blue baby disease in infants
 Excess fluoride causes fluorosis

Bioaccumulation is the “build-up of
chemicals in living organisms”.
The chemical accumulates because it
does not break down easily
(decomposers can’t break them down)
Biomagnification is the process where
chemicals accumulate AND become more
concentrated at each trophic level of the
food chain.
4

Suspended matter
• Biodegradable suspended matter causes DO depletion
• It reduced light penetration there by reducing photosynthesis and a corresponding
loss in food production
• Providing adsorption sites for harmful chemicals or biological organisms which can
effect flora and fauna of stream
Thermal discharge
Water is used for dissipation of waste heat in power plant and industries
This heated water is subsequently discharged into water bodies
Increase temperature of water has following effects:
• Increase Biological activities
• Cause death of some heat sensitive organisms
• DO concentration decrease this together with increased biological activities at high
temperature may result into anaerobic conditions. Resulting in bad odour
• Growth of Algae increases
• Toxicity of pollutants increase with increase in temperature

When lakes, streams and
estuaries are over
fertilized, excessive
production of aquatic
organic matter can
become a water quality
problem and as a result
the Eutrophication
process can be
enhanced!
6

Eutrophication is a natural process!
However, humans in their everyday activities can
exacerbate the process:
Point sources (can locate the cause)
• Sewage treatment plant discharges
• Storm sewer discharges
• Industrial discharges
Non-point sources (can’t locate the cause, it’s
everywhere)
• Atmospheric deposition
• Agricultural runoff (fertilizer, soil erosion)
• Septic systems

Eutrophication: a process by
which a body of
water progresses from its
origin to its
extinction. This process
happens in stages.
BEFORE EUTROPHICATION
AFTER EUTROPHICATION
7

LACK OF OXYGEN
GROWTH OF BACTERIA
DEATH OF PLANTS
SUFFOCATION
GROWTH OF PLANTS
ADDITION OF NITRATES
Eutrophication process in 6 stages

fertilisers
sewage
(liquid domestic
and industrial waste)
minerals
esp. nitrates
minerals
esp. phosphates
eutrophication
algal bloom
competition
for light
consumers can't
consume fast enough
dead plants dead algae
detritus
organicmaterial
Theprocessof
Eutrophication
8

for light consume fast enough
dead plants dead algae
detritus
more decomposers
use up oxygen
by aerobic respiration
(increased BOD)
aerobes die
(invertebrates,
fish, etc)
anaerobic bacteria
thrive. Release
NH , CH , H S4 4 2
The process of Eutrophication cont.
9

Biochemical Oxygen Demand (BOD).
This measures the rate of oxygen consumption by a
sample of water, and therefore gives a good
indication of eutrophication. A high BOD means lots
of organic material and aerobic microbes, i.e.
eutrophication

Before increases in nutrients:
11

Acceleration of Eutrophication :
12

Results of eutrophication :
13

Photo 1: Algal bloom in a lake.
Photo 1: Algal bloom in a lake.16

Photo 2: Overgrowth of floating aquatic plants.17

Photo 23: Lake Biwa, the largest lake in Japan during summer time showing
overgrowth of aquatic plants.
18

Photo 4: Fish
mortality due
to lack of
oxygen in an
Indonesian
lake.
19

Put in order the stages of Eutrophication!
LACK OF OXYGEN
GROWTH OF BACTERIA
DEATH OF PLANTS
SUFFOCATIONGROWTH OF PLANTS
ADDITION OF NITRATES

CONTROLL OF WASTE WATER
A wastewater treatment plant (WWTP) or wastewater treatment
works is an industrial structure designed to remove biological or
chemical waste products from water, thereby permitting the treated
water to be used for other purposes.
Functions of wastewater treatment plants include:
• Agricultural wastewater treatment – treatment and disposal of
liquid animal waste, pesticide residues etc. from agriculture.
• Sewage treatment – treatment and disposal of human waste, and
other household waste liquid from toilets, baths, showers, kitchens,
and sinks.
• Industrial wastewater treatment – the treatment of wet wastes from
manufacturing industry and commerce including mining, quarrying
and heavy industries.

Primary: removes 60% of
solids and 30-40% oxygen
demanding wastes
(physically)
Secondary: uses biological
processes to remove up to
90% of biodegradables
Tertiary: advanced
techniques
Disinfection: chlorine,
ozone, UV
What is not taken out???
20

Sewage treatment is the process of removing contaminants from wastewater, including
household sewage and runoff (effluents).
• It includes physical, chemical, and biological processes to remove physical, chemical
and biological contaminants.
 Stages of Sewage treatment plant
1. Pretreatment
Pretreatment removes all materials that can be easily collected from the raw sewage before
they damage or clog the pumps and sewage lines of primary treatment clarifiers. Objects that
are commonly removed during pretreatment include trash, tree limbs, leaves, branches, and
other large objects.
The influent in sewage water passes through a bar screen to remove all large objects like
cans, rags, sticks, plastic packets etc. carried in the sewage stream
Grit removal
Pretreatment may include a sand or grit channel or chamber, where the velocity of the
incoming sewage is adjusted to allow the settlement of sand, grit, stones, and broken glass.
These particles are removed because they may damage pumps and other equipment. For
small sanitary sewer systems, the grit chambers may not be necessary, but grit removal is
desirable at larger plants.

• Flow equalization
• Fat and grease removal
In some larger plants, fat and grease are removed by passing the sewage through a small
tank where skimmers collect the fat floating on the surface. Air blowers in the base of the
tank may also be used to help recover the fat as a froth. Many plants, however, use primary
clarifiers with mechanical surface skimmers for fat and grease removal.
2 . Primary treatment
In the primary sedimentation stage, sewage flows through large tanks, commonly called "pre-
settling basins", "primary sedimentation tanks" or "primary clarifiers". The tanks are used to
settle sludge while grease and oils rise to the surface and are skimmed off. Primary settling
tanks are usually equipped with mechanically driven scrapers that continually drive the
collected sludge towards a hopper in the base of the tank where it is pumped to sludge
treatment facilities. Grease and oil from the floating material can sometimes be recovered for
saponification.
Equalization basins may be used for temporary storage of diurnal or wet-weather flow peaks.
Basins provide a place to temporarily hold incoming sewage during plant maintenance and a
means of diluting and distributing batch discharges of toxic or high-strength waste which
might otherwise inhibit biological secondary treatment (including portable toilet waste,
vehicle holding tanks, and septic tank pumpers).

3. Secondary treatment
Secondary treatment is designed to substantially degrade the biological content of the
sewage which are derived from human waste, food waste, soaps and detergent. The majority
of municipal plants treat the settled sewage liquor using aerobic biological processes. To be
effective, the biota require both oxygen and food to live. The bacteria and protozoa consume
biodegradable soluble organic contaminants (e.g. sugars, fats, organic short-chain carbon
molecules, etc.) and bind much of the less soluble fractions into floc.
• Activated sludge
These mostly carbonaceous dissolved solids undergo aeration to be broken down and
biologically oxidized or converted to carbon dioxide. Likewise, nitrogenous dissolved solids
(amino acids, ammonia, etc.) are also oxidized (=eaten) by the floc to nitrites, nitrates, and,
in some processes, to nitrogen gas through denitrification.

Interestingly, like most living creatures, activated sludge biota can get sick. This many times
takes the form of the floating brown foam, Nocardia. While this so-called 'sewage fungus' (it
isn't really a fungus) is the best known, there are many different fungi and protists that can
overpopulate the floc and cause process upsets. Additionally, certain incoming chemical
species, such as a heavy pesticide, a heavy metal (e.g.: plating company effluent) load, or
extreme pH, can kill the biota of an activated sludge reactor ecosystem. Such problems are
tested for, and if caught in time, can be neutralized.
While denitrification is encouraged in some treatment processes, in many suspended aeration
plants denitrification will impair the settling of the floc and lead to poor quality effluent.
In either case, the settled floc is both recycled to the inflowing primary effluent to regrow, or is
partially 'wasted' (or diverted) to solids dewatering, or digesting, and then dewatering.

Disinfection
The purpose of disinfection in the treatment of waste water is to substantially reduce the
number of microorganisms in the water to be discharged back into the environment for the
later use of drinking, bathing, irrigation, etc.
4. Tertiary treatment
The purpose of tertiary treatment is to provide a final treatment stage to further improve the
effluent quality before it is discharged to the receiving environment (sea, river, lake, wet
lands, ground, etc.). More than one tertiary treatment process may be used at any treatment
plant. If disinfection is practised, it is always the final process. It is also called "effluent
polishing.“
Sand filtration removes much of the residual suspended matter. Filtration over activated
carbon, also called carbon adsorption, removes residual toxins

Technological Approach: Sewage
Treatment
 Physical and biological treatment
Fig. 22-16 p. 511
22

WATER QUALITY STANDARD
Indian Standard
Drinking Water - Specification
IS 10500 : 1991

Technical Terms
• BIS (Bureau of Indian Standards)
• Desirable limits
• Permissible limit
• PPM
• Hazen Units

Colour, Hazen Units
IS 10500-1991 Desirable : 5 Hz. , Permissible : 25 Hz.
Risks or effects Visible tint, acceptance decreases
Sources
Tannins, Iron, Copper, Manganese
Natural deposits
Treatment Filtration, Distillation, Reverse osmosis, Ozonisation

Odour
IS 10500-1991 Unobjectionable
Risks or effects Rotten egg, Musty, Chemical
Sources
Chlorine, Hydrogen sulphide, Organic matter, Septic
contamination, Methane gas
Treatment Activated carbon, Air stripping, oxidation, Filtration

pH
IS 10500-
1991
Desirable :6.5 – 8.5, Permissible
:No relaxation
Risks or
effects
Low pH - corrosion, metallic
taste
High pH – bitter/soda taste,
deposits
Sources Natural
Treatment
Increase pH by soda ash
Decrease pH with white vinegar
/ citric acid

Total Dissolved Solids (TDS)
IS 10500-1991 Desirable : 500 mg/l , Permissible : 2000 mg/l
Risks or effects
Hardness, scaly deposits, sediment, cloudy colored water,
staining, salty or bitter taste, corrosion of pipes and fittings
Sources
Livestock waste, septic system
Landfills, nature of soil
Hazardous waste landfills
Dissolved minerals, iron and manganese
Treatment Reverse Osmosis, Distillation, deionization by ion exchange

Hardness
IS 10500-1991 Desirable :300 mg/l , Permissible : 600 mg/l
Risks or effects Scale in utensils and hot water system, soap scums
Sources
Dissolved calcium and magnesium from soil and aquifer
minerals containing limestone or dolomite
Treatment Water Softener Ion Exchanger , Reverse Osmosis

Alkalinity
IS 10500-1991 Desirable : 200 mg/l , Permissible : 600 mg/lit
Risks or effects
Low Alkalinity (i.e. high acidity) causes
deterioration of plumbing and increases the
chance for many heavy metals in water are
present in pipes, solder or plumbing fixtures.
Sources
Pipes, landfills
Hazardous waste landfills
Treatment Neutralizing agent

Iron
IS 10500-1991 Desirable : 0.3 mg/l , Permissible : 1.0 mg/l
Risks or effects
Brackish color, rusty sediment, bitter or metallic taste, brown-
green stains, iron bacteria, discolored beverages
Sources
Leaching of cast iron pipes in water distribution systems
Natural
Treatment Oxidizing Filter , Green-sand Mechanical Filter

Manganese
IS 10500-1991 Desirable : 0.1 mg/l , Permissible : 0.3 mg/l
Risks or effects
Brownish color, black stains on laundry and
fixtures at .2 mg/l, bitter taste, altered taste of
water-mixed beverages
Sources
Landfills
Deposits in rock and soil
Treatment
Ion Exchange , Chlorination, Oxidizing Filter , Green-sand
Mechanical Filter

Sulphate
IS 10500-1991 Desirable : 200 mg/l, Permissible : 400 mg/l
Risks or effects
Bitter, medicinal taste, scaly deposits, corrosion, "rotten-
egg" odour from hydrogen sulphide gas formation
Sources
Animal sewage, septic system, sewage
By-product of coal mining, industrial waste
Natural deposits or salt
Sulphate Treatment Ion Exchange , Distillation , Reverse Osmosis
SO4

Nitrate
IS 10500-1991 Desirable : 45 mg/l, Permissible : 100 mg/lit
Risks or effects Methemoglobinemia or blue baby disease in infants
Sources
Livestock facilities, septic systems, manure lagoons,
Household waste water,
Fertilizers,
Natural Deposits,
Treatment Ion Exchange, Distillation, Reverse Osmosis
NO3-

Chloride
IS 10500-1991 Desirable : 250 mg/l , Permissible : 1000 mg/l
Risks or effects
High blood pressure, salty taste, corroded pipes, fixtures and
appliances, blackening and pitting of stainless steel
Sources
Fertilizers
Industrial wastes
Minerals, seawater
Treatment Reverse Osmosis , Distillation, Activated Carbon
Cl

Fluoride
IS 10500-1991 Desirable : 1.0 mg/l, Permissible : 1.5 mg/l
Risks or effects Brownish discoloration of teeth, bone damage
Sources
Industrial waste
Geological
Treatment
Activated Alumina, Distillation, Reverse Osmosis, Ion
Exchange

Arsenic
IS:10500-1991 Desirable: 0.05 mg/l Permissible: No relaxation
Risks or effects
Weight loss; Depression; Lack of energy; Skin and nervous
system toxicity
Sources
Previously used in pesticides (orchards)
Improper waste disposal or product storage of glass or
electronics, Mining
Rocks
Treatment
Activated Alumina Filtration, Reverse Osmosis, Distillation,
Chemical Precipitation, Ion exchange, lime softening

Chromium
IS 10500-1991 Desirable : 0.05 mg/l, Permissible : No relaxation
Risks or effects
Skin irritation, skin and nasal ulcers, lung tumors,
gastrointestinal effects, damage to the nervous system and
circulatory system, accumulates in the spleen, bones, kidney
and liver
Sources
Septic systems
Industrial discharge, mining sites
Geological
Treatment Ion Exchange, Reverse Osmosis, Distillation

Copper
IS 10500-1991 Desirable : 0.05 mg/l, Permissible : 1.5 mg/l
Risks or effects
Anemia, digestive disturbances, liver and kidney damage,
gastrointestinal irritations, bitter or metallic taste; Blue-green
stains on plumbing fixtures
Sources
Leaching from copper water pipes and tubing, algae
treatment
Industrial and mining waste, wood preservatives
Natural deposits
Treatment Ion Exchange, Reverse Osmosis, Distillation

Cyanide
Risks or effects Thyroid, nervous system damage
Sources
Fertilizer
Electronics, steel, plastics mining
Treatment Ion Exchange, Reverse Osmosis, Chlorination

Lead
Risks or effects
Reduces mental capacity (mental retardation), interference with
kidney and neurological functions, hearing loss, blood
disorders, hypertension, death at high levels
Sources
Paint, diesel fuel combustion
Pipes and solder, discarded batteries, paint, leaded gasoline
Natural deposits
Treatment
Ion Exchange, Activated Carbon , Reverse Osmosis,
Distillation
Brain
Nerve
Damage
Hearing
Problems
Digestive Issues
Stunted Growth

Mercury
Risks or effects
Loss of vision and hearing, intellectual deterioration, kidney
and nervous system disorders, death at high levels
Sources
Fungicides
Batteries, fungicides
Mining, electrical equipment, plant, paper and vinyl chloride
Natural deposits
Treatment Reverse Osmosis, Distillation

Zinc
IS 10500-1991 Desirable :5 mg/l, Permissible : 15 mg/l
Risks or effects Metallic taste
Sources
Leaching of galvanized pipes and fittings, paints, dyes
Natural deposits
Treatment
Ion Exchange Water Softeners, Reverse Osmosis,
Distillation

Total Coliform Bacteria
IS 10500-1991
95% of samples should not contain coliform in 100 ml
10 coliform / 100ml
Risks or effects Gastrointestinal illness
Sources
Livestock facilities, septic systems,
Household waste water
Naturally occurring
Treatment Chlorination , Ultraviolet, Distillation, Iodination

E.coliform Bacteria
IS 10500-1991 Nil / 100ml
Risks or effects Gastrointestinal illness
Sources
Livestock facilities, septic systems, manure lagoons
Household waste water
Naturally occurring
Treatment Chlorination , Ultraviolet, Distillation, Iodination

HEALTH EFFECTS OF CHEMICAL PARAMETERS
Parameter BIS Guideline value
(maximum
allowable)
General & Health effect
Total dissolved
solids
2000 mg/L Undesirable taste; gastro intestinal irritations;
corrosion or incrustation
PH 6.5-8.5 Affects mucous membrane; bitter taste; corrosion;
affects aquatic life
Alkalinity 600 mg/L Boiled rice turns yellowish
Hardness 600 mg/L Poor lathering with soap; deterioration of the quality of
clothes; scale forming; skin irritation; boiled meat
and food become poor in quality
Calcium 200 Poor lathering and deterioration of the quality of
clothes; incrustation in pipes; scale formation
Magnesium 100 Poor lathering and deterioration of clothes; with sulfate
laxative
Iron 1.0 Poor or sometimes bitter taste, color and turbidity;
staining of clothes materials; iron bacteria causing
slime
Manganese 0.3 Poor taste, color and turbidity; staining; black slime

Parameter
BIS Guideline value
(maximum allowable)
Aluminum 0.2 Neurological disorders; Alzheimer's disease
Copper 1.5 Liver damage; mucosal irritation, renal damage and
depression; restricts growth of aquatic plants
Zinc 15 Astringent taste; opalescence in water; gastro intestinal
irritation; vomiting, dehydration, abdominal pain,
nausea and dizziness
Ammonia - Indicates pollution; growth of algae
Nitrite - Forms nitrosoamines which are carcinogenic
Nitrate 100 Blue baby disease (methemoglobineamia); algal growth
Sulfate 400 Taste affected; laxative effect; gastro intestinal irritation
Chloride 1000 Taste affected; corrosive
Fluoride 1.5 Dental and skeletal fluorosis; non-skeletal

Parameter
BIS Guideline
value (maximum
allowable)
Phosphate - Algal growth
Arsenic 0.05 Toxic; bio-accumulation; central nervous system affected; carcinogenic
Mercury 0.001 Highly toxic; causes 'minamata' disease-neurological impairment and
renal disturbances; mutagenic
Cadmium 0.01 Highly toxic; causes 'itai-itai' disease-painful rheumatic condition;
cardio vascular system affected; gastro intestinal upsets and hyper
tension
Lead 0.05 Causes plumbism-tiredness, lassitudes, abdominal discomfort,
irritability, anaemia; bio-accumulation; impaired neurological and
motor development, and damage to kidneys
Chromium 0.05 Carcinogenic; ulcerations, respiratory problems and skin complaints
Pesticide 0.001 Affects central nervous system
Detergent - Undesirable foaming

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YnH0TCCP5FeWWymnswNh6NAoj_9Gsh_n3XEJfl4e2lSOgYMC=s170
16. https://lh5.ggpht.com/uKOrj2iAYD1YtiSI-M_74SLh-
49auuloZ2iUb4BztqVXnRH4_jst0L8auust41rcomdGog=s122
17. https://lh5.ggpht.com/tO3NmsW65lx00Ek1DWGAkU4AJiL2k8XaAtmZAfNlzOC0h4S
QCi753s7Af6PaAsHD0iMhc6w=s123
18. https://lh6.ggpht.com/h84-
Wlz3KSIGB7vgVqTZcn54l_eRq9hBuwFxW5Q283b_3Wyrhrp1D7emszNJVb_AfojEUw
=s120
19. https://lh4.ggpht.com/7vkeq3ecZciBJ5mXO_Uy4Fw-K5l1tcfV-C0SHb5jyEL8pu-
_tDpOIpE2Eg9dBTD0zCN-WQ=s85
20. https://lh4.ggpht.com/8kTMNilzVDs1gLGtSUdPhbhMlQYQB3SCbFrK0IMFL-
h3x83fxTHFD7zPxwcvDOMKmDzLdQ=s131

21. https://lh6.ggpht.com/fCleUI4vIXu7zbNHuFUsnddlTm1d6h-
r9gQGuCGvReFwVG3bSxOJbBIs85alMlhYkZ5z=s117
22. https://lh6.ggpht.com/OYq1NXaJbyGVt8pT6fFm8lsqC0DFnOaLamv0R9WBIY
7-uejxtKgShh4AX53zvVGl-WfpOBE=s113
23. https://lh4.ggpht.com/Ar3QIH8-FTsuKolU-
Gh711vf855sV4Rhw4ybVPJLdh2iIbhK0cecgweomUHvmAZiyP3Z=s105
Book/Web Resources
Environmental Pollution: Causes, Effects & Control by K.C Agrawal

Diploma. ii es unit 3.1 environment water pollution

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