1. Air Pollution: causes
and control
PRESENTED BY:
VISHNURAJ R.S
DEPT.AQUATIC BIOLOGY &FISHERIES

2. Air Pollution
Air is one of the vital part
of life .Air supplies with
oxygen is essential for our
bodies to live. Air is 99.9%
nitrogen, oxygen, water
vapors and inert gases. Due
to man made activities
along with some natural
processes many physical
addition of material that
turn the air impure or
unclean. That is called air
pollution.

3. Air Pollution
Air pollution primarily
comes from burning fossil
fuels such as natural gas,
petroleum, and coal.
Humans are the main cause
of air pollution. Industry,
including factories and
power plants, burn large
quantities of fuel. Burning
coal and petroleum releases
sulfur oxides and nitrogen
oxide into the air. Airplanes,
boats, and cars burn
petroleum, releasing carbon
monoxide and carbon
dioxide.

4. Air Pollution
Some air pollution is not directly caused by humans: for example,
animals emit carbon dioxide when they breathe, and volcanoes
release sulfur oxide. The forest fire produce huge amount of
CO,CO2, Nitrogen oxides, semi burnt hydro carbons, and ash.
The waste in landfills releases methane. Sulfur oxides, carbon
monoxide and carbon dioxide, and methane all have a very
negative effect on air quality. These pollutants can also contribute
to the greenhouse effect. The dust storm make the air full of
particulate sand particles.

5. Primary vs Secondary pollutants
• Not all of the pollutants found in the atmosphere
are the direct result of emissions.
• Many pollutants arise from chemical reactions in
the atmosphere with other substances or light
(photochemical reactions).
•Pollutant substances that are directly emitted into
the atmosphere = primary pollutants.
•Substances not directly emitted into the
atmosphere, formed by chemical reactions in the
atmosphere = secondary pollutants.

6. TYPES OF POLLUTION
 INDOOR POLLUTION
• Indoor air pollution occurs inside our homes, office and schools.
• The main types of indoor pollutants are tobacco smoke, gases
from stoves and furnaces, household chemicals, small fiber
particles, and hazardous fumes given off by building materials like
insulation , glue, and paint .
• In high amounts it causes headache, eye irritation, etc.
 OUTDOOR POLLUTION
• Gases and particulates form of pollutants pour into the
atmosphere from the burning of fuel to motor vehicles, heat
buildings, business and industrial processes , burning of garbage
etc…
• Outdoor pollution make huge impacts on atmosphere and the
organisms
• Acid rain , global warming, etc are some of its consequences .

7. TYPES OF POLLUTANTS
 Aerosols
– Particulates solid phase
• Dust
• Ash
• Fumes
– Solid and liquid
• Smoke (from combustion)
• Coastal aerosols
– Liquid
– Aggregate gases (sulfate, nitrate)
 Gases
COx
SOx
NOx
PAH

8. Six primary or “criteria” air pollutants
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Carbon monoxide (CO)
Sulfur oxides (SOx)
Nitrogen dioxide (NO2)
Ozone (O3)
Hydrocarbons
Particulate matter(PM2.5 _PM10)

9. Carbon Monoxide
•colorless, odorless, tasteless, non irritating
gas
•produced when carbon does not burn in fossil
fuels,ie incomplete combustion.
•Commonly present in automobile exhaust
•deprives body of O2 causing headaches,
fatigue, and impaired vision, it may lethal when
continually inhale concentration above
1000ppm over a period of 4 hours.

10. Sulfur Dioxide
•Colourless gas with penetrating and pungent
odour
•produced mainly when coal and fuel oil are
burned
•present in power plant exhaust
•narrows the airway, causing wheezing and
shortness of breath, especially in those with
asthma
The formation of SO2, SO3, and sulfuric acid
S + O2
2 SO2 + O2
SO3 + H2O
SO2
2SO3
H2SO4

11. Nitrogen Dioxide
•reddish, brown gas
•produced when nitric oxide combines
with oxygen in the atmosphere
•present in car exhaust and power
plants
•affects lungs and causes wheezing;
increases chance of respiratory failure.
•Smokers may readily develop lung disease as cigarettes and cigars
containing 330 to 1,500 ppm nitrogen oxides. Prolonged exposure
at 1 to3 ppm or even less may fatal.
•It also react with water to cause acid rain
4NO2+2H2O+O2 ------- 4HNO3

12. Ground Level Ozone
•It is a highly reactive pale-blue gas with penetrating
odour.
• at upper level, ozone shields Earth from sun’s
harmful UV rays
•at ground level, ozone is harmful pollutants
•formed from automobile, power and chemical plant
exhaust
•irritate respiratory system and asthma; reduces
lung function by inflaming and damaging lining of
lungs
•It also a green house gas

13. HYDROCARBONS
•Hydrocarbons are compounds that have
carbon and hydrogen
•Benzene, benzpyrene, methane, etc are
common hydrocarbon pollutants.
•The major sources are automobile and
industrial exhaust..
•Benzene: colorless, flammable liquid
pollutant have carcinogenic property…
•Benzpyrene: it is also carcinogenic,
•Methane is common green house gas .. It
produce by naturally along with human
activities.

14. Particulate Matter
•particles of different sizes and structures that
are released into the atmosphere…
•Lead, asbestos etc are some particulate
matter from man made sources…
•present in many sources including fossil
fuels, dust, smoke, fog, forest fire etc.
•Along with these industrial operations like
mining, polishing etc also produce..
•can build up in respiratory system
•aggravates heart and lung disease; increases
risk of respiratory infection

15. Control of Air Pollutants
Methods of air pollution control can be divided into two
categories:
•THE CONTROL OF PARTICULATE EMISSIONS
•THE CONTROL OF GASEOUS EMISSIONS
The term particulate refers to tiny particles of matter such as
smoke, soot, and dust that are released during industrial,
agricultural, or other activities.
Gaseous emissions are industrial products such as sulfur
dioxide, carbon monoxide, and oxides of nitrogen also
released during various manufacturing operations.

16. THE CONTROL OF PARTICULATE EMISSIONS
1.
Particulates – Cyclones
 separation by centrifugation –
Cyclone utilise centrifugal force generated by a spinning gas
stream to separate the particulate matter from the carrier
gas.
The general principle of inertia separation is that the
particulate-laden gas is forced to change direction. As gas
changes direction, the inertia of the particles causes them
to continue in the original direction and be separated from
the gas stream.

17. Cyclone separator
cleaned
outlet
dirty
gas inlet
particulate outlet
gas

18. 2.Gravitational Settling Chamber
• Like settling basins in water
and waste water treatment,
settling chambers provide
enlarged areas to minimize
horizontal velocities of air
flow thus allow time
for gravity to carry the
particle to the floor.
• These are simple in design
and operation but they
require large spaces for
installation and have
relatively low efficiency
especially for removal of
small particles.

19. 3.Particulates – Filtration
Fibre bags commonly used for control of
particulate emissions with very high
dust loadings and smaller particles.
• Filters consist of porous structure
composed of granular or fibrous
material which tends to retain the
particulate matter as the carrier
gas passes through the voids of the
filter.
•
The dust is collected on the inside of
the bag surface and the filtered gas is
discharged to the atmosphere 99% efficient

20. 4.Particulates – Wet Scrubbers
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spray systems where fine water droplets are sprayed
at high velocity at right angles to the emerging gas
Most of the particles in the gas stream are scavenged
by the water droplets, which fall and are collected
along with the particles
relatively low efficiencies (80-90%) and is usually
employed as a pre-cleaner to remove particles larger
than 5m

22. 5.Particulates – Electrostatic Precipitators
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pass dirty gas through a series of fine wires
(coronas) charged with DC current – causes
particles to aggregate & precipitate
Alternatively corona produces negative ions that
cause particles in the gas stream to become
negatively charged, and attracted to positive
terminal – where they aggregate and fall into a
collection hopper
Large precipitators and low gas flow rates give
better results

24. soot free gas escape
charged electrodes
soot laden smoke
inlet
earth point
removal of soot particles

25. •
Gaseous pollutants –Process
Modifications
simplest and least expensive methods for the control of
gaseous pollutants
• fuel substitution e.g. low sulfur coal, or fuel oils in place of
cheaper coal can greatly reduce the amount of SO2 emissions
at the source
• This type of source control is always the best approach
wherever possible
Gaseous pollutants - Combustion
• involves a series of complex chemical reactions in which
oxygen is combined with organic molecules, to form CO2 and
H2O
• commonly referred to as incineration or afterburning

26. Gaseous pollutants - Adsorption
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physical adsorption to solid surfaces
Reversible - adsorbate removed from the adsorbent by
increasing temp. or lowering pressure
widely used for solvent recovery in dry cleaning, metal
degreasing operations, surface coating, and rayon, plastic, and
rubber processing
limited use in solving ambient air pollution problems – with its
main use involved in the reduction of odour
Adsorbents with large surface area to volume ratio (activated
carbon) preferred agents for gaseous pollutant control
Efficiencies to 99%

27. •
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Gaseous pollutants - Absorption
Scrubbers remove gases
by chemical absorption in
a medium that may be a
liquid or a liquid-solid
slurry
water is the most
commonly used scrubbing
medium
Additives commonly
employed to increase
chemical reactivity and
absorption capacity

28. Gas pollutants – Vehicle emissions
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generally involve simple procedures such as maintaining the
correct tuning for the engine, or the use of catalytic converters
catalytic converters use Pt and Pd attached to some form of
ceramic material
extremely high surface area (in hundreds of m2) allows catalytic
materials to contact exhaust gases, oxidising them to CO2 and
water vapour

29. BIOFILTERS
• When applied to air filtration and purification, biofilters use
microorganisms to remove air pollution.[1] The air flows
through a packed bed and the pollutant transfers into a
thin biofilm on the surface of the packing
material. Microorganisms, includingbacteria and fungi are
immobilized in the biofilm and degrade the pollutant.
Trickling filters and bioscrubbers rely on a biofilm and the
bacterial action in their recirculating waters.
• The technology finds greatest application in treating
malodorous compounds and water-soluble volatile organic
compounds(VOCs). Industries employing the technology
include food and animal products, off-gas
from wastewater treatment facilities,pharmaceuticals

31. Bioscrubbers
• bioscrubbers, the compound to be degraded first
is absorbed in the liquid phase located in an
absorption tower filled with liquid. The operation
involves making the gas flow in a countercurrent
through the liquid where the contaminants and
oxygen are absorbed. Subsequently, the liquid is
fed to a reactor packed with an inert material
covered with biofilm that is responsible for
degrading the pollutant. Bioscrubbers are the
most suitable systems for the treatment of highly
water-soluble compounds

33. CONCLUSION
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Air pollution is a major global threat.
Natural and human activities causes pollution.
SOURCES!!!!
How it affects???
CONTROL MEASURES!!!