Seminar on “Environmental Issues, Air Pollution and

Controls”PREPARED BY:-RAHUL DUBEY

3rd SEM MECHANICAL ENGG.

SUBMITTED TO:-Ms. CHETNA WAHANEMr. PRABHAT SINGH RATHORE

CONTENTS• INTRODUCTION• WHAT IS ENVIRONMENT?• WHAT IS POLLUTION?• BASIC CAUSES OF POLLUTION• ENVIRONMENTAL MONITORING• TYPES OF POLLUTION• AIR POLLUTION• CAUSES OF AIR POLLUTION• AIR POLLUTANTS• AIR POLLUTION CONTROLS• ENVIRONMENTAL ISSUES• CONCLUSION

INTRODUCTION• Large human population is exerting

tremendous pressure on our natural resources.

• With increase in human population and great advancement in technology in the recent past, the waste materials have multiplied in amount as well as in kind, and this has resulted in contamination of environment.

• Today, almost every aspect of modern living possess potential health risks.

• Natural Resources like air, water, land, etc. are getting contaminated with toxic substances or chemical additives.

• It is possible that ultimately man may become a victim of self-created pollution.

• These global environmental changes are influencing not only air, water and land resources but also biological diversity and human health.

WHAT IS ENVIRONMENT?• Environment is the physical, chemical,

biological, cultural and aesthetic surrounding of living organisms, which contributes to the quality of their lives.

• Our environment is a complex and dynamic system, in which all forms of life are inter-dependent and inter-connected.

WHAT IS POLLUTION?• Pollution is any undesirable

change in physical, chemical or biological characteristics of environment which makes it harmful for humans, living organisms and cultural assets.

• Agents that bring about such an undesirable change are called as pollutants.

BASIC CAUSES OF POLLUTION

ENVIRONMENTAL MONITORING: PROCEDURE FOR THE CONTROL OF POLLUTION

The control of pollution requires environmental monitoring. This, in turn, needs

• Careful study of environmental characteristics,• Laying down environmental quality standards,• Periodic assessment of environmental

characteristics,• Noting the changes in the environment and

finding out their likely effect,

• Warning people in time of likelihood of pollution, and

• Planning strategies to tackle pollution such as educating people about pollution hazards, enacting environmental laws, legal action against offenders, etc.

PLAN SAMPLING

ASSIGN WORK

REVIEW RESULTS

ENVIRONMENT MONITORING STEPS

DUST COLLECTOR

POLLUTION IS OF FOLLOWING MAIN TYPES:-1. Atmospheric or air pollution,2. Hydrospheric or water

pollution,3. Lithospheric or land or soil

pollution,4. Radioactive pollution, and5. Noise or sound pollution.

TYPES OF POLLUTION

AIR POLLUTION

AIR POLLUTION• An undesirable change in the

physical, chemical, or biological aspects of air which makes it harmful for humans, for other living organisms and for cultural assets is called air pollution.

CAUSES OF AIR POLLUTION

a. HUMAN ACTIVITIES

• Industrialisation• Automobile emissions• Overpopulation• Deforestation• Nuclear explosion and explosives used in

wars• Fireworks• Thermal power stations, etc.

b. NATURAL PHENOMENA

• Volcanic eruptions• Electric storms and solar flares which

produce harmful chemicals• Forest fires • Natural organic and inorganic decays • Dust storms• Biological elements like pollen, spores, cysts,

bacteria and marsh gas.

AIR POLLUTANTS• GASEOUS AIR POLLUTANTS• PARTICULATE POLLUTANTS• RADIOACTIVE POLLUTANTS

GASEOUS POLLUTANTS• Oxides of sulphur• Hydrogen sulphide• Oxides of nitrogen• Oxides of carbon• Hydrocarbons• Photochemical oxidants• Fluorides

PARTICULATE POLLUTANTS• Dusts•Mists• Aerosols• Pollen, spores, cysts and

bacteria, etc.

RADIOACTIVE POLLUTANTS• They are released from

nuclear and war explosives.• They kill the tissues they

enter.

LUNG DAMAGE DUE TO PARTICULATES

Three types of steps can be taken to control air pollution:-• Separation of pollutants from harmless gases,• Avoidance of pollutants• Conversion of pollutants to harmless

materials.

AIR POLLUTION CONTROL

SEPARATION OF POLLUTANTS

Growing trees: certain plants (Phaseolus vulgaris, Coleus blumeri, Ficus variegata) can fix CO and some plants (Pinus, Junipers, Quercus, Pyrus, Vitis) can metabolise nitrogen oxides. Plantation of such species should be encouraged along with other plants

Use of sulphur and lead free good quality fuel.

Control of Particulate Matter:- we can use devices termed arrestors in the industries and catalytic converters in the automobiles.

• Arresters :- Control equipments such as gravity settling tanks or porous filters, electrostatic precipitators, cyclonic separators and trajectory separators can minimise air pollution.

• Catalytic converters:- This device has metals like platinum, palladium and rhodium as catalysts. As the exhaust passes through it,

CATALYTIC CONVERTOR

ELECTROSTATIC PRECIPITATOR

unburnt hydrocarbons are converted into CO₂ and water, and CO and nitric oxide are changed to CO₂ and N₂ respectively.

Control of Gaseous Pollutants:-1. Combustion method:- In this method,

oxidisable pollutants particularly in petrochemical, fertilisers, paints and varnish industries are burnt at high temperature.

2. Absorption method:- This method employs dry or wet scrubbers having packing material where gaseous pollutants are absorbed.

For instance, calcium hydroxide or a bed of lime is used to absorb sulphur dioxide. A fine spray of water dissolves nitrogen oxides, sulphur oxides and ammonia.

3. Adsorption technique:- This method is employed to remove toxic gases, vapour and inflammable compounds from the polluted air by using very fine solid particles (e.g., activated charcoal). The electrostatic precipitators remove smaller particles.

Using tall chimneys in factories reduce pollution of air at ground level.

Industrial smoke should be filtered before releasing into the air to remove particulate matter.

Poisonous gases should be removed by passing the fumes through water tower scrubber or spray collector.

Mining area should be afforested.

AVOIDANCE OF POLLUTANTS

• Use of automobiles should be minimised.• Conventional fuels (firewood, coal, oil) should

be replaced by electricity or natural gas. These fuels do not emit SO₃.

• Population should be brought under control.• Nuclear explosions and wars should be stopped.• Non-conventional fuel should be used which are

pollution free.

• Pollution free fuels (alcohol, hydrogen, battery power) should be developed for automobiles.

• Complete electrification of rail track will greatly reduce air pollutants.

CONVERSION OF POLLUTANTS

• It means conversion of pollutants into harmless materials.• This may be done by oxidation in

air or by chemical neutralisation of acids and bases.

ENVIRONMENTAL ISSUES

Acid Rain • Acidification of environment is a man-made

phenomenon.• Acid rain refers to precipitation with a pH of

less than 5.• It is a mixture of H₂SO₄ and HNO₃; the ratio of

the two acids vary depending on the relative quantities of sulphur oxides and nitrogen oxides present in the atmosphere.

• In the atmosphere, SO₂ and Noₓ are changed into sulphuric acid (H₂SO₄) and nitric acid (HNO₃) respectively by combining with oxygen and water.

2SO₂ + O₂ → 2SO₃SO₃ + H₂O → H₂SO₄

2NO + [O]→ N₂O₅ N₂O₅ + H₂O → 2HNO₃

ACID RAIN

EFFECTS OF ACID RAIN• Chlorosis• Necrosis• DefoliationPLANTS

• Results in acidification of water bodies• pH less than 5 kills plankton, molluscs and most

fishes in water bodiesFAUNA• Corrodes metals, marbles, painted

surfaces, slate, stone, etc.• Causes stone leprosy.ASSETS

Green House Effect and Global Warming

• The greenhouse effect is a naturally occurring phenomenon that is responsible for heating of earth’s surface and atmosphere.

• Only half of incoming solar radiations fall on Earth’s surface heating it.

• Earth’s surface re-emits heat in the form of infra-red radiation but part of it doesn’t escape into space as atmospheric gases (e.g., CO₂, CH₄, etc.) absorb a major fraction of it.

• The molecules of these gases radiate heat energy, and a major part of which again comes to earth’s surface, thus heating it up once again. The cycle repeats many times.

• The above mentioned gases are called greenhouse gases because they are responsible for the greenhouse effect.

• Increase in the level of greenhouse gases has led to considerable heating of earth leading to global warming.

Effects of Global Warming

Melting of polar and Himalayan ice caps.

Global environmental changes (e.g., El Nino Effect) and rise in

the earth’s average temperature

The total spectrum of changes that global warming can bring is

still under active research

Control Measures for Global Warming

ENERGY

• Cutting down use of fossil fuels• Increasing energy efficiency

PLANTATION

• REDUCING DEFORESTATION• PLANTING TREES

MISCELLANEOUS

GLOBAL WARMING AND GREEN HOUSE EFFECT

Ozone Depletion

• Ozone layer in the upper part of the atmosphere acts as a shield absorbing UV radiation from the sun.

• Ozone is continuously formed by the action of UV rays on molecular oxygen, and also get degraded into molecular oxygen in the stratosphere.

• This balance between production and degradation of ozone in the stratosphere has been disrupted due to enhancement of ozone degradation by chlorofluorocarbons (CFCs).

• In stratosphere, UV rays act on CFCs releasing Cl atoms.

• Cl degrades ozone releasing molecular oxygen, with these atoms acting merely as catalysts; Cl atoms are not consumed in the reaction. Thus, a single Cl atom can degrade large amount of ozone.

• Although ozone depletion is occurring widely in the stratosphere, the depletion is particularly marked over the Antarctic region.

• This has resulted in formation of a large area of thinned ozone layer, commonly called as the ozone hole.

OZONE DEPLETION

Depletion Of Ozone

INTERNATIONAL INITIATIVES FOR MITIGATING GLOBAL CHANGE

MONTREAL PROTOCOL •Agreement signed by 27 countries to limit the use of Ozone Depleting Substances.•Agreement to help developing countries implement the alternatives to CFCs.

EARTH SUMMIT •United Nations Conference on Environment and Development (commonly called EARTH SUMMIT)was held in Rio de Janero in 1992.•Recommendations of Conference on Climate Change were signed by 154 nations to limit the emissions of greenhouse gases at 1990 level.

KYOTO PROTOCOL •An agreement was signed by different countries in 1997 to mitigate global environmental change by taking appropriate measure to reduce emissions of greenhouse gases at a level 5% below the 1990 level by 2012.

CONCLUSION• Today, our environment is facing anthropological

threats.• Burning issues of global environmental change like

global warming and ozone depletion are threatening the existence of living world.

• The need of the hour is to stabilise the atmospheric concentrations of green house gases which is possible only when all the countries join hands in lowering the global emission of green house gases from their present levels.

THANK YOU