seminar on environmental issues, air pollution and controls


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Seminar on environmental issues, air pollution and controls Seminar on “Environmental Issues, Air Pollution and Controls” PREPARED BY:- RAHUL DUBEY 3rd SEM MECHANICAL ENGG. SUBMITTED TO:- Ms. CHETNA WAHANE Mr. 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. Human population size has grown enormously over the last hundred years- exerting tremendous pressure on natural resources Contamination - pollution 3 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. The adverse effects of chemical pollutants in the environment- not limited to us- pass on to future generations by way of genetic mutations, birth defects, inherited diseases and so on. 4 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. The need of the hour is to check the degradation and depletion of our precious natural resources and pollution without halting the process of development 5 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. Addition or excessive addition of undesirable materials to the environment or removal of desirable materials in excess. 6 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. ENVIRONMENT MONITORING STEPS DUST COLLECTOR POLLUTION IS OF FOLLOWING MAIN TYPES:- Atmospheric or air pollution, Hydrospheric or water pollution, Lithospheric or land or soil pollution, Radioactive pollution, and 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 THERE ARE two main causes of air pollution:- Human activities like industrialisation, automobile emission, overpopulation, deforestation, nuclear explosions and explosives used in wars, fireworks on festivals, thermal power stations, etc. Natural phenomena such as Volcanic eruptions releasing harmful gases and ashes Electric storms and solar flares which produce harmful chemicals Forest fires Natural organic and inorganic decays releasing methane, sulphur and other harmful substances Dust storms Biological elements like pollen, spores, cysts, bacteria and marsh gas. 15 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. Volcanic eruptions release harmful gases and ashes. Natural organic and inorganic decays release methane, hydrogen sulphide, sulphur and other harmful substances 17 AIR POLLUTANTS GASEOUS AIR POLLUTANTS PARTICULATE POLLUTANTS RADIOACTIVE POLLUTANTS GASEOUS AIR POLLUTANTS ARE IN GASEOUS STATE AT ORDINARY TEMPERATURE AND PRESSURE. THEY FREELY MIX WITH AIR WITHOUT SETTLING DOWN. 18 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 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, Vehicles fitted with catalytic converters should be run on unleaded petrol as leaded petrol would inactivate the catalyst in the converters. 25 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:- Combustion method:- In this method, oxidisable pollutants particularly in petrochemical, fertilisers, paints and varnish industries are burnt at high temperature. 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. Using tall chimneys in factories can reduce pollution of air at ground level. It can induce photochemical reactions in the stratosphere. 29 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. Public transports should be used. 31 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. These oxides are mainly produced by combustion of fossil fuels, smelters, industries, power plants, automobile exhausts, domestic fires etc. nitrogen oxides are also produced in atmosphere through lightening. 35 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 → 2SO₃ SO₃ + H₂O → H₂SO₄ 2NO + [O]→ N₂O₅ N₂O₅ + H₂O → 2HNO₃ ACID RAIN EFFECTS OF ACID RAIN Tajmahal in Agra poses a threat as the industries in AGRA are polluting the air 38 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 41 Control Measures for Global Warming 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 49 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