Module 2 ENVIRONMENTAL POLLUTION POLLUTION Pollution Undesirable changes
Module 2 ENVIRONMENTAL POLLUTION
POLLUTION • Pollution - Undesirable changes in the physical, chemical or biological characteristics of air, water and soil that harmfully affects the life or create potential health hazard of living organism • For short term economical benefit –Air –Water –Soil –Marine –Noise –Thermal –Nuclear
• Degradable/non-persistent pollutants • Slowly degradable/persistent pollutants
1. AIR POLLUTION • DEFINITION: Substances put into air by the activity of mankind, which cause harmful effect to his health, vegetables, property, etc.
What is air pollution? • contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health • Air pollution only occurs outdoors
Sources of Outside Air Pollution • Combustion of gasoline and other hydrocarbon fuels in cars, trucks, and airplanes • Burning of fossil fuels (oil, coal, and dinosaur bones) • Insecticides • Herbicides • Everyday radioactive fallouts • Dust from fertilizers • Mining operations • Livestock feedlots
• A major form of air pollution is emissions given off by vehicles. • The number of cars in EU has doubled between 1970 and 1994 – 3% per year
Sources of Indoor pollution • Efficient insulation • Bacteria • Molds and mildews • Viruses • animal dander and cat saliva • plants • house dust • Mites • Cockroaches • pollen
Role of Engines and Fuel • Different engines and fuel combinations give out different emissions in different quantities. • Some engines have catalysts which effectively remove part of the harmful gases.
CLASSIFICATION OF AIR POLLUTANTS ( on the basis of origin) • Primary air pollutants: Pollutants directly emitted to the air. Stationary Combustion Sources –Oxides of carbon (CO 2, CO) –Oxides of Sulphur (SO 2, SO 3) –Oxides of Nitrogen (NO, NO 2) –Hydrocarbons and combinations (CH 4, Benzyne)
Mobile Combustion Sources —Particulate lead (Pb(CH 3)4) —Aerosols (CCl 2 F 2, CCl 3 F) —Oxides of carbon (CO 2, CO) —Hydrocarbons and combinations
Acid rain
Classification according to state of matter 1. Particulate air pollutants : Finely divided solids and liquids dispersed in gaseous media. Eg : Dust , smoke , fly ash etc 2. Gaseous air pollutants: Organic gases like Benzene , Methane Aldehydes, Ketones, inorganic gases like CO 2, SO 2 etc
• An average man breathes 22000 times a day, and takes in 16 kg of air each day!!!!
Effects of air pollution on human health • Nose and throat irritation by SO 2, NO 2 • Eye irritation • Gaseous pollutants can cause odour nuisance • Irritation to respiratory track by SO 2, CO • Asthmatic attacks and bronchitis • CO and NO will reduce the oxygen carrying capacity of blood
• Hydrogen fluoride can cause flurosis and mottling of teeth. • Liver and kidney damages • Causes abnormality in mental development of children.
Effects of air pollutants on plants • SO 2 : Bleaching of leaves and killing of tissues • O 3 : Premature ageing and collapsing of leaves • NO 2: Suppressed growth • Fluorides: Necrosis at leaf tip. • Ethylene: dropping of leaves
Effects of air pollution on animals • The accumulation of the air pollutants in the vegetation and forage, and subsequent poisoning of animals , when they eat the contaminated vegetation/forage.
The pollutants mainly responsible for most livestock damages are: • Fluorine: Its effects are lack of appetite, rapid loss of weight, muscular weakness and death. • Lead: Chronic lead poisoning has been observed in animals that are grazing near lead mines. It causes paralysis and difficulty in breathing. • Arsenic: cause severe thirst, vomiting, irregular pulse and respiration, abnormal body temperature and death in acute cases.
Economic effects of air pollution • Corrosion: Damage of materials by corrosion. • The prime air pollutant of corrosion is SO 2. • In the presence of O 2 and moisture , it is converted to sulphuric acid. • Deposition of this acid on metal parts of building roofs, railway tracks and other structures cause enormous loss due to corrosion
• Damage to building materials: the acid deposition reacts with lime stone , marble and other building materials to cause deterioration of these things. • Damage to paints and protective covering: Pollutants like so 2, so 3 and Aerosols damage protective coating and paints of the surface.
Control measures to air pollution 1. Dispersion of source locations: Dispersion of the sources of air pollutants through allocation of land. i. e. by proper planning of industrial areas.
2. Dilution: Using tall stacks (exit pipes) • The pollutants discharges at a sufficient height • Where the air movements both horizontal and vertical is more and chance of downward movement of air (inversion condition) are less. • Dispersion of pollutants over a larger area in less time • Dilute the concentrations of pollutants near the source.
3. Substitution of raw materials: e. g. use of low volatile coal in place of high volatile coal, eliminates smoke and soot. 4. Substitution of fuels: desulphurization and deashing reduce emissions like SO 2 and ash. Use of natural gas instead of coal.
5. Modification of process: In case of disposal of waste by combustion, sanitary landfill can be used instead of incineration.
6. Modification of process equipment or repair and maintenance of existing equipments helps in reducing atmospheric pollution. 7. Reduction at source by using control equipments: Most effective method for • Ex: settling chamber: here the pollutants are allowed to settle under the effect of gravity
8. Filters: particulate matter can be filtered , if the fumes containing them are forced to pass through the filtering device. Eg: Cloth fabric, mats of wool, cellulose etc can be used as separator.
Control devices for gaseous contaminants • Adsorption: Passing a stream of effluent gas through a porous solid material called adsorbent contained in an adsorption bed. • The surface of the porous solid material attracts and hold the gas( adsorbate) by physical or chemical adsorption.
• Activated carbon: for eliminating odours , purifying of gases. • Activated alumina: for drying gases • Silica: for controlling and removing SO 2 and NO 2 Emissions.
• Absorption: Involves bringing of the effluent gas (absorbate) into contact with a liquid absorbent( solvent) so that one or more constituents of the effluent gas are removed or treated by the liquid absorbent. • Ex: use of ammonia solution to absorb SO 2 is an old process which is widely used in the fertilizer industry.
• Combustion: the combustion equipment is designed so as to push oxidation reaction as close as possible to completion so that minimum unburned compound are left. • Carbon monoxide and soot are by products of combustion at low oxidation while co 2 is the by product in the presence of sufficient oxygen.
• Combustion: the combustion equipment is designed so as to push oxidation reaction as close as possible to completion so that minimum unburned compound are left. • Carbon monoxide and soot are by products of combustion at low oxidation while co 2 is the by product in the presence of sufficient oxygen.
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