AIR POLLUTION CONTROL L 4

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AIR POLLUTION CONTROL course material by Prof S S JAHAGIRDAR,NKOCET,SOLAPUR for BE (CIVIL ) students of Solapur university. Content will be also useful for SHIVAJI and PUNE university students

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AIR POLLUTION CONTROL L 4

  1. 1. L-5 Units of measurement and definitions Air Pollution and Control (Elective-I)
  2. 2. Contents of unit-II • L-4  Classification of pollutants Quantity and composition of particulate & gaseous pollutant. pollutant. • Units of measurement (Already (Already covered).
  3. 3. Other way of classifying air pollutants
  4. 4. No. Group Examples 1 Sulphur compounds 2 Nitrogen compounds SO2, SO3, H2S, Mercaptans NO, NO2, NH3 3 Oxygen compounds O3, CO, CO2 4 Halogen compounds HF, HCl 5 Organic compounds 6 Radioactive compounds Aldehydes, hydrocarbons Radioactive gases
  5. 5. Natural Contaminants  Pollen is important natural contaminant because of its peculiar properties of irritation and allergy sometimes leading to bronchitis, asthma and dermatitis.  Pollen grains are discharged into the atmosphere from plants etc. The air transported pollen grains range mainly between 10 and 50 microns.
  6. 6. Aerosols • Aerosols: Aerosols refer to the dispersion of solid or liquid particles of microscopic size in the air. It can also be defined as a colloidal system in which the dispersion medium is gas and the dispersed phase is solid or liquid. • The diameter of the aerosol may range from 0.01 (or less) micron to 100 micron. The various aerosols are as follows:-
  7. 7. Smoke • Smoke consists of finely divided particles produced by incomplete combustion • Size- less than 1 micron • Coal smoke – 0.2 to 0.01 micron • Oil smoke – 1.0 to 0.03 micron
  8. 8. Mists • This term refers to a low concentration dispersion of liquid particles of large size. • Size- 500 to 40 micron
  9. 9. Fog • Fog refers to visible aerosols in which dispersed medium is liquid. • Formation by condensation is usually implied. • Reduces visibility • Size- 40 to 1.0 micron
  10. 10. Fumes • These are solid particles generated by condensation from gaseous state, generally after volatilization from melted surfaces and often accompanied by a chemical reaction such as oxidation. • Size varies from 0.1 to 1 micron
  11. 11. SOURCES OF ATMOSPHERIC DUST
  12. 12. No. Sources Examples 1 Combustion Fuel burning (Coal, wood, fuel oil) Incineration/burning (house and municipal garbage) 2 Material Loading and unloading (sand, handling and gravel, coal, ores, lime, cement) processing Crushing and grinding (ores, stone, cement, rocks, chemicals) Food processing (Flour, corn starch, grains) Cutting and forming (saw mills, wall boards, plastics) Metallurgical (Foundries and smelters) Industrial (Paper, textile manufacture etc. )
  13. 13. No. Sources 3 Earth moving operations 4 Examples Construction (roads, buildings, dams, sites clearance) Agricultural (soil filling, land operations) Mining (Blasting) Miscellaneo House cleaning us Mud road cleaning Crop spraying Poultry feeding Engine exhaust
  14. 14. Gases • Following are the main air pollutant gases (i) Sulphur dioxide: It is a major air pollutant gas produced by the combustion of fuels like coal. The main source of electricity production is by burning of fossil fuels in India and the whole world. The sulphur content of the coal varies from 1 to 4% and fortunately the Indian coal is low in sulphur content. SO2 is also produced in the metallurgical operations.
  15. 15. (ii)Oxides of nitrogen: Oxides of nitrogen are produced either in the production of nitric acid or in the automobile exhausts and as the effluent of power plants. Out of the seven oxides of Nitrogen (N2O, NO, NO2, NO3, N2O3, N2O4, N2O5) only nitric oxide and nitrogen dioxide are classified as the main pollutants. All the oxides of nitrogen are collectively known as NOX.
  16. 16. (iii) Carbon monoxide: It is produced because of the incomplete combustion of coal and other petroleum products. It is produced in the exhaust of automobiles. In the pollution check of vehicles mainly CO and unburnt hydrocarbons are measured.
  17. 17. (iv) Hydrogen sulphide: Hydrogen Sulphide is an obnoxious (bad smelling) gas. It is produced mainly by the anaerobic (in absence of air) decomposition of organic matter. Other air polluting sulphur compounds are methyl mercaptan and dimethyle sulphide etc.
  18. 18. (v) Hydrogen fluoride: It is an important pollutant even in very low concentrations. It is produced in the manufacturing of phosphate fertilizers.
  19. 19. (vi) Chlorine and hydrogen chloride: chloride: It is mixed in the air either from the leakages from water treatment plants or other industries where it is produced or used. Hydrogen chloride is also evolved in various industrial chemical processes. The main effect of chlorine is respiratory irritation which may be fatal.
  20. 20. (vii) Ozone: It is a desirable gas in the upper layers of atmosphere as it absorbs the UV radiation of sunlight. But near the earth surface it is a poisonous gas. It makes poisonous chemicals by photochemical reactions.
  21. 21. (viii) Aldehydes: They are produced by the incomplete oxidation of motor fuels and lubricating oil. They may also be formed because of photochemical reactions. Formaldehydes are irritating to the eyes.
  22. 22. Concentration of air pollutants • It is common practice to express the quantities of gaseous pollutants present in air as parts per million (ppm), thus,
  23. 23. • Therefore, 0.0001 % by volume = 1ppm Or 1 % by volume = 104 ppm
  24. 24. Mass of pollutant • The mass of pollutants is expressed as micrograms/cu. M of air • i.e.
  25. 25. Relation between ppm and micrograms/cu.m General relation (p)
  26. 26. Where, T= Temperature in Kelvin= 273 + temp in degree Celsius Mi = molecular weight of specie i R= universal gas constant p= pressure
  27. 27. ]x 103 1. at 250C and 1 atm pressure (760 mm of Hg)
  28. 28. 2. At 0oC and 1 atm pressure (760 mm of Hg) 22.41
  29. 29. important data required for problems • For calculation of Molecular wt we must know atomic wts of different elements • O = 16 •H=1 • C = 12 • S = 32 • N =14
  30. 30. Try this small but simple test • Calculate molecular wt.s of 1. CO2 2. NO 3. SO2
  31. 31. Objective questions 1. The air transported pollen grains range mainly between ________and________ microns. 2. ______________ consists of finely divided particles produced by incomplete combustion. 3. __________refers to visible aerosols in which dispersed medium is liquid.
  32. 32. 4. ________________ is oxidant gas formed by photochemical reaction. 5. _______________ are produced by the incomplete oxidation of motor fuels and lubricating oil. 6. 1 % by volume = _____ ppm
  33. 33. Theory questions Q1. Define the following 1. Fumes 2. Smoke 3. Aerosol 4. Mist 5. Fog Q2. Give relation between ppm and  gm/m3 at different conditions

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