Indian industries are undergoing through rapid changes including process changes, technological upgradation, organizational restructuring, business reengineering and globalisation. Table gives the growth in annual production figures for seven energy intensive industries from 1994/95 to 1999/2000.
Industries are traditionally the major source of air pollution since ages. Combustion of fuels, process emissions, usage of DG sets, fugitive emissions are the major sources in an industry. Emission will also depend on the type of fuel used in the industry. An industry based on gaseous fuel may pollute less than an industry based on solid fossil fuels such as coal or biomass. Presence of sulphur in various fuels also determines the SO2 emission from that process.
Industries also install air pollution control equipments to reduce the air pollution load from their stacks. Most common equipments are bag filters, electrostatic precipitators, wet and dry scrubbers, cyclones etc. Electrostatic precipitators works on the electric charge which attract the oppositely charged pollutant particles and remove it from the air stream. Bag filters does not allow the particles to pass through the finer holes of the bags from which the air stream is passed through. Wet scrubbers use different chemicals or water to wash the air stream and remove the pollutants form it. Lot of environmental legislations have been enforced on environmental pollution generated from industries which include legislation for:-
1) Environmental impact assessment
2) Stack emission standards
3) Coal beneficiation for reduced flyash content
4) Environmental clearance , Consent to operate , Consent to establish etc