Modern technologies to mitigate air pollution
- 1. MODERN TECHNOLOGIES TO MITIGATE AIR POLLUTION Presented by Jasia Jannat Exam roll:1857 Department of Soil,Water and Environment University of Dhaka
- 2. Air lets our living planet breathe—it's the mixture of gases that fills the atmosphere, giving life to the plants and animals that make earth such a vibrant place. Pollution is now a common place term, that our ears are attuned to. A physical, biological or chemical alteration to the air in the atmosphere can be termed as pollution. What is Air Pollution Air is almost entirely made up of two gases (78 percent nitrogen and 21 percent oxygen), with a few other gases (such as carbon dioxide and argon) present in absolutely minute quantities.
- 3. Sources of air pollution Source Natural source Dust and Wildfires Animal and Vegetation Volcanic activity Anthropogenic source Burning of fossil fuels Exhaust from factories and industries
- 5. Air Pollution Disasters 1.Bhopal Gas Leak (1984) 3,800 people died and approximately and 1,000 were reported with disabilities. Smog torpedoed air quality in Beijing and 24 other Chinese cities authorities to declare a national red alert for ‘severe fog’—the highest level of alerts in 2015. 2.Red Alert in China (2015) Fig: Bhopal Gas Plant
- 6. Air pollution in Dhaka City
- 7. The scenario of emission of air pollutants in Dhaka city
- 8. Identification of Air Quality PM2.5 10 μg/m3 (annual mean) 25 μg/m3 (24-hour mean) PM10 20 μg/m3 (annual mean) 50 μg/m3 (24-hour mean) Ozone 100 μg/m3 ( 8-hour mean) Nitrogen Dioxide 40 μg/m3 (annual mean) 200 μg/m3 (1-hour mean) Sulfure Dioxide 20 μg/m3 24-hour mean 500 μg/m3 10-minute mean The World Health Organisation (WHO) air quality guidelines are designed to offer guidance in reducing the health impacts of air pollution.
- 9. Modern Technologies To Control Air Pollution Control of particulates Cyclone: • Removes particulates by causing the dirty airstream to flow in a spiral path inside a cylindrical chamber. • Best at removing relatively coarse particulates and routinely achieve efficiencies of 90% for particles larger than about 20 μm (0.0008 inch). • Not sufficient to meet stringent air quality standards. They are typically used as pre-cleaners. Fig : Cyclone
- 10. Scrubber • Used to remove harmful materials from industrial exhaust gases before they are released into the environment. • There are two ways of scrubbing- wet and dry scrubbing. Electrostatic precipitators • Used for removing fine particulates from airstreams. • Particles suspended in the airstream are given an electric charge as they enter the unit and are then removed by the influence of an electric field. Fig: Wet Scrubber Fig: Electrostatic Precipitators
- 11. Bag house filters • One of the most efficient devices for removing suspended particulates is an assembly of fabric filter bags commonly called a bag house. • A typical bag house comprises an array of long, narrow bags each about 25 cm (10 inches) in diameter that are suspended upside down in a large enclosure. • Dust laden air is blown upward through the bottom of the enclosure by fans. Particulates are trapped inside the filter bags while the clean air passes through the fabric and exits at the top of the bag house.
- 12. • Absorption involves the transfer of a gaseous pollutant from the air into a contacting liquid such as water. • It can also be carried out in packed scrubbers, or towers, in which the liquid is present on a wetted surface rather than droplets suspended in the air. Control of Gases: Absorption Fig : Packed wet scrubber
- 13. Adsorption Gas adsorption methods are used for odor control at various types and stages of chemical-manufacturing and food-processing facilities in the recovery of a number of volatile solvents (e.g., benzene) and in the control of VOCs at industrial facilities. Activated carbon (heated charcoal) is one of the most common adsorbent materials. Fig: Fixed Bed Adsorber Incineration The process called incineration or combustion can be used to convert VOCs and other gaseous hydrocarbon pollutants to carbon dioxide and water.
- 14. • 11 Continuous Air Quality Monitoring Stations (CAMS) installed in 8 cities to monitor major air pollutants and to generate real time air quality data including air quality index for major cities. • For the first time in Bangladesh, 1 clean technology (VSBK) successfully introduced which emit around 60%-70% less particulate matter than the traditional fixed kilns. • CASE directly tackles pollution by encouraging the adoption of cleaner brick manufacturing technologies that require less energy such as New Zig Zag Kilns, Improved Zig-Zag Kiln, Vertical Shaft Brick Kiln, Mini Tunnel or Horizontal Shaft Brick Kiln, alternative building material and Tunnel Kiln. Air pollution control in Bangladesh
- 15. Conclusion Air pollution has become a major environmental issue due to rapid population growth, intensification of agriculture and industrialization. As without air we are nothing so it is high time to take steps. After considering merits and demerits of all technologies, electrostatic precipitators is very much feseable because it generates no negative environmental backlashes. Though it has high capital cost and takes a lot of space but it has the ability to handle very large gas flow rates with low pressure losses.
- 16. Pollution- If you don’t kill it It will kill you