Control of Air pollution by controlling Particulate Matters

Airborne Particulate Matters (PM) - Pollution Prevention and Control:

Airborne particulate matters (PM) emissions can be minimized by pollution prevention and emission control measures. Prevention, which is frequently more cost-effective than control, should be emphasized. Special attention should be given to mitigate the effects, where toxics associated with particulate emissions may pose a significant environmental risk.

Measures such as improved process design, operation, maintenance, housekeeping, and other management practices can reduce emissions. By improving combustion efficiency in Diesel engines, generation of particulate matters can be significantly reduced. Proper fuel-firing practices and
combustion zone configuration, along with an adequate amount of excess air, can achieve lower PICs (products of incomplete combustion). Few following steps should be adhered to control PM:

1. Choosing cleaner fuels - Natural gas used as fuel emits negligible amounts of particulate matter.

2. Low-ash fossil fuels contain less noncombustible, ash-forming mineral matter and thus generate lower levels of particulate emissions.

3. Reduction of ash by coal cleaning reduces the generation of Particulate Matter (PM) emissions.

4. The use of more efficient technologies or process changes can reduce PIC emissions.

5. Advanced coal combustion technologies such as coal gasification and fluidized-bed combustion are examples of cleaner processes that may lower PICs by approximately 10%.

6. A variety of particulate removal technologies, are available – these are (a) Inertial or impingement separators, (b) Electrostatic precipitators (ESPs) , (c) Filters and dust collectors (baghouses), (d) Wet scrubbers that rely on a liquid spray to remove dust particles from a gas stream.

The principal methods for controlling the release of particulate matter are summarized here.

• Identify measures for improving operating and management practices.

• Consider alternative fuels such as gas instead of coal.

• Consider fuel-cleaning options such as coal washing, which can reduce ash content by up to 40%.

• Consider alternative production processes and technologies, such as fluidized bed combustion, that result in reduced PM emissions.

• Select optimal particulate removal devices such as ESPs and Baghouses.

Air pollution by Particulate matters (Fine and Coarse Dust particles):

Air pollution by Particulate matters (Fine and Coarse Dust particles):

‘Fine particles’ are less than 2.5 micron in size and require electron microscope for detection, however, they are much larger than the molecules of Ozone etc., and other gaseous pollutants, which are thousands times smaller and cannot be seen through even electron microscope.

Fine particles are formed by the condensation of molecules into solid or liquid droplets, whereas larger particles are mostly formed by mechanical breakdown of material or crushing of minerals. ‘Coarse particles’ are between 2.5 to 10 micron size, and cannot penetrate as readily as of Fine particle; however, it has been seen these are responsible for serious health hazards. The severity of the health hazards vary with the chemical nature of the particles.

The inhalation of particles has been linked with illness and deaths from heart and lung disease as a result of both short- and long-term exposures. People with heart and lung disease may experience chest pain, shortness of breath, fatigue etc., when exposed to particulate-matter pollutants. Inhalation of particulate matter can increase susceptibility to respiratory infections such as Asthma, Chronic Bronchitis. The general medical term given for such lung diseases is ‘Pneumoconiosis’.

Emissions from diesel-fuel combustion in vehicles / engines / equipments; Dusts from cement plants, power plants, chemical plants, mines are a special problem, specially for those individuals breathing in close proximity to such atmosphere. Cars, trucks and off-road engines emit more than half a million tones of diesel particulate matter per year.

WE SEEK YOUR HELP TO SAVE ENVIRONMENT

Your few following small steps and effective decisions in everyday life would be a big leap in helping us to improve global environment.

1. Make energy efficient and conservation wise decisions in every sphere of life.
2. While driving motor vehicle, turn off the engine if waiting is longer. More fuel is wasted when idling than restarting. Be alert in traffic. Try to take alternate routes which have few signals to eliminate idling.
3. Warm-up the motor vehicle for one minute before moving. Accelerate gently and evenly and use your cruise control to maintain a steady speed.
4. Use motor vehicle's flow through vents instead of air conditioning (which decreases fuel efficiency by 21%) or by opening window.
5. Keep car engine tuned. A poorly tuned car wastes 15% more fuel. More fuel, means more pollution and travel fewer miles.
6. Properly inflate & align tires to save fuel & to reduce wear on tires over time.
7. Reduce the amount of miles you drive. Fewer distance driven, fewer polluting emissions created. Walk or ride a bike!
8. Use fuel efficient automobiles. Follow state guidelines on emissions testing & maintain any pollution-control devices.
9. Use public transportation when available.
10. Conserve electricity, including turning off lights when not in use.
11. Participate in recycling programs. Recycling conserves energy and also conserves natural resources.

Mechanism of Adverse Impact of Smoke Pollutant

Mechanism of Adverse Impact of Smoke Pollutant:

The main sources of smoke pollutants in urban areas are Petrol / Diesel driven motor vehicles, Fuel combustion in stationary sources including residential, commercial and industrial heating / cooling system and coal-burning power plants etc.

Petrol / Diesel driven motor vehicles produce high levels of Carbon Dioxide (CO2) / Carbon Monoxide (CO), major source of Hydrocarbon (HC) and Nitrogen oxides (NOx). Fuel combustion in stationary sources is the dominant source of Carbon Dioxide (CO2) and Sulfur Dioxide (SO2).

Carbon Dioxide (CO2) – This is one of the major gas pollutants in the atmosphere. Major sources of CO2 are due to burning of fossil fuels and deforestation. Industrially developed countries like USA, Russia etc., account for more than 65% of CO2 emission. Less developed countries with 80% of world’s population responsible for about 35% of CO2 emission. Due to high growth reported from less developed countries in last decade, it is estimated that, the Carbon dioxide emissions may rise from these areas and by 2020 their contribution may become 50%. It has also been seen that, Carbon dioxide emissions are rising by 4% annually.

As ocean water contain about 60 times more CO2 than atmosphere; CO2 released by the industry leads to disturbance of equilibrium of concentration of CO2 in the system. In such a scenario, the oceans would absorb more and more CO2 and atmosphere would also remain excess of CO2. As water warms, ocean’s ability to absorb CO2 is reduced. CO2 is a good transmitter of sunlight, but partially restricts infrared radiation going back from the earth into space. This produces the so-called “Greenhouse Effect” that prevents a drastic cooling of the Earth during the night. This so-called “Greenhouse Effect” is responsible for GLOBAL WARMING. Currently Carbon Dioxide is responsible for major portion of the global warming trend.

Nitrogen oxides (NOx) - They come mainly from nitrogen based fertilizers, deforestation, and biomass burning. Nitrogen oxides contribute mostly as atmospheric contaminants. These gases are responsible in the formation of both acid precipitation and photochemical smog and causes nitrogen loading. These gases have a role in reducing stratospheric ozone.

Sulfur Dioxide (SO2) - Sulfur dioxide is produced by combustion of sulfur-containing fuels, such as coal and fuel oils. SO2 also produced in the process of producing Sulfuric Acid and in metallurgical process involving ores that contain sulfur. Sulfur oxides can injure man, plants and materials. As emissions of sulfur dioxide and nitric oxide from stationary sources are transported long distances by winds, they form secondary pollutants such as nitrogen dioxide, nitric acid vapor, and droplets containing solutions of sulfuric acid, sulfate, and nitrate salts. These chemicals descend to the earth's surface in wet form as rain or snow and in dry form as a gases fog, dew, or solid particles. This is known as acid deposition or acid rain.

Choloroflurocarbons (CFCs) - Chlorofluorocarbons, also known as Freons, are greenhouse gases that contribute to global warming. CFCs are responsible for lowering the average concentration of ozone in the stratosphere.

Smog – Smog is the result from the irradiation by sunlight of hydrocarbons caused primarily by unburned gasoline emitted by automobiles and other combustion sources. Smog is created by burning coal and heavy oil that contain mostly sulfur impurities.

Air pollution by Industry

Air pollution by Industry:
Air pollution is the presence of high concentration of contaminations, dust, smokes etc., in the general body of air man breaths. Pollutants are mixture of solid particles and gases in the air. Some air pollutants are poisonous. Inhaling them can increase the chances of health problems. People with heart or lung disease, older adults and children are at greater risk from air pollution.

Prime sources of air pollution are the industrial activities or processes releasing large quantity of pollutants in the atmosphere. These pollutants are mainly: (a) Smoke comes out from various industries like, power plants, chemical plants, other manufacturing facilities, motor vehicles, etc.; (b) Burning of wood, coal in furnaces and incinerators; (c) gaseous pollutants from Oil refining industries; (d) dust generated and thrown to general atmosphere by various industries such as cement plants, ore / stone crushing units, mining industries due to rock drilling & movements of mining machineries & blasting etc.; (e) Waste deposition for landfills which generate methane; (f) Toxic / germ / noxious gasses and fumes generated from military activities and explosives blasting in mines.

Air pollution control devices / equipments for industries:
The commonly used equipments / process for control of dust in various industries are (a) Mechanical dust collectors in the form of dust cyclones; (b) Electrostatic precipitators – both dry and wet system; (c) particulate scrubbers; (d) Water sprayer at dust generation points; (e) proper ventilation system and (f) various monitoring devices to know the concentration of dust in general body of air.
The common equipments / process used for control of toxic / flue gases are the (a) process of desulphurisation; (b) process of denitrification; (c) Gas conditioning etc. and (d) various monitoring devices to know the efficacy of the systems used.