Question

Write some effective ways to control air pollution from petroleum and coal industries.

Answer 1

The main categories of air pollutants which are emitted from coal and petroleum industries are sulphur compounds (SOx), nitrogen compounds (NOx), carbon compounds ( CO2, CO ). In addition to these pollutants, particulate matter or lead emissions are also responsible.
The main criteria for controlling these emissions are :
Combustion in which the pollutants are destroyed
Conversion in which the pollutant is converted into less harmful one.
Collection in which the pollutant is prevented from going into the atmosphere.

Some of the methods employed by these industries are:
Benefication preocesses: In these processes, the mineral and the ash content in the coal is reduced before it is combusted. Hence releasing less amount of pollutants on combustion. This process is also called cleaning of coal. As it is carried out before the combusy of coal, it is a pre combustion method.

Scrubbers: Use of scrubbers is a widely used method for controlling the pollutants. It is a post combustion process in which the pollutants which are about to enter the atmosphere are made to pass through these scrubbers which capture the pollutants and prevent them from going into atmosphere.
It could be either dry scrubbing where the gases stream is made to pass through solid compounds such as sodium bicarbonate which neutraliszes the pollutants. In other cases nanoparticle laden scrubbers are used which adsorb the pollutants on their surface.
In case of wet scrubbing, the pollutants are made to pass through liquid sollutions e.g in case of CO2 capture, methanolamine is used as a solvent to absorb the CO2.

Air filters which employ a specific type of filtration media such fabric, sintered metal, ceramic to collect and remove dry particulates and contaminants and prevent them from going into atmosphere.
HEPA (high efficiency particulate air) filters or fabric filters are examples.

Desulphurisation process is used for the removal of sulphur compounds from the emission gases.
It involves removal of sulfur from a molecule or the removal of sulfur compounds from the flue gases. Eg. Limestone is used as a sorbent.

Selective catalytic reduction systems are another feasible method. These are basically control devices are used to mitigate nitrogen oxide (NOx) emissions produced by the burning of fuel compounds. These systems use ammonia to convert NOx into nitrogen and oxygen.