Pollutants

Pollutants are ingredients causing pollution. They may be gases, liquids, solids of different chemical composition or may be high pitched sounds. The pollutants are not deliberately manufactured. But they are the by products of manufacturing processes. At different stage of manufacturing, these pollutants may be generated. As they are not useful to manufacture any useful product of commercial value, they are sent out of the industries.

The pollutants from industries are of different types and carry varying importance. The type of pollutant generated out of manufacturing process depends upon the nature of materials used during manufacturing process as wall as technology adopted to process them.

Gaseous Pollutants

During the process of manufacture, most industries produce pollutants. Most common gaseous pollutants released by industries are:

Carbon monoxide

Highly dangerous gas with a high potentiality of causing cancer and respiratory ailments. Generally, it is evolved, when a fuel is burnt under limited supply of oxygen.

Carbon dioxide

It is also a pollutant, when generated in large quantity - because it can reduce the oxygen concentration in the air. It is a gas produced when fuel is burnt in adequate oxygen.

Normally, the atmospheric air will have 0.03% CO₂. When its concentration increases due to pollution, it reduces the percentage of oxygen in atmosphere.

Sulphur dioxide

Sulphur dioxide(SO₂) is one of the dangerous pollutant with a potentiality to form sulphuric acid, when mixed with water vapour. Water vapour commonly available in air can mix with SO₂ gas and produce sulphuric acid.

Such sulphuric acid is the cause of acid rain.

Dry and Wet Acid Deposition or Acid Rain

Hydrogen sulphide

Hydrogen Sulphide(H₂S) is one of the dangerous, pungent pollutant gas with many deleterious effects respiratory tract. It is released from many industries as a part of sulphonation process.

Hydrogen Cyanide (HCN)

When cyanide chemicals are used in manufacturing process, hydrogen cyanide is formed as a by product. It is a highly corrosive and poisonous gas leading to eye irritations, respiratory problems as well as other complications. In high doses, it can cause death.

Ammonia Gas

In many industries, ammonia gas (NH₃) is used as reducing agent. It is a corrosive gas with a high potentiality of causing throat irritations, burning of pharynx, oesophagus, etc. It can also cause digestive problems - when excess gas is inhaled.

Liquid Pollutants

Many liquid pollutants are evolved during the process of manufacturing pesticides, medicines and other chemicals. Liquid pollutants are also released during the process of refinement and processing. Some of them are dangerous and cause serious implications on drinking water quality.

The types of liquid pollutants can be

• acids - hydrochloric, acetic, fumaric, sulphuric, nitric, benzoic

• bases - hydroxides of sodium, calcium, magnesium

• carboxylic compounds

• nitrogenous wastes