(a) Explain the role of industries in increasing air pollution and suggest any three measures to reduce air pollution.

Role of Industries in increasing air pollution:

(i) Air pollution is caused by the presence of a high proportion of undesirable gases, such as sulphur dioxide and carbon monoxide.

(ii) Air borne particulate materials contain both solid and liquid particles like dust, sprays mist and smoke.

(iii) Smoke is emitted by chemical and paper factories, brick kilns, refineries and smelting plants, and burning of fossil fuels in big and small factories that ignore pollution norms.

(iv) Toxic gas leaks can be very hazardous with long-term effects.

Measures to reduce air pollution:

(i) Particulate matter in the air can be reduced by fitting smoke stacks to factories.

(ii) Electrostatic precipitators, fabric filters, scrubbers and inertial separators can also be fitted.

(iii) Smoke can be reduced by using oil or gas instead of coal in factories.

(iv) Authorities should impose heavy fines on industries violating emission laws.

(b) Explain the role of industries in increasing water pollution and suggest any three measures to reduce water pollution.

Role of industries in increasing water pollution:

(i) Water pollution is caused by organic and inorganic industrial waste and affluents discharged into rivers.

(ii) Main culprits are paper, pulp, chemical, textile and dyeing, petroleum refineries, tanneries and electroplating industries

(iii) They let out dyes, detergents, acids, salts and heavy metals like lead and mercury pesticides, fertilizers, synthetic chemicals with carbon, plastics and rubber, etc. into the water bodies.

(iv) Fly ash, phospho-gypsum and iron and steel slags are the major solid wastes in India.

Measures to reduce water pollution:

(i) Minimizing use of water for processing by reusing and recycling it in two or more successive stages

(ii) Harvesting of rainwater to meet water requirements

(iii) Treating hot water and effluents before releasing them in rivers and ponds.

(iv) Treatment of industrial effluents can be done in three phases

(a) Primary treatment by mechanical means. This involves screening, grinding, flocculation and sedimentation.

(b) Secondary treatment by biological process

(c) Tertiary treatment by biological, chemical and physical processes. This involves recycling wastewater.