Manufacturing Industries
Industrial pollution and its control
Describe how industry pollutes and how pollution can be controlled.
The price of industry. Industries help the economy grow, but they also pollute. There are four kinds of industrial pollution: air, water, land and noise. Thermal power plants pollute too.
Air pollution. Gases like sulphur dioxide and carbon monoxide, and tiny bits of dust, mist and smoke in the air. Smoke comes from brick kilns, chemical and paper factories, refineries and smelters, and from factories that ignore pollution rules. Toxic gas leaks can do harm for many years: the book asks about the Bhopal gas tragedy. Air pollution hurts people, animals, plants, buildings and the whole atmosphere.
Water pollution. Paper, chemical, textile and dyeing, refinery, tannery and electroplating industries pour dyes, detergents, acids, salts and heavy metals like lead and mercury into rivers. Thermal pollution: hot water from factories and power plants is let into rivers and ponds before it cools, which harms fish and other water life. India's main solid wastes are fly ash, phospho-gypsum and steel slag. Waste from nuclear plants can cause cancer and birth defects.
Land and noise.
- Land: dumped glass, harmful chemicals, packaging, salts and garbage make soil useless. Rain carries the poison down, so groundwater gets polluted too.
- Noise: machines, generators, saws and drills cause irritation, anger and stress, and can lead to hearing loss, a faster heart rate and higher blood pressure.
Cleaning up water. Every litre of factory waste water pollutes eight times as much fresh water. So:
- reuse and recycle water in two or more stages;
- harvest rainwater;
- treat hot water and waste before letting it out;
- control by law how much groundwater industries pump.
Treatment has three stages: primary (mechanical: screening, grinding, settling), secondary (biological), tertiary (biological, chemical and physical, and recycling the water).
Cleaning up air and noise.
- Fit chimneys with electrostatic precipitators, fabric filters, scrubbers and inertial separators to catch particles.
- Burn oil or gas instead of coal to cut smoke.
- Fit generators with silencers, redesign machines to be quieter and more energy-efficient, use noise-absorbing material, and give workers earplugs.
NTPC shows the way. NTPC, a big power company, holds ISO 14001 certification for managing the environment. It:
- uses modern equipment to the full;
- uses its ash instead of dumping it;
- manages ash ponds and recycles ash water;
- plants green belts;
- keeps watching the environment at all its power stations.
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