Chapter 22 Cleaner Technology

NIOS Class 12 Environmental Science Chapter 22

INTEXT QUESTIONS 22.1

1. Name the six categories of waste found in the surroundings.

Ans:

Industrial solid waste
Industrial liquid waste
Municipal solid waste
Municipal liquid waste
Gaseous waste
Radioactive waste

2. State the various ways the gaseous wastes can be used up.

Ans: Carbon dioxide emitted from various sources can be used to produce calcium carbonate; sulphur dioxide emitted can be converted into either elemental sulphur or gypsum. Gas from a petroleum field can be converted into methanol and petrol.

3. Define cleaner technology.

Ans: Cleaner technology is being used in industry to produce products and goods with minimal or no waste and pollution production.

4. What is “throw-away” economy? How is it responsible for accumulating waste?

Ans: The throw-away economy is using the products or goods once or partially and disposing of them as waste.

INTEXT QUESTIONS 22.2

1. What should be our priority in tackling waste management?

Ans: Our priority in tackling waste management is to reduce the production of waste. Waste prevention should be our priority rather than managing the waste once it has been produced.

2. What are the three Rs in waste management?

Ans: The three Rs in waste management are waste reduction, reuse and recycle. Reducing consumption and redesigning products, we can reduce waste. The reuse of products will reduce waste. Waste can be turned into useful products by recycling.

3. Give examples of primary and secondary recycling.

Ans:

Primary recycling occurs when the waste is recycled into a new product of the same type, like old newspapers that are recycled to produce new newsprint material.
Secondary recycling occurs when the waste material is converted into different products, like old automobile tyres are shredded and turned into materials to be used in rubberized road surfacing.

4. What is fuel-efficient car? How does it save resources?

Ans: A fuel-efficient car gives more mileage with less petrol and hence valuable resource like petrol.

INTEXT QUESTIONS 22.3

1. What is ‘background radiation’?

Ans: We receive a large amount of radiation from natural sources. It is present everywhere, all the time. This radiation is known as background radiation.

2. What is a radionuclide?

Ans: Radioactive atoms are known as “radionuclides.”

3. What are the different steps of the fuel cycle?

Ans: Nuclear “fuel cycle” begins with

Mining of uranium ore from the underground mines.
The ore is then crushed (milled) into sand and then concentrated using a solvent to produce “yellow cake”.
It is then sent to a factory where it is turned into fuel “pellets” which are packed into rods.
The rods are inserted in the core of a reactor, which undergoes a nuclear reaction under controlled conditions to avoid explosion.
The reaction (fission) produces tremendous heat, which boils water to make steam, and the steam turns a turbine to produce electricity.

4. Name the two recent nuclear disasters and their consequences?

Ans: Three Mile Island (USA) in 1979 and Chernobyl (Ukraine) in 1986. People at the site of the disaster suffered immediately by getting exposed to a high dose of radiation. Their chances of cancer increased. The effect of radiation spreads out to faraway places, exposing people to the risks of cancer and other health hazards.

5. Name three sites which can be used to dispose of nuclear waste.

Ans: Sites with low precipitation, with a deep water table and absence of surface water.

INTEXT QUESTIONS 22.4

1. What do you understand by the life cycle of a product?

Ans: “Life cycle” of a product means major activities in the course of the life span of a product that are acquiring the raw material for its manufacture, use, maintenance and final disposal.

2. What are the objectives of eco-labelling?

Ans: The main objectives of ecolabelling are as follows-

Protecting the environment and making consumers aware of environmental issues.
Encouraging efficient management of renewable resources to ensure their availability
to future generations.
Promoting efficient management of non-renewable resources, including fossil fuels.
Encouraging protection of ecosystems and species diversity.
Encouraging proper management of chemicals to prevent pollution.

3. What is the Indian ecolabel known as, and what is the symbol?

Ans: It is known as “Eco-mark,” and the symbol is an “Earthen Pot”. The earthen pot symbolizes a biodegradable, fully harmless material.

TERMINAL EXERCISE

1. Define the term ‘Cleaner Technology’. What is the main aim of the management of this concept?

Ans: ‘Cleaner technology’ is using technology in industries in such a way that the environment is protected from the harmful effects of waste accumulation and resulting pollution. The aim is to make industrial manufacturing processes cleaner and more sustainable by redesigning them, taking clues from nature, that is, how nature deals with wastes. In nature, waste or the leftovers of one organism becomes food for another organism, so that nutrients of the earth are endlessly recycled.

2. List the six major types of wastes generally produced.

Ans:

Industrial solid waste: Solid waste produced by thermal power plants in the form of coal ash, iron and steel mills as blast furnace slag, mud from sugar industries, lime mud from paper industry, gypsum from fertilizer industries, etc.
Industrial liquid waste: Liquid effluents from industries are discharged into the rivers or streams without any treatment.
Municipal solid waste: Vegetable rejects from domestic units and vegetable markets, plastic material, building debris,bio-medical waste, etc.
Municipal liquid waste: Sewage from hotels and residential colonies.
Gaseous waste: Various gases emitted from industrial installations, such as carbon dioxide emitted can be used to produce calcium carbonate. Sulphur dioxide can be converted into either elemental sulphur or gypsum. Waste heat from hot gaseous emissions can be recovered for suitable use.
Radioactive waste: The waste from nuclear power plants is highly hazardous to living organisms and therefore requires careful planning for its disposal and treatment.

3. Explain briefly the three ‘R’s of waste management.

Ans: The three Rs strategy of waste management involves reduce, reuse and recycle.

Reducing consumption and redesigning the product (s) are the best ways to cut waste production. Some of the ways to reduce resource use are
- To consume less, do not buy unless you absolutely need it
- Develop products that are easy to repair, reuse, and recycle.
- Design products which last longer and can be used for longer
- Reduce or get rid of unnecessary packaging, or use reusable and recyclable packaging.
Reuse: Reuse of products is an important way to reduce resource use, reduce pollution and waste. Reuse means cleaning and using the materials over and over, thereby extending the life span of the products.
Recycling: Recycling is an important way to collect waste material and turn it into useful products that can be sold and used again.

4. Explain the following terms:

(a) Throw away economy (b) Bioremediation (c) Ecolabelling (d) Ecomark

Ans:

(a) Throw-away economy: Throw away economy is using the products or goods once or partially and disposing of them as waste.
(b) Bioremediation: Bioremediation is the process in which a living organism, such as a plant, animal, bacteria, etc, is deployed to make hazardous wastes harmless.
(c) Ecolabelling: Labelling of environmentally beneficial goods and resources extracted by more sustainable methods.
(d) Ecomark: Eco Mark is the eco labelling scheme in India.

5. Give three examples of which waste production can be reduced by redesigning products or processes?

Ans: Some of the ways to reduce resource use by redesigning are:

Redesign manufacturing processes and products to use less material and energy. Example- Fuel-efficient cars which will give more mileage using fuel.
Redesign manufacturing processes to minimize waste, for example, the use of hydrogen peroxide instead of toxic chlorine to bleach paper in the manufacturing process.
Design products which last longer, like car tires which run for longer distances before they get damaged.
Reduce or get rid of unnecessary packaging, or use reusable and recyclable packaging.

6. Explain the terms primary recycling and secondary recycling. Give examples.

Ans:

Primary recycling occurs when waste is recycled into new products of the same type, like turning old newspaper into new newspaper material, used aluminum cans into new aluminum cans, and waste plastic bags into useful waste collection plastic bags.
Secondary recycling occurs when waste materials are converted into different products. For example, used automobile tyres can be shredded and turned into material to be used as rubberized road surfacing, and newspaper can be turned into cellulose insulation, short fibres from the paper pulp industry can be converted into paper boards.

7. Briefly state the steps of the ‘fuel cycle’ and the hazards that they cause.

Ans: Nuclear “fuel cycle” begins with

Mining of uranium ore from the underground mines.
The ore is then crushed (milled) into sand and then concentrated using a solvent to produce “yellow cake”.
It is then sent to a factory where it is turned into fuel “pellets” which are packed into rods.
The rods are inserted in the core of a reactor, which undergoes a nuclear reaction under controlled conditions to avoid explosion.
The reaction (fission) produces tremendous heat, which boils water to make steam, and the steam turns a turbine to produce electricity.

Hazards:

Uranium ore and mill waste remain heaped in deserts because there is no place to store them. They blow around with the wind and wash with rain, giving out radioactive gas for thousands of years in future.
New radioactive elements (Stronsium-90 and Plutonium-239) are also produced.
Radiations can be released from them.

8. Explain briefly the two nuclear disasters that took place in 1979 and 1986 with regard to causes, effects and preventive measures.

Ans:

The Three Mile Island disaster occurred on 14th March 1979.

Cause: The breakdown of the main pump and failure of the other auxiliary pumps led to the stoppage of the electricity-generating turbine.
The emergency coolant did flow, but it did not cool the reactor but the faulty meter showed it otherwise.
The core melt under this high temperature and radioactive steam was thrown into the atmosphere. This was a nuclear disaster.
Effects: Pregnant women and children were removed from the accident site. It was over a year before anyone could enter the plant.

Chernobyl (Ukraine) on 25 April 1986

Cause: A test to measure the amount of electricity that would be produced even if the steam was shut off, but the turbine would still be spinning, was conducted.
To reduce the output of steam, control rods were lowered into the core.
To prevent further delay in testing, the cooling system was manually turned off.
As the test or the experiment continued, the energy level of the reactor increased two thousand times, the fuel rods broke, and the cooling water turned into steam.
This resulted in the explosion that the reactor ripped off the concrete roof of the reactor.
Effects: Radioactive fumes spread caused radiation sickness and increased their chances of suffering from leukemia (blood cancer). Chernobyl put 300-400 million people at risk in fifteen countries.

Preventive Measures

Mechanical design of the reactor should be such that the reactor shuts down immediately under such conditions.

9. State five sites and locations where nuclear wastes can be disposed of.

Ans: Potentially usable sites or locations where nuclear waste can be disposed of should have some characteristics like-

Low precipitation
Deep water table
Slow-moving groundwater
Absence or near absence of exploitable resources in the area
Absence of surface waters
Low possibility of tectonic movement
Adequate buffer zone (in case the waste gets loose).

10. Explain the concept of life cycle assessment of a product.

Ans: Life Cycle Assessment (LCA) is a concept which considers the entire life cycle of a product. It involves all stages of the life cycle of the product, e.g. raw material extraction, material transportation, manufacturing, product use and disposal of out-of-service product, etc. Life Cycle Assessment (LCA) is done systematically:

Aim, or goal, i.e. define or describe the product, process or activity.
Inventory analysis, i.e. identify and quantify energy, water, material used and environmental releases (e.g. air emissions, solid waste disposal and wastewater discharge)
Impact assessment, i.e. assess the human and ecological effects of energy, water and material usage and the environmental releases identified in the inventory analysis.
Interpretation, i.e. evaluate the results inventory analysis and impact assessment to select the preferred product or service.