Using the Earth's resources and obtaining potable water

What do humans use the Earth’s resources for?

To provide warmth, shelter, food and transport.

Natural resources, supplemented by agriculture, provide food, timber, clothing and fuels.

Finite resources from the Earth, oceans and atmosphere are processed to provide energy and materials

Why does chemistry play an important role in improving agricultural and industrial processes?

To provide new products and in sustainable development, which is development that meets the needs of current generations without compromising the ability of future generations to meet their own needs.

What is water of appropriate quality is essential for?

Life. For humans, drinking water should have sufficiently low levels of dissolved salts and microbes.

What is potable water?

Water that is safe to drink is called potable water. Potable water is not pure water in the chemical sense because it contains dissolved substances.

What do the methods used to produce potable water depend on?

Available supplies of water and local conditions.

In the United Kingdom (UK), what type of water does rain provide?

Water with low levels of dissolved substances (fresh water) that collects in the ground and in lakes and rivers, and most potable water is produced by:

• Choosing an appropriate source of fresh water.

• Passing the water through filter beds.

• Sterilising

What do sterilising agents used for potable water include?

Chlorine, ozone or ultraviolet light.

What happens if supplies of fresh water are limited?

Desalination of salty water or sea water may be required. This can be done by distillation or by processes that use membranes such as reverse osmosis. These processes require large amounts of energy.

What do urban lifestyles and industrial processes produce?

Large amounts of waste water that require treatment before being released into the environment.

What do sewage and agricultural waste water require?

Removal of organic matter and harmful microbes

What may industrial waste water require?

Removal of organic matter and harmful chemicals.

What does sewage treatment include?

• Screening and grit removal.

• Sedimentation to produce sewage sludge and effluent.

• Anaerobic digestion of sewage sludge.

• Aerobic biological treatment of effluent.

Are the the Earth’s resources of metal ores limited or unlimited?

Limited.

As copper ores are becoming scarce, what do new ways of extracting copper from low-grade ores include?

Phytomining, and bioleaching. These methods avoid traditional mining methods of digging, moving and disposing of large amounts of rock.

What does phytomining use?

Plants to absorb metal compounds. The plants are harvested and then burned to produce ash that contains metal compounds.

What does bioleaching use?

Bacteria to produce leachate solutions that contain metal compounds.

What can the metal compounds can be processed to obtain?

The metal. For example, copper can be obtained from solutions of copper compounds by displacement using scrap iron or by electrolysis.