10.1 - Using the Earth's Resources & Obtaining Potable Water

What is sustainable development?

Development that meets the needs of current generations without compromising the ability of future generations to meet their own needs.

In the UK, how is potable water produced?

• Choosing an appropriate source of fresh water.

• Passing the water through filter beds to remove any solids.

• Sterilizing to kill microbes.

What are the sterilizing agents for potable water?

Sterilizing agents used for potable water include chlorine, ozone, or ultraviolet light.

• Chlorine is a toxic gas so the amount added to water has to be carefully monitored.

• Using ultraviolet light to kill microbes avoids adding chemicals to the water but is more expensive.

How is desalination carried out?

Desalination can be done by distillation or by processes that use membranes such as reverse osmosis. These processes require large amounts of energy.

What is reverse osmosis?

• Sea water is passed through a membrane that only allows through the water molecules.

• It needs high pressure to push the water through the membrane.

• The high pressure requires a lot of energy to produce.

How is wastewater produced and how is it treated?

• Urban lifestyles and industrial processes produce large amounts of waste water that require treatment before being released into the environment.

• Sewage and agricultural waste water require removal of organic matter and harmful microbes.

• Industrial waste water may require removal of organic matter and harmful chemicals.

What are the processes involved in sewage treatment?

• Screening and grit removal.

• Sedimentation to produce sewage sludge and effluent.

• Anaerobic digestion of sewage sludge.

• Aerobic biological treatment of effluent.

What do new methods of mining avoid in terms of disadvantages of traditional mining?

Avoids the disadvantages of traditional mining methods of digging, moving and disposing of large amounts of rock.

What is phytomining?

Uses plants to absorb metal compounds from the soil. The plants are harvested and then burned to produce ash that contains the metal compounds.

What is bioleaching?

Uses bacteria to produce leachate solutions that contain metal compounds.

What is the main advantage and disadvantage of phytomining and bioleaching?

These methods need less energy than traditional methods, and can work on low concentration ores but are slow to carry out.