4.10.1 - Using the Earth's resources and obtaining potable water

What do humans use Earth’s resources?

To provide warmth, shelter, food and transport.

What are natural resources used for?

When supplemented by agriculture, they are used to provide food, timber, clothing and fuels.

What are finite resources used for?

To provide energy and materials.

Give some examples of natural resources…

Plants, animals, fossil fuels, water and air.

What is the difference between finite and renewable sources?

Finite sources are limited and will eventually run out, however, renewable sources are unlimited and will never run out.

Give some example of finite resources…

Fossil fuels and ores.

Give some examples of renewable sources…

Water, wind and solar energy.

What is potable water?

Water that is safe to drink.

Why is potable water not pure water?

Because potable water as some dissolved substances in it such as mineral ions.

How is potable water produced in the UK? (fresh/ground water sources)

1. Choose an appropriate source of fresh water.

2. Pass the water through filtering beds. (dirt, sand, stones, twigs)

3. Sterilised the water using low amounts of chlorine, ozone, or ultraviolet light

How is potable water produced from oceans? (salty waters)

1. Desalination must take place first to remove salt, this can be done by distillation or by processes that use membranes (e.g. reverse osmosis)

2. Then the water is sterilised using chlorine, ozone, or ultraviolet light.

What is a disadvantage to deslanitation?

It takes up a lot of energy.

Examples of waste water and where it comes from?

Sewage, industrial waste water, agricultural waste water. (often contaminated)

Why does waste water have to be treated?

You need to remove; organic matter, harmful microbes and harmful chemicals.

What is the process of sewage treatment?

1. screening and grit removal, to remove any large insoluble substances

2. Then sedimentation to produce sewage sludge and effluent; this is where the water is transferred into a large settlement tank where smaller heavier insoluble solids with sink to the bottom (sewage sludge), and lighter insoluble matter will float to the top (effluent).

3. Then anaerobic digestion of sewage sludge will take place; this is where bacteria is added to the water to digest the organic matter and in turn they produce methane gas.

4. Then finally, aerobic biological treatment of effluent will take place to remove the effluent.

Are metal ores a finite or renewable resource?

Finite, because there is a limited supply of metal ores on Earth.

What is the traditional way of extracting metal?

Digging and moving around large amounts of rock with contain metals.

Why are traditional ways of extracting rocks no longer good?

Because metal ores supplies are scarce.

What are some alternative methods of extracting these metals?

Phytomining and bioleaching.

How does phytomining work?

It uses plants to absorb metals through their roots, and as the plants grow the metal accumulates in their stems and leaves. These plants are then harvested, dried and burned and the resulting ash contains the metal compounds where the useful metal can be extracted.

How does bioleaching work?

It uses bacteria that can break the ores to form acidic solutions, (a leachate), after you have the new metal ions you can use; electrolysis or displacement reactions to reduce them into the solid metal.

What is a disadvantage of phytomining?

It takes a long time for the plants to grow, produces greenhouse gases when plants are burnt into ashes.

What is the disadvantage of bioleaching?

Toxic substances are produced which can be harmful therefore have to be treated.