C14

Question 1

sewage

Answer 1

the general name for waste water from homes, businesses and industry. This, plus waste water from farming activities, must be treated at sewage plants

Question 2

sewage treatment

Answer 2

Removes organic matter and harmful microbes from sewage and agricultural waste water. This process makes sewage safe so that it can be returned to the environment.

Question 3

Industrial waste water

Answer 3

May also need harmful chemicals removing

Question 4

Sewage treatment stages

Answer 4

1. screening
2. sedimentation
3. aerobic biological treatment, anaerobic digestion of sludge

Question 5

screening

Answer 5

Removes large solid objects and grit from the waste water

Question 6

sedimentation

Answer 6

solid sediments (sludge) settle out from the mixture. The watery liquid above the sludge is called the effluent. The effluent still contains many potentially harmful microorganisms.

Question 7

Treatment of the effluent

Answer 7

aerobic biological treatment. In the effluent, useful bacteria feed on any remaining organic matter and harmful microorganisms.

Question 8

Treatment of the sludge

Answer 8

The sludge contains organic matter, including human waste. It is digested anaerobically by microorganisms.
The dried sewage sludge can then be used as a fertiliser or as a source of renewable energy.

Question 9

smelting

+ disadvantages

Answer 9

produces copper from copper-rich ores.
uses lots of energy
expensive and causes environmental pollution

Question 10

bioleaching

Answer 10

extracts copper from low-grade ores

Uses bacteria to produce a solution of copper compounds (leachate) from waste copper ores.

Question 11

advantages of bioleaching and phytomining

Answer 11

can extract copper from low grade ores- conserves resources
less of an environmental impact than smelting, reduced use of fossil fuels compared to smelting
more economical

Question 12

phytomining

Answer 12

extracts copper from low-grade ores
plants are grown on the low-grade copper ores
plants absorb copper ions
plants are burnt
copper is extracted from the copper compounds in the ash

Question 13

What happens to the copper after phytomining and bioleaching

Answer 13

Copper must be purified.
Scrap iron then added to solutions of the copper compounds to displace the copper.
Electrolysis can also be used to extract pure copper from solutions of copper compounds.

Question 14

stages of an LCA

Answer 14

extracting raw materials
product manufacture
product use/reuse/maintenance
recycle/waste management

Question 15

Why should an LCA be peer reviewed?

Answer 15

to check the data, and validility of the conclusions drawn.
(since allocating values to environmental impacts is subjective)
desirable if the LCA is made by the company making the product being assessed, and its results are used to make claims in advertising.

Question 16

aim of the ‘reduce, reuse, recycle’ campaign

Answer 16

reduce the use of limited resources and energy sources
produce less waste
reduce pollution

Question 17

Glass recycling

Answer 17

glass crushed and melted to make different glass products

Question 18

advantage of recycling metals

Answer 18

conserves the limited reserves of metal ores

reduces energy as energy needed to extract metal from ore

Question 19

recycling metals

Answer 19

Can be recycled by melting
Using recycled steel saves 50% of the energy used to extract iron and steel.
To conserve iron ore, some steel scrap is added to the blast furnace.

Question 20

What do human’s use the Earth’s resources for?

Answer 20

to provide warmth, shelter, food and transport.

Question 21

What has increased the supply of natural resources?

Answer 21

Farming of plants and animals

chemists developing synthetic alternatives to some natural resources

Question 22

finite resources

Answer 22

used up at a faster rate than they can be replaced

will eventually run out

Question 23

renewable resources

Answer 23

resources that can be replaced at the same rate that they are used.

Question 24

potable water

Answer 24

water that is safe to drink

Question 25

potable water should…

Answer 25

have sufficiently low levels of dissolved salts
and microbes.
not contain any harmful substances

Question 26

Is potable water pure?

Answer 26

No because it contains dissolved substances

Question 27

What does the methhod used to produce potable water depend on?

Answer 27

available supplies of water and local conditions.

Question 28

freshwater

Answer 28

rainwater, collects in lakes/rivers

contains low levels of dissolved substances

Question 29

producing potable water from fresh water

Answer 29

1. Obtaining fresh water from lakes/rivers
2. Passing the water through filter beds to remove solid particles
3. Sterilising the water to kill microorganisms by adding chlorine or ozone, or by passing UV light through the water
   Done in the UK as there are sufficient supplies of fresh water

Question 30

What is used if supplies of fresh water are limited?

Answer 30

Salty water or seawater (must be desalinated to become potable).

Question 31

Desalination

Answer 31

Can be done by distillation or reverse osmosis

These processes require lots of energy and is very expensive.

Question 32

Reverse osmosis

Answer 32

Can be done to desalinate water.

Uses membranes to seperate the water from the salts dissolved in it.

Question 33

How to identify pure water

Answer 33

1. Test the pH using universal indicator or a pH probe. Pure water has a pH of 7.
2. measure its boiling point. Pure water boils at 100 degrees celsius.
   Test for dissolved solids- do crystallisation. Any dissolved solids would be left in the evaporating basin.