Using resources Flashcards
What do humans use the Earth’s resources to provide?
warmth
shelter
food
transport
What does sustainable development do?
it meets the needs of the current generation without compromising the ability of future generations to meet their own needs
What do natural resources supplemented by agriculture provide?
food
timber
clothing
fuel
For humans, drinking water should have sufficiently low levels of _______ and _________
dissolved salts and microbes
Why is potable water not pure water?
because it contains dissolved substances
How is potable water made?
1) freshwater from a suitable source
2) passed through a filter bed to remove any solid particles
3) chlorine gas is added to kill any harmful microorganism
4) fluoride is added to drinking water to reduce tooth decay
What can be used to sterilise the water?
Ozone and ultraviolet
Where does the UK get fresh water from?
the rain that collects in the ground and in lakes and rivers
What could we use if freshwater supplies are limited?
Seawater can be desalinated to produce pure water
this can be done by distillation or reverse osmosis
- both these processes use a lot of energy, making them expensive and no practical for producing large quantities of fresh water
What happens in reverse osmosis?
the salty water is passed through a membrane that only allows water molecules to pass through.
Ions and larger molecules are trapped by the membrane so separated from the water
What needs to be removed from wastewater?
organic matter, harmful microorganisms and toxic chemicals
What are the steps for sewage treatment?
1) screening and grit removal
2) sedimentation to produce sewage sludge and effluent
3) aerobic biological treatment of effluent OR anaerobic digestion of sewage sludge
What happens during sedimentation?
In a settlement tank, heavier suspended solids sink to the bottom to provide sludge while lighter effluent floats on the top
What happens during Biological aerobic digestion?
effluent is removed from the settlement tank,
air is pumped through the water to encourage aerobic bacteria to break down any organic matter - including other microbes in the water
What happens during anaerobic digestion?
sludge is removed from settlement tank and transferred into larger tanks.
Broken down by bacteria
How can copper be extracted from copper-rich ores?
- by heating ores with carbon in a furnace (smelting)
- form solutions of copper salts by electrolysis
- displacement using scrap iron
Which electrode is pure copper formed at?
negative electrode
What are the two biological methods to extract copper from contaminated land?
- phytomining
- Bioleaching
What happens in phytomining?
plants absorb and store copper as they grow
plants are then burned and the ash produced contains copper in relatively high quantities
What happens in bioleaching?
a solution containing bacteria is mixed with low-grade ore
bacteria converts copper into a leachate solution, from which copper can easily be extracted
Why are phytomining and bioleaching better for the environment than traditional methods?
because traditional mining involves digging up and moving large quantities of rock and having to dispose of large amounts of waste material
Why is copper useful?
- it is a good conductor of electricity and heat
- it is easily bent, yet hard enough for water pipes and tanks
- doesn’t react with water, so it lasts for a long time
What are life cycle assessments (LCA) used to do?
assess the environmental impact of a product has over its whole lifetime
What are the stages of LCA?
1) extracting and processing
2) manufacturing and packaging
3) use and operation during its lifetime
(how long the product is used for and what damage it does to the environment)
4) product disposal
What does manufacturing and packaging in LCA assess
how much energy is used and how much pollution is caused when the product is being made
What does product disposal in LCA assess
- whether the product is disposed of in a landfill site which takes up space and pollutes land and water
- how much energy is used to transport waste to landfill, which causes air pollutants
- whether the product will be incinerated which causes air pollution
What does extracting and processing in LCA assess
- how much damage is caused when raw materials are extracted
- whether the extraction causes pollution due to the amount of energy needed
How useful are LCAs
- use of water resources, energy sources and production of some wastes can be fairly easily quantified
- allocating numerical values to pollutant effect is less straightforward and requires value judgement, so LCA is not a purely objective process
- selected and abbreviated LCAs cab ve devised ti evaluate a product but these can be misused to reach pre-determined conclusions
