Using Resources (Unit 10) Flashcards
Define Sustainable Development
Development that meets the needs of people today without compromising the ability of future generations to meet their own needs.
What are ‘finite’ resources?
Resources that can run out
What are ‘renewable’ resources?
Resources that can be easily replaced as they are used up
Define ‘sustainable’
Maintained at a certain level over long periods of time
What is potable water?
Water that is safe to drink
- there are low levels of dissolved salts/minerals
- free of microbes
Who needs potable water?
Humans: to drink
How do you treat ground water?
1) Choose fresh water source (e.g. rain, ground, rivers)
2) Filter out the solids
3) Sterilise to kill microbes
More specifically, how do you treat ground water?
1) Water is collected at a resevoir
2) Large insoluble objects are filtered (SCREENING)
3) Water is passed through sand and soil sediment where small particulates are filtered off
4) Chemicals added to rid of small particles
5) Treated to kill bacteria and pH is check to ensure it’s neutral
6) Water transported to homes, factories, offices
Name three ways water is sterilised.
Chlorine
Ozone
UV rays
When would one try to treat salty water?
In hot countries near the sea with little ground water/rain
What is an issue of treating salty water?
It is expensive
- as it requires a lot of energy
How do you treat salty water?
DESALINATION of salty water
- distillation (evaporated and condense water form salty solution)
- reverse osmosis (filter water via semi-permeable membrane)
What is the issue of reverse osmosis?
It requires a lot of energy
What’s different about treating waste water?
Have to remove organic matter using harmful chemicals
Define waste water
Sewage or dirty water
How do you treat waste water?
1) Screening: remove solids
2) Sedimentation: filter water through sediment to filter out smaller particles. This produces SEWAGE SLUDGE and EFFLUENT
3) Sewage sludge (solid, viscous) is processed by ANAEROBIC DIGESTION to remove harmful microorgansims from organic matter
4) Effluent (water bit) is treated by ANAEROBIC BIOLOGICAL TREATMENT which allows ‘good’ bacteria to feed of ‘harmful’ microorganisms. This is called AERATION
What happens to the effluent?
Effluent is discharged to sea, or can be sterilised with UV/ozone/chlorine to be used for drinking.
What happens to the sewage sludge?
Sewage sludge is used
- as a fertiliser
OR
- as a source for renewable energy e.g. BIOFUEL
What are ores?
Rocks with metal compounds
What are ores useful for?
Water pipes, electrical wires, computer components
What issue are we facing with metal ores? What’s the result of this?
They are finite resources and so are running out. That is why copper is expensive
What are scientists doing to tackle this problem?
They are extracting from low grade ores as they’re more plentiful.
What are the differences between high grade and low grade ores?
High grade ores have high % of metal
Low grade ores are <1% metal
Why was it economical to ‘smelt’/carbon heating or electrolysis of high grade ores?
The metal extracted compensated for the energy costs of the extraction process.
What are the issues of extracting from low grade ores?
- Using traditional extraction methods isn’t economical because the reward is too small
- More rocks have to be mined, which scars more land
How are scientists tackling the issues of extracting low grade ores?
High grade ores they use traditional methods e.g. electrolysis
BUT WITH LOW GRADE ORES, they use PHYTOMINING and BIOLEACHING
What is phytomining?
1) PLANTS are grown on metal ore
2) THEY take up metal ions/Cu+ from the soil and store in their cells
3) Plants are burnt to release the compounds stored in the plant
4) The metal ions/Cu+ in the ash are reacted with sulfuric acid to get copper sulfate salt.
5) Copper is displaced via smelting or electrolysis
What are the pros and cons of phytomining?
Pros: this process de-contaminates land filled with toxic metal
Cons: the plants have to be able to absorb copper/specific metal ions
What is bioleaching?
1) BACTERIA breaks down the copper in low grade ore/soil
2) THIS produces a metal SOLUTION or salt e.g. CuSO4
3) The copper/metal ions is displaced using ELECTROLYSIS or DISPLACEMENT REACTION
What is the salt solution from bioleaching called?
LEACHATE
At what electrode is the metal ion attracted to?
Negative electrode/cathode
What is the half equation for the electrolysis of copper?
Cu2+ (aq) + 2e- —> Cu (s)
How is the cooper/metal solution displaced?
Using a more reactive metal e.g. iron
What is screening?
Water is passed through an large mesh to filter out large particles e.g. leaves
Define sedimentation
Smaller particles are allowed to settle
Define sewage treatment
Process of removing organic matter, microbes, and chemicals from waste water
What is metal extraction?
Taking out pure metal from its ore
Define electrolysis
Decomposition of of molten or aqueous IONIC compound using electricity
What metal ion is becoming particularly expensive nowadays and why?
Copper as it is running out
What is reverse osmosis?
Water passed through membrane that only allows water to pass through. Needs high pressure to push water through membrane. Lot of energy so costly.
