C14: The Earth's resources Flashcards
what are finite resources
resources that are being used up faster than they can be replaced
what are renewable resources
resources that can be replaced at the same rate which they are used up
what is potable water
water that is drinkable
purifying potable water step 1
passing untreated water through filter beds made of sand and gravel to remove solid particles
purifying potable water step 2
adding ozone or chlorine to sterilise water by killing microorganisms
OR
passing ultra-violet light through the water
why don’t countries with salty water just distil it ?
it’s very expensive
what to countries with salty water do?
desalination (reverse osmosis)
what happens during reverse osmosis
membranes separate the water and salt in it. no heating and less energy
cons of reverse osmosis
energy still needed to pressurise water passing through
corrosion of pumps by salty water
what are the steps of sewage treatment
-arrives at pumping station
-screening
-primary sedimentation
-secondary treatment
-final treatment
what happens during screening
large objects are removed by a metal grid
primary treatment
solid settlement settle out from the mixture, paddles rotate and force the ‘sludge’ to sludge digestion
secondary treatment
useful bacteria feed on organic matter and harmful microorganisms, aerobic.
tank is continuously aerated with bubbling air
final treatment
useful bacteria settle, sediment recycled back into secondary or sludge.
water discharged back to rivers
sewage sludge treatment
-dried as fertiliser
-biomass fuel
-dried to form fuel ‘cake’
IT IS DIGESTED ANAEROBICALLY
two methods of extracting copper from copper-rich ores
-sulfuric acid produces copper sulfate solution
-smelting, heated to make impure copper. impure copper makes pure copper in electrolysis
two methods of extracting copper in low-grade copper ores
-bioleaching
-phytomining
explain bioleaching
bacteria feed on the ores, leachate (copper ions) obtained from waste copper ore. electrolysis used to make pure copper
explain phytomining
plants absorb copper ions grown on the soil, they are burnt and copper is extracted from copper compounds in the ash.
add sulfuric acid to make copper sulfate solution and use electrolysis.
what is the LCA
Life Cycle Assessment
what does the LCA assess?
the impact on the environment caused by:
-getting and processing raw materials
-making product
-using, reusing and maintaining
-disposing product
how is LCA carried out by measuring
-energy and material inputs and outputs
-potential environmental impacts
-interpreting results to make better eco product
summarised stages of LCA
raw mineral extraction -> manufacture -> use/reuse -> maintenacne -> recycle/ waste management
how do we recycle aluminium
melting scrap metal
how do we recycle iron and steel
use scrap material instead of extracting new material
copper recycling
difficult as usually an alloy, can be melted down from high-quality wires
