C14:TheEarth'sResources Flashcards
why do we rely on the earths resources
to make new products and provide us with energy
finite definition
resources that will eventually run out if we continue to exploit them
example of a finite resource
fossil fuels
renewable definition
resources that can be replaced as we use them up
example of a renewable resource
crops used to make biofuels
why can estimates of how long fossil fuels have left only be a rough estimate
because of the uncertainty involved in calculations
potable water
water that is safe to drink
how is water made fit to drink
by passing it through filter beds, adding chlorine or ozone or UV light through it
why is water passed through filter beds
to remove any solids
why is chlorine/ozone/UV light used in water treatment
to remove any microbes-sterilisation
why isn’t our drinking water made by distillation
as it requires a large amount of energy which makes it expensive
how can water be made fit to drink by reverse osmosis
by using membranes to separate dissolved salts from salty water but this method of desalination also uses energy to get the high pressure conditions needed
where does wastewater require treatment before being released into the environment
sewage works
what does sewage treatment involve
the removal of organic matter and harmful microorganisms and chemicals
name the stages of sewage treatment
screening, sedimentation, aerobic biological treatment
what happens in screening
the removal of large solids and grit
what happens in sedimentation
production of sewage sludge
what happens in the aerobic biological treatment phase
safe effluent released into the environment
effluent definition
watery liquid
what happens to the sewage sludge
it is separated, broken down by anaerobic digestion and dried
what can the sludge be used for
fertiliser and a source of renewable energy
how is most copper extracted
by smelting copper rich ores
what is happening to the amount of copper
becoming more scarce
what can electrolysis be used for with copper
purify impure copper e.g. copper metal obtained from smelting
how can copper be extracted from solutions of copper compounds
by electrolysis or displacement
2 ways scientists have developed to extract copper from low-grade ores
bioleaching and phytomining
what is used in bio-leaching
bacteria
what is used in phytomining
plants
explain phytomining
plants that absorb copper are planted on soil containing low-grade copper ores, the plants are burned and copper is extracted from copper compounds in the ash, leachate is then made, electrolysis makes pure copper
how can copper ions be “leached”
dissolved by adding sulfuric acid to make leachate of copper sulfate
explain bio-leaching
bacteria feed on low-grade ores, leachate is obtained, scrap iron and electrolysis is used to extract the copper from the leachate
how much copper comes from bioleaching
20%
what are LCAs
life cycle assessments
what are LCAs used for
to assess the environmental impact of products, processes or services
what do LCAs analyse
each of the stages of a life cycle from extracting and processing raw material to disposal at the end of its life including transportation and distribution at each stage
what is data available for
the use of energy, water, resources and production of some wastes
by assigning numerical values to the relative effect of pollutants involves what
subjective judgements
what are subjective judgements
judgements that are relative to the person making the judgement
what is the aim of reduce reuse recycle
to reduce our use of limited resources, energy and the waste we produce
what does recycling material save
energy and our limited finite metal ores, pollution is also reduced by recycling
