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
