C14 The Earth's Resources Flashcards
two types of natural resources
finite
renewable
what are renewable natural resources
natural resources that can be replaced at the same rate that they are used up
what are finite natural resources
natural resources used up faster than they can be replaced
what is potable water
water that is fit to drink
steps to produce potable water
- pass untreated water through filter beds made of gravel/sand to remove solid particles,
- passes through a screen to remove large objects like twigs,
- passes through settlement tank so soil and sand settle out,
- add aluminium sulphate and lime so dirt clumps together and sinks to the bottom for separation,
- add chlorine/ozone or pass through ultraviolet to kill harmful microorganisms (sterilise)
- check pH is neutral and store in reservoirs
why is water passed over ultraviolet or chlorine/ozone added
to kill harmful microorganisms/sterilise
what is desalination?
turning salty water usable and potable
two methods of salivation
distillation
reverse osmosis
summarise energy costs for distillation as desalination
expensive, a lot of money needed to boil so much water
even with reduced pressure
summarise costs for reverse osmosis as desalination
no money needed for heating
however expensive to pressurise the water
and replace corroded water pumps
four main steps of sewage treatment
- screening and grit removal to remove large particles
- sedimentation so tiny particles settle out of the still water, leaving sludge and effluent (liquid layer on top)
- sewage sludge is anaerobically digested by specific bacteria
- effluent is treated with aerobic bacteria to reduce volume of solid waste
what is done with extra sludge from sewage treatment?
- used as fertiliser,
- dried out into a ‘cake’ used to provide electricity
how is sludge digested during sewage treatment?
anaerobically by specific bacteria
how is effluent treated during sewage treatment?
with aerobic bacteria to reduce the volume of solid waste
two methods of obtaining copper metal from ore
- smelting: heat copper ore to form impure copper, then electrolyse it,
- use sulphuric acid to produce copper sulphate solution then displacing the copper from this with iron.
what is the aim of bioleaching and phytomining?
to extract copper from low-grade ores
how is copper obtained from bioleaching
plants absorb copper compounds,
the plants are harvested and then burned
to produce ash that contains copper compounds
which can be displaced by iron and electrolysed to obtain pure copper
how is copper obtained from phytomining
bacteria feed on low-grade metal ores
to produce leachate solutions that contain metal compounds
which can be obtained by displacement by iron and electrolysis
what is a Life Cycle Assessment?
a technique to assess the environmental impact of a process, product or service from the point of getting the raw materials to when they are disposed back into the environment
stages of a product/process/service considered in a LCA?
- extracting and processing raw materials,
- manufacture and packaging,
- use and operation during its lifetime,
- disposal at the end of its useful life, including transport and distribution.
environmental impacts of quarrying and mining
- damages animal habitats, stressing ecosystems,
- scarring landscape and causing noise,
- making groundwater acidic,
