C14 -the earths recourses Flashcards
what are natural resources classified as
Natural resources can be classified as finite and renewable
what are finite resources
finite resources = those that are being used up at a faster rate than can be replaced
what are renewable resources
renewable = those that can be replaced at the same rate that they are being used up at
Examples of finite resources and there uses
Examples of finite resources:
1. fossil fuels = used as energy sources and to make polymers and petrochemicals
2. trees = used for wood
3. metal ores = used to extract metals
4. limestone = used to make cement and concrete
what is potable water
potable water = water that is safe to drink
what are aquifers
aquifer = underground sources of water
what do natural sources of water tend to have
water from natural sources will contain dissolved minerals (salts), microorganisms from soil and decaying matter
what are 3 ways to make water potable
passing untreated water through filter beads made of sand and gravel to remove sand particles
the addition of chlorine or ozone which sterilises the water by killing microorganisms
passing UV light through the water also sterilises the water by killing microorganisms
how can seawater from marshes be purified
seawater or salty water from marshes can be purified by using distillation –> BUT it’s an expensive process
what is a disadvantage of normal distillation
it is expensive
what is an alternative to normal distillation
flash distillation = in reduced pressure, water boils at a lot less than 100 degrees Celsius so less energy is needed to evaporate it, so it is easier and cheaper to distill
what is desalination
desalination = converting salty water to potable, usable water
explain reverse osmosis
reverse osmosis = uses membranes to separate water and the salts dissolved in it
there is no heating so this uses less energy than distillation
energy is still needed to pressurise the water passing through
what is the problem with reverse osmosis
A problem with reverse osmosis is the corrosion of the pumps caused by salty water
PRACTICAL: analysis and purification of water samples
test the pH of a salty sample given by teacher
teacher will give another sample - desalinate by distillation
test half the sample by distilled water collected for pure water by measuring its boiling water - pure water boils at 100 degrees celsius
test the pH of the othr hald of the distilled water sample
why do we have to boil water instead of using other methods
u have to use these testing methods and not a test for water as those tests will only show the presence of water, not if it is pure or not
what is sewage
sewage = is the collective term for all waste water that drains into large sewer pipes
what is the first step in sewage treatment
screening - sewage passes through a grid that traps large objects and grit from the rest of the waste water
what are the steps in primary treatment
Primary Treatment:
in the first circular tank, solid sediments are allowed to settle out from mixture
large paddles rotate and push solids (called sludges) to the centre –> piped to a storage tank for further treatment
the watery liquid (effluent) flows into the next tank containing many potentially harmdul microorganisms
what are the steps in secondary treatment
Secondary Treatment:
In the second tank, useful bacteria feed on the remaining organic matter and microorganisms by breaking them down aerobically
tank is aerated by bubbling air through wastewater –> takes from hours to days depending on the quality of water, size of tank, rate of aeration and temperature
sludge is anaerobically digested
what are the steps in the final treatment
Final Treatment:
in the last tank, bacteria settles at the bottom as sediment –> recycled back into the tank or passed into the tank where sludge is treated
Treated water is safe enough to be discharged back into rivers
If a river is a particularly sensitive ecosystem, water can be filtered be more time through a bed of sand, or sterilised using UV light or chlorine
what are the concerns with using chlorine in water treatment
chlorine used is a concern as toxic organic compounds of chlorine can be formed in the environment
what is a use of sludge
after further treatment, sludge can be used as fertilisers on farms or as renewable energy
what does sludge contain and how is it broken down
sludge contains organic matter(human waste), suspended solids, water, and dissolved compounds
it’s digested anaerobically by microorganisms at the bottom of the tank
how can biological treatment be sped up
biological treatment can be carried out at 35-55 degrees celsius to speed up the process
what can we do with the breakdown of biological treatment products (name them)
breakdown products can include biogas which can be burned
or sludge can be dried out to make a crusty, solid cake which can be burned
what can impure copper be used for
impure copper can be used as a positive electrode in electrolysis to make pure copper
name two ways that we can obtain copper metal from the ore
two main methods used to obtain copper metal from the ore:
sulfuric acid - used to produce copper sulfate solution before extracting the copper metal
smelting (roasting) = copper ore is heated in a furnace with air to produce impure copper
explain phytomining
phytomining = plants that can absorb copper ions are grown on soil containing low grade copper ore
plants are then burnt and copper is extracted from copper compounds in the soil
copper ions can be dissolved from ash by adding sulfuric acid
explain bioleaching
bioleaching.= bacteria feed on low-grade metal ores - by a combination of biological and chemical processes a solution of copper
ions (leachate) can be obtained from waste copper ore - scrap iron and electrolysis are used to extract the copper from the leachate
what 4 things does the LCA assess
The Life Cycle Assessment (LCA) is used to assess the impact on the environment caused by:
getting and processing the raw materials
making the product (and any packaging)
using, reusing and maintaining the product
disposing of a product at the end of its useful lif
what is the LCA
The Life Cycle Assessment (LCA) is used to assess the impact on the environment
How is the LCA assessed
An LCA is carried out by:
listing all the energy and material inputs and outputs into the environment
- evaluating the potential environmental impacts of these inputs and outputs
- interpreting results to help make decisions about one material, process, product or service over another
summarise the stages of the LCA
the stages in a LCA can be summarised as:
raw material extracted –> manufacture –> use/reuse/maintenance –> recycle/waste management
what are output LCAs
outputs in a LCA are: atmospheric emissions, waterborne wastes, and coproducts
what is the aim of the Reduce,reuse, and recycle campaign
The aim of reduce, reuse and recycle campaigns are to reduce:
our use of limited resources
our use of energy
the waste we produce
what are the benefits of the Reduce, reuse, and recycle campaign
recycling metals reduces the need to mine the metal ore
this prevents pollution problems from extractions and reduces habitats being destroyed by mining
