Topic 10- using resources

what is the life cycle assessment

analyses different stages in a product in order to assess its impact on the environment

what are the 4 main stages of the LCA

1-extracting and processing the raw materials

2-manufacturing and packaging your product

3-using your product

4-product disposal

describe the extracting and processing the raw material

• extracting raw material needed for a product can damage the environment e.g. mining metals. As a result it causes pollution due to amount of energy needed. Processed which uses huge amount of energy and release pollutants.

describe the manufacturing and packaging in the LCA

• use lots of energy resources causing pollution e.g. carbon monoxide or hydrogen chloride

• produce lots of waste products which have to be disposed off

Describe the using of product in the LCA

• can damage the environment e.g. burning fossil fuels releases greenhouses gases and other harmful substances- fertilisers can leach into streams

• how long a product lasts and how many times it is used is alosa factor - products that need lots of energy to produce but are used for ages mean less waste in the long run

describe the product disposal in the LCA

• products are often disposed in landfill sites which takes up space and pollutes land and water- chemicals might seep out to ecosystems

• energy is used to transport waste to landfill

• products might be incinerated/burnt

what are the limitations/problems with the LCA

-making products involves loads of different steps- which is almost impossible to quantify them and so even with all the data it is difficult to assess the harm of each step

-because the LCA is so complex they can easily be manipulated to deliberately support a company do give the company positive advertising so they can be biased

what is potable water

is water that has been treated or is naturally safe for humans to drink

why is potable water not pure

Pure water would only contain H2O whereas potable water contains other dissolved substances as well

for water to be potable what does it need

• levels of dissolved substances need to be fairly low

• Ph between 6.5-8.5

• make sure no micro-organisms like bacteria or fungi are in it

what factor may depend on where you get potable water from

depending on where you live

how is rainwater a type of fresh water and what two places can it be found

-Rainwater is a type of fresh water and doesn’t have much dissolved in it- it can be collected as surface water (in lakes, reservoirs and rivers) or as ground water(in rocks that trap water under ground)

why does the south east of UK mostly use water from groundwater

because the surface water tends to dry up fast in warm areas

what are Pros of surface water

easy to access and replaced frequently

what are the 2 steps in treating fresh water

1-(FILTRATION) take fresh water and pass it through a wire mesh to prevent large twigs, then pass it through a bed of sand and gravel to filter out any other solid bits

2-sterillisation - to kill any harmful bacteria or microbes- can be done by bubbling chlorine gas through it or by using ozone or ultraviolet light

why do some countries use sea water and what process must it go through

use sea water because country doesn’t experience lots of rain, seawater must be treated by desalination

how to test whether water is potable from desalination

1-test for pH of water by using a pH meter - if its too high or too low you’ll need to neutralise it which can be done by titration.

2-test the water for the presence of sodium chloride- do this by a flame test or small sample. If sodium ions are present the flam will turn yellow. To test for chloride ions add a few drops of dilute nitric acid, followed by a few drops of silver nitrate solution if chlorine is present a white precipitate will form.

how to desalinate seawater

3-to distil the water, pour the salty water into a simple distillation apparatus (cooling jacket/condenser, thermometer) heat the flask and the water will boil, water vapour will evaporate and condense into liquid in the condenser to be collected as it runs out which separates it from the salt

4-then retest the distilled water to check salt has been removed and the pH of water is neutral 7.

what are the 3 main sources of water waste

domestic, agricultural systems and industrial

how does domestic produce water waste

domestic- water from showers, sinks and toilets- as soon as its flushed it goes to the sewers and to the sewage treatment plants

how does agricultural systems produce waste

agricultural systems- produces waste water from nutrient run of from fields and animal waste from farms

how does industrial produce water waste

industrial- refers to factories that make and use chemicals creating waste

how is domestic and agricultural waste treated

treated by removing any organic matter or harmful microbes before it can be put back into fresh water sources like rivers otherwise it would pollute water and cause health risk

how is water waste from industrial treated

waste water from industrial processes often contain harmful chemicals as well and so requires extra steps to remove them

how does sewage treatment work/ what’s it process

1-before being treated sewage is screened - this removes anything large as well as grit by passing it through a mesh

2-sewage then sits in a settlement tank and undergoes sedimentation where heavier solids sink to the bottom to produce sludge while the lighter part called effluent at the top

3-the effluent at the top is removed and treated by biological aerobic digestion - where air is pumped through the water to encourage aerobic bacteria to break down any organic matter

4-the sludge from the bottom is removed and transferred to large tanks where its broken down by bacteria- anaerobic digestion. This releases methane gas which is used as energy and the remaining digested waste is used for fertiliser.

5-for waste water containing toxic substances, additional stages of treatment may involve adding chemicals, UV radiation or using membranes