earths reasources Flashcards
whats a finite resource
something thats used up at a greater speed than it can be produced, usually natural made reasoruces
exaamples of finite reasoruces
limestone from hydrocarbons for builings
metal ores for mela extraction
crude oil for polymers and fuel
example of ethanol as a reneable resrouce
currently we use the hydrocarbon of ethene as a polymer/ fuel but we can use ethanol, made as a sugar plant
renewable reasources example
wood chips to be combusted at power stations
biofuels from recently dead plants
wave, hydroelectric, wind and solar fuel
what is potable water
water thats fit to drink
reasons water can become unclean
contains minerals from soil and ground
contains dissolved salts from oceans
dissolves and absorbs gases from the air as its precipitated
main steps of filtering water
passed through a crosshatched screen that collects any extremely large peices through filtration
sand and soil settle at the bottom
aliminium sulphate is added to the water making soluable solids clump together and collect as sludge/ mud for landfil with water at the top
chlorine is added to the clean water to make sure all bacteria is killed and then the ph is corrected incase of acidity
whats flash distillation
usually frac distillation to separate water works but is v expensive, here it can be done cheaper by using a lower pressure so that the water boils below 100c
what is desalination
converting salty water to pure, used in island countries and oil rich nations/deserts
whats reverse osmosis
using membranes to separate water and salt by membranes which remove the dissolves salt
no heating so less energy required than disstilation but is needed to pressurose the water
four main steps of sewage treatment and reasoning
screening
primary treatment
secondary treatment
final treatment
sewage has to be safe before it can be returned to the enviroment from toxins and bacteria etc
screening- sewage treatment- explained
like water treatment pass it througha metal grid to trap anything v large
primary stage- sewage treatment
solid sediments like sand can settle out and as sludge is pushed to the bottom where its piped out
secondary stage- sewage treatment
the water is now free of visable sludge but now bacteria feeds and decomposes any remaining microorganisms aerobically
final stage- sewage treatment
the water can go back to rivers
if needed it can be sterolised by chlorine/ ultraviolent radiation but then it may harm the ennviroment or need its ph altered
where does the bacteria go from the secondary stage
settles at the bottom of the tank, if its still a useful decomposer its recycled back to that stage or if not it can go with the sludge
uses of sludge after discarding in the prim treatment
it can be dried as fertiliser
it can form a biogas for renewable combustion
an be dried out to form a solid that can be combusted for electricity
four factors of a life cycle assesment
how the materials were sourced
how they were disposed of
how the product was used
how it was made
why to recycle alluminium
to requires HUGE amounts of energy to extract using electrolysis
recycling does not need to be extracted so mass saves energy
why recycle iron and steel
it is double the energy to extract iron and turn it to steel, mostly through combustion of finite reasources heating the iron in blast furnaces
enviromental impacts of mining ores rather than recycling
pollution arises from quarrying/ combustion
huge pits for mining scar the landscape
rain draining through exposed ores can become acidic slag heaps
limitations of LCA
its hard to find the data for each step for every product
companies can alter their LCA or lie to seem favourable
its hard to compare differnet harms eg climate change vs lung disease
criteria for potable water
no microorgansims
ph level between 6.5-8.5
level of soluable substances has to be kept low
test for water
anhydrous copper sulphate turns blue
