C14 Flashcards
whar are finite resources
being used up at a faster rate than they can be replaced
why are some predictions for how long finite resources will last invalid
they don’t take into account the significance recycling will have in the future
what is a more sustainable way of making plastic rather than using ethene from crude oil
use ethene made from ethanol which is made by fermenting glucose from sugar cane
how is fresh water treated to make it safe for drinking
passed through filter beds made of sand and gravel to remove solid particles and chlorine or ozone is added to sterilise the water by killing microorganisms or passing uv light through to not use chemicals
what is desalination
the process of converting salty water to potable water
what is reverse osmosis
a process to desalinate water which uses membranes to separate water and the salts dissolved in it
why is reverse osmosis better than distillation
no heating involved so less energy used however energy is still used to pressurise water
what is a con of distillation for purifying salt water
expensive because of energy costs involved in boiling large volumes of water
what is the process of sewage treatment
grit and large solid objects are removed from waste water.
solid sediments are allowed to settle out from the mixture into a storage tank
watery liquid flows to the next tank
useful bacteria feed on any remaining organic matter and harmful microorganisms break down anaerobically
useful bacteria is then recycled back to treatment tank so waste water can be discharged back into rivers
what happens to sludge from the sewage
dried and used as fertiliser on farmland
one of the breakdown products is biogas
what is biogas used for
power sewage treatment plants or provide electricity
