What is portable water?
- water that is safe to drink
- contains very low levels of dissolved salts and microbes
- free from harmful chemicals and substances
Difference between portable water and pure water?
- pure water only contains H2O molecules but portable water can include various forms of dissolved substances
Three steps to obtain portable water from fresh water?
1) select water source: in the UK water providers usually collect water from fresh water sources with low levels of dissolved substances
2) water is passed through wire and mesh sand beds to help remove solid particles
3) water treated with sterilising agents like chlorine and ozone or exposed to UV light to make safe from microbes
What does the methods used to produce portable water depend on?
- available supplies of water
- local conditions
Why does the UK primarily use groundwater?
- its drier southeast reigon Leads to less surface water
What is used in places where there’s les fresh water?
- desalination of salty water or sea water
How to find amount of dissolved solid in a water sample?
- record mass of dry evaporating basin using mass balance
- pour a known volume of water sample into evaporating basin
- heat evaporating basin until its mass stays constant when all the water has evaporated
- record mass of evaporating basin and contents
- mass of dissolved solid= end- start
Methods to purify water?
- add water sample to boiling flask
- heat water using Bunsen burner until boiling occurs
- water vapour will pass through condenser and condense
- distilled water will be collected in beaker, leaving any contents behind
How to analyse the water collected from purifying water?
- checking pH use a pH meter: should be close to 7
- check purity by checking boiling point: should be 100C
Where does waste water come from?
- household activities: bathing, washing dishes, flushing toilets, water typically goes into sewers
- agricultural run offs and industrial processes
What need to be done to sewage and agricultural waste water?
- remove harmful microbes and organic matter by treating so they can be returned to environment
Whats needed to be done to industrial water?
Removal of organic matter AND harmful chemicals
What are the 5 steps of the sewage treatment process?
1) screening and grit removal: removing large objects such as plastics, twigs..
2) sedimentation: water stored in large tanks so sludge (heavy solids) settles to the bottom and effluent floats to the top
3) effelunct treated with aerobic bacteria that consume organic matter
4) sludge from sedimentation tank broken down by bacteria in a no-oxygen environment—> produces methane and fertilisers
5) additional treatment necessary for water contaminated with hazardous chemicals which may include UV radiation and membrane treatment
Why do we desalinate water?
When theres less freshwater
Why can we use sewage treatment in areas where’s theres less freshwater?
- although theres more processes involved
- requires less energy than desalination
Two ways to produce salt from salty water?
Desalination and reverse osmosis
What are metal ores?
Finite resources
Why are alternative methods of extracting metal ores becoming more important?
Because metal ores are becoming harder to find and extract
Why is traditional mining harmful? What can be done instead?
- because digging and mining can damage the environment
- extract low grade ores which are rocks with small amounts of metal
What are the two methods for extracting low grade ores?
- photomining
- bioleaching
What is photomining? Three steps involved?
- using plants to absorb metal compounds from the soil
1) grow plants on the soil where there are metal compounds
2) harvesting them once they have absorbed the metal compounds and drying them
3) burning the dried plants to produce ash which contains the metal compounds
What is bioleaching? Steps?
- using Bacteria to extract metals
- bactria introduced to the ore where they produce leachate SOLUTIONS that contain metal compound
- leachate then collected and contains the desired compound
What happens after you get the metal compounds from photomining or bioleaching?
- dissolved in acid so they can be processed and extract the pure metal
