Using Resources Flashcards
Define potable water
Water that is safe to drink
Water of suitable quality essential for human life
For humans to water should have sufficiently low amounts of dissolved salts and microbes
How is potable water made in the UK
Water is filtered- leaves,stones,large material is removed
- water moves through settlement tank and any sediment settles at the bottom of tank
-aluminium sulfate is added. It makes the particles clump together and settle at bottom
-water is passed through fine sand and gravel to remove more particles
- sterilisation - water is sterilised (kills microbes) with chlorine or UV light
- check pH and adjust if needed
- water is then transported to homes and offices
Describe 2 methods for purifying salt water (desalination)
How is potable water made in foreign countries?
Desalination by distillation
- salty water is heated and water evaporates but salt is left
- water is cool, condensed and collected as pure fresh water
Desalination by reverse osmosis
- using high pressure, salty water is forced through a semi permeable membrane
- the salt is removed and the water moves through
What is the difference between potable water and pure water?
Potable water has microbes and dissolved substances but pure water doesn’t
Plan an investigation to find the total mass of dissolved solids in a 100cmcubed sample of the drinking water
Weigh evaporating basin
Add 100cmcubed of water
Reweigh the water and evaporating basin
Heat it using a Bunsen burner to evaporate water
Heat and reweigh until the mass stays constant
Repeat it 3 times
Find an average mass of dissolved salts
Describe how sewage water is treated
- sewage arrives and goes through a pumping station
- large objects are filtered from the water during screening
- primary sedimentation- large paddles swirl water and solids sink and are collected at bottom
- some sludge is digested (anaerobic in biogas tank), is used as solid fuel, fertiliser, biogas and landfill sites and generates electricity
- the sludge that isn’t digested- bacteria feed aerobically on organic matter and kill harmful bacteria during biological treatment (aerobic digestion)
- secondary sedimentation- good bacteria are removed here
- Cl2, O3, UV - sometimes water is disinfected/sterilised at this point using chlorine, ozone or UV light
- pumped into seas and rivers
What is the sludge when treating sewage water used for?
To make fertiliser, biogas, solid fuel and is dried and taken to landfill sites or used to generate electricity
Explain what happens in a biogas tank and how biogas is produced
- sewage waste (sludge) contains organic matter
- carried out at temperatures between 35-55 degrees Celsius
- in the digester microorganisms will respire anaerobically to produce biogas
- any solid matter left is pumped out and used as fertiliser
-the biogas produced can be burned to generate electricity (methane, CO2, hydrogen sulphides)
Why do we carry out life cycle assessments?
To assess the environmental impact of a product through all stages of its life
In what stages are life cycle assessments used?
- extracting and processing raw materials
- manufacturing and packaging
- use and operation during its lifetime
- disposal at the end of its useful life, including transport distribution at each stage
What are low grade copper ores
Rock that has small amounts of copper in it
How do we extract low grade copper ores?
Phytomining- uses plants
- plants are grown on low grade copper ores, they absorb copper ions from the soil by their roots - can grow plants on contaminated soil
- plants are burned which releases CO2. You are left with plant ash containing copper ions in copper oxide
- use electrolysis to extract copper from copper oxide but have to melt or dissolve the plant ash first
- this uses a renewable resource and carbon is neutral
- is a slow process but can be sped up by using fast growing plants
Bioleaching- uses bacteria
- bacteria feed on low grade copper ores and produce a leachate ( a solution that passes through and organism)
- this leachate contains copper ions
- use electrolysis to extract the copper from the leachate
- produces toxic chemicals that can be released to environment
- is a slow process
How do we extract copper rich ores?
Smelting (heat it lots) - heat copper carbonate a lot and it produces CO2 and copper oxide
- add sulfuric acid to copper oxide to make copper sulfate solution
- displacement- copper (CuSO4) + iron (fe) -> iron sulfate (FeSO4) + copper (Cu)
Or use electrolysis- to make copper and oxygen
Why do we make ammonia- nitrogen- based fertilisers?
- needed by plants for growth
- plants use it for making proteins
- plants take up soluble nitrate ions NO3 (aq) through their root hair cells
- we need nitrogen based fertilisers because when we harvest crops nitrogen is removed
Why is ammonia important?
- 80% nitrogen in atmosphere
- nitrogen gas is insoluble in water
- plants need a soluble form
- ‘fixing’ nitrogen- when gaseous nitrogen is turned into nitrogen compounds that can be absorbed in solution by plants
