C14 - Earths Resources Flashcards
What is sea water?
Water in the seas and oceans
What is ground water?
Water in underground streams, rocks, and aquifiers
What is fresh water?
Water in underground streams and rocks, rivers, lakes, ice caps, and glaciers
What is waste water?
Used water from homes, industry, and agriculture
What is Potable water?
Water that is fit to drink
What is pure water?
Water that is 100% pure and contains nothing else
What are the levels of microbes in Sea water?
High levels
What are the levels of dissolved substances in Sea water?
High levels
What are the levels of microbes in ground water?
low levels
What are the levels of dissolved substances in ground water?
low levels
What are the levels of microbes in fresh water?
low levels
What are the levels of dissolves substances in fresh water?
low levels
What are the levels of microbes in waste water?
high levels
What are the levels of dissolved substances in waste water?
high levels
What are the levels of microbes in potable water?
none or low levels
What are the levels of dissolved substances in potable water?
low levels
What are the levels of microbes in pure water?
none
What are the levels of dissolved substances in pure water?
none
How do you make potable water from fresh water?
1) Filtration
2) Sterilisation
What is filtration and what does it do when making potable water from fresh water?
*Filtration is done by passing water through a wire mesh screen then filter beds (usually sand)
*This removes solids
What is sterilisation and what does it do when making potable water from fresh water?
*Sterilisation is done by adding chlorine, treating with ozone, or using UV light
*This kills microbes in the water
What process makes potable water from sea water?
Desalination
What are the 2 desalination methods?
* Distillation
* Reverse Osmosis
How does reverse osmosis work?
Salt water is put through a partially-permeable membrane, which only allows water molecules to pass through. This happens as the membrane stops larger molecules and ions passing through
What are the 6 stages of waste water treatment?
1) Screening and grit removal
2) Primary sedimentation tank
3) Aeration
4) Final settling tanks
5) Sludge treatment
6) Burners
Explain the process of waste water treatment:
- Waste water flows into sewers
- Large solids and grit are removed in Screening and grit removal
- Organic waste sinks to the bottom as sludge in the Primary Sedimentation tanks, whilst the remaining water (effluent) is taken from the top
- Good Bacteria kill harmful bacteria in aeration tanks where air if pumped through the effluent to provide aerobic conditions
- The good bacteria sink to the bottom as sludge in the Final settling tanks
- Treated water is returned to the environment
- Sludge from the Primary Sedimentation tanks and the final settling tanks is digested in anaerobic digestion by bacteria in the sludge treatment, releasing Methane
- Methane is burned for heat and electricity generation in the Burners
What are the requirements for water to be considered potable?
*should have a pH between 6.5 and 8.5
*Dissolved substances present in only small regulated amounts
*free of bacteria or harmful microbes
Where is desalination often used to produce fresh water?
regions with a very hot climate, such as Saudi Arabia
Why is desalination not ideal for producing large quantities of fresh water?
It is an expensive process as it requires large amounts of energy
What is effluent?
liquid waste or sewage discharged into a river or the sea
What does the sludge produced when treating waste water contain?
Undigested organic matter
Where is most copper extracted from?
From copper-rich ores
How is copper extracted from copper-rich ores?
*The copper ore is smelted (roasted) and purified
Why are scientists developing new ways of extracting copper from low-grade ores?
*Smelting uses high amounts of energy which is expensive and can cause pollution of the environment
*Copper ores are becoming scarce
What 2 ways are scientists attempting to extract copper from low-grade ores?
*Bacteria - Bioleaching
*Plants - Phytomining
What is bioleaching?
Bioleaching uses bacteria to produce leachate solution from waste copper ore
What is leachate solution?
A solution of copper compounds
How can copper be extracted from leachate solutions following bioleaching?
*The metal compounds can be displaced using scrap iron
*The metal compounds can be broken down by electrolysis and the copper can be extracted
What is phytomining?
Phytomining is when plants are grown on soils containing low-grade copper ore. The plants absorb the copper ions, then the plants are burnt and the copper is extracted from the copper compounds in the ash.
What are the negatives of unconventional methods of extracting copper?
They are very slow processes
What is a blast furnace?
The huge reaction vessels used in industry to extract iron from its ores
What is a life cycle assessment (LCA)?
carried out the assess the environmental impact of products, processes, or services at different times in their life
What is non-renewable?
Something which cannot be replaced once it is used up
What is thermal decomposition?
The breakdown of a compound by heating it
What are the 4 stages in an LCA?
*Raw Material Extraction
*Manufacture
*Use/Reuse/Maintainence
*Recycle/Waste Management
Why should an LCA be peer reviewed?
The check the data and the validity of the conclusions
Give an example of a product which can be reused
Glass bottle
Explain how a glass bottle can be reused
Glass can be crushed and melted to make different glass products
Give an example of a material which can be recycled
Metal
explain how metals can be recycled
Metals can be recycled by melting and recasting or reforming into different products. Some scrap steel can be added to the iron from a blast furnace to reduce the amount of iron that needs to be extracted from iron ore.
What are the benefits of recycling?
Recycling conserves limited reserves of materials. Extraction of raw materials (especially metals) have large environmental impacts, such as acid rain and global warming. Mining and quarrying to extract metal ore can cause visual, noise, and dust pollution as well as destroying habitats
