Using resources Flashcards
(15 cards)
What do humans use the earth’s resources for
To provide warmth, shelter, food and transport
what is sustainability
Meeting the needs of the current generation without compromising the needs of the future generation
What is potable water
Water that is safe for humans to drink. It isn’t pure water as it contains dissolved minerals, but still is safe.
Turning freshwater into drinking water
- Mesh filtration: large objects such as sticks are removed through a mesh wire
- sand and gravel filtration: finer particles are filtered out of the water
- sterilisation: sterilisation of the water takes place either using chlorine, UV light or Ozone, to remove any harmful microbes and bacteria
Seawater treatment
Desalinisation
1. distillation - sear water is heated to 100 degrees which is the boiling point of water. Water will evaporate first and turn into steam. Steam is cooled and condenses into a liquid: pure water. Salt stays behind
- reverse osmosis:
Using water pressure to filter seawater. Water molecules are small enough to fit though the membrane whilst mineral ions are too large to fit through
Waste water treatment proccess
Organic matter and harmful microbes must be removed
- screening: removes large insoluble objects such as wet wipes
- sedimentation: large organic matter sinks to the bottom of the tank, forming sewage sludge. Lighter and smaller sediment floats to the top and is called effluent
- Air is bubbled into the effluent. Aerobic bacteria break down organic matter and kill harmful microbes. Water is safe to release back into rivers
- Anaerobic bacteria digest the sewage sludge, forming methane that can be used for fuel, and digested sludge that can be used in fertilisers
How does Phytomining work
Using plants to absorb metal compounds from the soil. The plants are harvested and then burned to produce ash that contains the metal compounds
How does bioleaching work
using bacteria to produce leachate solutions that contain metal compounds
These metal compounds are then obtained by displacement reactions or electrolysis
Advantages of Phytomining
- more sustainable than traditional mining: doesn’t scar the land
- allows extraction of low grade ores
- process uses less energy overall than traditional mining
- avoids digging, moving and disposing of large amounts of rock
Disadvantages of phytomining
- much slower process than traditional mining as you need to wait for the plants to grow
- yield of metal obtained is much smaller
- Land used to grow plants can be used to grow crops instead for food production
Advantages of bioleaching
- less environmentally damaging than traditional mining methods: doesn’t require large scale excavation and scar the landscape
- can extract metals from low grade ores
- process produces fewer sulfur dioxide emissions - cleaner
Disadvantages of bioleaching
- very slow process, less suitable for large scale demand
- can produce toxic by-products such as sulfuric acid
- concentration of metal in solution is often low, and further purification is needed, adding to the overall cost and complexity
What does the life cycle assessment asses
- extraction and process of raw materials
- manufacture and packaging
- use and operation during tis lifetime
- disposal at the end of its useful life, including transport and distribution
Advantages of recycling
- less acid rain
- less pollution
- less mining
- less landfill
- energy for extraction saved
- metal ore reserves last longer
- less quarrying
- creates local employment in recycling sectors
Disadvantages of recycling
- collection problems
- transport problems and cost of transport - fuels are still burned which release Co2, when transporting these materials
- difficult to separate metals from appliances
