topic c10- using resources

• natural resources come from the Earth, sea and air e.g. cotton

  • can be used for fuel, clothing, shelter, food, transport, heating
• synthetic products

  • products improved by man-made processes
  • e.g. rubber
• agricultural products

  • enhance natural resources for our needs
  • e.g. fertiliser
• finite (non-renewable) resource

  • aren't formed quickly enough to be "replaceable"
  • fossil fuels + nuclear fuels
  • e.g. uranium and plutonium
• many modern materials are made from finite resources e.g. plastics + metals
• finite and renewable resources

  • mining is bad for the environment
  • however, it provides useful products
  • social, economic + environmental effects of extracting finite resources
• sustainable development

  • meeting the needs of the present society
  • while not damaging the lives of future generations
• to improve sustainability

  • reduce
  • reuse
  • recycle
  • it decreases the amount of finite resources we need to extract + wastes less energy
• recycling metals

  • helps to save on the large amounts of energy required to mine + extract them
  • waste metal -> melted down -> remade into new products
  • the amount of separation required depends on the metal and final product
• recycling glass

  • waste glass -> separated by colour + chemical composition -> crushed + melted -> reshaped
  • glass bottles can be reused without reshaping
• copper ores

  • a finite resource that is becoming scarce
  • we can improve sustainability by extracting from low-grade ores
• bioleaching

  • bacteria are used to convert copper compounds in the ores into soluble copper compounds
  • separating the copper from the ore in the process
  • the leachate (solution produced) contains copper ions which can be extracted e.g. by electrolysis or displacement
• phytomining

  • growing plants in soil that contains copper
  • the plants cannot use or remove the copper so it builds up in the leaves
  • the plants can be harvested dried and burned in a furnace
  • the ash contains copper compounds from which copper can be extracted
• extracting copper ores

  • traditional methods, damage the environment
  • new methods are less damaging, but are slow
• life cycle assessment

  • an assessment of the environmental impact of a product over each stage of its life
• LCA stages

  • raw materials
  • manufacturing + packaging
  • using the product
  • product disposal
• each LCA stage for a plastic bag

  • raw materials- crude oil
  • manufacturing + packaging- key compounds extracted by fractional distillation; waste has other uses
  • using the product- reusable
  • product disposal- recyclable, not biodegradable
• each LCA stage for a paper bag

  • raw materials- timber
  • manufacturing + packaging- takes a lot of energy to pulp timber and creates lots of waste
  • using the product- single-uses
  • product disposal- biodegradable and recyclable
• selective LCA

  LCA where some information has been removed to make a product look better than it really is
• potable water

  • water that is safe to drink
  • not pure, as it contains dissolved salts with pH's between 6.5 an n d 8.5
  • rainwater is a type of fresh water (doesn't have much dissolved in it)
• types of water

  • ground water
  • salt water
  • waste water
• ground water

  • source- underground rocks
  • treatment- must be filtered + sterilised
• salt water

  • source- sea water
  • treatment- must be desalinated
• waste water

  • source- sewage treatment + agricultural systems
  • treatment- requires a lot of treatment
• filtration

  a wire mesh screens out debris e.g. twigs and then gravel + sand beds filter out any other solid bits
• sterilisation

  • the water is sterilised to kill any harmful bacteria or microbes
  • this can be done by bubbling chlorine gas through it or by using ozone or ultraviolet light
• how to test and distil water

  1. test the pH of the water with a pH meter; if its too high or too low you can neutralise it with a titration
  2. test the water for sodium chloride; you need to test for sodium ions via a flame test and chloride ions by adding nitric acid + silver nitrate solution (a white precipitate should form)
  3. to distil the water, pour the salty water into a distillation apparatus and heat the flask
  4. then retest the distilled water to see if sodium chloride has been removed
• waste water treatment

  • agricultural systems, industrial processes and sewage all contain waste water
  • waste water containing toxic substances may require extra chemical treatment
• sewage treatment part 1

  1. sewage is screened- removing large bits of material e.g. twigs
  2. sedimentation occurs- effluent floats and solids sink to produce sludge
  3. effluent is removed and treated by aerobic digestion- air is pumped through the water to make the aerobic bacteria break down organic matter
• sewage treatment part 2

  4. sludge is removed and gets broken down via aerobic digestion

  5. anaerobic digestion breaks down organic matter, releasing methane gas; methane can be used as an energy source + digestion waste can be a fertiliser

  6. waste water that contains toxic substances may require additional treatments e.g. adding chemicals, UV radiation, using a membrane