C10 - Using Resources

• Potable water - water that is good quality and safe to drink
• Fresh water - contains low levels of dissolved salts
• Potable water:

  1. Fresh water collected
  2. Passed through a filter bed to remove solid particles
  3. Chlorine or ozone added to kill microorganisms
  4. Fluoride added to reduce tooth decay
• Seawater can be desalinated:

  • Distillation
  • Reverse osmosis
• Distillation:

  1. Water is boiled into steam
  2. Steam is condensed into pure water
• Pure water - only H2O and no other contaminants
• Waste water must be treated to remove:

  • Organic matter
  • Microorganisms
  • Toxic chemicals
• Sewage treatment:

  1. Screening to remove grit
  2. Sedimentation to separate sewage sludge and useful effluent
  3. Anaerobic digestion by bacteria of sludge
  4. Aerobic digestion by bacteria of effluent
• Copper is useful:

  • Good conductor of electricity and heat
  • Malleable but hard enough to make pipes
  • Does not rust so lasts a long time
• Smelting - copper ore is heated with carbon in a furnace to produce copper metal. The copper is then purified by electrolysis
• Copper is obtained through:

  • Smelting
  • Electrolysing solutions of copper salts
  • Displacement using scrap iron
• Electrolysis of copper - positive copper ions move to negative electrode and form pure copper
• Extensive mining of copper has caused us to run out of copper rich ores. This means we need new methods to extract copper from other sources
• Copper can be extracted from:

  • Low-grade ores (small amounts of copper)
  • Contaminated land (using biological methods)
• Phytomining:

  1. Plants grow on contaminated land
  2. They absorb copper ions from the earth
  3. Plants are burned and the ash produced contains copper in relatively high quantities
• Bioleaching:

  1. A bacterial solution is mixed with a low-grade ore
  2. Bacteria convert the copper into a leachate solution from which copper can be extracted
• Corrosion - metals chemically react with oxygen and water. Rusting is when iron or iron alloys corrode
• Corrosion methods which prevent oxygen and water from reaching metal (but coating can be damaged):

  • Painting
  • Electroplating
  • Greasing
• Sacrificial protection:

  • Block of magnesium (more reactive) are attached to the iron or iron alloy
  • The magnesium is more reactive so it reacts and loses electrons instead
• Galvanising:

  • Object coated in zinc
  • Zinc stops oxygen and water from reaching metal and stops corrosion
  • Damage to the coating doesn't matter as it still does sacrificial protection
• Aluminium is protected from corrosion by a thin layer of aluminium oxide as a barrier
• Glass:

  • Soda-lime glass - sand, sodium carbonate, limestone. Used for windows
  • Pyrex/Borosilicate glass - sand, boron trioxide, higher temp. Used for glassware, cookery, headlights.
• Pottery and bricks:

  • Clay ceramics
  • Made by shaping wet clay and heating them
  • In the furnace, water is removed and reactions cause clay to harden
• Composites - two materials with different properties combined to create a material with improved properties e.g concrete, fibreglass
• Life Cycle Assessments (LCAs) - used to assess the environmental impact a product has over it's whole lifetime
• LCAs measure the impact of:

  • Extracting raw materials
  • Processing raw materials
  • Manufacturing products
  • How it is used
  • How it is transported
  • How it is disposed of
• LCAs:

  • Some aspects are easy to quantify e.g amounts of energy/water used.
  • Some aspects are more subjective and can be biased or influenced by advertisers
• Reducing use of resources:

  • Glass, metals, and plastics must be used wisely and reused and recycled where possible to save money, energy, and resources, and to reduce waste and damage
  • Many products are made from finite resources so we will run out unless we reduce use and recycle them
• Reuse:

  • Waste glass is crushed, melted, and reused
  • Some waste plastic can be recycled into material
  • Metals can be melted down and reused
• NPK fertilisers:

  • Nitrogen, Phosphorus, Potassium
  • Different proportions of N, P, and K to provide nutrients
  • This is written as numbers: N-P-K
• Fertilisers are used to replace elements in soil that are needed for plant growth
• Ammonia:

  • Used to increase nitrogen content
  • Can be oxidised to produce nitric acid
  • Can neutralise nitric acid to produce ammonium nitrate
  • Ammonium nitrate is a fertiliser rich in nitrogen
• Phosphate rock:

  • Phosphate compounds are used as fertilisers e.g ammonium phosphate, calcium phosphate, superphosphate