Using resources

• Water is often found with other substances dissolved in it. These substances can be harmful so we treat water to make it potable (safe for human consumption).
• To make water portable we need to:

  1. reduce the concentrations of microbes in it

  2. Reduce concentrations of dissolved minerals and salt in water
• Pure water only has one molecule which is H2O.
• We can get potable water from:

  fresh water

  sea water

  waste water
• Rain water is fresh water.
• The most expensive to treat is sea water because distillation and reverse osmosis (2 methods of desalination) use high amounts of energy
• When treating water we put it through a 2-step treatment process:

  Filtration

  Sterilisation- using ozone, chlorine or UV
• 2 types of natural resources

  renewable

  non-renewable
• Supplements to Earth's natural resources:

  agriculture- larger quantities of food

  Synthetic products- synthetic polymers in tyres
• The development of useful synthetic products reduces the need for natural products.
• Natural resources include:

  Food

  Wood for building

  Fuels

  materials exp. cotton
• What are we trying to remove from waste water by treating it?

  Organic matter

  Harmful microbes

  Harmful chemicals
• The Haber process is an example of an industrial process that generates large amounts of waste water.
• The steps in sewage treatment are:

  Screening/ grit removal

  Sedimentation- separation into heavier sludge and lighter effluent.

  Sludge (solid)- Anaerobic digestion

  Lighter effluent- Aerobic treatment
• Main sources of waste water are: domestic, industrial, agricultural, and sewage
• Metal ores are finite resources and availability is rapidly decreasing. We extract them from the ground using mining but causes significant environmental damages.
• Metal ore extraction causes:

  Habitat destruction- threatens biodiversity

  Landscape scars

  Pollution
• Properties of copper:

  Malleable

  Unreactive

  Conducts heat and electricity well
• The pure metals are obtained using electrolysis or displacement reaction.
• Copper-rich ores (materials containing lots of copper) are in short supply because of historical overexploitation.
• Alternative ways to extract copper:

  Phytomining- Plants absorb copper ions into roots, burn then obtain copper from the ash

  Bioleaching-Bacteria produce LEACHATE solutions that contain copper ions that can be extracted.
• Phytomining extracts copper from contaminated land

  Bioleaching extracts copper from low- grade ores and it is slow
• Life Cycle Assessments (LCAs) assess all four stages of a product’s life cycle to try and calculate its total environmental impact.
• 4 stages of LCA:

  Extraction and processing of raw material

  manufacturing & packaging

  products use

  disposal of the product
• Comparative LCAs have shown that paper bags may actually be more harmful than plastic bags as their manufacture requires more energy and their lifespan is far shorter.
• The use of resources can be reduced by reusing and recycling existing materials, or just by encouraging people to use them less.
• We can reduce resource usage by:

  reuse

  recycle

  convince people to use less

  reducing energy and materials needed to make
• We can recycle metals by melting them and reshaping it.
• Recycling glass

  sort, crush, melt and reshape
• Benefits of recycling metals

  less burning of fossil fuels

  conserves finite resources

  less energy used