c10 - using resources

• potable water is water that is safe to drink
• filtration and sterilisation ; Chlorine, ozone or UV light used for sterilisation
• waste water requires treatment before being let back into freshwater sources
• waste water process : screening, sedimentation, anaerobic digestion of sludge and aerobic digestion of effluent
• Polymers can be made to replace some natural rubber (from trees)
• synthetic fibres replace wool

• Bioleaching : Certain bacteria can break down ores to produce an acidic solution containing copper(II) ions. - solution is called leachate

• Bioleaching does not need high temperatures, but it produces toxic substances, including sulfuric acid, which damage the environment
• phytomining : plants absorb metal compounds, the plants are burned and the ash contains the metal compounds
• phytoextraction is slow
• phytomining reduces the need to obtain new ore by mining
• a life cycle assessment asses the environmental impact of products
• environmental impacts of products depend on obtaining and processing raw materials, manufacturing and packaging, product operation and disposal
• some glass products can be melted down and reshaped : reuse
• Scrap steel and iron can be kept together and added to iron in a blast furnace - less iron ore required
• benefits of recycling : saves finite metal, less waste in landfills and less energy
• Metals can be melted down and recast into a new shape
• Limited raw materials are used to make metals, glass, clay ceramics and most plastics
• sustainable development: Use lower energy and lower waste processes, se fewer non-renewable and finite fuels
• paper bags - timber (sustainable)
• paper weighs more than plastic so transport cost increased
• paper bags are single use and are easily damaged
• paper bags are easily desposable and biodegradable
• plastic : crude oil - non-renewable : fractional distillation and cracking
• plastic bags can be reused
• plastic bags can sometimes be recycled but are not biodegradable
• what is sustainable development?

  • development that meets the needs of current generations without compromising the ability of future generations to meet their own needs
• in the uk, potable water is produced by?

  • choosing a appropriate source of fresh water
  • passing the water through filter beds to remove any solids
  • sterilising to kill microbes
• what are the sterilising agents for potable water?

  • chlorine, ozone or UV light
• how is desalination carried out?

  • can be done by distillation or by processes that use membranes such as reverse osmosis
  • require large amounts of energy
• what is reverse osmosis?

  • sea water passed through a membrane that only allows through water molecules
  • high pressure requires a lot of energy to produce
• how is waste water produced & how is it treated?

  • urban lifestyles & industrial processes produce large amounts of waste water : require treatment before released
  • may require removal of organic matter & microbes or harmful chemicals
• what are the processes involved in sewage treatment?

  • screening & grit removal
  • sedimentation to produce sewage sludge & effluent
  • anaerobic digestion of sewage sludge
  • aerobic biological treatment of effluent
• what is phytomining?

  • uses plants to absorb metal compounds from the soil
  • plants are harvested then burnt to produce ash that contains metal compounds
• what is bioleaching?

  • uses bacteria to produce leachate solutions that contain metal compounds
• main disadvantages of bioleaching & phytomining?

  • need less energy than traditional methods
  • can work on low concentration ores
  • slow to carry out
• describe stages of LCA's:

  • extracting & processing raw materials
  • manufacturing & packaging
  • use & operation during lifetime
  • dispose at the ned of useful life
  • transport included at every stage
• how do we reduce the use of resources?

  • reusing & recycling
  • reduces use of limited resources, energy consumption, waste & environmental impacts
• advantages of recycling?

  • less acid rain
  • metal ore reserves last longer
  • less landfill waste
• disadvantages of recycling ?

  • collection / transport problems
  • cost of transport
  • difficult to separate materials