Please enable JavaScript.
Coggle requires JavaScript to display documents.
C14: THE EARTH'S RESOURCES (Finite and Renewable Resources (Esimates…
C14: THE EARTH'S RESOURCES
Finite and Renewable Resources
We rely on the Earth's natural resources to make new products and provide us with energy
Some of these natural resources are finite, meaning that they will run out eventually if we continue to exploit them (eg, fossil fuels)
Others are renewable, meaning that they can be replaced as we use them up (eg crops used to make biofuels)
Esimates of the tie left before fossil fuels run out can only be rough estimates because of the uncertainty involved in the calculations
11 more years of oil
21 more years of coal
14 more years of gas
Safe Drinking Water
Water is made fit to drink by passing it through filter beds to remove solids and adding chlorine, ozone or by passing ultraviolet light through it to reduce microbes (sterilisation)
Water can be purified by distillation, but this requires large amounts of energy making it expensive
Reverse osmosis used membranes to separate dissolved salts from salty water, but this method of desalination also uses energy to make the high pressures needed
Treating Waste Water
Waste water requires treatment at a sewage works before being released into the environment
Sewage treatment involves the removal of organic matter and harmful microorganisms and chemicals
The stages include screening to remove large solids and grit, sedimentation to produce sewage sludge, and aerobic biological treatment of the safe effluent released into the environment
The sewage sludge is separated broken down by anaerobic digestion and dried
It can then be used as fertiliser or a source of renewable energy
Extracting Metals From Ores
Most copper is extracted by smelting copper rich ores, although supplies of ores are becoming scarcer
Copper can be extracted from solutions of copper compounds by electrolysis or by displacement using scrap iron
Electrolysis is also used to purify impure copper (copper metal obtained from smelting)
Scientists are developing ways to extract copper using low-grade copper ores. Bacteria are used in bioleaching and plants in phytomining
Life Cycle Assessments
Life Cycle Assessments are carried out to assess the environmental impact of products, processes or services
They analyse each of the stages of the life cycle, from extracting and processing raw material to disposal at the end of its useful life, including all transport and distribution
The stages in an LCA can be summarised as: raw material extraction, manufacture, use/reuse/maintenance, recycling/waste management
Assigning numerical values to the relative effects of pollutants involves subjective judgment, so LCAs using this approach must make this uncertainty clear
Reduce, Reuse and Recycle
There are social , economic and environmental issues associated with exploiting the Earth's limited supplies of raw materials such as metal ores
Recycling metals saves energy and our limited, finite metal ores (and fossil fuels)
The pollution caused by the mining and extraction of metals is also reduced by recycling