10. Using Resources

Industries use Earth's natural resources to make useful products.
Sustainable operation means minimizing use of limited resources, energy, waste, and environmental impact.
Chemists also develop ways to dispose of products so materials and stored energy are reused.
Pollution, waste disposal, and land use change harm the environment. Environmental chemists study these effects and find ways to reduce damage.

5.10.1.1 Using Earth's resources and sustainable development

Humans use Earth's resources for warmth, shelter, food, and transport.
Natural resources plus agriculture provide food, timber, clothing, and fuels.
Finite (limited) resources come from Earth, oceans, and atmosphere for energy and materials.
Sustainable development meets present needs without stopping future generations from meeting theirs.
Chemistry improves agriculture and industry to produce new products sustainably.
Examples: Natural products can be replaced or supplemented by agricultural or synthetic products.
Distinguish: Finite vs renewable resources.

5.10.1.2 Potable water

Potable water is safe to drink, containing low dissolved salts and microbes, but is not chemically pure.
In the UK, potable water is mainly from fresh water (rain, rivers, lakes).
Production steps:
1. Select fresh water source
2. Filter through filter beds
3. Sterilise using chlorine, ozone, or UV light
If fresh water is limited, salty water or seawater is desalinated by:
- Distillation
- Membrane processes (e.g., reverse osmosis)
Desalination requires high energy input.

5.10.1.3 Waste water treatment

Urban and industrial waste water contains organic matter, microbes, and harmful chemicals.
Treatment includes:
1. Screening and grit removal
2. Sedimentation producing sludge and effluent
3. Anaerobic digestion of sludge
4. Aerobic treatment of effluent
Potable water is easiest to obtain from fresh water, harder from waste water, and hardest from salt water.

5.10.1.4 Alternative methods of extracting metals (Higher Tier)

Metal ores are limited; copper ores are becoming scarce.
New extraction methods:
- Phytomining: Plants absorb metal compounds; plants are burned to get metal-rich ash.
- Bioleaching: Bacteria produce solutions containing metal compounds (leachate).
Metals can be extracted from solutions by displacement (e.g., scrap iron) or electrolysis.
These methods avoid traditional mining (digging and disposing of large amounts of rock).
Evaluate pros and cons of biological extraction methods.

5.10.2.1 Life cycle assessment (LCA)

LCAs assess environmental impact at each product stage:
- Raw material extraction and processing
- Manufacturing and packaging
- Use during lifetime
- Disposal, including transport and distribution
Some impacts (water, energy use) are easy to quantify; pollutant effects require subjective judgements.
LCAs can be selective or abbreviated and may be misused to support biased claims.
Compare LCAs, e.g., plastic vs paper shopping bags.
Use numerical skills to interpret LCAs: decimals, ratios, percentages, significant figures, graphs.

5.10.2.2 Ways of reducing the use of resources

Reduce, reuse, recycle materials to cut use of limited resources, energy, waste, and environmental harm.
Materials like metals, glass, ceramics, plastics are made from finite raw materials; processing often uses limited energy resources.
Quarrying and mining cause environmental damage.
Some products (e.g., glass bottles) can be reused; others are recycled by melting and reforming.
Recycling metals reduces need for extraction; mixing scrap steel with iron ore reduces extraction demand.
Evaluate different ways to reduce limited resource use based on information.