C14: Earth's Resources Flashcards
renewable energy?
sources of power that can be replenished/used again
e.g timber
finite resources?
have limited supply that will eventually run out
e.g metal ores/minerals from earth’s crust
potable water?
water that is safe to drink (not pure, bc contains dissolved substances)
how to obtain potable water?
- suitable fresh water source chosen
- filtration : water is passed through filter beds to remove different sized insoluble solids
- sterilisation: UV light/Ozone/Chlorine kill microbes
what is desalination and process?
involves treatment of sea water to remove salt by distillation or reverse osmosis
reverse osmosis: Salt water put through partially permeable membrane.
- Only water molecules can pass through it, as membrane stops larger molecules passing
concentrated –> dilute
why is desalination not ideal when producing large quantities of fresh water?
expensive
sewage treatment process?
Screening/grit removal : remove large materials (e.g plastic bags/twigs/grit) by screening
Sedimentation: water in a tank –> heavier solids sink to bottom (sewage sludge)
- lighter material (effluent) floats to top
Aerobic Digestion : effluent removed/treated by aerobic digestion to reduce volume of solid waste (digestion breaks down organic matter/bacteria)
Anaerobic Digestion : anaerobic digestion of sewage sludge - releases methane
why is phytomining/bioleaching needed?
some metal ores are becoming scarce (copper/nickel ores)
- to extract these metals from low grade ores , phytomining/bioleaching is needed to meet GLOBAL DEMAND
How is phytomining/bioleaching better for envrionment?
- avoids envrionmental damage by avoiding traditional ways of mining (digging, moving and disposing large amounts of rock)
what is phytomining?
- uses plants to absorb metal compounds
- plants are harvested/burned to produce ASH dissolved in acid that contains metal compounds
- these are processed to obtain metal
what is bioleaching?
- uses bacteria to separate metal from ore
- to form acidic solutions containing metal compounds - leachate
- compounds can be reduced to solid metal form / extracted by displacement or electrolysis
what is life cycle assessment?
carried out to assess envrionemntal impact of products in each of these stages :
- extracting/processing raw materials
- manufacturing/packing
- use and operation in lifetime
- disposal
why is LCA subjective?
- some stages are more diffiuclt to allocate numerical value to
- have to make a judgement
how are selective/abbreviated LCAs misused?
- can be used to advertise product (DONT GIVE COMPLETE PICTURE)
How are glass botles reused?
- can be crushed/melted to make different glass products
