C14(The Earths Resources) Flashcards
What is potable water
Drinkable water
Water can be purified by …
Distillation but this requires large amounts of energy which makes it expensive
Reverse osmosis uses …
Membranes to separate dissolved salts from salty water
How is fresh water treated to make it safe to drink
-Passing the untreated water through filter beds made of sand and gravel to remove solid particles
-The addition of chlorine or ozone to sterilise the water by killing microorganisms
What are the stages of sewage treatment
-Screening
-primary treatment
-secondary treatment
-final treatment
What happens in the screening stage
Removes large solid objects and grit from the rest of the waste water by passing sewage through a metal grid that traps the large objects
What happens in the primary treatment stage
-In the first tank Large paddles rotate pushing the solids called sludge towards the centre of the tank
-there the sludge is piped to a storage tank for further treatment
-The water liquid above the sludge flows into the next tank
What happens in the secondary treatment stage
In the second tank useful bacteria feed on any remaining organic matter and harmful microorganisms still present, breaking them down aerobically
What happens in the final treatment stage
-In the last tank the useful bacteria are allowed to settle out to the bottom of the tank as a sediment
-The sediment is either recycled back into the secondary treatment tank
How is the sewage sludge treated
-It’s separated, broken down by anaerobic digestion and dried
-It can provide us with fertiliser and a source of renewable energy
Most copper is extracted by …
Smelting copper rich ore
What are LCAs(life cycle assessment)
Tests Carried out to assess the environmental impact of products, processes or services
How are LCAs carried out
listing all the energy and material inputs and all the outputs into the environment
What are the stages in an LCA
Raw material extraction —> manufacture —> use/reuse/maintenance —> recycle/waste management
Recycling metals saves …
Energy and our limited finite metals ores
