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Can every mixture be separated?
- Through this whole chapter we have separated things using differences in size, density and solubility .
- But separation is not always this simple. Your book asks a very practical question — imagine trying to separate all the ingredients in a glass of lemonade once they have been mixed. Can you do it?
- Once lemon juice, sugar and salt are stirred into water, pulling them apart again by ordinary physical methods is extremely difficult.
Where does separation happen without us doing anything?
- Separation goes on constantly in nature — and inside our own body.
- The biggest example is our kidneys , which filter our blood without stopping, remove the waste substances from it and keep the whole body healthy.
What bigger separation problems does the world face today?
Separation on a large scale
Separation today
Bigger than a laboratory
Cleaning water
Removing plastic waste from oceans and rivers
Treating sewage
Uses:
Sedimentation
Coagulation
Filtration
Sorting waste
At home:
Dry waste → recycle
Wet waste → compost
- Removing plastic waste to clean our oceans and rivers is one of today's biggest challenges.
- Dirty sewage water must be treated before it is released into the environment. Sewage treatment plants use, on a very large scale, the very techniques we have studied in this chapter — sedimentation, coagulation and filtration .
- The clean water they produce can be reused for flushing toilets or watering plants.
- Another important task is segregating the waste that leaves our homes. Separate it into dry and wet waste and the dry part — plastic, paper, glass and metal — can be recycled, while the wet part such as food scraps and vegetable peels can be composted.
- Researchers today are finding new ways to recover valuable materials such as lithium from old mobile phone and laptop batteries.
Improve the way we separate waste and water, and recycle what we recover, and we make the whole world cleaner, healthier and more sustainable.
