Water for drinking
Waste water and Where water is stored in rocks beneath the ground. must be treated to make them Water that is safe to drink. or safe to drink.
Treating fresh water
Fresh water contains objects that must be removed to make it potable. These include large objects such as branches and leaves, Unable to dissolve in a particular solvent. For example, sand is insoluble in water. A general term for a small piece of matter. For example, protons, neutrons, electrons, atoms, ions or molecules. such as grit, and harmful Microscopic living things such as archaea, bacteria and some species of eukaryotes. .
Different separation methods and treatments are used to deal with them:
- large objects are removed by screening using grids
- a coarse filter bed made from clean sand and gravel removes larger insoluble grit particles
- aluminium sulfate is added to clump smaller insoluble particles together, which then settle to the bottom in a sedimentation tank
- a fine filter bed removes very small insoluble particles
- chlorine gas is added to kill harmful microorganisms
Treating seawater
Seawater contains too much dissolved salt to make it suitable as drinking water. However, pure water can be produced from seawater by Separation method used to separate a solvent from a solution..
The seawater is boiled and the water Gas formed below the boiling point of a substance. is then cooled. It Turned from a gas or vapour into a liquid, usually as a result of cooling. to form pure water, leaving the salt behind.
It is expensive to produce drinking water this way because large amounts of energy are needed to heat the seawater. However, water produced by distillation is useful in the laboratory for dissolving substances. It does not contain any dissolved Electrically charged particle, formed when an atom or molecule gains or loses electrons. that might interfere with a chemical analysis.