Producing Potable Water from Freshwater

What are the main stages of producing potable water from freshwater?

Choose a suitable freshwater source, filter the water and sterilise it.

What is filtration?

A process that removes insoluble solid particles from water.

What does filtration remove from water?

Suspended solids and some other particles.

What does filtration not reliably remove?

Dissolved salts and all microorganisms.

What is sterilisation in water treatment?

Treatment used to kill or inactivate harmful microorganisms.

Why is sterilisation necessary?

To reduce the risk of waterborne disease.

What methods can be used to sterilise drinking water?

Chlorine, ozone or ultraviolet light.

Why is chlorine added to drinking water?

To kill or inactivate microorganisms and help prevent microbial contamination in the distribution system.

How does ultraviolet light help treat water?

It inactivates microorganisms.

How does ozone help sterilise water?

It acts as a strong oxidising agent that destroys or inactivates microorganisms.

Why is water filtered before sterilisation?

Suspended particles can shield microorganisms and interfere with treatment.

Why must water sources be carefully selected?

To minimise contamination and treatment requirements.

Why is sterilisation different from filtration?

Sterilisation kills or inactivates microorganisms, while filtration removes particles.

Does sterilisation remove dissolved salts?

No.

Why may potable water still contain dissolved minerals?

They are not necessarily harmful at the concentrations present.

What is one advantage of producing potable water from freshwater?

It generally requires less energy than desalination.