10.5 Making Water Drinkable

  1. What is meant by the term “Water treatment”?

Water treatment is the process of making water suitable for a desired end use (such as drinking, cleaning)

2. Briefly describe the 7 steps of the Water Treatment Process based on the diagram on page 20:

Step 1: Intake – Large objects are kept out of the treatment plant using

metal screens (ie. Leaves, sticks, garbage)

Step 2: Addition of Chemicals – ALUMis added to the water and stirred

Step 3: Coagulation and Flocculation – water is cleaned for the first time

Coagulation – when something clumps/sticks together into something larger (happens in our blood)

Flocculation – the formation of FLOC (chemical and waste solids)

Step 4: Sedimentation – in a settling tank the water slows down and heavy particles sink to the bottom, cleaner water moves along the top

Step 5: Filtration –sand and charcoal filters clean the water

Sand filter – removes the remaining solids

Charcoal filter–removes any smell

--- now water is clear, colourless and odourless ---

Step 6: Disinfection – Water is cleaned using chlorine, it kills microorganisms

Step 7: Storage – treated water is stored to later use (in water towers, underground reservoirs, pipes)

3. Is clear, colourless, and odourless water always safe to drink? Explain.

Not always … because some contaminants may not have a smell, colour or be visible to the eye. Examples are microorganisms, chemicals, pharmaceuticals (medicine) can all be hidden.

4. Describe the following alternative methods of water treatment and explain where/why they might be used:

Reverse Osmosis :when water is forced through a small screen (filter), it leaves behind everything but the water particles because the holes are really small. This is sometimes used for businesses or homes.

Ultraviolet (UV) Radiation :used to destroy viruses and micro-organisms (bacteria) by emitting radiation on to the water supply. This is used in hospitals to stored water they may use.

Boiling :by heating water to boiling, you can kill most micro-organisms

5. How can hard water be treated?

“Hard water”is water with calcium and magnesium dissolved in it. Water softening chemicals (“water softeners”) help get rid of hard water

6. What is meant by “sustainability”?

It means working and behaving in a way to protects resources and have them for the future generations

7. What are two items that currently cannot be removed from water?

1. pharmaceuticals – drugs like antibiotics and hormones (medicines)

2. oil-based liquids – oil-based paint, motor oil