Increasing Sustainability By Treating Contaminated Water Flashcards

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1
Q

Why might water need to be treated

A

Water that is abstracted is not always suitable drink or use as it may be contaminated

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2
Q

What is the first step of water treatment

A

Removal of litter
Uses a screen to remove debris
I.e. leaves and plastics

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3
Q

What is the second step in water treatment

A

The water is allowed to remain static
Solids settle on the bottom
The sediment is dredged out and removed

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4
Q

What is sedimentation

A

When the solids in water settle at the bottom

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5
Q

What is the third stage of water treatment

A

Aeration
Takes a long time
Air pumped in tanks
Helps bacteria decay organic matter

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6
Q

Why is oxygen used in aeration

A

Bacteria like oxygen with a high dissolved oxygen content
Means heavy metals that might be in water become insoluble

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7
Q

What is the fourth step in water treatment

A

Flocculation
Tiny clay particles that won’t settle at the bottom of the tank
Forced to coagulate

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8
Q

How does a flocculant work

A

Mixed with water
Makes clay attract to each other
Makes them dense enough to settle at bottom

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9
Q

What is the fifth step in water treatment (filters)

A

Water is pumped through filters
Layers of coarse and fine sediments
Very slow process

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10
Q

What sediments are used in filtration

A

Sands
Gravel
Charcoal

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11
Q

Why is the carbon layer important (water cleaning)

A

Remove organic chemicals (pesticides)
Known as activated carbon

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12
Q

What is activated carbon

A

As organic absorb to it so they no longer dissolve into the water

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13
Q

What’s is the sixth step in water treatment

A

Water is sterilised to kill any pathogens that still exist
Mainly done using UV
Ozone and chlorine also used

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14
Q

Why isn’t chlorine as good for sterilisation

A

It only last long enough to get through the pipes to you

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15
Q

What is stage seven of water treatment

A

Neutralise the water by adjusting the pH
Used if water was sterilised with chlorine

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16
Q

Why does chlorinated water need neutralising

A

As makes the water too acidic
Crushed lime used to reduce acidity

17
Q

What is the eighth stage of water treatment? (Softening)

A

Ion exchange
Occurs where calcium and magnesium are removed to soften the water.

18
Q

Why might ion exchange also be used

A

Down to remove mercury and lead that have contaminated water

19
Q

Why is zeolite used for water treatment?

A

Toxic ions absorb to it

20
Q

What is the 9th and optional step

A

Florine additive
Helps to keep teeth healthy
Only occurs in 24 countries