C14.3 - Treating waste water Flashcards Preview

GCSE Chemistry Required Practicals > C14.3 - Treating waste water > Flashcards

Flashcards in C14.3 - Treating waste water Deck (23):
1

The 1st step of sewage treatment

The 1st step of sewage treatment is screening

2

The 1st step of sewage treatment is screening.
Once the sewage arrives at the sewage treatment plant, the first step is to do what?

Once the sewage arrives at the sewage treatment plant, the first step is to remove:
1. Large solid objects
2. Grit
from the rest of the waste water

3

The 1st step of sewage treatment is screening.
Once the sewage arrives at the sewage treatment plant, the first step is to remove large solid objects and grit from the rest of the waste water.
The sewage does what?

The sewage passes through a metal grid that traps the large objects

4

The 2nd step of sewage treatment

The 2nd step of sewage treatment is primary treatment

5

The 2nd step of sewage treatment is primary treatment.
In the first circular tank, the solid sediments are what?

In the first circular tank, the solid sediments are allowed to settle out from the mixture

6

The 2nd step of sewage treatment is primary treatment.
In the first circular tank, the solid sediments are allowed to settle out from the mixture.
Large paddles do what?

Large paddles rotate, pushing the solids, called sludge, towards the centre of the tank

7

The 2nd step of sewage treatment is primary treatment.
In the first circular tank, the solid sediments are allowed to settle out from the mixture.
Large paddles rotate, pushing the solids, called sludge, towards the centre of the tank.
There the sludge is what?

There the sludge is piped to a storage tank for further treatment

8

In the 2nd step of sewage treatment, what does the watery liquid (effluent) above the sludge do?

In the 2nd step of sewage treatment, the watery liquid (effluent) above the sludge flows into the next tank

9

In the 2nd step of sewage treatment, the watery liquid (effluent) above the sludge flows into the next tank.
Although no solid matter is visible, this effluent still does what?

Although no solid matter is visible, this effluent still contains many potentially harmful microorganisms

10

The 3rd step of sewage treatment

The 3rd step of sewage treatment is secondary treatment

11

The 3rd step of sewage treatment is secondary treatment.
In the second tank, useful bacteria do what?

In the second tank, useful bacteria feed on any remaining:
1. Organic matter
2. Harmful microorganisms
still present

12

The 3rd step of sewage treatment is secondary treatment.
In the second tank, useful bacteria feed on any remaining organic matter and harmful microorganisms still present, doing what?

In the second tank, useful bacteria feed on any remaining:
1. Organic matter
2. Harmful microorganisms
still present, breaking them down aerobically (in the presence of oxygen)

13

In the 3rd step of sewage treatment, how is tank aerated?

In the 3rd step of sewage treatment, the tank is aerated by bubbling air through the waste water

14

In the 3rd step of sewage treatment, the tank is aerated by bubbling air through the waste water.
How long can this take?

This can take from several:
1. Hours
to
2. Days

15

In the 3rd step of sewage treatment, the tank is aerated by bubbling air through the waste water.
This can take from several hours to several days, depending on what?

This can take from several hours to several days, depending on the:
1. Quality of the waste water
2. Size of the tank
3. Rate of aeration
4. Temperature

16

The 4th step of sewage treatment

The 4th step of sewage treatment is final treatment

17

The 4th step of sewage treatment is final treatment.
In the last tank, the useful bacteria are what?

In the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment

18

The 4th step of sewage treatment is final treatment.
In the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment.
The sediment is either what?

The sediment is either:
1. Recycled back into the secondary treatment tank
Or,
2. Passed into the tank where the sludge is treated

19

The 4th step of sewage treatment is final treatment.
In the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment.
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated.
At this point, the treated waste water is what?

At this point, the treated waste water is safe enough to be discharged back into rivers

20

In the 4th step of sewage treatment, in the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment.
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated.
At this point, the treated waste water is safe enough to be discharged back into rivers.
However, what can happen if the river is a particularly sensitive ecosystem?

If the river is a particularly sensitive ecosystem, the water can be filtered one more time through a bed of sand

21

In the 4th step of sewage treatment, in the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment.
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated.
At this point, the treated waste water is safe enough to be discharged back into rivers.
However, if the river is a particularly sensitive ecosystem, the water can be filtered one more time through a bed of sand.
If necessary, what then can happen?

If necessary, the water can then be sterilised by:
1. Ultraviolet light
Or,
2. Chlorine

22

In the 4th step of sewage treatment, in the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment.
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated.
At this point, the treated waste water is safe enough to be discharged back into rivers.
However, if the river is a particularly sensitive ecosystem, the water can be filtered one more time through a bed of sand.
If necessary, the water can then be sterilised by ultraviolet light or by chlorine.
However, the release of chlorine into rivers does cause what?

The release of chlorine into rivers does cause concern

23

In the 4th step of sewage treatment, in the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as a sediment.
The sediment is either recycled back into the secondary treatment tank or passed into the tank where the sludge is treated.
At this point, the treated waste water is safe enough to be discharged back into rivers.
However, if the river is a particularly sensitive ecosystem, the water can be filtered one more time through a bed of sand.
If necessary, the water can then be sterilised by ultraviolet light or by chlorine.
However, why does the release of chlorine into rivers cause concern?

The release of chlorine into rivers does cause concern, because toxic organic compounds of chlorine can be formed in the environment