One of our 1,106 wastewater treatment works

When you fl ush the toilet or pull a plug out, the water disappears. Do you know where it goes?

How we treat wastewaterOnce you fl ush the toilet or let water go down the plughole, it enters a network of pipes and pumps which leads to a wastewater treatment works. This is also called a sewage treatment works. Here it is treated before it is returned to our rivers and seas. In some areas, houses which are not connected to the sewers have septic tanks for their wastewater. The tank is buried underground and has to be emptied by special lorries.

Why do we treat wastewater?We need to remove some of the ingredients in wastewater that might harm the environment by polluting the rivers and the sea.

How do we do it?The wastewater treatment process is done in four main stages. Follow the diagram overleaf to fi nd out more.

Cleaning wastewaterFact fi le 8

Every day Anglian Water collects more than 960 million litres of wastewater from around 5.5 million customers.

Did you know that when we treat wastewater we create a soil conditioner called biosolids, which is used in agriculture?

septic tank

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See if you can create your own fi lter to turn muddy water back into clean water again. You can use different materials to see how good they are at fi ltering the water.

Safety warningYou may need to ask for the permission or the help of an adult to cut the plastic bottle up.

What to do1 Cut the bottom off the plastic

bottle.

2 Push cotton wool into the neck of the bottle. Make sure it is in tightly.

3 Rinse the stones and gravel that you will be using until they are clean.

4 Add stones so that they fi ll a quarter of the bottle.

5 Add gravel so that the bottle is half full.

6 Add sand almost to the top.

7 Rest the bottle on the clear container.

8 Mix some soil with some clean water in a jug to make dirty water and carefully pour it into the bottle.

Recycling waterActivity 8

Learning objective:To fi nd out how to separate solutions using fi ltration.

You will need:• Soil/water mixture• Cotton wool• A jug• Sand• Beakers• Gravel• A large clear plastic bottle• Scissors• Stones• Filter paper (optional)

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Observations1 Write down what you can see happening to the dirty

water as it passes through the fi lter.

2 What can you see happening inside the bottle?

3 How clean is the water in the bottle base?

Investigating furtherHere are some questions you could fi nd the answers to:

1 What happens if you pour the water collected in the clear container through the fi lter again?

2 What happens if you add fi lter paper?

3 Which material do you think is the best at fi ltering the dirty water and why?

4 Investigate other materials to design your own water fi lter.

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