To provide pupils with information about how water is collected. To check their knowledge and understanding of the information

Transcription

1 Water Treatment 1a/b How is water collected for us to use? Aims: To provide pupils with information about how water is collected To check their knowledge and understanding of the information Materials: Worksheets 1a and 1b at the appropriate level Map of Scotland Coloured chalk Clear plastic beakers Method: Read Worksheet 1a Tell the class the key pieces of information about - reservoirs - where they are, how they are made - how the water is cleaned - key words such as silt - underground reservoirs Pupils may be familiar with visiting reservoirs for picnics or walks

2 Water Treatment - Worksheet 1a How is water collected for us to use? It is easy to turn on the tap to get clean water, but a lot of things have to happen to allow us to do that. First of all, water has to be taken away from its natural cycle. Do you know how that happens? Most of the water used today is collected and stored in man-made or natural lochs called reservoirs. Rainfall is highest in hilly areas, so this is where most reservoirs are. Reservoirs are made by building a dam across the upper part of the river. The water then collects and makes a huge loch. So, even if it does not rain for several weeks, there will still be water available. before The dam has to be made of very strong, thick concrete to hold back the huge amount of water behind it. The amount of water flowing through the dam is controlled by opening and closing valves. after The water in the reservoir needs to be cleaned before it is ready for us to drink. The river has carried lots of bits of grit and dirt down with the water. Some of this grit and dirt will sink to the bottom of the reservoir as silt. This happens because the water in the reservoir is deep and still. The rest is removed at the water treatment works which makes the water clean and safe to drink. pumping station Sometimes we take water from natural lochs like Loch Lomond. intake pipe Sometimes a reservoir forms naturally underground. Rainwater soaks into the ground and through the rock below. It happens where there are rocks like chalk and limestone. They soak up a lot of water. They are a bit like underground sponges. The water then collects in a space between layers of rock. We call this an aquifer. We collect water from the aquifer by drilling boreholes in the rock. The water is then pumped out. Wherever we get it from, all water must go to the water treatment works to be made safe and clean before it is piped to our taps. soil rock aquifer (underground reservoir)

3 Water Treatment - Worksheet 1a How is water collected for us to use? When you turn on the tap to get a glass of water do you ever think how it got there? Most of the water that is used today is collected and stored in man-made or natural lochs called reservoirs. There is more rain in the hills so this is where most reservoirs are. Reservoirs are made by building a dam across the upper part of a river. The water collects and makes a huge loch. before after The dam has to be made of very thick and strong concrete so that it will hold the water behind it. By opening and closing valves you can control how much water gets through the dam. The water in the reservoir needs to be cleaned before we can drink it, as the river has carried lots of bits of grit and dirt down with the water. Some of this will sink to the bottom of the reservoir. The rest is taken out at the water treatment works which makes the water clean and safe to drink.

4 Water Treatment - Worksheet 1b How is water collected for us to use? Answer the following questions. 1. Where does most rain fall? 2. What does a reservoir store? 3. Why does a dam have to be strong? 4. Where does the water go when it leaves the reservoir? Can you unscramble these words? 1. rieevrros 2. mad 3. servir 4. tgir 5. Ivaevs

5 Water Treatment - Worksheet 1b How is water collected for us to use? Read the information sheet. Your Name: hnjkh Find the word or group of words in the information sheet that mean the same as: a man-made loch a barrier across a river a place where water is made safe and clean an underground reservoir a hole drilled through the earth to reach underground water Answer the following questions: Where is rainfall highest? What does a reser voir stop? Why does a dam have to be strong? Where does the water go when it leaves the reser voir? Why does most of the silt sink to the bottom in a reser voir? What kind of rocks absorb a lot of water? Can you unscramble these water words? 1. rieevrros 2.afruqie 3.tisl 4. tgir 5. mad 6. servir 7. Ivaevs 8.oeoehbrls Experiment: You can try a simple experiment to show how chalk soaks up water. Put some coloured chalk end up in a dish of shallow water. Write down what happens.

6 Water Treatment 2. How does clean water get into our homes? Aims: To provide pupils with information about how water reaches their homes Materials: Worksheet 2 Method: Ask pupils how they think water travels from the treatment works to the taps in their home Hand out Worksheet 2 Read together and identify how water is being used and the location of the stop cock and the water main Pupils write up answers Ask them to find out where the stop cock is at home

7 Water Treatment - Worksheet 2 How does clean water get to our homes? When clean water leaves the water treatment works it travels through large pipes called water mains which are buried underground. There is a water main under the road outside your house and the water in your tap comes through a pipe from that water main. Hard level A stop-cock in the house or sometimes in the garden, can be opened or closed to allow you to turn the supply from the water main to your house on or off. It's a bit like turning a tap on or off. Look at the picture above. 1. List the ways you can see water being used. 2. Find and label: the water main the stopcock 3. Most of the time the stop-cock is open as we are constantly using water at home. Can you think of any reasons you might want to turn off the water coming into the house? Scottish Water 2004

8 Water Treatment 3. Clean water investigation Aims: For pupils to research algae and bacteria Materials: Worksheet 3 Method: Ask pupils what they think algae and bacteria are. Provide them with a description Hand out Worksheet 3 - set the task and give pupils a deadline to return the information When the task is complete discuss their findings

9 Water Treatment - Worksheet 3 Clean water investigation The water that collects in reservoirs is not clean enough to drink. It contains mud, clay and living things such as: algae and bacteria. Hard level These particles are so small you need a powerful microscope to see them, however they can also be very dangerous and some cause serious illness if they are in drinking water. Find out all you can about: algae and bacteria Make drawings.

10 Water Treatment 4. Collecting water Aims: To enable pupils to find out how water can be collected To identify parts of the world where water is collected in these ways Materials: Worksheet 4 Method: Review with the pupils their understanding of how water arrives in their homes Explain that this is not the case in some parts of the world If there has been recent media reports about drought conditions share with pupils and discuss Hand out Worksheet 4 and ask pupils to answer the questions The investigation could be a homework activity

11 Water Treatment - Worksheet 4 Collecting water Have you ever thought how lucky you are to be able to turn on a tap and have all the water you need? In the past people had to collect their water from ponds, streams, rivers or wells. In some countries today, people still collect water this way. Investigation: -Try to find out the names of some countries today that are likely to be collecting their water from rivers, streams and ponds. - What is the term used when we talk about this kind of country? Look at the pictures above and try to answer these questions: 1. Can you think of any problems there might be with collecting water from rivers, steams and ponds? 2. What are the health risks? 3. Do you think it is better to collect water from a well than a river? If so, why? 4. What are the advantages of tap water? 5. Can you think of any disadvantages of tap water? Scottish Water 2004

12 Water Treatment 5. Water treatment and the environment Aims: To enable pupils to understand the process of water treatment To introduce pupils to the scientific processes involved in water treatment Materials: Worksheet 5 Method: Remind pupils that before water from the reservoir reaches their home it has to be cleaned at the water treatment works Hand out Worksheet 5 and discuss with the pupils or teach the process and use card as a follow up

13 Water Treatment - Worksheet 5 Water treatment and the environment How does water get into our homes? How is it treated to make it safe for drinking? Once it is collected in a reservoir it is taken to a water treatment works where 5 different things happen to it. 1. Screening Leaves, twigs and any large debris are removed by screens. Hard level 2. Clarification Mud and silt are removed. Alum (aluminium sulphate) and lime (calcium hydroxide) are added to make them group together to make sludge. This is taken away to be safely disposed of at a landfill site. 3. Filtration Most treatment works have to filter their water. Sand removes any little bits and any remaining colour. 4. Disinfection The water now looks clean but what we can't see must be taken out. Chlorine is added to kill the bacteria (think of the swimming baths). 5. ph correction Just before leaving, lime (calcium carbonate) is added to adjust the ph. The water is too acidic without it. This also prevents lead from old pipes getting into the water. The water is now ready for drinking. What happens now? The water is stored in large tanks called Ser vice Reser voirs. From there it goes along a massive pipe and pumping network into our homes.

14 Water Treatment 6. Why must water be treated? Aim: To give pupils knowledge and understanding of the water treatment process and why it is necessary Material: Worksheet 6 Method: Hand out worksheet and discuss the content with pupils Link to their investigation of algae and bacteria

15 Water Treatment - Worksheet 6 Why must water be treated? Why must water be treated? - to reduce risks to public health - to comply with the law Water taken from the environment contains many sorts of bacteria: micro-organisms, minerals, natural and man-made substances, as well as dirt and colour. Hard level Some can be harmful. The purpose of water treatment is to convert this 'natural' water into water that is wholesome and safe to drink. How? Water Treatment - Upland catchments Intake 1. Reser voir 2. Clarification wells 3. Filtration 4. Disinfection 5. Treated water storage 1. Store water 2. Alum is added. This removes the peaty colours. 3. Gravel beds trap any dirt as the water flows through. 4. Enough chlorine is added so that the last house supplied has water without germs. 5. The clean sterile water is kept in a storage tank then passed to houses and factories.

16 Water Treatment 7. Making water clean and safe Fantastic Filters Aims: To provide experience of filtering water To enable pupils to recognise the effectiveness of different filters To relate this to their knowledge of the water treatment process Materials: Measuring jug, a small amount of gravel, 3 empty glass jars, 3 plastic cups that fit the jam jars Worksheet 7 Method: Decide whether you will conduct the experiment as a class in small groups or organise small groups to do it at different times during the day/week Remind pupils that water from the environment is not clean enough to drink and has to go through the water treatment process Tell them that they are going to try different ways of filtering dirty water Hand out Worksheet 7 at appropriate level Pupils conduct experiment and write up their findings

17 Water Treatment - Worksheet 7 Fantastic Filters Can you make a filter to clean dirty water? How to find out: 1. Make some holes in the bottom of your plastic cups. 2. Fill your plastic cups like this: Hard lev:::::l You will need: gravel only sand only sand and gravel 3. Sit each one on top of an empty jar. 4. Stir your water then carefully pour equal amounts into each of the cups. 5. Compare the water in each jar. Write up your experiment: - measuring jug with soil and water mixed up together - three empty jars - three plastic cups - some sand - some gravel Start like this: Try to answer these questions: Use labelled diagrams: 1. What we used. 2. What we did. 3. What happened to the water poured into each jar? 1. Which material let the water through the fastest? 2. How clean was this water? 3. Which jar has the cleanest water? 4. What do you think has happened to the dirt in the water? 5. Which material do you think made the best filter? Why? What happens at the water treatment works? When raw water leaves the reservoir it goes to the water treatment works to be cleaned and made safe to drink. One way of cleaning water is to use sand and gravel filters to trap bits of dirt. These are often called slow sand filters. Can you think why?

18 Water Treatment - Worksheet 7 Fantastic Filters Can you make a filter to clean dirty water? How to find out: 1. Make some holes in the bottom of your plastic cups. 2. Fill your plastic cups like this: Hard level You will need: gravel only sand only sand and gravel 3. Sit each one on top of an empty jar. 4. Stir your water then carefully pour equal amounts into each of the cups. 5. Compare the water in each jar. Try to answer these questions: - measuring jug with soil and water mixed up together - three empty jars - three plastic cups - some sand - some gravel 1. Which material let the water through the fastest? gravel only sand only sand and gravel 2. How clean was this water? 3. Which jar has the cleanest water? 4. What do you think has happened to the dirt in the water? 5. Which material do you think made the best filter? gravel only sand only sand and gravel 6. Why do you think this is?

19 Water Treatment 8. Making water clean and safe Magnetic attraction Aims: To enable pupils to understand how the chemicals react with the dirt in the water and make it clean and safe Materials: A magnet Iron filings A sheet of paper Worksheet 8 Method: Decide whether you will conduct the experiment as a class or in small groups Explain that water from the reservoir has tiny bits of dirt in it which have to be taken out before the water can be piped into their homes Review which chemicals are used in the process (Worksheet 5) explaining that they are like a magnet Hand out equipment and Worksheet 8 at appropriate level Pupils conduct experiment and write up their findings

20 Water Treatment - Worksheet 8 Magnetic attraction Water from the reservoir has tiny bits of dirt in it, so small we can't see them. These bits have to be taken out before the water can be piped to our homes. At the water treatment works they add chemicals to this water. The chemicals pull the tiny bits of dirt together to make big bits. What to do: Hard lev: You will need: - a magnet - iron filings - a sheet of paper - worksheet 8 1. Spread the filings over the sheet of paper. 2. Place the magnet in the middle of the filings. What happens? Write up your experiment: Start like this: 1. What we used. 2. What we did. 3. What happened. Try to answer these questions: 1. In this experiment the chemicals are like the magnet. What are the tiny bits of dirt like? 2. How does this experiment help you to understand what happens to the tiny bits of dirt in the water? What happens next? Can you think of an experiment which would show why the tiny bits of dirt had to be big bits before this could happen? Discuss this with your group and try it out. There are different ways the water can be treated now. One way is to pass it into large tanks where the big bits of dirt drop down to the bottom of the tank. The water at the top of the tank is much cleaner and passes on to the next stage of treatment. Another way is to add tiny air bubbles to the tank so that the sludge will float up to the surface. It looks a bit like chocolate mousse! The water is then removed from the bottom of the tank.

21 Water Treatment - Worksheet 8 Magnetic attraction Water from the reservoir has tiny bits of dirt in it, so small we can't see them. These bits have to be taken out before the water can be piped to our homes. At the water treatment works they add chemicals to this water. The chemicals pull the tiny bits of dirt together to make big bits. What to do: 1. Spread the filings over the sheet of paper. 2. Place the magnet in the middle of the filings. What happens? Hard level:: You will need: - magnet - iron filings - a sheet of paper - worksheet 8 Write up your experiment: Start like this: 1. What we used. 2. What we did. 3. What happened. Try to answer these questions: 1. What happened when you put the magnet in the middle of the iron filings? 2. In this experiment the chemicals are like the magnet. What are the tiny bits of dirt like? What happens next? There are different ways the water can be treated now. One way is to pass it into large tanks where the big bits of dirt drop down to the bottom of the tank. The water at the top of the tank is much cleaner and passes on to the next stage of treatment. Another way is to add tiny air bubbles to the tank so that the sludge will float up to the surface. It looks a bit like chocolate mousse! The water is then removed from the bottom of the tank.

22 Water Treatment 9a/b Water treatment quiz Aim: To assess pupils' knowledge and understanding of the water treatment process in a fun way Materials: Worksheet 9a/b Method: This can be used as an assessment/homework activity Hand out a copy of Worksheet 9 to each pupil Review answers as a whole class using the answer sheet provided

23 Water Treatment - Worksheet 9a Water Treatment Quiz True or False? Are the following statements True or False? Circle the answer. 1. Water taken from the environment contains many sorts of bacteria. True False Hard level 2. Water collected from the environment is treated to change it into water that is safe to drink. True False 3. Leaves, twigs and rubbish are allowed to float into the tanks where water is stored. True False 4. Alum and lime are added to remove mud and silt. True False 5. A big sieve is used to trap any dirt as water flows through. True False 6. Lime is added so that every house has clean water. True False 7. Clean, sterile water is kept in a storage tank then passed to houses and businesses. True False

24 Water Treatment - Worksheet 9b Water Treatment Quiz Answer Sheet 1. True. The water contains many sorts of bacteria micro-organisms, minerals, natural and man made substances as well as dirt and colour. Hard level 2. True. Some water from the environment can be harmful. It is treated to make it into water that is safe to drink. 3. False. Leaves, twigs and any large debris are removed by screens at the first stage of the treatment process. 4. True. The alum and lime are added to make the mud and silt stick together to make sludge. 5. False. Sand and gravel beds are used to trap any dirt as the water flows through. 6. False. Enough chlorine is added so that the last house supplied has water without bacteria. 7. True. After the treatment process, the clean water is stored in large tanks called Service Reservoirs and then goes through the pipe system to our homes and businesses.