Water for Everyone: S3 - the Solar Still Solution STEM Challenge 2014 We are Megan, Astrid, Freddie, and Nicholas We are all musicians in Year 8 at Wells Cathedral School in Somerset Hello. Thank you for inviting us here today. We are very excited to be here! We are Megan, Astrid, Freddie and Nick, and we are all musicians at Wells Cathedral School. We also love science, and we developed a Solar Still to provide water for everyone!

Water is for life and for people: Everyone needs clean water to life a healthy life but many people don’t have access to clean water. Many people catch unpleasant and life-threatening diseases by drinking dirty water. And by the time we finish speaking 5 children will have died from diarrhoea alone. Everyone needs clean water to live a healthy life. We often take clean water for granted in the UK. Many people in other countries don’t have clean water to drink. Did you know that five children will have died from diarrhoea caused by drinking dirty water by the time we finish speaking?

We decided to make a Solar Still A Solar Still uses distillation to separate clean water from dirty water. Solar energy heats the water so that it evaporates to release clean water vapour. The warm vapour rises and condenses on a cool surface to form clean water droplets. We decided to develop a solar still to provide clean water for people who don’t have access to it The solar still is based on distillation, which is used to separate clean water from dirty water. It uses heat to convert liquid water into clean water vapour through evaporation. The warm vapour rises upwards until it meets a cooler surface where it condenses to form clean water droplets which are collected in container

How does it work? Evaporation Condensation Distillation Solar radiation warms the water up. As it warms up, the water turns into water vapour. A solar still is a piece of distillation apparatus that uses solar energy to heat up water. The water vapour is separated from a mixture and collected through condensation. Distillation is used for lots of processes like making perfume or making whisky! We used it to make clean water Condensation Water vapour condenses on a cold surface. Clean water droplets can be collected to drink. Distillation Distillation apparatus separates clean water from a mixture by evaporation. Then it collects the water by condensation.

Our solution was the S3 Solar Still We developed the Solar Still Solution (S3) which can produce clean drinking water for anyone, anywhere in the world. It is made from cheap, locally available items, and is lightweight and easy to carry around. It uses solar energy and can safely separate clean drinking water from saltwater and dirty water. We decided to develop a cheap and portable solar still to produce clean drinking water for anyone, anywhere in the world We made it from cheap and locally available items which we took from our parents’ kitchens and garages We designed it to work using solar energy so that people could use it anywhere even if there wasn’t any fuel available to burn

We made the S3 Still using recycled items from our parents’ kitchens! We used metal for the raw water cup so that it heated the water quickly. We used plastic for the water collection container sterilised with boiling water and coated it in white tape so that it reflected solar radiation to stop the potable water we collected from heating up and evaporating again. We used a clear plastic bag to allow solar radiation to reach the water in the cup without losing too much energy, and to provide a surface for condensation to collect on An old metal measuring cup to hold the dirty water. A metal jam sieve without its handle, for the water to drip through. A sterilised white plastic tub to collect the water and keep it cool. A clear plastic sandwich bag to let the sunshine in and allow condensation. Some fine metal wire to make a dome frame to hold the bag open. Two old elastic bands to hold the dome in place and seal the Still.

We tested the still to see if it could separate freshwater from saltwater We made a salt solution and put it in the metal cup. We set up the Still and collected the water in the plastic tub. We tested it using silver nitrate solution which would turn the water cloudy if there was any salt in it Once we fixed a hole in the measuring cup, the water from the tub stayed clear. Silver nitrate was added to water collected in the S3 tub. If salt was present, the water would turn cloudy. We did three replicates and all three stayed clear. We had made freshwater!

We tested the S3 Still to see if it could make clean water that was free from microbes We made a salt solution and put it in the metal cup. We set up the Still and collected the water in the plastic tub. We tested it using silver nitrate solution which would turn the water cloudy if there was any salt in it Once we fixed a hole in the measuring cup, the water from the tub stayed clear. We made some agar plates. We sterilised some needles in a hot flame. We used them to put water from the tub on the agar. We had a control plate with no water on it. We also had a dirty water plate to make sure microbes would grow. We incubated the plates for 24 hours in a warm place.

The S3 Still produced clean drinking water! We found no microbe growth on our Agar plates for the Still samples. There was no growth on the control plate either. There was lots of microbe growth on the dirty water sample plate. The test had worked. Our S3 Still could produce clean drinking water as long as we kept it clean. 1 2 3 The results were really encouraging. The control didn’t grow any microbes, but the dirty water sample did, so we knew the test would work if microbes were present. Both of our Still samples came out clean, with no microbe growth The S3 Still could produce safe, clean drinking water!

Our project found a solution to provide Water for Everyone! The S3 Still was cheap to make, free to run, lightweight and portable. It easily produced freshwater from saltwater. Our tests showed that as long as the equipment was sterile, it could produce freshwater that was free from microbes. We really enjoyed doing this project. Thank you! We had great fun doing this project, and are really proud of our Still. It was cheap to make, it costs nothing to run it, and it can produce freshwater from salty water We think it would work with other kinds of dirty water too We wanted to make sure the water would be safe to drink, and our tests showed that it would, but we had to take care to keep the Still clean We think it might help people who don’t have access to clean water. May be it could save lives!