Can solar energy purify unpurified water?

If I leave the unpurified water facing the sun, then the solar energy will kill the bacteria leaving me with purified water.

• A large box

• A small, clear, and clean glass bowl

• Clear plastic wrap

• A large rubber band

• A small rock or weight

• Unpurified water

• Tap water

• An open outside area where the sun is constantly shining

• Water analysis strips

1. Collect unpurified water from a local water source.

2. Test the unpurified water with the water testing strips and test for bacteria

3. Then test the tap water with the water testing strips and test for bacteria

4. Grab your bucket and fill about a quarter of the bucket up with the unpurified water.

5. Place a small clear glass bowl in the center of the bucket.

6. Cover the bucket with the clear plastic wrap, secure with the rubber band, and place the rock on the plastic wrap and make sure it is on the center of the bowl.

7. Place the bucket with the water facing the sun.

8. Throughout the day, change the bucket so it is facing towards the sun

9. After monitoring it for several hours, the water should have evaporated into the bowl.

10. Remove the glass bowl

11. Now test the water with the test strips and bacteria container

12. Compare the condensated water to the unpurified water and the tap water

Independent Variable- The local water source water

Dependent Variable- The results of the test strips and the growth of bacteria in the water

Constants- the amount of water and the the size of the container

Control- The tap water and unpurified water (that hasn't been purified)

The purpose of this experiment was to find out if solar energy can purify unpurified water using a solar still. This experiment is important to me because I believe that this method of water purification is useful to communities in need. My hypothesis was: If I leave the unpurified water facing the sun, then the solar energy will kill the bacteria leaving me with purified water. My results do support my hypothesis. The unpurified water from a local lake grew harmful coliform bacteria making it unable to drink. The lake water was higher in hardness whereas the tap water was lower in hardness making it soft. The water that was placed in a waterstill under the sun did not grow any harmful bacteria. The test strips results show a little bit of a difference from the water that I purified myself.

For my project, I decided to build a simple solar still for water purification. A solar still is used to purify water by using solar energy and the water cycle. Water is purified with the heat of the sun which evaporates the water. Water vapor then condenses on a cool surface and drips down a collection bin. My solar still used a clear box where I put the unpurified water. It had a bowl in the center which is used as my collection bin. The box had a clear plastic wrap on top of it and that's what I used as my cool surface. The unpurified water evaporated onto the clear wrap, the weight of the rock helped it drip down into the collection bin. This method of water purification is useful in poor rural communities and countries where there is no access to drinkable water. Another benefit of this project is that it uses solar energy and therefore, it is a benefit to the environment. My hope is that many people and places will benefit from my results.

I began my experiment by collecting 2 gallons of unpurified water which I got from my local lake. I used tap water from home as my control. I tested the unpurified water from the lake and tap water using a drinking water test kit so I could compare it to the condensed water after placing in the sun. I also placed the tap water and lake water each in two different bacteria test kits. After 48 hours of growing the bacteria in the container, it indicated that there was harmful bacteria in the lake water making it undrinkable. As expected, the tap water did not grow bacteria. I used three plastic boxes and filled a quarter of each box with the unpurified lake water. Next, I placed a glass bowl in the center of each box. I covered each box with the clear plastic wrap, secured them with a rubber band, and placed the rock on the center. Each of my experiments were placed in direct sunlight for 2 days. I tested the condensed water in the glass bowl after the two days of sunlight. I also used bacteria containers to test the condensed water for harmful coliform bacteria. I was happy to see that no bacteria grew after purification with solar energy. My hypothesis was correct. I wrote the data in my graphs.

The main reason I chose to do this experiment was because I read that one-tenth of the world's population does not have access to clean drinking water. After doing some research, I learned that a simple solar still can help those communities have access to purified water from an unpurified source of water. This year in my science class with Mrs Castillo, I learned about the water cycle. The water cycle was a big part in my experiment because it consisted of evaporation, condensation, and precipitation. I used those 3 principles in my experiments. I'm very happy with my results knowing that it can help a lot of people in need.

My project can help poor rural communities who dont have the money to buy expensive equipment for water purification. A solar still can be built anywhere and it gives you clean drinking water. Not only are solar stills like mine inexpensive, but theyre also all natural! I used the sun's energy which is a natural element and I also used the water cycle. I hope my project can help anyone in need of clean drinking water.

“Solar Water Distillation” by Safe Water Drinking Foundation, January 1998 on safewater.org

Solar Water Still by Interesting Engineering, January 4th 2020 on interestingenineering.com

Water Treatment Center Science by Science Buddies, July 21, 2016 on Science buddies water treatment center

Sunlight-powered Purifier Could Clean Water For The Impoverished by Science Mag, February 3, 2017 on Sunlight-powered Purifier Could Clean Water For The Impoverished

School Projects On Water Purification Treatments by Lee Johnson December 15, 2018 on School Projects On Water Purification Treatments

ACKNOWLEDGEMENTS