Our planet and our bodies are composed mainly of water. That is why we need water to survive. We get water from the food and drink we take in every day. What if you go to a place where you are uncertain of the water’s quality? This is where water purification steps in. When you know how to treat water, you can drink from anywhere, as long as you sterilize it after.
What you need:
• Timer or a stopwatch
• Half a liter of dirty water (water from your tap or swamp water)
• Plastic spoon
• A 2-L soda bottle with its lid
• 1 large metal spoon
• 2-L soda bottle sliced in half (this requires the help of someone handy)
• Rubber band
• 1000 ml beaker
• 1 cup of small pebbles
• 2 20-ounce cups
• 1 coffee filter or filter paper
• 1 cup of coarse sand
• 1 cup of fine sand
• 1 tbsp of aluminum potassium sulfate (alum)
How you make it:
Get the 2-L plastic bottle with its lid and into it, pour the dirty water. Take note of the water’s odor and appearance.
Replace the lid of the bottle and shake it robustly for about half a minute. Pour the water into the two cups alternatingly, 10 times.
Then, pour the water into the plastic bottle that doesn’t have a top half. Notice how the water looks and smells.
With your plastic spoon, add 2 tablespoons of alum into the water contained in the plastic bottle that doesn’t have its upper half. With the same spoon, stir the water slowly for about five minutes. Notice what happens to the water.
Let the water stand for 20 minutes, undisturbed. Check it every 4 to 5 minutes. Note its appearance and odor.
With a rubber band, fix the filter paper to the bottle’s mouth. Cut off the bottom part of the bottle. Then, place it upside down inside the beaker.
Place the pebbles inside the inverted bottle. Pour the sand over the layer of pebbles. Lastly, add the fine sand over the sand layer.
Pour out the two liters of regular tap water carefully over the layers you created. Do this while keeping the layers undisturbed. Watch the water run out of the bottle’s mouth, into the beaker. Pour out the filtered tap water out of the beaker and keep it in a clean, clear or white plastic cup.
Pout out the top two-thirds of the dirty water into the layers, but do not pour out the sediments. Pour out the filtered dirty water into a clean, clear or white plastic cup.
Compare the resulting water samples. Do they smell or look different at all?
This water filtration unit took us through the five steps in the purification of water:
• Aeration. Oxygen is added into the water, while other gases escape from the water.
• Coagulation. Solid particles including particles bind together, resulting in clear water.
• Sedimentation. Gravity pulls the sediments to the bottom of the container.
• Filtration Floc and sediments are removed from the liquid.
The only thing that’s missing is disinfecting the water so that it could be free of microorganisms and pathogens.