It covers two-thirds of the Earth's surface and makes up about 60% of adult's bodies, including 75% of our brains! Each day we need to consume more than two liters of the stuff—through liquids we drink and foods we eat. Although there's plenty of H2O around, much of it is either inaccessible or inconsumable to humans. But with water treatment, we're able to purify water and get what we need.
CAUTION: Adult supervision required when handling chemicals and/or cutting objects. Remember to use proper safety equipment when experimenting.
Because we won't disinfect our water, it is NOT safe to drink.
What you do:
Pour swamp water in the 2-liter bottle with a lid. Notice how it looks
Put the lid on the bottle and shake vigorously for 30 seconds. Then pour
the water back and forth between the two cups about 10 times.
Pour the water into the bottle with its top cut off. Again notice how
the water looks and smells.
Add 2 tablespoons of alum to the water in the bottle with the top cut
off. Use the spoon to slowly stir the water for five minutes. What do
you notice about the water as you stir it?
Now let the water sit undisturbed for 20 minutes, checking it every five
minutes to note how it looks and smells (without moving it).
Use a rubber band to secure the filter paper to the mouth of the bottle
with its bottom cut off. Put it upside down in the beaker.
Pour the pebbles into the bottle. Then pour the coarse sand on top of
the pebbles and the fine sand on top of the coarse sand.
Carefully pour about two liters of clean tap water through, being
careful not to disturb the top layer of sand. Pour the rinsed water out of
Pour the top 2/3 of the swamp water through the filter, taking care to
leave the sediment in the swamp water bottle.
Once all the water has passed through the filter, compare the swamp water
to the filtered water. How do they look and smell different?
There are five steps to basic water purification: aeration, coagulation, sedimentation, filtration, and disinfection. Our project took us through the first four. Aeration adds air to the water. It allows gases trapped in the water to escape and adds oxygen to the water. Coagulation is the process which allows dirt and other suspended solid particles to chemically “stick together” into floc (clumps of alum and sediment). During this step, the water is also clarified, or made clear and colorless. Sedimentation is the process that occurs when gravity pulls the particles of floc to the bottom of the container. So as the water sits undisturbed, most of the floc settles, preparing the water for the next step. Filtration is the process where remaining solid particles and floc are separated and removed from the from the water. Disinfection is the final step, in which water is chemically treated to remove bacteria and other micro-organisms. These unseen bacteria can cause severe sickness and even death in humans.
Because we didn't disinfect our water, it is NOT safe to drink.