what is it?: Bio-filter, as a homemade filter, is composed of three separate layers of gravel, sand, and activated charcoal. It is a streamlined method of filtering impurities in the water starting from the biggest up to the most minuteimpurities in the water.

WHAT TO DO:
1. Turn the water gallon container upside down.

2. Cut a hole at the top of the container. This is where you will pour your materials and water for filtering.

3. The first layer must be gravel.Gravel is basically pebble-like rock that acts as a filter for common debris found in water such as a small sticks, fallen leaves, and even tiny creatures that are either an animal or an insect.

4. The second layer filled with sand. Sand can further filter out smaller particles in the water that the gravel was not able to catch.

Materials needed: 

Procedure on how to build the system:

Scientific principle(s) behind how the system works:

Possible difficulties in constructing the system in class:

1) Cotton wool

2) Sand

3) Charcoal (preferably powdered, or buy charcoal pieces and grind them up)

4) Gravel

5) An empty water bottle with the bottom cut off

6) A support system for the water bottle, e.g. a plank of wood with a hole

7) Dirty water 

1) Place the empty water bottle upside-down into the support system, plank of wood with a hole.

2) Pack layers of materials, cotton wool, sand, ground charcoal and gravel, into the water bottle.  

(Place cotton wool at the bottom (in the neck of the bottle), to prevent the other packing   materials from falling through. Above the cotton wool comes the ground charcoal, then the sand, and then the gravel. (As an optional extension to this exercise, the thickness of the layers can also be varied to see how this affects the purification process.)

3) Pour in the dirty water and let it seep through the materials and drip into a bowl which can be                                        

collected at a bowl underneath the support system.

4) After, all the water has drained into the bowl, boil it to kill the bacteria remained in it.

 

1) This experiment investigates the physical process of removing solid impurities of varying sizes and the chemical process of removing dissolved particles by sorption to charcoal. 

1) Materials may be hard to get.

2) Water cannot be boiled since there is no gas supply in the classroom.

3) Results may be inaccurate

 

 

Find a hot place set up

Procedure on how to build the system :Fill bowl with water place cup in the middle of the bowl. 

Cover the bowl with the plastic wrap and with the rubber band wrap the ends of the plastic wraps.

Place the stone in the middle of the plastic wrap

Leave it outside and come back later

You will find clean drinkable water in the cup

Scientific principle(s) behind how the system works: similar to the earth’s water cycle but downsized. The water from the bowl gains heat and evaporates leaving behind the dirty materials heavier than water.the evaporated water known as water vapour comes into contact with the plastic it condenses and turns into water droplets.due to gravity the droplet goes to the middle due to the stone and drops into the cup. This process contines and the water in the cup is drinkable

Possible difficulties in constructing the system in class : 

Important factor that can’t be controlled is the weather

Takes very long

Proedure:
Step 1: Mince the banana peel into small pieces (it is to increase the surface area) 

Step 2: Place the minced banana peel into a bottle containing the dirty water 

Step 3: Wait for an hour before pouring the bottle's contents out and filter it with a coffee filter to remove the banana peel and other small substances from the water

Scientific Explanation:
Banana peels contains atoms of nitrogen, surfer and organic compounds such as carboxylic acids. These acids are charged such that their negatively charged electrons pair are exposed, allowing them to bind with metals in the water that usually have a positive charge, therefore removing harmful metals from the water effectively.

Possible Difficulties: 
-Mincing of Banana peel in class would be messy
-Time constraints as banana peel needs to soak in the contaminated water for a long period of time
-Results may not be very accurate