What it shows
Coagulants make tiny suspended particles clump together and sink. Comparing alum (phitkari) with crushed moringa seed shows two ways to clear turbid water before filtering.
The science
Clay particles in muddy water carry a small electric charge that keeps them apart. Alum gives positive ions that neutralise this charge, and moringa proteins attach to the particles, so they clump into flocs that settle. A clearer jar means a better coagulant.
Materials
Cost: under Rs 50. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- Four clear jars or bottles
- Muddy water (clay soil stirred in water)
- Alum (phitkari) and moringa seeds
- A mortar or a clean stone to crush seeds
- A spoon and a timer
- A laser pointer or a torch for a clarity check
- A white card with a black cross
Safety
For this project: An adult must supervise crushing seeds. Do not drink any of the treated water, because it is not tested. Alum can irritate eyes, so wash hands after use.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
All the safety rulesStep by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Stir the same amount of clay soil into 500 ml of water in each jar to make equally muddy water.
Leave jar 1 as the control with nothing added.
Add a pinch (0.5 g) of alum to jar 2 and stir for one minute.
Crush five moringa seeds into a powder and add to jar 3, stirring for one minute.
Add both alum and moringa to jar 4 for a combined test.
Let all jars settle undisturbed and note the time.
At 10, 30 and 60 minutes, look through each jar at the black cross card and note how well the cross is visible.
Rate the clarity from 1 to 5 and plot against time for each jar.
What you should see
The jars with alum or moringa clear faster than the control, and the clarity ratings show which coagulant is faster.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1What is coagulation?
Clumping of tiny particles into larger ones.
2Why do flocs settle?
They are heavier than single particles.
3Why is the water still not safe to drink?
Germs and dissolved chemicals may remain.
4What step follows coagulation in a treatment plant?
Settling, filtration and disinfection.
Take it further
Vary the dose of alum from 0.1 g to 1 g and find the best amount.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
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