Experiment: Water Treatment – Coagulation
date | aim | method
| equipment | results
| conclusion | follow-up
Date
14 June 2007 by Quest 1. Links in with Water
Treatment.
Aim
To accelerate the settling of dirt particles from muddy water.
Method
Half fill three test tubes with muddy water. Ensure their levels are
the same.
In two other test tubes make up solutions of 1 measure of FeSO4
with one pipette of water, and 3 measures of FeSO4 with one
pipette of water.
Add one of these solutions to each of two of the muddy water test tubes.
Top the third test tube up to the same level with pure water – it is
our control test tube.
Stir to mix then leave to settle.
Shake to see if the FeSO4 has had any effect.
Equipment
- Iron(II) sulphate (FeSO4)
- Water.
- Mud.
- Test tubes, water dropper (known as a pipette).
- Metal spatula.
- Cloth for mopping up spills.
Results/Observations
The ferrous sulphate crystals when dissolved in water gave the water a pale
yellow colour.
Nothing seemed to happen for a long time of settling, and each of the
three test tubes seemed to be settling equally quickly. However, a small
difference was visible with the 3 measure tube.
When the test tubes were stoppered and shaken it was obvious that the
test tube with 3 measures of FeSO4 had particles that settled
out very quickly, as opposed to the other test tubes which stayed muddy
after the shaking. The 3 measure test tube still had cloudy water though.
Conclusion
Iron(II) sulphate makes a big difference in making dirt particles settle
out of water, but only if enough is used.
Very muddy water may need a
lot of FeSO4 to work.
Follow-up
17 September 2008: After leaving the test tubes for ages (one and a
quarter years), one was stained a yellow colour from excess ferrous
sulphate. Where the settled mud at the the bottom of the test tube
had collected was not stained. This shows it's not just porcelain
that's affected by this sort of staining.
|
