ACTIVITY 2 : Water Treatment
Coagulation and Flocculation
"Wow, Kopi O Gao!" today's activity started off with the amazement from many people. Each team was required to bring a 1.5 litre bottle of "swampy dirty water" today and so we brought a bottle of blackish water which is the mixture of black soil and water. It is also worth mentioning that we were instructed to watch several videos related to turbidity test, normal distribution and coagulation and flucculation process before this activity. This has definitely helped enhance our understanding about the purpose of this activity.
Hypothesis Testing
Turbidity Test and Coagulation-Flocculation
Firstly, we fill in our soil water into 3 transparent cups prepared by teachers. One cup served as control, one cup is added in with 5 mil of alum and last one with 10 mil of alum.
Left : Control
Middle: 5 mil alum
Right : 10 mil alum
After that, we stirred 5 and 10 mil alum cups for 5 minutes. The purpose of stirring is to dissolve the alum in water.
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| Stirring |
After the 5 minutes stirring, we tested our water with various tests : Temperature Test, Turbidity Test, pH Test, Dissolved Oxygen Test and Conductivity Test. The most important test of this activity is actually the Turbidity Test. Throughout the Turbidity Test, we were required to wear nitrile gloves in order to keep our fingerprints off the sample bottles. The water filled in the sample bottle must also not exceed the white line and we have to rub the surface of the sample bottle with clean cloth before testing it with the turbidity meter.
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| Turbidity Meter |
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| White Line of Sample Bottle |
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| After 5 minutes |
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| After 10 minutes |
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| After 15 minutes |
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| After 20 minutes |
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| After 30 minutes |
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| After 25 minutes |
Noticed that the turbidity readings of 5 mil alum water (76.4) and 10 mil alum water (84.2) is almost the same. We can assume that 5 mil alum added in water has the same effect with 10 mil alum added in water.
In addition, Dr. Xin Yi taught us about one and two tailed test and hypothesis test. She also showed us how to we do the tests using Excel. After the lesson, we were given a mathematics question and assigned to solve it in pair.
This question is highly relevant to our activity today, it is to prove that whether there is any difference between the percentage of reduction of turbidity by using 5 mg/L and 10 mg/L.
This is our solution:
We successfully prove our assumption that there is actually no difference between using 5 mg/L and 10 mg/L of alum. It is significant especially to the industry because the use higher concentration of alum will increase the cost. To conclude, we have learnt about the coagulation-fluccolation process and also the way to make use of mathematics to maximise usage of our resources.
Thank you for reading this! Bye :D
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