To determine the quantity of Alum required to Coagulate a given sample of water
Apparatus Required: Flacculator with stirring device, beakers
Reagents Required: Alum solution by dissolving 14.28 gm alum in distilled water
Procedure:
- Fill 6 beakers with 1 litre water sample.
- Attach the beakers to stirring device.
- Add coagulant solution in progressive volumes of 0.25 ml, 0.5 ml, 0.75 ml, 1.0 ml, 1.25 ml, 1.5 ml into the series of six beakers.
- Flocculate them @ 60-80 rpm followed by gentle stirring @ 30 rpm for 15 minutes.
- After completion of stirring remove the beakers from the device.
- Let them to stand for 30 minutes so that flocs settles.
- Select the minimum doses giving the best floc & settling characteristics.
Calculation:
Selected Optimum dosage: x ml/l of water sample
Optimum dosage in mg/l: 14.28x