Jar Test

The optimum level of coagulant dose will depend upon the nature of the raw water.
Carry out a jar test by dosing a series of samples with coagulant of varying concentrations, say 10-100 mg/l. Stir rapidly for one minute and then gently stir for ten minutes. leave to stand for 30 to 60 minutes. Compare the turbidity of each sample to determine teh lowest effective dose of coagulant.
If it is possible to adjust the ph, carry out a further test on samples at the optimum dosage but with the ph adjusted over a range of values say ph5-ph8. theis will indicate the optimum ph for coagulation.
Alum and ferric sulphate are normally dosed at a solution strength of between 3 and 7 per cent.