each
coagulant was added into the sample water under rapid stirring.
The HA solution was stirred rapidly at 600 rpm for 2 min after
coagulant dosing followed by slow stirring at 200 rpm for 10 min
and then settled for 30 min. Then, sludge volume (SV) was
determined by direct reading as percentage of sludge/mL of water
treated [30].