Fig. 6 shows the removal of HA and DOC from the river water
with each PAC dosage. This method displayed high removal even at
30 mg/L of PAC. Besides that, it also indicated little coagulation and
low removal with NaOH. The higher the dosage of PAC, the higher
was the removal ratio. The lowest residual DOC concentration of
4.5 mg-C/L, which is lower than the water quality standards for
drinking water in Indonesia, was obtained with 70 mg/L of PAC. The
sedimentation velocity in this method was also high and achieved
92.7% of HA removal in 5 min. It indicated that CaCO3 shortens the
settling time after the coagulation process. The SV produced after