PAC solution was prepared by slow base injection of Na2CO3
into AlCl3 solution at room temperature. Analytical grade of
AlCl3·6H2O and Na2CO3 reagents was dissolved in deionized
water as original solutions. Na2CO3 solution was slowly added
into Al solution under magnetic stirring. The amount of
Na2CO3 varied with the target basicity ([OH]/[Al] molar ratio,
B value). PAC with B value of 1.5 was chosen. The PAC stock
solution with an Al concentration of 10.0 g/L was diluted to
2.0 g/L with deionized water before it was used for coagulation