The effect of second coagulant dose on the regrowth of flocs formed by charge neutralization and sweep coagulation using titanium tetrachloride (TiCl4)

► Complete floc regrowth occurred under charge neutralization without additional TiCl4. ► Limited regrowth of flocs occurred at pH 10 without additional coagulant. ► Regrowth of the broken flocs could be improved with appropriate additional TiCl4. ► It was better for second TiCl4 dose to be added at the end of breakage period.