With rapid mixing, 1 g kaolinwas added to 1 L of the mixture.
After resting the mixture for 30 min, 600mL of the supernatant
from each liter of the mixture was decanted. An aliquot of 10 L
of the collected supernatantwas mixed with 0.072 g/L NaHCO3,
1.2244 g/L NaClO4 and suitable volumes of the stock humic or
salicylic acid solution to yield the final synthetic raw water with
50 mg/L CaCO3 alkalinity, 10−2M ionic strength and 10 NTU
turbidity.
The coagulationwas carried out with rapid mixing at 100 rpm
for 40 s, slow mixing at 20 rpm for 10 min, and followed by a
settling period of 10 min. Samples of the treated water were
collected at a depth of 3 cm below the surface; they were analyzed
for residual turbidity and particle sizes distribution with
a HACH-2100 turbidimeter and a Hiac/Royco MC100S particle
counter. After having been filtered through 0.45m filter
paper, the filtrate was measured using UV absorbance at 254 nm
(UV254) and the DOC