and low-alkalinity raw water than conventional coagulants in the
treatment of raw water with low turbidity [14,20].
When both concentrations and types of NOMs in raw water of
low turbidity are different, the coagulation mechanism changes
accordingly [23–26]. PASiC or PAFSiC, when added directly to
raw water, can either be effectively adsorbed onto the surface
of colloids, thus neutralizing the surface charge, or react chemically
with NOMs to form larger molecules. Both mechanisms
change the water treatment efficiency. Most previous studies
concentrated on the removal of either NOM or particles from
the raw water with higher concentrations of NOMs and turbidity
than in natural water. Few studies targeted the coagulation
mechanisms for water containing both particulates and NOMs.
In this study, a synthetic water with low-turbidity (less than 8
NTU) and low-alkalinity (50 mg/L as CaCO3) prepared with
kaolin and humic acid or salicylic acid were used to investigate
the removal mechanisms and the influence of turbidity or NOMs
on removal efficiency.