Abstract:
Surface water pollution has increased, owing to industrial development and population growth. Consequently,
it is important to find alternative drinking water treatment strategies, which cater for changes in the quality of
raw water. This study compared the efficiency of different coagulants in treating raw water that feeds a drinking
water treatment plant (WTP). Using jar testing equipment and a number of physicochemical parameters,
an investigation was conducted to establish optimum conditions for aluminium chloride (A), ferric chloride
(B), and chitosan (C), and their performance compared with aluminium sulphate (D), which is the coagulant
used at the WTP. The turbidity removal efficiencies for the single coagulants were in the order: B (95.7%) > A
(94.7%) > C (94.4%), at optimum coagulant doses of 60, 50, and 0.6 mg/L, respectively. The coagulants achieved
high removal efficiencies for turbidity, total dissolved solids (TDS), ultraviolet absorbance at 254 nm (UV254)
and conductivity under acidic conditions. For dual coagulants, there was a gradual increase in the removal
efficiencies of the tested parameters with increasing pH. Combined coagulants were more effective compared
to single coagulants, with highest removal efficiencies being exhibited by the A/C combination. Overall, the
coagulants proved to be suitable alternatives to D, since they had comparable performances.
