Effect of coagulant treatment on the metal composition of raw water

Abstract

This study reports the results of an investigation on the use of two coagulants, namely Al2 (SO4)3 and Fe2 (SO4)3 which were investigated for their capabilities to reduce the metal levels of raw river water samples when treated. Generally, the percentage removal of the metals from raw water samples increased with mg/l dosage of either coagulant used. Although both coagulants were efficient in removing Cr and Ni, generally Fe2 (SO4)3 was proved to be the more efficient coagulant for the removal of all the metals studied. Fe2 (SO4)3 was 89.58% efficient in removing Cr and 99.73% efficient in removing Ni. It was 68.42% efficient in removing Zn, 40.14% efficient in removing Mn and 35.29% efficient in removing Cd (all at 13 mg/l dosage of coagulant). Judging from these results and taking into consideration the potential health threat to man from the possible Al contamination of treated water from the use of aluminium-based coagulants, the use of Fe2 (SO4)3 as coagulant in water treatment for the removal of suspended matter was preferred and would be highly recommended.


WaterSA Vol.28(3) 2002: 293-298