Abstract

Coagulation, softening and disinfection processes are of great importance in water treatment. In this study, experiments were conducted in the laboratory to investigate the coagulation, softening and disinfection properties of Piliostigma thonningii Schum (PT) leave in the treatment of synthetic and natural waters. Synthetic turbid water of high and medium turbidities was prepared in the laboratory using bentonite clay, kaolin clay and black cotton soils. A series of experiments was performed on high (439.7- 487 NTU) and medium (160.8 NTU) turbid waters with 83, 167, 333, 500, 835 1169 mg/l of the coagulant (PT). Effects of pH and temperature on flocculation efficiency of the coagulant have been investigated. Bacterial reduction and hardness of water softening properties of the leave were also studied. The results showed that PT was effective in turbidity removal and softening but less effective in disinfection than. PT recorded 83.15 high turbidity removal; 90.21 medium turbidity removal. 900 mg/l initial water hardness was reduced by PT to 383.67 mg/l (57.37%). PT showed 99.72% disinfection activity. The best result for turbidity removal was found at pH ranges from 7 to 7.5 and at temperatures between 20 and 30oC. Although the leave showed some levels of effectiveness, the water treated with this leave did not meet standard. The leaves are therefore not adequately effective in water treatment.