Comparative Study on the Coagulating Potentials of Alum and Moringa Oleifera in Raw Water Treatment

Abstract

Comparative analysis was carried out on Alum and Moringa oleifera seed powder in respect of their coagulating effects in water purification which was conducted for a period of six months from January to June 2017. Jar test was conducted to determine the optimum dosages of the coagulant needed in the treatment of raw water. The concentration of the dose selected for the jar test were; 0.02g/L, 0.04g/L, 0.06g/L and 0.08g/L for all the two coagulants. Physicochemical parameters of raw water samples from Suma River showed that turbidity ranged between 30.6 to 89.9 NTU, pH from 6.84 to 7.40, temperature from 29.5^oC to 31.8^oC, TDS from 198 to 260mg/l, total hardness from 74 to 140mg/l, DO from 4.0 to 6.3mg/l, Colour from 360 to 542 PtCo, Alkalinity from 120 to 136mg/l, Conductivity from 289 to 344µS/cm, Iron from 0.89 to 1.5mg/l and Manganese from 1.83 to 2.10mg/l. The turbidity of the sample treated with alum significantly reduced (29.45 ± 5.79 NTU) at p<0.05 compared to that of untreated water (59.17 ± 8.44 NTU). Furthermore, turbidity of alum treated water was significantly lower than M. oleifera (37.53 ± 6.35 NTU). Total hardness for alum reduced from 136 to 70mg/L, M. oleifera from 136 to 74mg/L. DO for alum reduced from 6.3 to 3.3mg/L, M. oleifera from 6.8 to 3.2mg/L. There was a significant reduction in the colour of water treated with Alum (264.2 ± 16.9 PtCo), Moringa oleifera (353.8 ± 17.8 PtCo) compared to the control (Untreated water). However, alum treated water exhibited better clarity (p<0.05). The iron content of alum water (0.80 ± 0.08mg/l) was significant lower than that of the untreated water, M. oleifera treated water. The water treated with M. oleifera achieved neutral pH whereas treatment with alum made water slightly acidic.