Turbidity Removal Competence of Moringa stenopetala Seed as a Coagulant in Reservoir Water Purification: The Case of Legedadi Dam in Ethiopia

Conventional drinking water treatments are often inappropriate in developing countries due to their high cost and availability of chemicals; hence, they are looking towards organic coagulants, like Moringa stenopetala. Laboratory experiments were carried out on the sampled water taken from Legedadi reservoir to assess the turbidity removal competence of Moringa stenopetala (MS) tree seed. Different concentrations of 50, 100, 150, 200, 250 and 300 mg/L were prepared from a 1000 mL of distilled water extract of Moringa stenopetala fine powder and applied to sampled water taken from Legedadi reservoir adjusted to different turbidity levels of 50, 200 and 400 NTU and to different pH level of 5, 6, 7, 8 and 9 using H2SO4 and NaOH (lime). The experiments showed that the highest turbidity removal was achieved at MS dosage of 150 mg/L (15 mL/L) for adjusted initial turbidity of 50 (94.1%) and 150 (98.8%) NTU and 200 mg/L (20 mL/L) for adjusted initial turbidity of 400 NTU (98.3%). Maximum turbidity removal occurred at neutral pH. Furthermore, the residual turbidity determined satisfied the WHO guidelines for drinking water (<5 NTU). The column experiment was accomplished for 94 min of detention time which gave the average overall removal efficiency of 77.7%. In general, water treatment with Moringa stenopetala tree seed powder is competent in removing impurities from turbid water but calls for detailed and rigorous scientific study on Moringa stenopetala in order to fully understand the characteristics of the plant and exploit its full potential for further recommendation in water treatment.