Abstract: A comparative study of Moringa oleifera Lam. seeds and chemicals as coagulant demonstrated that M.oleifera seeds was effective in purifying water, the effect was similar to polyaluminium chloride. As a natural, safe coagulant, M.oleifera seeds was able to reduce turbidity of water to below the World Health Organization's guideline value of ≤5FTU for drinking water, so it can be used to substitute the chemical coagulants in water treatment. Both M.oleifera seeds and the oil cake can remove turbi-dities of water, there was no obvious difference in terms of their effect and thus both can be used for water purification. In concern of the cost and comprehensive use of the seeds, the oil cake was more economic and reasonable. When the turbidity of water was 150.6FTU, the optimal dosage of M.oleifera seeds for water purification was 0.2g seeds per 1L water.

Key words: turbidity, water purification agent, Moringa oleifera Lam.