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Samples of municipal and industrial wastewaters were treated by coagulation-flocculation and sedimentation, using a crude water extract of dry Moringa oleifera seeds as a primary coagulant. The quality of the treated wastewater was analyzed and compared to that of the wastewater treated with alum. Experiments were conducted at various dosages of the crude 5% (wt/v) water extract of dry shelled and non-shelled Moringa oleifera seeds, using jar-test equipment. Parameters of quality of the wastewaters were measured before and after the treatment to evaluate the removal efficiency on the major pollutants of concern in wastewater treatment, such as suspended solids, chemical oxygen demand (COD), nutrients (phosphorus and nitrogen), microorganisms and heavy metals. Results showed that Moringa oleifera seeds were efficient as a primary coagulant in wastewater treatment for removal of suspended solids and microorganisms, and also removal of some metals. Nutrients and COD were not successfully removed. COD and nutrients were somehow increased by coagulation using Moringa oleifera seeds. Compared to alum, Moringa oleifera seeds produced 4 to 6 times less sludge volume. Alum was found to be quite effective in phosphorus removal. The increase in COD and nutrients observed in the case of Moringa oleifera seeds might be avoided by using purified proteins instead of the crude water extract.
Ndabigengesere et al. (Sat,) studied this question.