Active agents and mechanism of coagulation of turbid waters using Moringa oleifera

Abstract

Moringa oleifera is a tropical plant whose seeds contain an edible oil and water soluble substance which has excellent coagulation properties for treating water and wastewater. The efficiency and properties of Moringa oleifera as a natural coagulant in water treatment were studied and compared with alum, which is presently the most widely used industrial coagulant. It is show that the active agents in aqueous Moringa extracts are dimeric cationic proteins, having molecular weight of 13 kDa and isoelectric points between 10 and 11. The mechanism of coagulation with Moringa oleifera appears to consist of adsorption and neutralization of the colloidal charges. Compared to alum, the optimal dosage of shelled Moringa oleifera seeds was almost the same (50 mg/l). In case of the non-shelled seeds, the dosage is greater (500 mg/l) for low initial turbidity waters. The purified proteins are more effective coagulants than alum. As a coagulant, Moringa is non-toxic and biodegradable. It is environmentally friendly, and unlike alum, does not significantly affect the pH and conductivity of the water after the treatment. Sludge produced by coagulation with Moringa is not only innocuous but also four to five times less in volume than the chemical sludge produced by alum coagulation. So, as a coagulant, Moringa oleifera may be a potentially viable substitute to alum. © 1995.