INFLUENCE OF OPERATING PARAMETERS ON TURBIDITY REMOVAL BY COAGULATIONWITH MORINGA-OLEIFERA SEEDS

A model turbid water was treated with Moringa oleifera seeds as a natu ral coagulant and various phenomena like coagulation flocculation and sedimentation were observed in detail using jar-test equipment under l aboratory conditions. Influence of pH, temperature, cation concentrati on and anion concentration of test water was studied. Also investigate d was the effect of intensity and duration of rapid mixing as well as slow mixing on turbidity removal. Experiments were conducted at optimu m dosage of a crude 5% (wt/v) water extract of dry non-shelled Moringa oleifera seeds. It was found that variation of pH, cation concentrati on, anion concentration and rapid mixing did not significantly affect the coagulation activity of Moringa oleifera seeds, while temperature and slow mixing did. Lower temperatures increased the residual turbidi ty, and in case of slow mixing, an optimal intensity and duration of 4 0 RPM and 40 minutes respectively were found, which corresponds to a v elocity gradient G equal to 25 sec(-1) and a product Gt value of 6 x 1 0(4). Hence, for best results in turbidity removal in coagulation with Moringa oleifera seeds, only slow mixing is recommended at the optimu m intensity and duration. Longer sedimentation time should be provided when treating colder waters.