Coagulation of some humic acid solutions by Moringa oleifera Lam seeds:: Effect on chlorine requirement

Experiments were carried out to study humic acid solutions and surface waters coagulation by Moringa oleifera Lam seeds aqueous extract. High amounts of such extract (up to 10 g/L) were required to clarify humic acid solutions whereas 0.5 g/L were used to remove 90% of initial turbidity of a surface water. The treatment of water with low turbidity (< 10 NTU) was difficult; flocs were formed but did not settle down. There was no pH effect when the initial turbidity was lower than 50 NTU. The extract could also be used as adjuvant during the coagulation of humic acid solutions by ferric chloride. The effect was obvious at low concentrations of chemical coagulant (less than 60 mg Fe/L). In addition, the results were consistent with the fact that aqueous Moringa oleifera Lam seeds extract released a high amount of organic compounds in treated solutions leading to a high chlorine requirement.