The use of Moringa oleifera as a natural coagulant in surface water treatment

Abstract

Abstract Moringa oleifera (MO) seed is a natural plant with active bio-coagulate compounds that can be used for water clarification since it reduces the use of chemical-based coagulants. This study aims to evaluate the impact of Moringa oleifera (MO) seeds and MO seeds with a reduced amount of oil as coagulants in conventional water treatment to remove cyanobacteria from different natural surface waters. Tests were performed for waters with low (5–10 NTU) and high (30–60 NTU) initial turbidity with and without Microcystis aeruginosa cells and for MO integral powder, MO oil-extracted with ethanol and with a pressurized technique, and MO extracted with NaCl. The results show that MO oil-extraction is not necessary when using MO seeds as a coagulant in coagulation/flocculation/sedimentation (CF/S). Chlorophyll a and turbidity removals were up to 85% for high-turbidity waters, with 50 mg·L−1 MO obtained, for MO integral powder and for all of the MO extraction methods used. Therefore, for these waters, integral powder (without any extraction) can be used. For low-turbidity waters and using a 1 M saline extraction of the active coagulant compound, chlorophyll a and turbidity removals were approximately 60%. It was also demonstrated that MO is capable of removing some of the organic matter present in water, namely, aromatic organic matter, between 40 and 50% when using MO extracted with NaCl. However, dissolved organic matter results showed an increase independent of the type of MO extraction used.