CaCl2 applied to the extraction of Moringa oleifera seeds and the use for Microcystis aeruginosa removal

The Moringa oleifera seed coagulant provides high efficiency for water treatment, especially for bacteria removal and potentially cyanobacteria. The present study evaluates the difference between two saline extracts of M. oleifera Lam seeds in the removal of Microcystis aeruginosa cells, using dissolved air flotation (DAF). Samples were generated by synthetic water spiked with humic acid and M. aeruginosa cells to obtain 25 NTU. The saline extracts were obtained by seed extraction using 1 M NaCl or CaCl2, and dosages from 25 to 200 mg L−1 were applied from each of the extractions. The CaCl2 coagulant extract showed a better efficiency, achieving 78.9% cell removal when applying a dosage of 50 mg L−1. Comparison of saline extractions and aqueous extraction suggested that calcium ions participate in coagulation/flocculation process, as a response of its double-valency. The CaCl2 extract of the M. oleifera seeds is indicated for the treatment of water with the presence of cyanobacteria, even in water with low turbidity, a condition not commonly evaluated in other studies.