Application of defatted Moringa oleifera seeds from compressed propane extraction in the removal of emerging microorganisms

The aim of the present study was to investigate the applicability of the defatted residue, generated after oil extraction from Moringa oleifera (MO) seeds by pressurised propane, as coagulant in the coagulation/flocculation/dissolved air flotation (C/F/DAF) process for removing emerging microorganisms. MO seeds (with no extraction) were also evaluated for comparison purposes. MO is a natural plant with active bio-coagulating compounds that can be used for water clarification, since it reduces the use of chemical-based coagulants. The experiment consisted of three stages. In the first stage, the species Cylindrospermopsis raciborskii was cultivated in the laboratory. The second stage consisted of seed-oil extraction by pressurised propane and application in the C/F/DAF process. The experiments were conducted at temperatures of 30 degrees C-60 degrees C, pressures of 80-120 bar and a constant solvent flow of 1 mL min(-1). In the third stage, C/F/DAF assays were performed with the purposes of comparing the efficiencies of the whole powder and defatted powder as coagulants in dosages in the range of 25-500 mg.L-1. Oil extraction of MO seeds by pressurised propane at a pressure of 80 bar and a temperature of 30 degrees C obtained the highest yield of oil (39%-42%). This indicated that compressed propane is an efficient technique for extracting oil and obtaining a defatted powder with high protein content (41.72%). Between the two preparations of MO seeds as coagulant at their respective optimal dosage (50 mg.L-1), the defatted powder showed the best efficiency in the removal of chlorophyll-a (97.4%), turbidity (84%), with zeta-potential values close to zero.