Moringa oleifera seed extract-mediated flocculation as an efficient method for harvesting Chlorella lewinii biomass

The aim of this research was to investigate the potentials of harvesting Chlorella lewinii through flocculation by Moringa oleifera seed extract. Water, ethanol, and sodium chloride solution were used to extract flocculating agents from both whole and de-fatted Moringa oleifera seeds and their ability to flocculate C. lewinii cells were evaluated. The effects of extracting solvents, extract concentration, incubation period and culture age on flocculation efficiency were investigated. The lipid contents of the biomass harvested by flocculation using M. oleifera seed extract were compared with those harvested by centrifugation. The results showed that 1M sodium chloride solution was the most effective solvent for extracting M. oleifera active ingredient. The optimum extract concentration was 600±0.10 mg/L with approximately 60±0.46 % efficiency, while the optimum length of period for incubating a mixture of cell culture and seed extract was 80±0.26 min. Defatted Moringa oleifera seed extract was more efficient than whole seed extract with an efficiency of 50%. The percentage lipid content of biomass harvested by centrifuge and moringa extracts decreased in the following order: Centrifugation-(22.55%) > de-fatted seed extract (16.63%) > whole seed extract (14.42%).  These results indicate that M. oleifera seed extract is a reliable method of harvesting microalgae biomass.