Phytoremediation of Secondary Effluent from Palm Oil Mill by Using Oleaginous Microalgae for Integrated Lipid Production and Pollutant Removal

To replace petroleum-based fuels, fast-growing microalgae are currently receiving attention as alternative sources of fuels. In this study, twelve microalgae strains from three genera representing oleaginous microalgae, namely Botryococcus, Scenedesmus and Chlorella, were screened. The selected strains from each genus were applied in integrated lipid production and phytoremediation of secondary effluent from palm oil mill. Among the strains tested, Chlorella sp. C-MR was the most suitable strain to be cultivated in the effluent, due to its high growth rate and high lipid productivity. The optimal conditions for lipid production were: dilution of effluent at 1:1 (COD 1266 mg/L) and light intensity of 40 μmol/m2 s. The semi-continuous cultivation of this microalga was effective for sustained lipid production (0.19–0.24 g/L) and pollutant removal, i.e., COD removal (58–65 %), nitrogen removal (71–99 %) and phosphorus removal (42–64 %). The microalgal lipids contained mainly saturated fatty acids (>85 %), which are suitable for producing biodiesel with high cetane number and oxidative stability.