Simultaneous biological desalination and lipid production by Scenedesmus obliquus cultured with brackish water

Brackish water is a good choice for algae cultivation in achieving simultaneous biological desalination and biodiesel production. Scenedesmus obliquus was cultured in BG-11 medium of varying salinities (1.2, 2.8, 4.8, 6.8 and 8.8 g L− 1 NaCl) for 16 days. The growth rate decreased as salinity increased. The sedimentation efficiency (60 min) was almost the same (77%-83%) in all treatments except for algae treated with 8.8 g L− 1 NaCl, the value of which was 54%. The highest lipid content of 21% was observed in the sample treated with 8.8 g L− 1 NaCl compared with 16% in the control. The desalinization rate and removal of NaCl increased significantly as salinity rose. The lipid content increased with increasing salinity but lipid production decreased with increasing NaCl addition because of growth inhibition caused by salt stress. The optimum initial NaCl concentration was not confirmed but an initial NaCl concentration of 4.8 g L− 1 is the acceptable concentration for the treatment. Under these conditions, lipid production was about 100 mg L− 1 and the removal of NaCl reached 1.0 g L− 1. Our results indicated that it is possible to achieve simultaneous biological desalination and lipid production using brackish water.