Enhanced biodiesel production by optimizing growth conditions of Chlorella marina in tannery wastewater

In this study, marine microalgae such as Nannochloropsis marina, Chlorella marina, Thalassiosira sp. and Duna-liellasalina were studied for their lipid-producing ability by culturing them in secondary effluent from tannery wastewater treatment plants. Among the four marine microalgae studied, Chlorella marina showed maximum biomass and lipid yield of 3.84 g/L and 1.56 g/L, respectively, with resulting lipid content of 42%. Furthermore, chlorella species were studied under optimized culture conditions of 27 degrees C, with 8% CO2 concentration, 250 mu mol photon m-2 s(-1) light intensity and 6 mmol/L nitrogen concentration, resulting in increased biomass yield 215% L-1 day(-1). Also, the biodiesel obtained by direct transesterification yields 3.5 g/L, which is promising. Likewise, the biodiesel's oxidative stability, Iodine number, cloud point and viscosity were analyzed and were within the standards. Hence, this study signifies that tannery effluent could be a suitable feedstock for marine microalgae in biofuel production.