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 Dunaliellasalina 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 °C, with 8% CO2 concentration, 250 µmol 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.