Biomass and lipid enhancement in Chlorella sp. with emphasis on biodiesel quality assessment through detailed FAME signature

•MgSO4, salinity and light intensity were optimised to enhance biomass and lipid.•The optimum biomass productivity and lipid content were 372.50 mg L−1 d−1 and 32.57%.•Saturated and unsaturated C16 and C18 were identified as major FAMEs.•High polyunsaturation deteriorated the biodiesel properties.•Favourable biodiesel properties were obtained with decreased lipid content.

In this study, the concentrations of MgSO4, salinity and light intensity were optimised for maximum biomass productivity and lipid content in Chlorella sp. Lipid synthesized at varied experimental conditions was also assessed in detail for biodiesel properties through FAME analysis. FAMEs mainly composed of C16:0, C16:1(9), C16:3(7, 10, 13), C18:0, C18:1(11), C18:2(9, 12), C18:3(9, 12, 15). The optimum biomass productivity (372.50 mg L−1 d−1) and lipid content (32.57%) was obtained at MgSO4-150 ppm; salinity-12.5 ppm, and light intensity-25 μmol m−2 s−1. However, at this condition the cetane number, a major biodiesel property was not complying with worldwide biodiesel standard. Therefore, further optimisations were done to check the suitability of biodiesel fuel. The optimum biomass productivity (348.47 mg L−1 d−1) and lipid content (12.43%) with suitable biodiesel fuel properties was obtained at MgSO4-50 ppm, salinity-25 ppm and light intensity-100 μmol m−2 s−1. The validation experiments confirmed the closeness of predicted and measured response values.