Economic analysis for simultaneous production of microbial lipid and citric acid by oleaginous yeast cultivated on purified crude glycerol

Yarrowia lipolytica SKY7 (YL) is capable of producing lipid and citric acid simultaneously during fermentation. It is necessary to evaluate the industrial feasibility for simultaneous production of microbial lipid and citric acid by YL. In this study, energy balance and economic assessment were conducted for two different scenarios for simultaneous production of lipid and citric acid (CA)-(a) high lipid producing scenario (with subsequent conversion to biodiesel) and (b) high CA producing scenario. Energy balance revealed that both scenarios were equally energetically favorable. Economic analysis revealed that for same quantity of purified glycerol valorized, high lipid producing scenario was more economical than high CA producing scenario. For annual utilization of 22,710.43 tonnes of purified glycerol, net unit production cost (after incorporating price of by-products: KH2PO4, citric acid, crude glycerol, and cell debris) for high lipid producing scenario was 0.49 $/L B10. For high CA producing scenario, net unit production cost (after incorporating price of by-products: KH2PO4, biodiesel B10, crude glycerol, and cell debris) was 0.83 $/kg CA. High lipid producing scenario with simultaneous production of CA proves economically viable.