Biovalorization of wastewater of fish canning process by Yarrowia lipolytica for biodiesel and animal feed supplement production

Microbial treatment of industrial wastewater, following with the production of the valuable products using the biomass of the same cells, enhances the economic benefits of biorefineries. The current study aimed to explore the potential of the oleaginous yeast Yarrowia lipolytica for oily and saline fish canning wastewater biotreatment and to evaluate the features of the yeast biomass for biodiesel and animal feed supplement production. Using Y. lipolytica EBL13 in wastewater reduced chemical oxygen demand by 85% during 7 days. In addition, other parameters, including biological oxygen demand (59%), nitrate (51%), sulfite (50%), total suspended solids (85%), total hardness (15.6%), oil (68.2%), and total phosphorus (91%), were decreased significantly compared to untreated samples. However, pH and ammonia were increased. Amino acid and fatty acid composition analysis of Y. lipolytica biomass showed the presence of essential amino acids and fatty acids in significant quantities, respectively. From 50.2% of protein content derived from the yeast biomass, 16.5% was related to essential amino acids. In addition, linolenic acid (0.15%) and eicosapentaenoic acid (0.21%) as essential omega-3 fatty acids and linoleic acid (22.15%) as essential omega-6 fatty acid were observed in the fatty acid profile. Predicted biodiesel physicochemical parameters such as cetane number (55.7 min), iodine value (76.4 g Iod/100 g oil), and degree of unsaturation (83.54) met the EN 14214 specifications. Y. lipolytica can be introduced as an ideal candidate for fish canning wastewater treatment and production of biodiesel and animal feed supplements. Graphical abstract