Synergistic biodiesel production from food flavourant industry wastewater using Rhodotorula mucilaginosa and Chlorella vulgaris

The global energy demand is increasing every day, and the search for renewable and cost-effective sources of energy production is evident with the increased research on renewable energy. Energy production using waste materials has also increased the circular bioeconomy in industries. The thrust of the present day's research is to derive useful products and energy from waste, and this study aimed to examine the synergetic effect of microalgae and yeast in treating food industry wastewater and biodiesel production. Rhodotorula mucilaginosa and Chlorella vulgaris were used for sustainable biodiesel production using food-flavourant-producing industry wastewater (FFPIWW) as a nutrient source. The combination of co-culture and pure culture was studied in response to nutrient (BOD & COD) removal and lipid production. Rhodotorula mucilaginosa - Chlorella vulgaris coculture (RmCvcc) exhibited a maximum nutrient removal and biodiesel yield. RmCvcc yielded a maximum biomass and lipid yield of 7.236 g/L and 5.063 g/L, respectively. Further, the nutrient removal in pure cultures was also significantly less than that in RmCvcc. The higher self-sedimentation property of RmCvcc after remediation proves the process's applicability in the industrial sector. The maximum unsaturated fatty acid composition of RmCvcc biodiesel proved a better burning capability required for commercial applications. The higher lipid content of RmCvcc (69 %) proved it to be an excellent renewable source for biodiesel production. The coculture of Rhodotorula mucilaginosa and Chlorella vulgaris effectively reduced COD and BOD in FFPIWW. Simultaneous inoculation provided the best results for both nutrient removal and biomass production. The resulting biomass had a high lipid content that was suitable for biodiesel production. The biodiesel produced has higher unsaturated fatty acid, which is essential for engine applications. In a nutshell, the results proved the RmCvcc as a complete enhancer for both FFPIWW treatment and biodiesel production. Food industry wastewater could be the sole source of microbial lipid production.