Valorization of lipidic food waste for enhanced biodiesel recovery through two-step conversion: A novel microalgae-integrated approach

The present study designed an innovative route for two-step biodiesel recovery from lipidic food waste followed by microalgae cultivation. Optimization of oil conversion showed the highest fatty acid methyl esters (FAMEs) recovery of 92.6% (lipid basis). Microalgal lipid accumulation enhanced by the increased lipid-free waste hydrolysate ratio in the medium, where the maximum lipid content of 26.2 dw% was recorded using 50% hydrolysate. Application of 30% hydrolysate ratio resulted in the maximum recorded lipid productivity, which was 99.4% higher than that of the control and insignificant with 40% hydrolysate. Waste oil-derived FAMEs showed 69.0% higher saturated fatty acids (SFAs) proportion than that of algal lipids. In contrast, the highest polyunsaturated fatty acids (PUFAs) proportion (48.8% of total fatty acids) was recorded in microalgal lipids. The study concluded that mixing microalgal lipids with waste oil (1:1, w/w) provides a desirable practical route for enhanced biodiesel production complying with the international standards.

Automated summary

This study developed an innovative approach for biodiesel recovery from lipidic food waste and microalgae cultivation, achieving the highest lipid content with 50% hydrolysate and the highest lipid productivity with 30% hydrolysate. Compared to algal lipids, waste oil-derived FAMEs had higher proportions of saturated fatty acids, while microalgal lipids had the highest proportion of polyunsaturated fatty acids.