Optimizing the subcritical water valorization of insect (Hermetia illucens l.) farming waste for biodiesel production

Abstract

To counter the proliferation of secondary waste streams generated on insect (black soldier fly) farms, the present study integrated green water technology and acid-catalyzed transesterification as a basis to assess further value extraction potentials. By valorizing the waste streams, a process was developed to promote the circular economy paradigm. In this regard, wastes generated from a local insect farm were initially subjected to subcritical water extraction (SWE) for lipid recovery. The SWE process was optimized such that an enhanced lipid yield of 13.31 wt% was obtained at temperature, time, and solid loading conditions of 236.8 °C, 10 min of extraction, and 1 g/ 100 mL respectively. The lipids recovered were then subjected to an acid-catalyzed transesterification reaction for the production of a fatty acid methyl ester (FAME) mixture. A preliminary economic assessment of the process was also undertaken. The results showed that the wastes had the potential to be economically employed in the production of biodiesel that satisfied fuel property standards. In addition, the potential of employing the side streams as an animal feed was also highlighted due to the determined dominance of oligopeptides, which are known for their favorable bioactive properties. The results indicated that insect farming waste is a promising renewable source for high-quality biodiesel and animal feed production through the environmentally friendly biorefinery.