Food waste-derived black soldier fly (Hermetia illucens) larval resource recovery: A circular bioeconomy approach

Black Soldier Fly (Hermetia illucens [L.], Diptera: Stratiomyidae) larvae (BSFL) production from food waste is gaining interest. Food waste, a heterogeneous mix of agro-food and catering leftovers serves as a challenging feedstock for BSF growth due to its varying nutrient composition. BSF, are classified as polyphagous insects with a digestive system featuring midgut for digestion and nutrient absorption. The conversion of food waste by BSFL is heavily influenced by Enterococcus, Klebsiella, Morganella, Providencia, and Scrofimicrobium, which play a vital role in substrate utilization. These microbes determine growth patterns, longevity, oviposition, and egg hatchability, which are intricately tied to the sugar and protein content of their dietary substrates. Pre-treatment techniques including hydrothermal treatment, ionization, pulse electric field discharge, and microbial treatment showed better efficiency in improving the wet waste biomass surface area and waste recovery ratio. In terms of environmental sustainability, a life cycle assessment (LCA) of food waste to BSF conversion facility yields a low global warming potential (GWP) score of 17.36 kg CO2 per ton of functional unit with a significant environmental impact during pre-treatment of food waste at a mass-rearing of BSFL. Therefore, this review emphasizes the digestive system, and gut microbiota of BSFL, with food waste-nutrient utilization by the BSFL. Environmentally promising steps involved in the valorization of food waste resources were evaluated in detail. This review also covers the international regulations involved in food waste fed BSFL, and techno-economic assessment to optimize its valuable nutrients for the new economy in waste management with less environmental footprint.