Environmental sustainability assessment of a biorefinery platform utilizing black soldier Fly larvae for organic waste valorization

Abstract

The bioconversion of organic fraction of municipal solid waste (OFMSW) via black soldier fly larvae (BSFL) offers an efficient solution for sustainable waste management and energy challenges in emerging economies and low- and middle- income countries. In this context, the present study examines alternative biorefinery approaches to sustain biodiesel production along with animal feed from BSFL cultivated on OFMSW. These include different processes for larval drying (microwave and a combined infrared-hot air device), oil extraction (mechanical and solvent-based methods), and biodiesel production (conventional and ultrasound-assisted transesterification). Following the technical evaluation, a consequential life cycle assessment (CLCA) was conducted as early environmental sustainability guidance to examine the environmental performance of waste-to-biofuel scenarios. The system boundary was expanded to include the use phases via combustion of diesel-biodiesel blend as B20 blend. Anaerobic digestion (AD) and combined heat and power (CHP) system were applied across all scenarios to valorize the frass generated during BSFL rearing. The defatted protein-rich BSFL meal was processed and utilized as animal feed, while the digested frass was employed as organic fertilizer. The scenario with an infrared-hot air drier, solvent-based oil extraction, and ultrasound-assisted biodiesel production yielded optimal environmental outcomes, with avoided impacts across climate change, human health, ecosystem, and resource scarcity, measured as: −1248 kg CO₂ eq, −0.0013 DALY, −4.45 × 10⁻⁶ species.yr, and − 7.06 USD2013 per tonne of OFMSW treated, respectively. The technology showed significant environmental benefits across most mid-point categories, with the greatest improvement in human non-carcinogenic toxicity (net value: −356.5 to −358.8 kg 1,4-DCB) due to landfill avoidance, except for terrestrial ecotoxicity, mainly driven by outdated, fuel-intensive transportation, which contributed 72 % of the induced impacts in this category. Moreover, compared to other biodiesel feedstocks like waste cooking oil, rapeseed oil and soybean oil, BSFL lipid, demonstrated superior performance across environmental impact categories, establishing them as a more sustainable feedstock alternative for biodiesel production.