Evaluating the environmental impacts of coupling insect farming with anaerobic digestion in food waste biorefineries

Integrating black soldier fly (BSF) bioconversion with anaerobic digestion (AD) provides a complementary pathway for food waste (FW) management that addresses limitations of stand-alone AD. By diverting a portion of the solid residue from FW pre-treatment to BSF treatment, the system eases digestate handling while producing dried larvae as a high value animal feed. To evaluate environmental performance at scale, this study combines material flow analysis (MFA) and life cycle assessment (LCA) to compare a BSF–AD configuration with a conventional mesophilic AD baseline at a full-scale food waste biogas plant in China. Relative to business-as-usual, the BSF–AD system reduced total energy use to 84 kWh per tonne of FW (vs. 97 kWh/t), driven largely by a 30% decrease in digestate-treatment energy demand. LCA results indicate a 34% lower climate change impact (54 vs. 82 kg CO₂-eq/t) and a 73% reduction in resource use (151 vs. 557 MJ/t). Sensitivity analysis shows that allocating a larger share of solids to BSF further improves climate and resource outcomes, though potential trade-offs in human health indicators may arise. Overall, integrating BSF with AD can shrink the carbon footprint, enhance resource recovery, and inform more sustainable FW management strategies. • Exploring black soldier fly farming combined with AD for food waste treatment. • Assessing the environmental impact of energy and resource recovery from food waste. • Enhancing carbon footprint management via the synergy of AD and insect farming. • Reducing electricity consumption through combined AD and insect farming.