Valorization of organic wastes through black soldier fly larvae bioconversion: reducing greenhouse gas emissions

ABSTRACT Graphical abstract illustrating black soldier fly larvae treatment of faecal, chicken, and pig manure, showing bioconversion setup and reduced greenhouse gas emissions and global warming potential. Poor biowaste management contributes to greenhouse gas (GHG) emissions such as methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O). Black soldier fly larvae (BSFL, Hermetia illucens) bioconversion offers a sustainable approach for treating organic wastes while reducing emissions and recovering valuable resources. However, the global warming potential (GWP) associated with BSFL treatment of different waste substrates remains insufficiently characterized. This study quantified GHG emissions (CH4, CO2, N2O, and NH3) during BSFL bioconversion of human faecal matter (FM), pig manure (PM), and chicken manure (CM) using calibrated gas sensors. Emissions from BSFL-treated substrates were compared with those of untreated controls, and a cradle-to-gate life cycle assessment (LCA) was conducted to determine GWP in CO2-equivalent (CO2-eq). In the control treatments, GWP was highest in CM (0.194 kg CO2-eq), followed by FM (0.072 kg CO2-eq) and PM (0.005 kg CO2-eq). BSFL treatment significantly reduced emissions across all substrates, resulting in GWP values of 0.011 kg CO2-eq for CM, 0.006 kg CO2-eq for FM, and 0.001 kg CO2-eq for PM. The greatest reduction was observed in CM, indicating that BSFL treatment was effective for this substrate. These findings demonstrate that BSFL bioconversion can substantially reduce GHG emissions from organic wastes while supporting a circular bioeconomy approach to waste valorization.