Valorization of biowastes using Hermetia illucens’ larvae and quantification of resultant greenhouse gas emissions

For the transition from linear to circular economy in biowaste management, valorization and recycling are becoming increasingly pertinent in environmental management. In the present study, the greenhouse gases (GHGs) emitted from pig manure (PM), chicken manure (CM) and faecal matter (FM) during black soldier fly Larvae (BSFL) bioconversion and the accompanying changes of carbon and nitrogen were studied. The study used small-sized sensors for measuring GHGs and ammonia emissions while simulating real larval rearing conditions for 13 days. Our results indicate that BSFL can grow on substrates with different initial carbon/nitrogen ratios till pupation. The average weight of harvested larvae was 77.3–156 mg/larvae with a corresponding waste reduction rate ranging between 57.11 and 82.68%. Carbon reduction was 67.44, 64.66 and 70.69% while nitrogen reduction was 55.36,47.69 and 44.37% for CM, PM and FM substrates, respectively. The carbon and nitrogen reductions were statistically significant across the treatments. Cumulative CO2, NH3, CH4 and N2O emissions during biodegradation ranged between 40.912 and 218.452 mg/kg, 0.259 and 0.842 mg/kg, 4.40 and 20.239 and 0–0.042 mg/kg, respectively. Compared to open composting, BSFL bioconversion of FM, CM and PM resulted in decreased GHGs and ammonia emissions. These results indicate that valorization of biowastes using Hermetia illucens' larvae is an environmental reliever of GHGs.