18 / 2023-04-28 11:06:23

Unraveling the role of particle sizes on the bioconversion efficiency of food waste by black soldier fly larvae

Food waste; Black soldier fly larvae; Particle size; Bioconversion efficiency; Gut microbial community

Black soldier fly larvae (BSFL) bioconversion is a natural based and environmentally friendly strategy for food waste recycling, which produces high-value insect protein and organic matter. The particle size of food waste plays a crucial role in the treatment scale, transmission mode and bioconversion efficiency of bioreactor. However, there is rare research on the impact of particle sizes on BSFL bioconversion. Therefore, in this study, we investigated the effect of particle sizes on food waste bioconversion by BSFL and harbored gut microbial mechanism in present study. The particle size range of 4 mm-10 mm increased the conversion rate (E2, 52.4±2.27%; E5, 38.9±0.95%) and has fewer global warming potential (E2, 9.06±0.85 g CO₂-eq/kg larvae DM) than the over-crushing group (E5 10.87±0.71 g CO₂-eq/kg larvae DM). However, there was a significant difference in ammonia emissions between the E2 (2.15±0.38 mg/kg larvae DM) and E5 (0.24±0.08 mg/kg larvae DM). The gut microbial community in E2 was dominated by Enterococcus (68.5%) and Lactobacillus (27.0%) with the function of chemoheterotrophy and fermentation. Over-crushing group (E5) had a higher abundance of pathogenic bacteria such as Morganella (60.9%) and a lower abundance of Enterococcus and Lactobacillus (28.2% and 9.4%). This study has demonstrated that appropriate crushing of food waste can enhance its bioconversion by BSFL. However, excessive crushing can result in the aggregation of BSFL above the reactor, leading to gut dysfunction and consequently, higher gas emissions and lower conversion efficiency.