Briquetting of black soldier fly frass as a post-harvest stabilization strategy

ABSTRACT The production -consumption cycle needs a transition towards a circular economy where waste valorization is included. This study investigated briquetting as a stabilization method for black soldier fly frass (BSFF) with faecal matter, pig and poultry manure as the larval feed. Herein, dried BSFF was pyrolyzed at 350 °C for 2 h to produce biochar then mixed with charcoal dust in equal ratio to produce bio-briquettes through densification, with a binder (10 wt%). One-way ANOVA showed statistical significance in carbon, nitrogen, hydrogen, and oxygen. There were significant differences between calorific value, volatile matter, fixed carbon, moisture and ash content of the bio-briquettes. Fixed carbon, volatile matter, moisture, and ash content ranged from 29.66 ± 0.86 to 42.01 ± 0.92, 29.26 ± 0.52 to 32.59 ± 0.80, 2.95 ± 0.1 to 5.08 ± 0.04, and 21.48 ± 0.14 to 37.20 ± 0.29, respectively. Calorific value ranged from 16.25 ± 0.57 to 20.70 ± 0.53 MJ/kg, which exceeds the minimum requirement of 14.5 MJ/kg recommended for non-woody briquettes. During combustion, concentrations of NOx, N2O, CO, and CO2 varied significantly. Briquetting is a potential stabilization method for frass resulting in waste reduction, bioenergy production, reduced adverse effects of climate change, and enhanced sustainability.