Potential biomethane production from frass of Tenebrio molitor and Hermetia illucens reared on by-products based diets

The rising demand for sustainable protein sources has led to increased interest in insect farming and the potential valorization of insect farming by-products, such as frass. This study explores the potential of insect waste biomass, frass, as a substrate for biomethane production through anaerobic digestion. Frass from Tenebrio molitor and Hermetia illucens, reared on various byproduct-based diets, was analyzed for its physicochemical composition and subjected to Biochemical Methane Potential (BMP) tests. Despite physicochemical differences, there was no statistically significant effect of diet on biogas or biomethane production. ANOVA revealed a marginal (p = 0.0589) trend toward higher biogas production from Tenebrio molitor frass, which translated into higher average methane yields for Tenebrio molitor (229.2 ± 72.7 l CH4·kg−1VS) compared to Hermetia illucens (167 ± 75.6 l CH4·kg−1 VS). These results suggest that frass composition linked to insect species has a stronger influence on methane yield than the type of diet used within a single species, due to the basic dietary requirements of the species itself. Nevertheless, frass from both Tenebrio molitor and Hermetia illucens shows promising potential for sustainable bioenergy production.