Frass4Gas

Pre-treatment of industrial insect breeding residues for anaerobic digestion


Project details


Funding agency: Early Stage Funding - University of Innsbruck
Period: Oct. 2022 - Oct. 2023
Budget: 10,400 €
Function: PI
Link: Frass4Gas


Description


Within a growing insect-based industry, the black soldier fly (BSF; Hermetia illucens) has emerged as one of the most promising species to be used in large-scale rearing facilities. Its ability to efficiently convert a broad variety of organic wastes into high quality protein and fat suitable for animal feed production shows great potential to close loops in food production cycles, thereby promoting the concept of a circular economy. Insect frass, which constitutes a mixture of shed larval skins, larval feces and undigested residual substrates, accumulates as an inevitable by-product during insect rearing. The physicochemical properties of frass are known to be strongly shaped by larval activity and its accompanying microbiota. Past studies have shown an enrichment of nitrogen, phosphorus, and potassium after organic wastes were processed and digested by BSF larvae, making frass highly interesting as soil amendment and fertilizer in agriculture. However, only few studies have focused on the use of insect frass as (co-)substrate for biogas production as alternative treatment method. Its application in anaerobic digestion could be preferred in cases where the frass’ source substrate limits its use as fertilizer or whenever energy production is of greater priority than an agricultural application. The lack of studies creates the need to further sound out suitable ways for pre-treatment, optimal loading rates, and the frass’ impact on microbial stability during anaerobic digestion.


Involved students

  • Nazlıcan Yalçin (intern)
  • Julia Rothärmel (student assistant)