Fly larvae composting research presented at Matologi

Vesa Hiltula, Benny Björk, Evgheni Ermolaev and Nils Ewald. Photo: Ingrid Strid.

Evgheni Ermolaev and Nils Ewald from SLU Kretsloppsteknik together with Vesa Hiltula and Benny Björk from Eskilstuna Strängnäs Energi och Miljö AB presented the latest research results and the large-scale implementation progress of the fly lave composting system developed in the group from 2011. Matology is a yearly exhibition held by SLU in Stockholm with focus highlighting the latest trends in sustainable food systems.

The FAT larva – a future feed for animals?


In the last week of May, SLU was arranging the “Thesis Day”-event for the second year in a row. This was an opportunity for bachelor’s and master’s students to present their degree projects in the form of scientific posters. Six students were also chosen to arrange oral presentations of their projects. Nils Ewald was one of these students. As you might remember, Nils finished his master’s thesis about the fatty acid composition of the black soldier fly larvae earlier this spring.

1-2 tons food waste treated by BSF composting in Eskilstuna


In the past 2 years, the environmental engineering group has been collaborating with the waste management company of Eskilstuna in order to treat food waste with black soldier fly larvae. This technology, developed within the group over the past 10 years, aims to recover the nutrients present in organic waste streams and reintroduce them into the food chain by producing feed for livestock. With this collaboration, a pilot plant was set up with the goal of treating 1 ton of food waste per day. After having successfully achieved a stable production of 1 million young larvae per day in the fly colony at SLU, the next step was to treat 1 ton of food waste with the larvae at the pilot plant. Not only did we managed to treat 1 ton of food waste per day but recently managed to double the treated food waste reaching 2 tons per day. Right now, we are back in the lab to analyse the results.

Kretsloppsteknik at the Human Nature arranged by Axfoundation


This year’s event had the theme below the surface, and brought up a wide range of interesting topics; from deep-sea research to the psychology of how we look at and manage the threat of climate change.  At dinner Axfoundation presented their vision of future food and that’s where we came into the picture. On the menu were cabbage and pumpkin fertilized with frass (insect compost) from our fly larvae reared on food waste, served with chicken and rainbow trout that had insects as their main protein source. The larvae used in the feed were reared on reclaimed bread and vegetable waste from Sorunda grönsakshallar.

Visit from our dear neighbours


On the 12th of March we had a visit from our colleagues at the Norwegian Institute of Bioeconomy Research (NIBIO). On the visit came Trond Mæhlum, Bente Føreid, Thorsten Heidorn and Anders Enoksen. From our group Björn Vinnerås, Jennifer McConville and Cecilia Lalander joined. We presented about our different ongoing projects on safe nutrient recycling: Björn presented on urine drying and Cecilia on fly larvae composting while Jennifer presented her work on the readiness of the Swedish wastewater sector for a technology transition. We were updated on an ongoing project on sustainable and circular urban farming systems that is a collaboration between stakeholders in Europe and China (Sino-European innovative green and smart cities). We were happy to know that the delegation from Norway come to visit us for inspiration on possible technologies. We hope that we in the future will be able to collaborate on some of these exciting technologies.

Contact: Cecilia Lalander

Project opportunity: Life cycle assessment of large scale fly larvae composting in Swedish conditions


Photo: Viktoria Wiklicky

Titel: Livscykelanalys av fluglarvskompostering under storskaliga svenska förhållanden

Title:Life Cycle Assessment of Large Scale Fly Larvae Composting in Swedish Conditions
Credits: 30 credits
Level: Advanced
Subject: Technology or environmental science
Start: As soon as possible

Kristina Lundgren, M.Sc. thesis on pretreatments in BSF composting


Just at the end of January, Kristina Lundgren presented her master thesis at Uppsala University. The aim of the thesis was to increase the understanding of how bacteria may affect fly larvae composting with the black soldier fly. The results showed no significant impact on the survival, final biomass or reduction of substrate when bacteria isolated from BSF eggs where inoculated into the substrate (food waste). However, interestingly the variation in resulting biomass and material reduction was decreased when any bacteria or group of bacteria were added to the food waste. Hence, the system became easier to predict, which especially is desirable when scaling up the system. The audience seemed intrigued by fly larvae composting as a waste management tool and had questions both regarding large scale facilities and the possibility that inoculation bacteria might yield positive effects in other substrates.

Read the abstract or entire thesis in Diva portal.

Lovisa Lindberg, M.Sc. Emissions of greenhouse gases and ammonia during fly larvae composting


Every day, greenhouse gases leak out to the atmosphere around the world, which has a negative impact on the climate. These leakages occur, among other things, from poorly managed and unplanned landfills where a lot of the organic waste ends up. What can be done to get something out of value from organic waste and prevent it from ending up in landfills, which would reduce greenhouse gas emissions? The black soldier fly larvae can be used for this purpose as they feed on organic waste and can halve the amount of waste. The larvae can be separated from the treated waste and then be used in animal feed and the treatment residue can be used as an organic fertilizer. The resources in the organic waste need to be reintroduced into the cycle in order to create a sustainable society since the assets of the earth are declining, this by converting waste and using the resources in waste.

Since it is prohibited to feed production animals with animal by-products according to Article 22 (1) (b) of Regulation (EC) No 1774/2002 of the European Parliament and of the Council, the larvae cannot be fed organic waste because the fly is considered to be a production animal. Vegetable substrates, on the other hand, are permitted to feed the larvae, but more knowledge is needed on how the larvae can absorb the difficult nutrients of these substrates. One solution could be to pretreat the substrate, which was investigated in this study where the pretreatments were performed with fungi or with ammonium solution, respectively.

The purpose of this study was to evaluate emissions of greenhouse gases, carbon dioxide, nitrous oxide and methane gas, and ammonia from fly larvae composting and how efficiently fly larvae composting works for the degradation of vegetable substrates. For more detailed information on the subject, read the thesis (in Swedish) or abstract (English), published in Diva.

New Publication Polymers 2019, 11, 287; doi:10.3390/polym11020287

The material that was produced by the defatted larvae.

A Protein-Based Material from a New Approach Using Whole Defatted Larvae, and Its Interaction with Moisture
Nazanin Alipour, Björn Vinnerås, Fabrice Gouanvé, Eliane Espuche and Mikael S. Hedenqvist

A protein-based material created from a new approach using whole defatted larvae of the Black Soldier fly is presented. After removing the larva lipid and adding a plasticizer, the ground material was compression molded into plates/films. The lipid, rich in saturated fatty acids, can be used in applications such as lubricants. The amino acids present in the greatest amounts were the essential amino acids aspartic acid/asparagine and glutamic acid/glutamine. Infrared spectroscopy revealed that the protein material had a high amount of strongly hydrogen-bonded β-sheets, indicative of a highly aggregated protein. To assess the moisture–protein material interactions, the moisture uptake was investigated. The moisture uptake followed a BET type III moisture sorption isotherm, which could be fitted to the Guggenheim, Anderson and de Boer (GAB) equation. GAB, in combination with cluster size analysis, revealed that the water clustered in the material already at a low moisture content and the cluster increased in size with increasing relative humidity. The clustering also led to a peak in moisture diffusivity at an intermediate moisture uptake.

Insects fed on waste as fish feed


As part of the result of the Vinnova financed project Five tonnes of fishes in different dishes that aims at producing fish reared exclusively on Swedish produced feed, fish reared on insect based protein were tested and evaluated against fish reared on conventional fish feed. The protein in the test feed comprised of a 1:1 mixture of pea and insect protein. The insects (black soldier fly larvae) were fed stale bread. In total, 25 kg of rainbow trout in this first trial. To the joy of all, the fish fed with insects tasted really well, which suggest that it is feasible that insect can be a part of sustainable Swedish fish feed in the future.