Blog from the Environmental Engineering Research Group at SLU
On Thursday the 12th of September at 12:15 pm CET, Cecilia Lalander will tell her view on the matter. Tune in! It will be available online afterwards if you don’t have time to watch live.
Worth knowing is the SLU University Library’s popular science lunchtime lecture series. Here, exciting and recent research results from SLU are presented. We offer a light lunch, and after the lecture listeners have the opportunity to ask questions.
In our article Recirculating frass from food waste bioconversion using black soldier fly larvae: Impacts on process efficiency and product quality recently published in the Journal of Environmental Management, we showed that food waste-derived frass, an unstable fertilizer with phytotoxic properties when used fresh, can be reused in the bioconversion process as part of the larvae’s feed. This approach offers several benefits for both the process and the quality of the resulting larval biomass and frass fertilizers.
Several studies reported phytotoxicity (adverse effects on plant growth, physiology or metabolism cause by several different substances) in frass from black soldier fly larvae (BSFL), especially when growing crops in greenhouses and using frass as a fertilizer or growing media. We believe that this phytotoxicity is related to the fact that waste bioconversion with BSFL is very rapid (< 14 days), and that there therefore is no time for the organic matter to be stabilized. Stabilizing this “fresh” frass’ organic matter is crucial for its safe use as a fertilizer or soil amendment. However, studies have shown that the post-composting of frass can be the major source of greenhouse gas emissions and increase the overall environmental impact of this treatment. Finding a more viable and sustainable way of stabilizing fress frass was the main goal of this study.
The hypothesis of the study was that a significant portion of the organic matter in food waste-derived frass remains relatively undigested, allowing the BSFL to further consume and digest it, thereby increasing the degree of decomposition. This hypothesis was confirmed, as the frass produced after consuming the food waste with frass inclusion (called recirculated frass) had a lower organic matter content than the fresh frass. In addition, several characteristics of the recirculated frass pointed towards higher maturity and higher stability, which indicates that it is safer to use as fertilizer. Interestingly, not only the resulting frass, but also the larval biomass was positively affected with this frass recirculation process. A significant correlation of larval biomass composition and frass-inclusion rate was establisheda, showing that as frass inclusion increased, the larval biomass had higher protein content and lower fat content. Considering that protein ingredients are the most expensive input in animal feeds, this is likely to be of interest to the insect industry.
One of the most intriguing findings of this study was that recirculating frass back into the bioconversion process significantly increased the larval yield per unit of waste. This indicates that incorporating fresh frass into the larvae’s diet allows for a higher biomass of larvae using the same amount of waste. This innovative method for enhancing both the process and product quality is highly promising. We are now developing new studies on frass recirculation to better understand the underlying mechanisms and explore any additional benefits this approach may offer.
We are not even halfway through June, and we already have two major highlights to share.
On June 5th, the Ambassador of Japan, Mr. Noke Masaki, visited us. Björn demonstrated the urine diversion toilet and explained the benefits of urine dehydration technologies. The Ambassador then came down to the BSF container, where Cecilia gave a short presentation of the technology and our research on the topic. Ivã and Viktoria then guided our visitors through the BSF lab, answering questions about the rearing and fertilising potential of the flies and their frass.
A week later, a joint delegation from Kenya-Lycksele came by for lectures from Björn and Cecilia, followed by visits to the urin diviring toilet and dehydration system, followed by a tour of the fly container, where Viktoria showed the eager participants around.
Knowing that our technologies and ideas gain international interest keeps us motivated to continue contributing to a circular society.
On April 23rd, representatives of the EU ambassadors came for a visit to the ET Department and had a pe[e]k at our urine diverting toilet where Björn and Prithvi talked ab  out the future of urine dehydration and the potential it harbours.
After the toilet, the visitors went on to our Black Soldier Fly container were Cecilia, in bitter cold winds, shared our vision on how to contribute to a circular food and feed production, if food waste would get accepted as a feed source for insects.
The evening ended with a dinner at the castle in Uppsala where ideas and visions for the future were exchanged.
Last week, Cecilia and Viktoria embarked on a night-train journey to attend the grand opening of ENORM biofactory in Midjytland, Denmark. On the 5th of December, ENORM opened its doors and welcomed visitors to inaugurate Scandinavias biggest insect company. The long-term goal of ENORM is processing substantial amounts of organics to produce equally substantial volumes of insect-derived products.
To say that we were impressed is an understatement, and we wish ENORM all the best with their endeavors.
If you want to know more, see their linkedin post of the event and an episode of Vetenskapsradion PĂĄ djupet (in Swedish) in which they interview Jane Lind Sam, the founder of Enorm.
Evans Were has joined the Kretsloppsteknik group as a Postdoc Research Fellow. At SLU, Evans will investigate the mechanisms and dynamics of infectious biological agents, including prions, bacteriophages, and spore-forming bacteria in the process of bio-conversion of biowaste using black soldier fly (Hermetia illucens) larvae. Larvae of H. illucens remarkably convert biowaste into larval biomass (high-quality protein feed) and residue (biofertilizer) as end products. Understanding the dynamics of infectious biological agents within this process is crucial to ensure process safety and efficacy.
Evans worked as a technical assistant researcher at the Hans-Ruthenberg Institute, University of Hohenheim. There, he taught bench techniques (including microbiology and molecular biology) to graduate students. Before joining Hohenheim, Evans worked as a research assistant at the International Institute of Tropical Agriculture (IITA) in Uganda. At IITA, Evans optimized methods for molecular characterization of plant pathogenic microorganisms and supported phytopathology and plant breeding teams. This work led to the discovery of novel genetic traits that enhance resistance to some of the most economically important diseases of banana, a crop that provides food security and income for over 400 million people globally.
Evans was born and raised in Uganda, where he completed his diploma and BSc degree in Biological Sciences, and MSc degree in Molecular Biology from Makerere University. Evans earned his Doctorate in 2023 from the University of Hohenheim, Germany where he studied the notorious phytopathogenic fungus, Fusarium oxysporum f. sp. cubense tropical race 4.
Hi, our names are Ava & Evelina. We are two 17 year old girls in our final year studying Natural science (Naturvetenskap) at Rosendalsgymnasiet. For nearly three years we’ve been studying topics based around scientific subjects. Part of our studies consists of a scientific rapport, called a Gymnasiearbete (highschool diploma work), a requirement needed to graduate next summer. Throughout the next couple of weeks we’ll be doing laboratory work in the Department of Energy and Technology at SLU. We intend on focusing on the link between larvae and algae infected mussels from the Baltic Sea. We’ll be guided by Viktoria Wiklicky and Dr Cecilia Lalander who will help us in carrying out our studies.
Keeping a viable and productive Black Soldier Fly colony up and running can be hard sometimes, this is why it is great to have international relationships and colleagues to help you out when your colony needs to be replaced. Our Black Soldier Fly colleagues from Estonia picked up their new stock of larvae from SLU last week and finally also visited SLU facilities. The newest developments on both sides were discussed over lunch and after a tour through the (new) container based fly lab, larvae were sent off to their new home at the Estonian University of Life Sciences in Tartu.
Viktoria just returned from Benin which she visited in October to work together with colleagues from IITA at completing the goals of workpackage I + III in our VR funded project ‘Insect farming for feed production and organic waste management in Benin‘. Together they investigated and sampled waste streams from the south and the north of Benin and worked on improving the Black Soldier Fly colony at IITA, to secure a stable and high production of Black Soldier Fly larvae for future waste treatments. The visit was ended with a fruitful final discussion, where the gained knowledge and experience was shared with the rest of the work groups, both at SLU and IITA.
IITA, the International Institute of Tropical Agriculture, is a non-profit institution that generates agricultural innovations to meet Africa’s most pressing challenges of hunger, malnutrition, poverty, and natural resource degradation. Working with various partners across sub-Saharan Africa, they aim to improve livelihoods, enhance food and nutrition security while increasing employment, and preserve natural resources.
About the project:
The project is funded by VR (VetenskapsrĂĄdet) and the objective is for Black Soldier Fly Farming to contribute to solving socio-economic and environmental issues in Benin by reducing the adverse impact of inadequate waste management, while at the same time improving agricultural productivity with locally sourced products.
We are happy to share our new publication “Advances in substrate source composition for rearing black soldier fly larvae as a protein source“, published as a chapter of the book “Insects as alternative sources of protein for food and feed”, published by Burleigh Dodds Science Publishing
In this chapter, Cecilia and IvĂŁ discuss some of the challenges faced by the BSF industry in relation to the feed substrates available for rearing this amazing insect species. Bioconvesion is affected by many variables and it is not easy to always have good predictability of the process and product composition combined with environmental sustainability.
We strongly believe that the real value of BSF larvae can only be extracted when waste streams are used as feed substrate (especially post-consumer waste) and when the larvae end up as feed for livestock. This, in our view, is the real path to sustainability!