For optimal growth and development, black soldier fly larvae require a balanced diet. This study focused on how nutrients other than protein, specifically fat, starch, fibre, and ash, affect larval growth, body composition, and the quality of the leftover material called frass. To isolate the effects of these nutrients, five types of organic byproducts: fast food (FF) waste, solid pig manure (PS), mushroom stems (MS), slaughter waste (SW) and poultry meal (PM), were used to create six different diets, all with similar protein levels (about 22% DM). The results showed that diets rich in fat and starch, such as those based on FF waste, produced the heaviest larvae (155.9 mg), which also had high fat (30.31% DM) and protein contents (52.74% DM). In contrast, diets based on PM, which were low in fat and starch but high in fibre and ash, resulted in lower larval weight, which had lower fat content but variable protein content depending on other diet ingredients. Similar dietary protein levels yielded different larval protein contents, indicating that other nutrients may have influenced how protein was stored. However, other components of the diet, especially fat and ash, were consistently reflected in both the larvae and the frass. Overall, the study shows that nutrients other than protein play important roles in larval development and should be considered when designing black soldier fly diets.

The use of insects as feed and food can be part of the solution towards a circular economy, in case the safety of insect products is assured. Black soldier fly larvae (BSFL, Hermetia illucens ) can be reared on different waste streams. However, before BSFL can be legally reared on these streams, the safety of BSFL for feed and food should be assessed thoroughly. This study aimed to investigate several food safety aspects of BSFL grown on waste streams. Therefore, BSFL were reared for 7 days on substrate mixtures of waste streams with similar protein and moisture content. These waste streams included fast food waste (FF), mushroom stem (MS), pig manure solids (PS), poultry meal (PM) and slaughter waste (SW). The substrates, BSFL and the frass were analysed for the presence of metals and veterinary drugs. The substrates and BSFL were also analysed for presence of DNA of ruminant, pig and chicken. Some of the metals accumulated in BSFL, although the concentrations in BSFL (as these would be manufactured as feed) were below maximum limits for feed. Only traces of some of the analysed veterinary drugs were found in the BFSL and no accumulation thereof was observed. DNA of ruminant and pig was traced back in BSFL samples, however, chicken was not. A good understanding of the presence of food safety hazards and possible variance thereof in potential substrates, such as waste streams, and their possible residues in insects is necessary for implementation of this circular way of insect feeding in the food chain.

Elephants in Artis Zoo (Amsterdam, the Netherlands) produce high quantities of manure daily, which is currently being discarded as waste. Potentially, elephant manure could be used as a fertiliser and/or soil improver. To explore this, an aerobic incubation experiment was carried out in the laboratory. Results were evaluated by modelling, using default values of dairy cow slurry (DCS) for comparison. It was hypothesised that 1) elephant manure would mineralise slowly and, 2) release relatively small amounts of N compared to dairy cow slurry. The carbon content and C:N-ratio in elephant manure were 419 g kg-1 and 36:1, respectively. The estimated humification coefficient of elephant manure was 0.32, indicating faster mineralisation than of DCS in The Netherlands (0.7). Modelling the results showed that after 10 years of annual additions of 100 kg Norg ha-1, total carbon build-up from elephant manure and DCS was ca. 4800 and 6800 kg ha-1, and total nitrogen mineralisation was 540 and 490 kg N ha-1, respectively. The higher mineralisation rate from elephant manure compared to DCS could be due to occurrence of priming during the incubation experiment and/or different qualities of organic matter fractions. It was concluded from this experiment that elephant manure could be suitable as both a soil improver and fertiliser, and recommendations for follow-up research are given.

Black soldier fly (BSF) frass, resulting after bioconversion of organic materials by Hermetia illucens larvae can be used as fertilizer. This overview provides a literature summary of the main (macronutrient) components in frass and its reported effects on plant growth/health and soil. Frass composition is highly dependent on the substrate. Based on average composition, BSF frasses show resemblances to cow manure (C/N ratio, N content), pig slurry (P content), poultry manure (DM, Kcontent) and compost (DM). The frass has a higher organic matter content than compost and beforementioned manure types. Frass seems to be a fast acting fertilizer. Most of the nitrogen is organic,but ammonia content is highly variable. Reported effects on plant growth were often positive or neutra lbut also sometimes negative compared to organic and mineral control fertilizers and there seem to be maximum application rates above which positive effects diminish. Several authors mention that post-treatment of frass (for example by aerobic composting) is necessary to obtain a stable/mature product.Usually the frass is relatively high in P content, which may require extra N fertilizer addition. Severa lauthors state that chitin in the BSF frass likely benefits resistance to plant pathogens. Finally, adding frass can induce changes in the microbial community of the soil/plant rhizosphere. BSF frass can be used as a circular fertilizer in agriculture.

This document gives a short overview of the current (national and EU) legislation (as on December 2022) on the bioconversion of several organic streams by insect larvae and compost worms. Legislation concerns different substrates, the status of the invertebrates themselves and the status of the resulting insect frass and vermicompost. Dutch and EU legislation on the production of insect larvae as feed for farmed and pet animals has been developed and adapted in recent years, for example the allowance of different feed products from designated insect larvae species as fish, poultry and pig feed. The legislation is still in development. Recommendations are given.

Vermicomposts are earthworm faeces after processing of different organic wastes. The composition is variable and dependent on the nature of the substrate. Several characteristics make vermicomposts interesting for agriculture (plant growth/health, soil health) such as their macronutrient content (N, P, K, organic matter) and specific components (humic acids, phytohormones, enzymes). This literature overview describes multiple researches on the effects of vermicompost in agriculture with a focus on macronutrient content and plant growth.

Black soldier fly larvae (BSFL) are considered a commercially viable solution for global organic waste problems. The objective of this study was to assess the feasibility of rearing BSFL on a wide range of low-value waste streams and its potential to transform them into high-quality animal feed and fertilizer. Six waste streams of different origins were selected and each tested in triplicate. Several parameters were analysed: growth performance, waste reduction index (WRI), conversion efficiency (ECI) and larval composition. Frass composition was also analysed. Larvae reared on fast food waste (FFW) had the highest ECI and WRI and the lowest values when reared on pig manure slurry mixed with silage grass (PMLSG) and slaughter waste (SW). The highest protein content was found for larvae reared on mushroom stems (MS) although this substrate had the lowest protein content. Moreover, the frass nutritional profile was proportionally related to the substrate's nutritional profile: the protein-rich substrate (SW) resulted in protein-rich frass and the low-protein substrate (MS) resulted in protein-poor frass. The same was true for the lipid content. In conclusion, this study showed that BSFL can be successfully reared on a wide range of waste streams that can affect the larval and frass chemical compositions.

BSF larvae are highly efficient in converting all kinds of waste streams into larval protein richbiomass and organic matter. These properties make the BSF larvae perfect candidates for upgrading local waste streams into organic fertilizer in the pilot project ‘Kringlooplandbouw Veenkoloniën’ (circular agriculture Veenkoloniën). In this report different regional substrates, such as germinated barley, barley dust, secondary food industry sludge, primary sludge, pig manure solids, or combinations of these, were used to grow BSF larvae. The growth of the larvae was closely monitored. At the end of the 7 day experiment, the dry matter of the larvae, the growth rate per day, the conversion rate of the substrate and the ease of separating the frass from the larvae were determined. The BSF larvae grew on each substrate, but the highest growth rate (fresh weight) was observed when the larvae were grown on the substrate of germinated barley + barley dust. The observed growth rate was 10.0 mg/day of fresh weight respectively. The highest substrate conversion index (WRI) based on dry matter of 11.93 g/d was observed in primary sludge + germinated barley. Overall, these regional substrates show potential as a feed stream for the cultivation of BSF larvae.

In an experiment described by Elissen et al. (2019) on anaerobic digestion of black soldierfly (BSF, Hermetia illucens) larvae frass, the frass had been previously hygienised due to Dutch law. However, when the frass would stay on the same premises this hygienisation step may not be necessary. A synergistic effect of mixing insect frass with cattle slurry would provide a more positive business case for the insect farmer, since the frass becomes an interesting co-substrate for digesters, resulting in lower disposal costs or even benefits. To determine this synergistic effect, three substrates were tested in lab-scale mesophilic anaerobic digestion tests: Insect frass of BSF larvae grown on agricultural side-streams, either hygienised at 60 °C for 24h or non hygienised and cattle slurry. Also combinations of cattle slurry with insect frass were tested. Biogas production was determined by measuring gas pressure and analysing gas composition. No synergistic effect of adding insect frass to cattle slurry was found in this experiment, and neither differences between hygienised and non hygienised insect frass were found. In other words, adding insect frass to a cattle slurry digester will not lead to an increase in biogas production different from that expected based on adding up biogas productions of the single substrates. However, the partial replacement of cattle slurry with insect frass will increase the amount of biogas produced per digester volume with a factor 3.5 to 9 for respectively 10 % and 30 % replacement. Therefore, it is still interesting to add insect frass to a cattle slurry digester.

This report describes five experiments to observe the growth of Dendrobaena veneta and Eisenia fetida on substrates originating from Avebe (potato starch and protein producer), Holland Malt (maltings) or others ( kitchen and garden wastes). The substrates include Tarra (Avebe), Secondary food industry Sludge (Holland Malt and Avebe), Barley Dust (Holland Malt), Germinated Barley (Holland Malt), Bokashi (Jansen Wijhe), Potato Peels (van Vulpen voeders), vegetable fruit and garden waste (van der Wal and Ogar), Apple pulp (van Vulpen voeders), Champost (Koolen champignons CNN) and Carrot and Pumpkin Peels (van Vulpen voeders). The compost worms’ growth was monitored for 4-6 weeks. The compost worms were able to convert the substrates into dry, light and powdery vermicompost high in nutrients and organic matter. The compost worms themselves increased in biomass and produced eggs. The protein content of the compost worms ranged between 57.1 and 68.3 % of DM, whereas the fat content ranged between 7.8 and 9.1% of DM. Tarra and Secondary food industry Sludge (Avebe) are suitable substrates for vermicomposting, when mixed with other substrates. Germinated Barley and Secondary Food Industry Sludge (Holland Malt) are less suitable for vermicomposting, due to substrate instability, even when mixed with other substrates. Additions of barley dust and chalk make the substrates’ texture and composition more suitable for the worms to feed on.

This report starts with a literature review on the topic. From literature it is known that fungi can selectively digest lignin, thereby releasing other components which may subsequently be easily converted into biogas during anaerobic digestion of normally recalcitrant compounds. In addition, several authors have found that commercial fungi can be grown on alternative substrates such as digestates. Four substrates (flax shives, solid fractions of ACRRES digestate, Greendal digestate and cow manure) were incubated with 10 fungi species (Coprinus comatus, Ceriporiopsis subvermispora, Pleurotus ostreatus, Pleurotus eryngii, Lentinula edodes, Hypholoma frowardii, Clitocyba dusenii, Bjerkandera adusta, Hypholoma fasciculare, Gymnopilus sapineus and Kuehneromyces mutabilis). Most combinations of substrates and fungi resulted in growth/colonization, except for all combinations with Greendal digestate, probably due to fungicidal compounds. The most successful combinations were those with P. eryngii, P. ostreatusand G. lucidumon ACRRES digestate, flax shives and cow manure, based on visual signs of fungal colonisation (air mycelium). In general, (average) biogas productions from the different substrates with or without fungal pre-treatmentdid not vary to a large extent and were relatively low (35-73 nm3biogas per ton product). Although in some graphs a slight positive effect on biogas treatment seemed to be taking place, statistical analysis showed that treatment of cow manure with P. ostreatus,P. eryngiiand G. lucidumdid not significantlyincrease the amount of biogas that could be collected. Fungal pretreatment of flax shives also did not lead to increased biogas production with P. eryngiiand G. lucidumand even to a significantly lower biogas production with P. ostreatus.

Insects can play an important role to upgrade waste streams into high-grade proteins and fats as food and feed ingredients or non-food products. The aim of this research was to assess the feasibility to use waste streams with a low value for direct application as animal feed as substrates to grow BSF larvae in terms of larval growth rate, waste reduction index, and efficiency of conversion of ingested feed. The growth of black soldier fly (BSF), Hermetia illucens larvae and conversion of biowaste was assessed in triplicate in biowaste substrates: chicken feed (CF; reference diet), pig manure solid (PMS), Betafert® solid (BTFS), swill (SW), olive pulp (OP), pig manure liquid mixed with chicken feed (PMLCF), and silage grass (SG). Per kilogram fresh substrate 2500 starter (8-days-old, second instar) larvae were incubated in 21 plastic containers (75 × 47 × 15 cm). The BSF larvae were fed according to a batch feeding system. Highest growth rate was found in larvae reared on SW (13.4 mg/d). Larval growth rate was even higher than in larvae reared on the reference substrate CF (7.2 mg/d). Growth rate in larvae reared on PMLCF (7.3 mg/d) did not differ from CF, whereas growth rate of larvae reared on PMS (3.2 mg/d) was lower than on CF. Growth rate of larvae reared on BTFS, OP and SG was very low (0.6, 0.2 and 0.7 mg/d, respectively). Waste Reduction Index (WRI) was highest on SW (11.3), followed by PMLCF (9.3), and both were higher than WRI on CF (8.5). Waste Reduction Index further decreased in descending order from PMS, SG, BTFS to OP (7.6, 4.0, 2.9 and 1.7, respectively). The Efficiency of Conversion of Ingested substrate (ECI) was highest on SW (0.31), followed in descending order by PMLCF, CF and PMS (0.25, 0.21 and 0.18, respectively). The substrates OP, BTFS and SG (0.16, 0.15 and 0.14, respectively) resulted in a lower ECI than other substrates. Highest CO2 and lowest NH3 concentrations were found above substrates with the highest larval growth performances. This study showed that BSF larvae can be reared on different biowaste substrates; the growth rate of the larvae was extremely high on SW. The effects of chemical composition and physical properties of the substrates on larval growth and gas emissions should be further considered.

As a growing demand for food and feed resources arises, alternative feed and food resources are sought to relieve pressures on the environment and existing food and feed resources. One alternative that has been given increasing interest is the application of black soldier fly (BSF) larvae to waste streams. In the context of the biobased economy, black soldier fly larvae convert waste streams into valuable insect biomass and organic fertilizer (frass). Applying black soldier fly larvae to manure has the potential to close loops within agri-food supply chains (Bortolini et al., 2020). This report explores the profitability potential of producing black soldier fly larvae on pig manure by individual pig farmers in the Netherlands. If profitable, producing black soldier fly larvae can diversify farmers’ income streams and help farmers to increase the circularity and sustainability of their business. However, while steps have been taken to broaden EU legislation with regards to black soldier fly larvae, it is currently not yet legal to produce and sell black soldier fly larvae raised on manure.

For mushroom production usually a mixture of horse and chicken manure and straw is used. For every kg of mushrooms, 5 kgs of waste is produced, a total of 800.000 tonnes per year in the Netherlands. Processing options are often either costly or complex. As the champost contains high salt concentrations, washing results in a solid (less salty) fraction with better re-use options and a nutrient-rich liquid fraction. On the latter fraction growth of five species of commercially relevant micro algae was tested in small-scale well tests. In addition, the press water was also treated with H2O2/UV to reduce the brown colour of the solution. In the majority of the triplicate well tests, growth of three of the five common saltwater algae species (Nannochloropsis gaditana, Porphyridium purpureum, and Tetraselmis chuii) on press water fractions of spent mushroom waste (champost) was found to be comparable to or better than their growth on control media. Dunaliella salina growth was relatively low. Arthrospira platensis only grew on press water when treated with H2O2. Overall, the results indicate that washing of champost results in a mineral rich solution suitable for growth of several (saltwater) algae.

This report describes two bioassays for testing disease suppression by BSF frass in an agricultural soil with two crops: sugar beet (Beta vulgaris) and cress (Lepidium sativum). In the bioassay with beet, soil was infected with the plant-pathogenic fungus Rhizoctonia solani while in the bioassay with cress, soil was non-infected or infected with the plant-pathogenic fungus Pythium ultimum. Both concentrations of the BSF frass (7.5 and 15 g/kg soil) proved to be useful as soil application, leading to good plant emergence and growth of sugar beet and cress plants. The highest concentration of BSF frass (15 g/kg soil, both as total product) had a large fertilizer effect. In experiments with cress without addition of Pythium (i.e. with only natural soil infections), disease suppression with BSF frass was found. In all tests, keratin was added as a positive control treatment, which had a higher disease suppression effect than BSF frass but comparable fertilizer effects.

In literature, the synergistic effect of several substrates on feedstocks for anaerobic digestion/methane production is described for several substrates. Champost from mushroom production, vermicompost from worm composting/vermiculture and BSF (black soldier fly) larvae frass from insect production were therefore tested for this report for their synergistic effect. It was found that insect frass had a very high biogas/methane production as a single substrate. Addition of the frass led to a concentration dependent biogas production in mixtures with ‘old’ digestate higher than was expected based on the results of the single substrates. Champost resulted in some biogas production but from vermicompost hardly any biogas could be produced. Also, no synergistic or concentration effects could be noted from the latter two.

Dit rapport beschrijft groei op en omzetting van de dikke fractie (28 % droge stof) van digestaat door E. fetida wormen (compostwormen) in 6 kweekbedden van elk 5 m2. De begindichtheid van de wormen was 5 kg/m2. Het digestaat was afkomstig uit de ACRRES vergister die gevoed werd met rundermest en natuurgras. In de vijf weken durende proef bij Lumbriculus te Oostwold werd het voorgecomposteerde digestaat continu omgezet in wormencompost waarbij 22 % (natgewicht) van het digestaat afgebroken werd. De omzettingssnelheid was 1.6-3.2 kg (3.2-6.4 L) per kg levende wormen (per m2) per week. Door het opeten van het digestaat veranderden structuur van en nutriënten in het digestaat: De ontstane wormencompost had een korrelige lichte structuur en ammoniak nam bijvoorbeeld met 65 % af. Ook groeiden de wormen in biomassa en produceerden ze cocons. De gemiddelde groei in natte wormenbiomassa was 4 % per week. De maximale snelheden werden nog niet bereikt in dit experiment, maar het is duidelijk dat vermicompostering tot een substantiële afbraak van de dikke fractie van digestaat leidt en de productie van een nieuwe meststof (wormencompost) en nieuw eiwit (wormenbiomassa).

In Task 9.4 a socio-economic assessment of the systems defined in Task 9.1 was performed for the PUFAChain process by Wageningen Research (former DLO).The result is an international working paper that documents the approach, method and results of this socio-economic assessment.This includes a macro-economic assessment, a LCC (Life Cycle Costing, micro-economic) analysis, followed by an overall SWOT analysis taking into account the different parts with emphasis on the socio-economic aspects.The macro-economic assessment focuses on market analysis and competiveness and provides information about market and price developments.Both peer-reviewed and generic data sources were used.The LCC (micro-economic) analysis uses both existing information and tools in development from the Interreg project EnAlgae, combined with data from Task 9.1 and the project partners.UNEP/SETAC guidelines for LCC were taken into account.The macro-and micro-economic analyses both identify profitability and market competiveness of the systems.The SWOT analysis has been updated during the project and takes into account the results of the other three analyses.When useful, reference systems/products were assessed as well.The integrated socio-economic analysis, presented in a data table, includes all major social and micro-economic aspects, such as impacts on employment and public acceptance of new technologies.Institutional, legislative and political aspects are included if applicable.UNEP/SETAC guidelines for sLCA (social life cycle assessment) and recent methodological literature are taken into account.The results will be used as input for Task 9.5.

The aquatic worm Lumbriculus variegatus (Lv) contains high levels of proteins and can provide an excellent fish food. Large-scale production of Lv on low value organic substrates, such as by-products produced during wheat processing, therefore can be a promising and sustainable concept for the aquaculture industry. Growth and reproduction of Lv on different combinations of wheat based derivatives was studied at fixed isoenergetic levels (expressed by the chemical oxygen demand of the food), but at different carbon to nitrogen (C:N) mass ratios under controlled conditions in specifically designed test-beaker tests. Growth and reproduction rates were compared to those on Tetramin®, a substrate known to give excellent growth of Lv. Although Lv did exhibit a growth response on single as well as on mixed wheat fractions, growth was mainly controlled by the C:N ratio of the diets. Lower C:N ratios of typically 6-7 gave a much better performance than high C:N ratios of approximately 20. It was discussed this is probably caused by Lv relying on the presence of proteins for their carbon and energy source. Although growth and reproduction rates were not as high as on the control diet, the results are promising for the development of a worm biomass production system operating on by-products from the wheat processing industry.