Potentials and Limitations of the Bioconversion of Animal Manure Using Fly Larvae

Abstract

Bioconversion of organic waste using fly larvae (such as Hermetia illucens and Musca domestica) is often presented as a promising and sustainable alternative because of its ability to generate high economic value products from excreta, waste or low value-added materials in short term, with the potential to promote a circular economy in agricultural systems. However, bioconversion of some organic waste, such as animal manure, could limit the use of bioconversion products because of contaminants presents in the substrate, offering risks of toxic substances entering the food chain and consequent effects on human health and the environment. This review provides an overview of the limitations and potentials of bioconversion process of cattle, swine, and chicken manure using fly larvae, focusing on nutrient recycling, environmental impacts, direct greenhouse gas emissions, heavy metals, antibiotics, and pathogenic organisms. Potential advantages identified include the ability to reduce manure volume and nutrients, produce biofertilizer and high protein and fat content larval biomass, and reduce environmental impact compared to composting and other protein and oil production sources, as well as, to reduce some metals, antibiotics and pathogenic organisms found in manure. On the other hand, some metals, antibiotics, bacteria, and parasites may be retained or bioaccumulated in larval biomass. Direct use of larval biomass from bioconversion of animal waste, as animal feed, is not recommended, and biofertilizer requires additional treatment before release to agricultural soil, aiming to ensure food and environmental safety.

Fish Feeds in Aquaponics and Beyond: A Novel Concept to Evaluate Protein Sources in Diets for Circular Multitrophic Food Production Systems

“…With the above details on feces composition and recovery in mind, important macronutrients were compared between the experimental feces and other relevant raw materials (Figure 5), including animal manures (often suggested as waste streams to be used for BSF larvae production [23,[105][106][107][108]), poultry feed (a common reference diet in BSF trials [109][110][111]) as well as BSF larvae themselves. Disregarding the PBM feces, the other experimental feces appear approximately similar to other animal manures in terms of CP, CF as well as EAA, and ash content (except for the BSF feces with lower ash content) with perhaps slightly higher content of NEAAs, yet somewhat reduced GE content.…”

Upgrading ammonia-nitrogen from manure into body proteins in black soldier fly larvae

“…Manure bioconversion with black soldier fly larvae (BSFL) is envisioned as a new potentially sustainable, and circular management method to treat surplus manure (van Huis, 2019). If safety standards for metals, antibiotics, pathogens and parasites are met (Sanchez Matos et al, 2020) the larval biomass obtained after bioconversion could be used as protein-rich ingredient. Thereby, it can replace feed ingredients having a high environmental impact, such as soybean and fish meal, and contribute to the circular economy (Heuel et al, 2021;Van Zanten et al, 2015).…”

Farmed insects for sustainable food systems

“…Manure treatment with black soldier fly larvae (BSFL) is an innovation that could bring multiple benefits at once. BSFL can modify the physical, chemical and biological properties of manure in one to two weeks and thus modify the initial moisture and nutrient levels (Sanchez Matos et al, 2020). When safe (Charlton et al, 2015;Van Raamsdonk et al, 2017), the larvae could be used as feed for aquaculture or livestock (Moula et al, 2018) and hence decrease the dependency on imported high-protein feeds with high environmental impact such as soybean and fish meal (Heuel et al, 2021;Van Zanten et al, 2015b).…”

“…Manure bioconversion with black soldier fly larvae (BSFL) is envisioned as a new potentially sustainable, and circular management method to treat surplus manure (Van Huis, 2019). If safety standards for metals, antibiotics, pathogens and parasites are met (Sanchez Matos et al, 2020) the larval biomass obtained after bioconversion could be used as protein-rich ingredient. Thereby, it can replace feed ingredients having a high environmental impact, 92 Incorporation of manure ammonia-nitrogen into black soldier fly larvae such as soybean and fish meal, and contribute to the circular economy (Heuel et al, 2021;Van Zanten et al, 2015b).…”

“…In addition, the residual material of the bioconversion process (i.e., mix of uneaten manure, and insect frass and exuviae) is considered an attractive fertilizer because of improved humification properties relative to fresh manures (Wang et al, 2021). In the last years, various studies reported the bioconversion efficiency of BSFL on different manure types (see Sanchez Matos et al (2020) for an overview), and recent studies quantified NH 3 and GHG emissions during this process (Chen et al, 2019;. Although more quantitative environmental data is becoming available for broader sustainability assessments, the role that BSFL bioconversion can have in reducing NH 3 emissions through its direct use has so far received limited attention.…”