Inclusion of blue mussels in the diet of Black Soldier Fly (Hermentia illucens) : the effect on compost process efficiency

Sammanfattning: Abstract The management and handling of organic waste in primarily low-income developing cities, due to high urbanization has become a global problem. The main form of waste handling in these cities are landfilling, due to it being the cheapest and easiest option. Not only are nutrients wasted, but landfills of mixed waste create strong emission of greenhouse gasses and a leachate that affects groundwater quality. This major problem in addition to a higher demand for food due to the increase of the world population leaves us two problems to solve; to handle waste and produce food. The Black Soldier Fly (Hermetia illucens) and its larvae can solve both of these problems in one. The organic waste is fed to the fly larvae and the larvae produce biomass (larval weight) and a residue similar to un-mature compost. The larvae can then be fed live to animals or made into pellets to feed animals such as fish, and the residue can be used as fertilizer. However, in order for the larvae to be able to be extruded into pellets or fed live to ex. hens, an optimal protein and fat content of the larvae is needed. A higher protein and lower fat content of the larvae is optimal for both pellet production and to feed to animals. It has previously been found that an inclusion of mussels can lower the fat content and increase the protein content of the larvae. In this article, different amounts of mussels are included in the larvae diet apart from bread and cabbage to see if it has an effect on the compost process efficiency. The experiment is done by larvae being added to different ratios of bread: cabbage: mussels. The larvae are then harvested and process efficiency parameters; BCE (biomass conversion efficiency), survival percentage, material reduction and respiration are calculated. It was found that mussel inclusion was equivalent to a higher feeding load per larva. The BCE of the treatment with a higher feeding load and the treatment with the highest mussel inclusion were the same, meaning that mussel inclusion is equivalent to a diet with high amounts of carbohydrates. Mussel inclusion in the larva diet seems to be beneficial from a BCE standpoint and suits as a substrate as pH and survival was not negatively affected by the mussels.