Valorisation of Organic Waste -Effect of the Feeding Regime on Process Parameters in a Continuous Black Soldier Fly Larvae Composting System Title: Valorisation of Organic Waste -Effect of the Feeding Regime on Process Parameters in a Continuous Black Sol

Abstract Municipal solid waste-and especially organic solid waste management has become a major challenge in both developing and developed countries and is often related to the spread of diseases. At the same time, an increase in the demand for animal feed protein causes disturbances in (marine) ecosystems and nutrient recycling in soils is unsatisfactory in many places. These issues have a major negative impact on the environment. Black soldier fly composting could solve these problems; by using the larvae of the black soldier fly (Hermetia illucens) to process organic waste and produce two valuable products: black soldier fly larvae, which could be used as chicken and fish feed, and the residue that can function as an organic fertiliser. The aim of this study was to identify specific process parameters leading to optimised performance of a continuous black soldier fly composting system. This was accomplished by measuring specific parameters (pH, compost maturity, total solids, organic content) on various points along two plug flow reactors operated with different larval feeding regimes (40 mg dry food/larva/day and 60 mg dry food/larva/day) and identifying differences between the two regimes. The pH, compost maturity, total solids, organic content, prepupal weight, material reduction and biomass conversion rate did not differ significantly (P<0.05) between the two feeding regimes. However, survival rate of the larvae was significantly higher (100%) when fed with 60 mg total solids food/larva/day in comparison to when following the feeding regime with 40 mg total solids food/larva/day (70%). A material reduction of 68% (85% on wet basis) and a wasteto-biomass conversion rate of 19% on a total solids basis was achieved in the system. It was found that black soldier fly composting can process more waste than what was expected per larva and day. However, further studies are needed in order to increase the total amount of waste treated in the unit. Popular science summary Municipal solid waste, and especially organic solid waste management has become a major challenge in both developing and developed countries and is often related to the spread of diseases. At the same time, an increase in the demand for animal feed protein causes disturbances in (marine) ecosystems and nutrient recycling in soils is unsatisfactory in many places. These issues have a major negative impact on the environment. Black soldier fly composting could solve these problems by using the larvae of the black soldier fly (Hermetia illucens) to process organic waste and produce two valuable products: black soldier fly larvae, which could be used as chicken and fish feed, and the residue that can function as an organic fertiliser. The results of this experiment show that a black soldier fly composting system can reduce the weight of the waste by 85%. The larvae have also shown to be very efficient in storing the organic waste as biomass in there body. Nearly 20% of the waste was converted to larval biomass. Lastly the prepupae, which is the stage where the larvae start the process of transforming into a fly, weighed around 220 mg each. In this experiment, two feeding regimes (i.e. feeding a set amount of organic waste to a different amount of larvae in two systems) were compared. Eight parameters were measured in the two systems to identify the differences and the performance of black soldier fly composting in general. It was shown that the system where the larvae were fed with more organic waste per larva and day performed better because in the other system, more larvae died. The cause of the high mortality was probably the density of the larvae. The results of the experiment could change the way organic waste is processed, especially in developing countries where there is currently no incentive for people to start separating their waste. If people would be able to process their organic waste with black soldier fly larvae and sell the larvae afterwards, the organic waste would become a valuable resource and a shift in the organic waste value-chain would be introduced