Black soldier flies present an excellent opportunity for improving the management of municipal wastes. Obviously, bioconversion is a by far superior approach to landfilling – pretty much anything short of dumping garbage into the nearest river is. However, it is also superior to traditional composting because nutrients are captured and recycled for agricultural use rather than simply released into the environment while compost is being formed. Furthermore, black soldier fly larvae can handle some organic toxins without bioaccumulating them and they suppress a range of pathogenic bacteria.
Employing black soldier flies to tackle municipal waste disposal also does not require major investments in new infrastructure. Larval production can be added to existing facilities using a decentralized model: adults are kept at a separate location, while newly hatched larvae are brought to landfills and transfer stations for processing wastes collected from residents and businesses in the area. All that may be required in such a setting is some space to place bins with growing larvae and to house sorting equipment that separates fully grown larvae from the spent substrate.
Despite this simplicity, introducing black soldier flies into a municipal waste management system is still more involved than simply backing up a garbage truck into a bioreactor room. First, there is always an issue of contamination of food waste with other materials, ranging from plastic spoons to alkaline batteries. These can introduce toxins, such as heavy metals, interfere with separation of fully grown larvae from their frass, etc. Second, contents of municipal waste are usually rather variable and inconsistent. Since nutrient composition of harvested larvae is strongly affected by their diet, this variation may be problematic for their future use in animal feeds. Constant adjustment of feed formulations to meet nutritional requirements of animals based on each incoming batch of harvested larvae is likely to be impractical.
While important, these challenges are not insurmountable. They can be addressed through presorting of municipal food wastes, adding them to other wastes to achieve more uniform composition, pooling larvae fed on different substrates, and so on. Also, black soldier flies reared on municipal wastes may be more suitable for industrial uses, such as biodiesel or lubricants, rather than as an ingredient for animal feeds.