Faecal sludge management with the larvae of the black soldier fly (Hermetia illucens) — From a hygiene aspect

• A system for simultaneous treatment for human waste and animal feed protein production was investigated in the presented study.
• Black soldier fly larvae feed on organic waste and are high in proteins and fat, which make them ideal as feed for animals.
• Focus of the study was the fate of pathogen and indicator microorganisms in the insect driven treatment system.
• The concentration of Salmonella spp. greatly reduced, but no effect on Ascaris suum ova was established.
• A post-treatment step is recommended, but this is greatly simplified by the significant mass reduction.

Inadequate and lacking sanitation and wastewater treatment systems can lead to the spreading of diarrhoeal diseases. One contributing factor in the lack of such treatment systems is the lack of economic incentives for stakeholders throughout the service chain. However, the organic fraction of the waste is high in valuable plant nutrients and could be reused in agriculture and as animal feed. For example, grown larvae of the black soldier fly, Hermetia illucens L. (Diptera: Stratiomyidae), make an excellent protein source in animal feed, while the feeding activity of the larvae substantially reduces the dry mass of the treated material. This study examined the effect of black soldier fly larvae on the concentration of pathogenic microorganisms in human faeces and found a 6 log10 reduction in Salmonella spp. in human faeces in eight days, compared with a < 2 log10 reduction in the control. No increased reduction was observed for Enterococcus spp., bacteriophage ΦX174 or Ascaris suum ova.

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