Researchers at the BITS Pilani Hyderabad campus have developed a low-cost system that uses black soldier fly larvae to convert vegetable, fruit and cooked food waste into protein-rich biomass, offering a compact approach to on-site organic waste processing.
The system was developed by Sankar Ganesh Palani, assistant professor in the Department of Biological Sciences, and his research graduate, Atun Roy Choudhury. According to the researchers, black soldier fly larvae consume organic waste during a feeding cycle of approximately two weeks, converting it into biomass faster than conventional composting processes, which can take weeks or months.
The unit was designed using materials available at hardware shops and costs about Rs 2,500 to build. It consists of an egg-laying and hatching vessel paired with a harvesting bucket. A 7 cm to 8 cm layer of coconut coir and sand filters leachate, or liquid draining from the decomposing waste. The filtered liquid is recirculated to maintain moisture levels between 50 per cent and 60 per cent and to help mature larvae move into the harvesting bucket.
This arrangement is intended to reduce manual handling during harvesting. Its enclosed design also addresses one of the main barriers to decentralised organic waste processing: unpleasant odour. The researchers said the system is both affordable and space-efficient, making it suitable for locations where large composting facilities are not available, although the report does not specify any commercial or municipal deployment.
During initial trials, the researchers recorded a yield of approximately 2 kg of larvae per day over a 20-day period. Choudhury said black soldier flies are harmless and that their larvae feed on vegetable and fruit waste, cooked food and manure. “They do most of their eating in a two-week larval stage, converting waste into body mass far more efficiently than warm-blooded animals,” he said.
The output has potential value beyond waste reduction. The researchers said black soldier fly larvae contain approximately 20 per cent protein and 25 per cent fat, making them a potential alternative feed ingredient for poultry, pig and aquaculture sectors. The residual organic material, known as frass, can also potentially be used as a soil amendment.
The system therefore combines three functions in one small unit: processing organic waste, producing biomass that could be used as an animal-feed ingredient, and recovering a residual material with possible agricultural use. The report does not establish whether the larvae or frass have received regulatory approval for feed or soil applications, or whether the unit has been tested at city-scale waste volumes.
