Black soldier fly bioconversion is a technology that converts food waste into high-protein fish feed through the use of black soldier fly larvae. It can contribute to food waste recycling in Hong Kong, however, there are still some technical challenges to overcome. Two challenges were identified in this study, namely the unsatisfactory performance in residue separation and the low larval survival rate, and these were solved by moisture control of the food waste and temperature control in the larval environment, respectively.

Pre-consumer and post-consumer food waste with different moisture content (70%, 75%, and 80%) was fed to the black soldier fly larvae in a temperature-controlled rotary drum reactor. It was found that the residue (i.e., larval excreta and undigested materials)...[ Read more ]

Black soldier fly bioconversion is a technology that converts food waste into high-protein fish feed through the use of black soldier fly larvae. It can contribute to food waste recycling in Hong Kong, however, there are still some technical challenges to overcome. Two challenges were identified in this study, namely the unsatisfactory performance in residue separation and the low larval survival rate, and these were solved by moisture control of the food waste and temperature control in the larval environment, respectively.

Pre-consumer and post-consumer food waste with different moisture content (70%, 75%, and 80%) was fed to the black soldier fly larvae in a temperature-controlled rotary drum reactor. It was found that the residue (i.e., larval excreta and undigested materials) can be effectively separated from the insect biomass by sieving, for both types of food waste at 70% and 75% moisture content. However, sieving of the residue was not feasible for food waste at 80% moisture content. The optimal harvesting time for maximizing the economic value of the insect biomass was determined as Day 12 for pre-consumer food waste, whereas the optimal harvesting times for post-consumer food waste at 70% and 75% moisture content were Day 11 and Day 6, respectively. High larval survival rates of 99 – 100% were achieved at the optimal harvesting time, with appropriate temperature control using the rotary drum reactor. Furthermore, the overall crude protein content of the insect biomass and the residue retained after sieving at the optimal harvesting time was 41.2 – 49.6% on a dry matter basis, which meets the dietary protein requirement for high-value fish species like sea bass and grouper, and thus has a high economic value. This study provides significant insights for the waste treatment industry so as to improve the operations and the economic return when employing black soldier fly bioconversion for food waste recycling.