Upcycling nutrients from poultry slaughterhouse solid waste into value-added bioproducts using black soldier fly larvae cultivation.

The objective of this work was to test the hypothesis that black soldier fly larvae (BSFL) can be grown successfully on dissolved air flotation solids from poultry slaughterhouses by blending it with food waste. Dissolved air floatation (DAF) solids generated from poultry slaughterhouse wastewaters have high water content (>70%) and the solids are rich in fats (50-60%) and proteins (20-30%) on a dry weight basis. BSFL bioconversion of fat-rich wastes has been a challenge in the past and, in the current work, we have tested the effects of blending DAF solids with post-consumer food waste at different substrate ratios (1:0, 1:0.33, 1:1, 1:3, 0:1). The results indicate that BSFL conversion of DAF solids alone results in low bioconversion efficiency (BCE) (2.6%), substrate reduction (SR) (47.0%), biomass yield (BY) (10.4%), biomass gain (BG) (7.9 g) and feed conversion ratio (FCR) (9.8). However, BSFL reared on food waste and DAF solids at a ratio of 1:1 resulted in high BCE of 28.1%, SR of 82.7%, BY of 36.7%, BG of 58.8 g and a FCR of 2.7 which was better than BSFL growth on food waste alone. This suggests that DAF solids, despite their high fat content, may provide critical nutrients to BSFL. For example, BSFL accumulated higher levels of mono- and polyunsaturated fatty acids when DAF solids were incorporated into their diet. The results of this study enable a new valorization pathway for poultry DAF solids which are currently land-applied and are a nuisance to surrounding population centers.