Co-treating of chicken manure with wet market waste by black soldier fly larvae for synergetic bioconversion enhancement and gas reduction

Adding organic wastes to chicken manure (CM) for co-digestion by black soldier fly (BSF) larvae is an effective means to improve the efficiency of manure degradation and bioconversion, but the trade-off in carbon (C) and nitrogen (N) distribution and environmental impact is still unclear. Six substrates were provided for BSF bioconversion: CM (control), vegetable waste (VEG), slaughtered chicken waste (SCH), discarded fish organs (DFI), the mixture of CM, VEG, and SCH with a 1:1:1 ratio (Mix1) and the mixture of CM, VEG, and DFI with a 1:1:1 ratio (Mix2). The effects on BSF growth performance, nutrient accumulation and environmental emissions were examined. In comparison with CM, VEG reduced 29.65 % of NH 3 emission, but the larvae yield (13.04 %) and nutrient accumulation were also decreased. Final larvae weight (16.20 % and 41.52 %) and survival ratio (26.00 % and 25.78 %) in animal-waste (SCH and DFI) treatments were improved, whereas the NH 3 (SCH) and CO 2 (DFI) emissions were significantly increased. Mix1 and Mix2 greatly improved the larval conversion efficiency and frass maturity, while reducing NH₃ emission (24.45 % and 14.08 %) and GHG emissions (38.42 % and 56.38 %). In addition, the mixed substrates (Mix1 and Mix2) exhibited superior performance in enhancing larval protein (2.93 % and 14.52 %) and biomass yield (75.99 % and 101.07 %) compared to CM. The quantitative distribution of C and N nutrients indicated that Mix1 was functional in gas mitigation, while Mix2 in insect biomass accumulation. In conclusion, co-conversion of CM with VEG and DFI is critical for synergistic emission reduction and nutrient accumulation in the BSF system. • Animal and/or plant waste addition in chicken manure reduced GHG emission in the BSFL system. • Discarded fish organs had higher larvae yield and nutrient accumulation than other animal source waste. • A mixture of discarded vegetables, fish waste, and manure achieved the most N retention (95.71 %) and larval utilization ratio (43.52 %).