Decomposition and Characteristics of Pig Manure–Sawdust Mixture Composted by Black Soldier Fly (Hermetia illucens L.) Larvae

Abstract

Interest in using insects to treat surplus manure without environmental impacts is growing. Black soldier fly (BSF, Hermetia illucens L.) larvae show promising potential for transforming organic waste. Moreover, they can breed and grow in organic waste. In addition, using bulking agents in organic waste is effective in optimizing composting process like volume density. In this study, we focused on the decomposition and characteristics of a pig manure–sawdust mixture post-treatment at different growth stages of BSF larvae. For the experiments, 4 kg of pig manure was mixed with 1 kg of sawdust and then treated with 0.5 kg of either second instars (Group 1) or third instars (Group 2) of BSF larvae. The two experimental groups were randomly assigned three replicates per group. For Experiment 1, the results showed that the decomposition efficacy of the second-instar BSF larvae was better than that of the third-instar BSF larvae. In Experiment 2, the two BSF larval groups did not improve the characteristics, including pH, moisture, ADF, NDF, and hemicelluloses of the pig manure–sawdust mixture. These findings provide a scientific basis for improving the decomposition efficacy of second-instar BSF larvae reared on a pig manure–sawdust mixture. BSF larvae did not affect pH and moisture in treated pig manure–sawdust during composting.