The effects of different moisture contents on greenhouse gas (GHG) emissions frompig manure (PM) digested by
black soldier fly larvae (BSFL) as well as the accompanying changes of nitrogen and carbon contents in gaseous
emissions and residues were studied. A mixture of PMand corncob at the ratio of 2.2:1 was prepared with a moisture content of 45%. Then, distilled water was added to adjust the moisture contents of the mixture to 55%, 65%, 75% and 85%, respectively. The prepared mixtures were digested by BSFL for eight days. The results indicated that BSFL could reduce CH4, N2O and NH3 emissions respectively by 72.63–99.99%, 99.68%–99.91% and 82.30–89.92%, compared with conventional composting, while CO2 emissions increased potentially due to BSFL metabolism. With increasing moisture content, the cumulative CH4 emissions increased, while cumulative NH3 emissions peaked at 55% moisture content and then decreased. Interestingly, the tendency of total cumulative CO2 emissions was consistent with that of the total weight of BSFL. The total GHG emissions were about only 1% those from of traditional composting at the optimum moisture content (75%), which was the most favorable for the growth of BSFL. The nitrogen and carbon contents of BSFL content in all treatments accounted for 1.03%– 12.67% and 0.25%–4.68% of the initial contents in the rawmaterials, respectively.Moreover, the residues retained 71.12%–90.58% carbon and 67.91%–80.39% nitrogen of the initial raw materials. Overall, our results suggest that BSFL treatment is an environment-friendly alternative for decreasing CH4, N2O andNH3 emissions as well as reducing global warming potential (GWP). |
