Effect of adding bamboo biochar into the compost at different dosages on greenhouse gas emissions was investigated by analyzing the dynamic characteristics of the process of municipal sludge composting with four different composts (S1:adding 2.5% bamboo biochar, S2:adding 5% bamboo biochar, S3:adding 10% bamboo biochar, CK:without bamboo biochar). The results showed that CH4 emissions mainly occurred during the heating period and the beginning of the altithermal period, accounting for 99.01%-99.81% of the total emissions. When the added bamboo biochar is less than 5%, CH4 emissions decrease with the increase in the amount of bamboo biochar. If it is more than 5%, CH4 emissions will clearly increase. CO2 emissions mainly occurred during the heating period and the altithermal period, accounting for 75.65%-86.58% of the total emissions. Adding bamboo biochar can reduce 3.37%-13.48% of the CO2 emissions but there is no significant difference between the treatments (P>0.05). N2O emissions mainly occurred during the heating period and the rotten period. Adding bamboo biochar can reduce the emissions of N2O; the more the amount of bamboo biochar, the less N2O emissions (P<0.05). The emission factors of CK, S1, S2, and S3 were 44.10, 37.57, 35.10, and 35.44 kg·t-1 of dry sludge, respectively. S1, S2, and S3 showed 14.81%-20.41% reduction in greenhouse gas emissions owing to the addition of bamboo biochar, indicating that bamboo biochar can reduce the carbon emissions in the process of sludge composting.
Keywords: bamboo biochar; compost; emission characteristics; greenhouse gas; municipal sludge.