不同用量竹炭对污泥堆肥过程温室气体排放的影响

采用城市污泥为堆肥基质,设置4个堆肥处理,分别为添加2.5%竹炭(S1,占污泥的质量分数)、添加5%竹炭(S2)、添加10%竹炭(S3)和未添加竹碳(CK),研究城市污泥堆肥过程中温室气体的动态变化特征及添加不同用量竹炭的影响.结果表明,CH_4排放主要在升温期和高温前期,占排放总量的99.01%~99.81%.当竹炭添加量低于5%时,CH_4排放量随添加量的增加而减少;竹炭添加量高于5%时,其排放量又明显增加.CO_2排放集中在升温期和高温期,占排放总量的75.65%~86.58%;添加竹炭可减少3.37%~13.48%的CO_2排放,但处理间不存在显著差异(P0.05).N_2O排放集中在升温期和降温腐熟期,添加竹炭能减少16.37%~41.52%的N_2O排放,竹炭添加量越多,减排效果越好(P0.05).S1、S2和S3处理CO_2排放当量(以干污泥计)分别为37.57、35.10和35.44 kg·t~(-1),比CK处理减少了14.81%~20.41%.添加竹炭能降低污泥堆肥温室气体排放,其中,以S2处理的减排效果较为显著.

Effects of Bamboo Biochar on Greenhouse Gas Emissions During the Municipal Sludge Composting Process

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.