生物质炭对城市污泥堆肥温室气体排放的影响

采用城市脱水污泥为研究对象,设置两种堆肥处理(试验组:添加水稻生物质炭;对照组:未添加生物质炭),考察污泥堆肥过程温室气体动态变化特征以及添加生物质炭的影响。结果表明:生物质炭能提高堆体温度、延长堆体高温期、加快堆体腐熟,减少堆体TC(总碳)、TOC(总有机碳)和氮素损失(特别是减少NH_4~+-N的损失),两种处理TC、TOC和TN(总氮)均呈显著性差异(P0.05)。CH_4排放主要集中在高温期和降温期,占CH_4总排放量的76.40%~82.40%,添加生物质炭会促进CH_4排放。CO_2排放主要集中在高温期和降温期,占排放总量的78.77%~78.83%,添加生物质炭能减少CO_2排放。超过84%的N_2O排放集中在腐熟期,添加生物质炭能减少堆肥过程中N_2O排放,试验组N_2O累积排放量比对照组低18.94%。添加生物质炭对污泥堆肥处理具有一定的温室气体减排作用,试验组与对照组CO_2排放当量(以干污泥计)分别为60.21 kg·t~(-1)和67.19 kg·t~(-1),添加生物质炭能减排温室气体10.39%。

Influences of biochar on greenhouse gas emissions during municipal sludge composting

Effects of biochar on greenhouse gas emissions were investigated by analyzing the dynamic characteristics of municipal sludge composting with and without biochar. The results showed that adding biochar increased the pile temperature, extended the altithermal temperature period, increased the decomposition rate of the composting pile, and reduced total carbon(TC), total organic carbon(TOC), and nitrogen loss(especially for NH₄⁺-N). The TC, TOC, and total nitrogen(TN) levels showed significant differences(P<0.05) between the two treatments. CH₄ emissions mainly occurred during the altithermal temperature period and cooling phase in both the treatments, accounting for 76.40%~82.40% of the total emissions. Biochar increased the CH₄ emissions, but this increase was non-significant compared with composting without biochar. CO₂ emissions were primarily concentrated in the altithermal temperature period and cooling phase, accounting for 78.77%~78.83% of the total CO₂ emissions. Unlike CH₄ emissions, biochar reduced CO₂ emissions. In addition, over 84% N₂O emissions occurred in the rotten period. Biochar significantly reduced the N₂O emissions, which were 18.94% lower than the treatment without biochar. CO₂ emission equivalents of dry sludge were estimated to be 60.21 and 67.19 kg·t^-1 in the with and without biochar treatments, respectively. The significant reduction in greenhouse gas emissions of 10.39% in the biochar treatment indicated that adding biochar reduced the greenhouse effect during sludge composting.