污泥堆肥及其土地利用全过程的温室气体与氨气排放特征

目前我国污泥堆肥及其土地利用全过程的温室气体(N2O、CH4)与氨气(NH3)排放数据极其缺乏,难以满足温室气体减排和氮素保存的需求.本研究通过原位观测,首次开展污泥堆肥及其土地利用全过程温室气体和氨气排放特征的研究.结果表明,基于机械翻堆条垛(turning windrow,TW)工艺的全过程温室气体排放因子(eCO2/干污泥,196.21 kg·t-1)是基于强制通风+机械翻堆条垛(aerated turning pile,ATP)工艺的1.61倍.N2O主要来自土地利用过程,CH4主要来自堆肥过程.ATP工艺的温室气体排放当量(eCO2/干污泥,12.47 kg·t-1)远低于TW工艺(eCO2/干污泥,86.84 kg·t-1).TW工艺的氨气排放因子(NH3/干污泥,6.86 kg·t-1)略高于ATP工艺(NH3/干污泥,6.63 kg·t-1).NH3是全过程最主要的N素损失形式,其中TW和ATP堆肥工艺因NH3排放造成的氮素损失相当,均约占堆料TN损失量的30%.而N2O和CH4带来的N、C元素的损失可以忽略不计.这些结果表明ATP是一种环境友好的污泥堆肥工艺.

Emissions of Greenhouse Gas and Ammonia from the Full Process of Sewage Sludge Composting and Land Application of Compost

There is a great uncertainty of greenhouse gas (GHG) reduction and nitrogen conservation from the full process of sludge composting and land application of compost in China due to the lack of emission data of GHG such as N₂O and CH₄ and ammonia (NH₃). The purpose of this study is to get emission characteristics of GHGs and NH₃ from the full process with on-site observation. Results showed that the total GHG emission factor from full process of the turning windrow (TW) system (eCO₂/dry sludge, 196.21 kg·t^-1) was 1.61 times higher of that from the ATP system. Among the full process, N₂O was mostly from the land application of compost, whereas CH₄ mainly resulted from the sludge composting. In the sludge composting of ATP, the GHG emission equivalence of the ATP (eCO₂/dry sludge, 12.47 kg·t^-1) was much lower than that of the TW (eCO₂/dry sludge, 86.84 kg·t^-1). The total NH₃ emission factor of the TW (NH₃/dry sludge, 6.86 kg·t^-1) was slightly higher than that of the ATP (NH₃/dry sludge, 6.63 kg·t^-1). NH₃ was the major contributor of nitrogen loss in the full process. During the composting, the nitrogen loss as NH₃ from both TW and ATP was nearly the same as 30% of TN loss from raw materials, and the N and C loss caused by N₂O and CH₄ were negligible. These results clearly showed that the ATP was a kind of environmentally friendly composting technology.