低碳氮比条件下猪粪堆肥氨气和温室气体排放

Emission Characteristics of Ammonia and Greenhouse Gas during the Low C/N Ratio Swine Manure Composting

针对养殖场粪便产生量大、外加碳源物质成本高,堆肥需要添加大量的碳源物质,并且猪粪堆肥实际生产过程中氨气(NH_3)和温室气体(GHG)排放数据缺乏的问题,开展了低碳氮比(C/N)条件下的猪粪堆肥试验。试验采用箱式堆肥法,使用Innova 1312对氨气(NH_3)、氧化亚氮(N_2O)、甲烷(CH_4)和二氧化碳(CO_2)气体进行24h在线连续监测。结果表明:堆肥箱体内日平均温度超过50℃的持续天数均超过10d,满足国家相关标准的无害化要求;经过31d的好氧发酵,每千克初始原料鲜重的NH_3、N_2O、CH_4和CO_2的累计排放分别为2.27、0.07、0.24、135.72g,NH_3的排放主要集中在堆肥第1周和翻堆后10d,分别占总排放的31.09%和36.15%,GHG排放主要集中在第4周,占总排放的30.9%;在不考虑CO_2时,N_2O是GHG的主要贡献气体,贡献率为72.02%。堆肥过程中物料气体(NH_3、N_2O、CH_4和CO_2)累计排放量均与p H值呈现良好的正相关(P<0.01)、与含水率和C/N呈现良好的负相关(P<0.01)。建议对猪粪堆肥过程中NH_3的控制应集中在堆肥第1周和翻堆后,GHG减排应重点关注堆肥后期N_2O的排放。

The animal farms produce large amount of manure, and the composting process of animal manure needs to supply external carbon source material, which adds the treatment cost. In addition, the available data about the gas emission during low C/N composting of pig manure are lack. Hence, the emission of NH3 （ammonia）, N2O （nitrous oxide）, CO2 （carbon dioxide） and CH4 （methane） during the composting of pig manure was monitored continuously using an Innova 1312 monitor. The results showed that the daily average temperature inside composing bin over 50℃ was more than 10 days, which could secure pathogen inactivation and meet the non-hazardous requirement of national standards. After 31d composting, cumulative emissions of NH3, N2O, CO2 and CH4 per kg initial matter were 2.27, 0.07, 135.72 and 0.24g, respectively. The NH3 emissions occurred mainly in the first week and 10 days after turning, which account for 30.02% and 36.15% of the total NH3 emission, respectively. Nevertheless, GHG （greenhouse gases） emissions focused on the fourth week, accounting for 30.9% of the total emissions. If CO2 was not considered, N2O was the main contributor to GHG, with a contribution rate of 72.02%. There was a positive correlation （P〈0.01） between the accumulated amount of gas emission （NH3, N2O, CH4 and CO2） and the pH value during composting, and a good negative correlation with water content and C/N ratio （P〈0.01）. Therefore, the control of NH3 during the composting of pig manure should be focused on the first week and after turning of the composting process, while GHG emission reduction should focus on the N2O emission during the later period of composting （the fifth week）.