冬季侧窗通风猪舍氨气和温室气体排放特征

Ammonia and greenhouse gas emissions from enclosed pig house with side-vent ventilation in winter season

冬季猪舍通风管理方式影响猪舍内的环境质量以及污染物的排放,为确定改造后猪舍侧窗负压通风系统6阶段管理对冬季舍内环境质量以及氨气和温室气体排放的影响,对舍内温度、湿度和空气流速等环境指标进行了测定,采用水分平衡方程确定了不同通风阶段猪舍的通风率,利用INNOVA 1412多气体分析仪-连续采样测试技术,对冬季猪舍NH3、N2O、CH4和CO2的排放进行了测定,确定了不同通风量条件下氨气和温室气体的排放率。结果表明,冬季侧窗通风密闭式育肥猪舍平均温度为13.7℃,湿度为69.7%,舍内最大温度与湿度差值分别为3.2℃和39.6%,平均通风率为6207 m^3·h^-1(单头生猪通风量:24.9 m^3·h^-1),舍内平均空气流速为0.28 m·s-1,满足了育肥猪生长的要求;冬季试验猪舍中NH3平均浓度范围在8.42~15.63 mg·m^-3,CO2平均浓度范围保持在2509~5303 mg·m^-3之间,CH4浓度变化在1.11~5.90 mg·m^-3,可满足冬季育肥猪生长的需求;单头生猪NH3、CO2和CH4的平均排放率分别为250.0 mg·h^-1、79.9 g·h^-1、57.7 mg·h^-1,单头生猪累积日排放量分别为6.0 g·d^-1、1.92 kg·d^-1和1.39 g·d^-1,试验期间没有监测到N2O的排放;采用的6级通风管理模式显著影响NH3、CO2的平均排放率,对CH4的排放影响不显著。

This study evaluates the impact of a side-vent(SV)negative pressure ventilation system of six-stage management on the environmental quality and emissions of ammonia(NH3)and greenhouse gases(GHGs)in an enclosed pig house during winter.Temperature,relative humidity,and air velocity data were obtained inside and outside of the pig house,and the barn ventilation rates were measured using the moisture(H2O)balance equation at inlets and outlets at six stages.In addition,air samples were obtained from the inlets and outlets of the pig house to measure GHG concentrations using a custom-made multiplexer gas sampling system equipped with an INNOVA 1412 monitor.The analysis showed that the average air temperature and relative humidity inside the pig house were 13.7℃and 69.7%,respectively.The difference between maximum and minimum temperature and relative humidity was 3.2℃and 39.6%in pig house.The moisture balance ventilation rate of the pig house was 6207 m^3·h^-1,whereas the ventilation rate of a single pig was 24.9 m^3·h^-1.The air velocity inside the pig house was 0.28 m·s-1.The gas concentrations inside the pig house in winter were 8.42~15.63 mg·m^-3 for NH3,2509~5303 mg·m^-3 for carbon dioxide(CO2),and 1.11~5.90 mg·m^-3 for methane(CH4).The average emission rates of a single pig based on hourly means were 250.0 mg·h^-1 for NH3,79.9 g·h^-1 for CO2,and 57.7 mg·h^-1 for CH4,whereas the cumulative daily emissions were 6.0 g·d^-1,1.92 kg·d^-1 and 1.39 g·d^-1,respectively.No emission of nitrous oxide(N2O)was observed.Therefore,ventilation management has a significant impact on the emissions of NH3 and CO2.No significant difference in CH4 emissions are noted among the different ventilation stages.