牛粪垫料再生系统温室气体排放及其对环境的影响

Research on greenhouse gas emissions of bedding recovery unit system and its impact on environment

为深入了解牛床垫料再生系统的工艺技术特点及对环境的影响程度,对垫料再生系统处理过程中物料特性和温室气体排放进行测试。结果表明:BRU系统的核心—发酵仓,其运行过程基本不改变物料的理化特性,随着出料流量的增大,仓内温度和CO_2、CH_4及N_2O的排放速率均显著降低,而相对湿度则明显提高;牛场粪污固液分离后经垫料再生系统处理,每1.00t牛粪的CO_2、CH_4、N_2O气体排放量分别为2.15~5.04kg、1.95~7.25g、27.09~58.11mg,1.00t鲜牛粪温室气体排放量相当于3.60kg CO_2当量。BRU系统和好氧发酵2种垫料生产系统的生命周期评价结果显示,BRU系统对环境影响远小于好氧发酵系统,仅为好氧发酵系统的9%,其环境友好性优于好氧发酵系统。

Bedding recovery unit（BRU）has been applied in some dairy farms,which not only reduces the cost of cattle farms,but also turns wastes into measure,thus improves the utilization efficiency of the solid cow manure resources.In order to understand the technical features and environmental impacts of the BRU system,the material characteristics and greenhouse gas emissions during system operation are investigated in this study.The results show that：The core of the BRU system,dry drum,doesn＇t change the physical and chemical properties of the manure,and with the increasing of discharge flow,the temperature in dry drum and the emission rates of CO2,CH4 and N2O are significantly reduced,while its relative humidity is significantly increased;After the process of solid-liquid separation and BRU system,one ton manure releases CO2,CH4 and N2O in the levels of 2.15-5.04 kg,1.95-7.25 g and 27.09-58.11 mg,respectively.The total greenhouse gas emission of the BRU system is 3.60 kg CO2 equivalent per ton fresh manure.Based on the result of the life cycle assessment,it is concluded that the environmental impact contribution of the BRU system is only9% of the aerobic composting system,which means the BRU system is more environment-friendly than the aerobic composting system.