密闭反应器堆肥技术氨减排潜力研究

Reducing ammonia emission via reactor composting technology

堆肥是将粪尿肥料化处理循环利用于土壤的重要技术,但堆肥过程中约有50%的氮素以氨气形态挥发,不仅降低了堆肥产品的养分价值,更诱发了雾霾天气发生,严重污染大气环境。因此,减少堆肥过程的氨排放对于提高有机肥品质、降低堆肥过程产生的环境影响具有重要意义。针对实际生产中不同堆肥技术氨排放量不明,氨减排潜力及经济效益缺乏的问题,本研究通过生产规模试验,定量分析了条垛式堆肥和密闭反应器堆肥过程中的氨排放量、氨回收效率及其影响因素,并对不同堆肥技术进行了经济效益分析。结果表明,与条垛式堆肥相比,密闭反应器堆肥可减少氨挥发61.1%(P<0.01),结合氨气洗涤回收技术(洗气塔)可实现82.3%(P<0.01)的氨减排;氨气回收效率随吸收时间显著降低,吸收液温度和铵根离子浓度是影响氨回收效率的关键因素。密闭反应器堆肥技术粪便处理成本(116.9元∙t^(-1))高于传统条垛式堆肥处理成本(87.4元∙t^(-1));然而,以条垛式堆肥为对照,密闭反应器堆肥及反应器结合洗气塔技术每减少1 kg氨气的成本为22.0元和16.5元,低于欧盟氨减排成本。综上所述,密闭反应器堆肥可显著降低堆肥过程中的氨挥发,与洗气塔结合使用可将堆肥过程中排放的大部分氨气进行回收,是一种高效、可行且具有较大氨减排潜力的堆肥技术。

Composting is an important way to recycle manure into soil as an organic fertilizer or conditioner.However,approximately 50%of the total nitrogen in manure is lost in the form of ammonia during composting,and this loss has an environmental impact on human health.Therefore,to reduce ammonia emission during the composting process to improve the quality of organic fertilizer and reduce its impact on the environment,this study intends to explore a composting method with low ammonia emissions,economy,and high efficiency.In this study,we used quantitative data from full-scale composting systems(windrow composting and reactor composting)in an industrial sheep farm to compare the ammonia emissions from traditional windrow composting and reactor composting,and quantitatively analyzed the ammonia recovery efficiency and influencing factors of gaseous scrubbers,as well as the economic benefits of windrow composting,reactor composting,and reactor composting combined with scrubbers.The results showed that windrow composting and reactor composting emitted 193 g NH_(3) and 75 g NH_(3) for 1 ton dry compost materials,respectively.Compared with traditional windrow composting,reactor composting reduced ammonia emissions by 61.1%(P<0.01),which was further increased to 82.3%(P<0.01)when the reactor was composted with a gaseous scrubber.The ammonia recovery rate decreased with an increase in the absorption time.The result showed that ammonia recovery rate of the scrubber was 82.0%(P<0.05)when the solution was fresh and gradually decreased to 39.8%(P<0.05)after 5 h.In addition,the ammonia recovery rate was significantly influenced by the temperature and NH_(4)^(+)-N concentration of the absorption solution.For instance,the ammonia recovery rate decreased from approximately 80%to 20%when the temperature of the solution increased from 30℃to 40℃to 50℃.In terms of the cost of composting,reactor composting needed 116.9 Yuan per ton of manure,which was higher than that of traditional windrow composting(87.4 Yuan per ton of manure).The ammonia reduction costs of reactor composting and the scrubber were 22.0 Yuan per kg NH_(3) and 16.5 Yuan per kg NH_(3),respectively,when compared with windrow composting,which was lower than the value of the European Union.In addition,reactor composting had a higher efficiency than windrow composting,with composting cycles of 8 and 45 days for reactor composting and windrow composting,respectively.In conclusion,reactor composting can significantly reduce ammonia emissions,and most of the ammonia can be recovered when combined with a gaseous scrubber.The pH,NH_(4)^(+)-N concentration,and temperature of the scrubber solution significantly affected the ammonia recovery rate.Improving the ammonia recovery rate and operational stability of the gas washing tower is a direction for future research to develop ammonia emission reduction technology.Consequently,reactor composting combined with a gaseous scrubber is recommended,which is an efficient and feasible composting technology with great potential for reducing ammonia emission.