我国南方某填埋场作业面氨气释放和扩散规律分析

为了研究氨气对填埋场周边环境的影响,采用现场静态箱试验测试了杭州市某填埋场作业面氨气的释放速率.把静态箱方法得到的氨气释放通量作为Calpuff模型及高斯模型释放源强,对填埋场中氨气的扩散进行了模拟,并将两种方法得出的氨气扩散范围进行了比较.结果表明:研究区由于气温等原因,氨气释放通量8月最强,1月最弱,两者相差达4倍.Calpuff模拟结果表明源强越大,最终扩散距离越远,且氨气浓度在距作业面300~600 m处达到最大.高斯模型模拟结果表明,该地区大气稳定度较稳定条件下(E级)更有利于氨气的扩散;风速越大,氨气在扩散过程中越易被稀释,最终扩散影响距离越短.大气稳定度为E级条件下,Calpuff模型得出影响距离是高斯模型结果的1.16~1.69倍,高斯模型相对于Calpuff模型低估了该地区氨气扩散的能力.该现场试验和模型模拟的结果对填埋场臭气控制具有重要的指导意义.

Analysis of ammonia emission and diffusion at a working face on a municipal solid waste landfill in south of China

The static chamber was used to monitor the flux of ammonia emitted from the working face of a landfill in the south of China. Ammonia dispersion was determined by the Gaussian model and the Calpuff model, on the basis of the flux data obtained from the static chamber. The evaluation results obtained from the two models were compared. The results show that the maximum and minimum ammonia fluxes were observed in August 2016 and January 2017, respectively. The ammonia flux observed in August 2016 can be 4 times greater than that obtained in January 2017 due to the significantly difference in temperature. The results of the Calpuff model indicate that the diffusion distance increases with the increase of ammonia source intensity. The maximum concentration of ammonia was 300~600 m away from the working face. The results of the Gaussian model also indicate that ammonia diffusion tends to happen under the slightly stable conditions (e.g., grade E). The ammonia diffusion distance decreases with the increase of wind speed. The results of the impact distance evaluated by Calpuff model is 1.16~1.69 times greater than that obtained by the Gaussian model under the condition of stability grade E. The Gaussian model may underestimate ammonia diffusion distance. The results of field experiments and model simulations can be useful for the odour gas control for landfills.