老龄渗滤液氨氮在地下咸水条件下变迁过程研究

垃圾进入填埋场后将持续近百年的降解,其产生的渗滤液对周边环境造成了长时间污染。海滨填埋场作为沿海地区生活垃圾的一种重要处理方式,在垃圾长时间稳定化过程中,老龄渗滤液泄漏引发的地下环境问题具有一定的独特性。文章以老龄渗滤液氨氮为指标,通过构建砂箱实验来研究老龄渗滤液在咸水条件下的迁移转化过程。结果表明:在地下咸水环境中,渗滤液氨氮较易沿水流水平方向扩散,扩散速度随空间推移不断降低,而垂直方向运移速度相对较慢;同时老龄渗滤液的碳物质的迁移速度低于氨氮的迁移速率,因此在离污染源较近的位置,碳物质浓度随运移时间浓度增加较大;而对于老龄渗滤液中的其他氮则比氨氮运移速度要慢。对于浓度较低的老龄渗滤液,其在地下环境中污染范围相对较小,如果污染源得到控制,其地下环境中具有良好的自我净化能力。

Natural Attenuation Process of NH3-N in Aged Leachate Leakage Under the Salt Water Condition

Landfill is predominated MSW disposal process in China,and most of landfills located in the shoaly land without proper liner system due to the lack of the construction fee in the coastal region.The mitigation of leachate under the saltwater condition is something special due to the seawater intrusion.NH4+-N in leachate is in a high concentration in the entire landfill stabilization process,and understanding the mitigation of NH4+-N in the salt water condition will be important for the pollution control from landfill.Sand-box model facility was applied to simulate the migration and transportation process of NH4+-N from aged leachate,which was designed based on a working Landfill in Shanghai.It was found that NH3-N preferred to diffuse in horizontally direction,compared to that in the vertical direction.The diffusion rate decreased as the distance extended.The transportation process of carbon substances in the aged leachate is lower than that of N substances,and more carbon substances accumulated in the area near to the leaking point.The diffusion rate of the other N types in aged leachate,such as NO3-,NO2-,is also lower than that of NH4+-N.Therefore,NH4+-N could be one of the dictators for the leachate leakage from landfill.