非正规垃圾填埋场包气带介质的污染物阻滞能力研究

非正规垃圾填埋场已成为地下水的潜在污染源,给城市供水安全带来了极大风险。以北京某非正规垃圾填埋场的3种典型包气带介质为研究对象,以Br-为示踪剂,采取土柱实验和数值模拟相结合的方法,通过对场区3种典型包气带介质饱和与非饱和状态下的Br-迁移速率的比较,探讨包气带介质对污染物的阻滞能力。结果表明,Br-在不同包气带介质饱和状态下的迁移速率为中砂>细砂>砂质粉土,这可能与不同介质中粉粒和粘粒的含量有关,同时介质的有机质含量也会影响Br-的迁移速率,但前者因素占了主导作用;在Br-迁移过程中,不同包气带介质的含水量是影响其迁移速率的主要因素,若能合理控制场区的地下水位,使得包气带介质长期处于非饱和状态,将会大大延缓垃圾渗滤液中污染物向地下水迁移;针对特定的非正规垃圾填埋场,可采取抽水等措施,控制场区的细砂和砂质粉土层处于非饱和状态,充分利用包气带介质在非饱和状态时较强的污染物阻滞能力,阻隔或延缓垃圾渗滤液中的污染物进入地下水中。

Study on the pollutant retarded capability of different media in aerated zone of informal landfill

The informal landfill was the potential pollution source of groundwater which had brought great risk to security of municipal water supply.In this paper the author selected three typical porous media from a Beijing informal landfill to study their retarded capability to pollutant.The column experiments were conducted with Br-as tracer,and the migration velocity of Br-in saturated and unsaturated media was determined and compared.Results showed that the migration velocity of Br-in three saturated media followed the order of medium sand>fine sand>sandy silt,which was possible determined by the content of silt and clay particles in media;the organic matters in media also had little effect on Br-migration velocity.The moisture content was the key factor that influencing the Br-migration.Controlling the level of underground water in a reasonable state so as to make the media in the unsaturated condition would greatly decrease the Br-migration velocity.So the measures,such as water pumping,should be taken to the certain informal landfill to retard pollutant migrate into groundwater by decreasing moisture content of aerated zone.