不同质地土壤对填埋场渗滤液的吸收净化效能

用沙土、粘土和壤土为材料 ,研究不同质地土壤对填埋场渗滤液的吸收净化效能 .结果表明 ,不同质地土壤净化效能差异较大 ,壤土和粘土各处理第 1周内对 COD的去除率达到 90 %以上 ,对 NH₃^- N的去除率为 87%～97%之间 ,而沙土各处理对COD的去除率在 84%～89%之间 ,对 NH₃- N去除率在 45%～78%之间 .各处理对 COD和 NH₃^- N的去除率逐步下降 ,4周后有的呈波动反弹 .粘土对 P的去除效果最好 ,几乎全部吸收 .对金属的去除效果也以粘土和壤土较好 .不同质地土壤净化效能随土层厚度的增加而增强 ,栽植狗牙根能促进土壤对 COD、P、NH₃^- N以及金属等吸收与净化 ,对毒性的去除能力也增强 ,体现了植物对土壤净化系统的增效作用 .

The Purification Potentials of Different Soil with Different Depths to Leachate from Li Keng Landfill in Guangzhou City

Soil with different texture(sandy soil,clay soil and loamy soil)were used to attenuate leachate from Li Keng landfill in Guangzhou city.They were employed to pack columns of different depths of 0.3,0.5 and 1.0m,soil columns were respectively treated by growing Cynodon dactylon and not growing C.dactylon. Leachate was drained into the soil columns each day for 8 weeks.The percolated leachates were collected weekly and their properties were analyzed.It was revealed that the purification efficiency of all soil columns decreased as the soil depth decreased,growing plant(C.dactylon)could improve the efficiency.Clay soil and loamy soil had higher capacity to remove COD and ammonia,clay soil had the highest ability in absorption of P,and the metal contents of leachate percolated from the clay soil columns were lower than that of loamy soil.However,loamy soil had significantly higher ability to absorb metal in leachate,especially for heavy metals.Toxicity test of percolated from soil columns in the different stages indicated that the removal of toxicity of the same depth soil with different textures showed significantly difference(P<0 01),but that of the 1.0m columns with different textures displayed significantly difference(P<0 01).