地层介质对垃圾渗滤液的pH缓冲性能研究

pH Buffering Capacity of Geological Media on Landfill Leachate

通过一维土柱穿透实验和静态实验,分别从空间和时间2方面研究了不同天然地层介质对垃圾渗滤液的pH缓冲性能.结果表明,细砂、粉砂和粘土的本底pH缓冲容量分别为79.9.pH-1mmol/kg、207.5.pH-1mmol/kg、456.4.pH-1mmol/kg.受垃圾渗滤液污染后,除细砂外,随着时间的延长、离污染源距离的减小,每种介质总的pH缓冲容量都逐渐减小;其中碳酸钙缓冲体系的缓冲容量均逐渐增大;硅酸盐、阳离子交换缓冲体系的缓冲容量无明显变化;铝、氧化铁缓冲体系的缓冲容量逐渐减少,但土壤铝缓冲体系的缓冲容量则呈现出先增大后减少的趋势.细砂各个缓冲体系的缓冲容量随时、空变化均呈现出略微增大的趋势.4种介质对渗滤液的pH缓冲能力的顺序是:细砂<粉砂<粘土<土壤.土壤、粘土对垃圾渗滤液有较好的pH缓冲性能,同时对渗滤液中各种污染物的迁移、扩散也有较好的控制作用.

The one-dimensional breakthrough soil column experiment and static experiment were constructed to investigate the spacial and temporal pH buffeting capacity of the four natural geological media. Experimental results indicate that the background pH buffering capacity of fine sand, silt sand and clay is 79.9·pH^-1 mmol/kg,207.5·pH^-1 mmol/kg,456.4·pH^-1 mmol/kg respectively. With the time going on and the distance closer to the leaching source, for each medium which is contaminated by the landfill leachate, the total pH buffering capacity decreases, the buffering capacity of calcium carbonate buffering system decreases, the buffering capacity of the silicate and cation exchange buffering system have no obivous changes, and the buffeting capacity of the aluminium and ferric oxide buffeting system also decrease, but the soil＇s buffeting capacity of aluminium buffering system increases at first and then decreases. The temporal and spaeial buffering capacity for each buffeting system of the fine sand all increase appreciably. The order of the pH buffering capacity of the geological media on landfall leachate is fine sand 〈 silt sand 〈 clay 〈 soil, The soil and clay have a good pH buffeting capacity on landfill leachate as well as the controlling effect of the pollutants＇ transferring and diffusion.