垃圾填埋场排水层渗透性变化特征实验研究

An Experimental Research on Permeability Feature of Drainage Layer in Waste Sanitary Landfill

以室内模拟实验为技术手段,选用8种粒度成份的砂砾为排水层材料,研究了填埋场渗滤液水质及其变化规律对排水层渗透能力的影响,建立了反映排水层渗透性(k)与渗滤液水质(CODr)、排水层结构(avρgl.d10)和排水孔隙度间关系的淤堵模型,以及排水层渗透系数、排水孔隙度与有效粒径间的函数关系.结果表明:排水介质的有效粒径对排水层渗透系数和排水孔隙度的变化速率有重要影响;经过砂砾层的渗流后,渗滤液水质发生显著变化,pH值有所提高,COD,Ca2+,Mg2+,TVFA,总硬度,总碱度,NH4+-N和TSS,VSS等参数有不同程度的降低,且随渗流时间具有一致的变化趋势,水质参数与排水介质粒度成份无关;渗滤液中的化学作用、生物膜的生长、固体悬浮物的沉聚,在排水介质孔隙中生成了无机盐类沉聚物和生物膜等物质,这是降低排水层渗透能力的主要原因;排水介质颗粒大小与淤堵物的组成成份及相对含量无关.

By means of laboratory experiments, using eight kinds of granulometric composition sands and gravels as material of drainage layer, the effects of leachate water quality and its var- iation regulation on permeability behavior of drainage layer in waste sanitary landfill were dis- cussed. The clogging model between drainage layer permeability coefficient （ k ） and leachate water quality（CODr）, drainage layer fabric（ a,ρgl·d10） and drainage porosity. The function concerning drainage layer permeability coefficient, drainage porosity and effective particle size, were proposed. The results show that the effective particle size has an important influence on the change rate of permeability coefficient and drainage porosity, the leachate water quality changes greatly, the pH values increase to a certain extent, while COD, Ca^2＋ , Mg^2＋ , TVFA, total rigidity,total alkalinity, NH^4＋--N, TSS, VSS and so on, decrease in different extent and present similar change tendency with time, but the leachate water quality is irrelevant with the granulometric composition of drainage medium;the generation of mineral salts and biomembrane in drainage medium pore from chemical process of leachate, biomembrane growth and solid suspended sedimentation resulted in the decreasing of permeability; the components and their relative contents of the clogging matter are not relative to granulometric composition of the drainage medium particle size.