危废填埋场导排层淤堵的时空分布特征

导排层淤堵导致的渗滤液水位过高是引发危险废物填埋场环境安全事故的主要原因之一,研究危险废物填埋场导排层淤堵规律,揭示其时空变化特征和主要影响因素具有重要的意义.本研究采用重庆某危险废物填埋场渗滤液原样作为导排流体,以卵石为导排颗粒,选择垂向Column装置模拟实际危险废物填埋场的淤堵特征和规律.对无反滤层装置的淤堵实验研究表明:时间上,导排层淤堵呈现出明显的阶段特征,初期(0~2 个月)孔隙度较为稳定,中期(3~4月)孔隙度缓慢下降,后期(5~6月)孔隙度急剧下降;空间上,越靠近入水口(0~10cm),淤堵越严重;时间越长不同高度处淤堵差异越明显.对不同反滤层装置淤堵的比较研究表明:反滤层的存在有利于控制淤堵物的产生,且土工布反滤层的效果好于细颗粒反滤层;反滤层存在条件下,导排系统的整体导排能力下降(60cm水头压力下的导排流量仅为无反滤层条件下的1/2).因此在导排层上方安置反滤层时需谨慎考虑.

Spatial and temporal characterization of drainage clogging in hazardous waste landfill

Build-up of leachate upon liner system due to failure of LCDS (leachate collectionand drainage system) often lead to various environmental accidents in hazardouswaste landfill. It is therefore significant to explore the mechanism and mainfactors of LCDS clogging in hazardous waste landfill. This study uses the original leachate from the hazardous waste landfill as drainage fluid, gravel as the drainage material, and selects vertical Column device to simulate the clogging role of drainage in actual hazardous waste landfill. The test study on non-clogging filtration layer of the device showed that: from the aspect of time, there are three distinct phases in terms of the development of drainage layer clogging, which are the beginning period of stable condition, and the metaphase of slowly clogging, and the final phase of sharp decline in porosity.From the aspect of space, the clogging were most serious at the inlet position, and it then decreased with the distance from inlet. In addition, the clogging extent is different among different height, and the difference become even more obvious as time. The experiment also indicates that the filter layer play a positive role to control the production of clogging, but a negative role to maintain its drainage capacity. With the presence of geotextile filter layer, the drainage flow are merely half of the flow without any filter layer. It is therefore suggested that filter layer should be installed above the drainage before careful consideration.