固化污泥对渗滤液中氟阻滞作用的数值分析

摘要

The solidified sludge as a new type of liner material should be at the bottom of municipal solid waste landfill site to prevent the contamination of the pollutant leakage.The hydrodynamic dispersion test was conducted to investigate the postponing effect of solidified sludge.It was very difficult to obtain hydrodynamic dispersion parameters of sludge solidified layer with low permeability by the existing column tests and methods.The flexible wall parameter was proposed and improved to solve the problem.Because of the high concentration and strong penetrating power, fluorine ion was chosen as the typical representative.The hydrodynamic dispersion parameters could be calculated by the breakthrough curve of fluorine ion.And then,the two dimentional definite method was used to analyze the transference scope and concentration distribution of fluorine ion in solidified sludge layer and surrounding in 60 years.The situation without solidified sludge layer had a contrast with the above.The results showed that the solidified sludge layer had an important postponing effect on the transference of fluorine ion.Because positive pollutants had weaker penetrating ability than negative ones.The solidified sludge also had a strong blocking effect on the positive pollutant such as heavy metals or other positive pollutants,which could further delay the pollution of landfill leachate.%固化污泥是一种新型填埋场底部防渗阻滞材料，为论证其防渗阻滞作用的有效性，需进行典型污染物的穿透试验，但由于固化污泥渗透性很低，采用常规土柱试验很难得到污染物透过其迁移时的相关参数。为解决该问题，用柔性壁渗透试验代替传统土柱试验。渗滤液中污染成分较多，取含量较高且较易穿透的污染物即氟离子作为典型污染物，首先进行穿透试验获得迁移参数，然后结合二维有限元法研究分析其在防渗阻滞层及周边岩土环境中60 a内的运动迁移范围、浓度分布情况，并对比分析未设防渗阻滞层的情况。研究表明，在填埋场底部设置固化污泥防渗层对于以氟为代表的阴性污染物有较好的延迟阻滞作用。由于阳性污染物的穿透能力较阴性污染物弱，因而固化污泥防渗层对重金属等阳性污染物也应具有较强的阻滞作用，从而能进一步延迟填埋场渗滤液对周边环境的污染。