垃圾渗滤液中COD在饱水带迁移的模拟研究

Simulating Migration of COD from Landfill Leachate in Saturated Water Zone

[目的]模拟研究垃圾渗滤液中COD在饱水土层中的迁移变化特征。[方法]以广州市李坑垃圾填埋场为例,选取渗滤液中COD为特征污染物,采集排水沟两侧饱水带土层,通过试验确定吸附、降解与弥散系数,构建了饱水带COD迁移数学模型。考虑不同场龄渗滤液中COD的浓度差异,分别以不同场龄渗滤液的COD浓度为边界条件,利用模型数值解预测COD饱水土层中的迁移变化特征,并基于地下水质标准,对COD环境影响进行了评价。[结果]COD在饱水带土层中的衰减主要发生在离排水沟10m的范围内(衰减83%)。老年、中年、年轻垃圾渗滤液将地下水污染为Ⅲ类水的最远距离分别为29.2、37.2和47.9m,将地下水污染为Ⅴ类水的最远距离分别为27.1、33.2和44.1m。[结论]为填埋场区周围地下水污染防治提供了理论依据。

[Objective]The aim was to simulate the migration of COD from landfill leachate in saturated water zone.[Method]COD from Likeng landfill leachate in Guangzhou was selected as the characteristic contaminant.Soil samples of the saturated water zone on both sides of drain were collected.Relevant parameters of the model were obtained by experiments,and the migration model of COD was established.Considering the differences of different field ages in leachate concentrations of COD,different concentrations were taken as boundary conditions to make the COD environmental impact assessment based on groundwater quality standards.[Result]The COD decay occurs mainly within 10 m away from the drain（attenuated by 83%）.The most long-distances that old,middle-aged and young landfill leachate polluted the groundwater into the Class Ⅲ water and the Class Ⅴ water were 29.2,37.2,47.9 m and 27.1,33.2,44.1 m,respectively.[Conclusion]The research provides theoretical basis for groundwater antipollution around landfill.