地下水循环井技术对含水层典型NAPL污染物的修复模拟

采用静态批试验分析苯和萘在均质中砂上的吸附特性,同时利用二维模拟槽分析其在地下水中的迁移特性并采用地下水循环井技术进行修复治理. 结果显示:苯和萘在均质中砂上的吸附符合线性等温吸附,萘的吸附系数为0.0075L/g,明显大于苯(0.0034L/g)；苯在横向和纵向的浓度锋面迁移距离均明显大于萘, 50d后,地下水中ρ(苯)、ρ(萘)的最高值和平均值分别为119.11、14.97mg/L和64.03、5.19mg/L；启动循环井修复,靠近循环井的地下水循环扰动大,气、水两相间的传质作用强,有机物被优先去除,逐渐形成一个以循环井为中心的锥形修复区域；累积曝气14h后,地下水中ρ(苯)趋于检测不出,但ρ(萘)存在明显拖尾现象,拖尾浓度达到1.82mg/L；各列单元苯衰减系数变幅较小,萘的衰减系数则存在两侧低、中间高的趋势,残留的萘基本上集中分布于远离循环井、模拟槽的两侧区域. 可见污染物的挥发性及其在地下水中的迁移性是影响循环井修复效果的主导因素,污染物挥发性越强,其迁移越快,循环井修复的效果越好. 

Remediation Simulation of Groundwater Circulation Well of NAPL Contaminated Aquifer

A series of batch experiments were carried out to study the adsorption property of benzene and naphthalene by the medium sand. A two-dimensional simulated sand box was set to investigate the mobility of benzene and naphthalene in the groundwater. A groundwater circulation well (GCW) was employed to remedy benzene and naphthalene contaminated aquifer. Experiment results demonstrated that:both of the adsorptions of benzene and naphthalene by the medium sand showed linear relationship, and the naphthalene adsorption coefficient was 0.0075L/g, which was higher than that of benzene, 0.0034L/g. Benzene mobility rate was faster than that of naphthalene in the groundwater in both vertical and longitudinal directions. The highest and average concentration of benzene and naphthalene were 119.11,4.97mg/L and 64.03,5.19mg/L in leakage for 50days, respectively. A cone-shaped influence area was gradually formed around GCW in which groundwater disturbance intensity. Contaminants mass transferred from the water phase into the air phase were extremely hard due to the strong disturbance, and directly resulted in contaminants preferential remove that existed near GCW. Benzene concentration was up to zero in 14h aeration, while naphthalene concentration remained at a high level that reached to 1.82mg/L. There was a small change of benzene attenuation coefficient for each column. In contrast, naphthalene attenuation coefficient showed different trends with higher ones near GCW and lower ones far from GCW. The lower attenuation coefficients simultaneously determined that the residual naphthalene distribution. Therefore, volatility and mobility of contaminants were dominating-factors on the removal efficiency, and they have positive effects on the removal efficiency.