摘要
曝气法(Air sparging,AS)已经成为修复地下水、土壤有机污染的重要技术,与数值模拟技术相结合可优化修复条件。文章利用TMVOC多相流模型研究了地下水位处LNAPL层的迁移转化,并通过情景模拟比较曝气法对污染修复的贡献率。只考虑地下水水流的对流-弥散作用时,目标污染物苯并没有得到彻底去除,只是通过下边界流出。60 d苯的质量损失率仅为1.79%;而连续曝气30 d后苯的去除率就可达到31.4%,最终脉冲曝气苯的损失率为44.8%。增大曝气量能提高气相渗透率及气相-液相接触面积,扩大污染物修复范围;当超过某一值(12 m3/h),其增量对污染物修复影响甚微。当曝气点位于低渗透岩层下方时,低渗透岩层会阻碍气流的垂向迁移,位于低渗透岩层上方的污染物很难得到除去。曝气法适用于溶解、挥发性较好的污染物。
Air sparging（AS） has become an important technique for remediating organic contaminated groundwater and soil.Combined with numerical simulations,design of AS remediation approaches can be optimized.TMVOC,a multiphase flow simulator,was used to study the migration and transformation of LNAPL at the groundwater table.Contribution of AS to pollution remediation was investigated through numerical simulation.When only considering the groundwater convection-dispersion effect,benzene was not remediated and it left the modeling area through downstream boundary.After 60 d,mass loss of benzene was only 1.79% without AS;remediation efficiency can reach 31.4% after continuous 30 d AS,and final removal rate of benzene was 44.8% when pulse AS was over.Increased AS rate can increase gas permeability and gas-liquid contact area,which lead to enhancement of remediation scope.When the rate exceeded a certain value of 12 m3/h,effect of rate increment on remediation was minimal.When AS point was located below a low permeability formation and pollutants were located above the formation,the pollution will be difficult to be removed,because low permeability rock can impede the vertical migration of gas.AS is more efficient for dissolved and volatile contaminants.
出处
《环境科学与技术》
CAS
CSCD
北大核心
2012年第2期19-24,共6页
Environmental Science & Technology
基金
国家自然科学基金(40873076)
