零价铁PRB修复2,4-DNT污染地下水模拟研究

研究了零价铁(Fe0)作为PRB墙体介质材料去除地下水环境中2,4-二硝基甲苯(2,4-DNT)可行性.通过室内试验研究地下水环境中Fe0去除水相2,4-DNT效果以及降解动力学参数,并结合一假设地下水受2,4-DNT污染的场地,采用Visual Modflow模拟Fe0墙体材料PRB(Fe0-PRB)修复地下水中2,4-DNT降解效果并评价其可行性.结果表明:在模拟过程中,PRB能有效控制并减少污染羽面积,降低污染浓度;污染4a后,污染地下水的2,4-DNT总质量约1.46×104kg,可推知PRB修复达标耗用Fe0材料为8.76×104kg;渗透系数增大导致地下水速率增大,2,4-DNT与墙体Fe0材料接触时间不充分,污染物污染下游地下水,同时也加速PRB上游污染羽面积减少.因此,结合数值模拟是有效的评价PRB介质材料修复地下水污染效果及确定PRB参数的重要手段之一.

Simulation on remediation of 2,4-DNT in groundwater by zero-valent iron

The removal effect of aqueous-phase 2,4-DNT by zero-valent iron and the degradation kinetics parameters were investigated by laboratory tests. Visual Modflow was used to simulate the removal effect of 2,4-DNT in groundwater by using permeable reactive barrier (PRB) technology with zero-valent iron(ZVI-Fe0) as reactive material and estimate its feasibility at a hypothetical site. The results showed that the pollution plume was effectively controlled and reduced by the technology. 8.76×104 kg ZVI should be consumed to remove 1.46×104kg 2,4-DNT after four years’ contamination. The simulation also showed that as the increasing of the hydraulic conductivity, more pollutant flowed downstream due to the insufficiency contact of 2,4-DNT and ZVI. Numerical simulation is a effective approach to evaluate the remediation efficiency of PRB and determine the parameters of PRB.