利用生物渗透性反应墙修复地下水Cr(VI)污染的数值模拟

为降低地下水中的Cr (VI)污染,选择生物反应过程中常见的电子供体(糖蜜)和连二亚硫酸盐分别作为渗透性反应墙(PRB)的反应材料和生物杀灭剂,以期能促进生化反应还原Cr (VI)的同时还能阻止生物堵塞效应.采用PFLOTRAN软件模拟以糖蜜为反应材料和连二亚硫酸盐为生物杀灭剂的PRB修复非均质含水层中重金属污染的生物化学反应过程.结果表明,该PRB技术能有效降低Cr (VI)浓度至0.1mg/L以下;提高生物杀灭剂的注入浓度,注入速率以及降低糖蜜初始浓度可避免生物堵塞效应,达到修复Cr (VI)污染与提高PRB使用寿命的双重目标.研究成果可为类似场地地下水重金属污染修复的最优设计方案提供决策依据.

Numerical simulation of groundwater remediation of hexavalent chromium contaminated site by the bio-permeable reactive barrier

In order to reduce Cr(VI) in groundwater, the common electron donor (molasses) and dithionite in the biological reaction process were selected as the reactant and biocide of PRB, for the purpose of promoting the biochemical reaction to reduce Cr(VI) and preventing the bioclogging effect. PFLOTRAN software was adopted to simulate the biochemical reaction process of PRB with molasses as the reaction material and dithionite as the biocide to remove heavy metal pollutant in the heterogeneous aquifer. The results show that the PRB technique can reduce the Cr(VI) concentration to below 0.1mg/L; the bioclogging effect can be avoided by designing the concentration of biocide, injection rate and initial concentration of molasses, in order to achieve the dual goal of removing Cr(VI) and improving the longevity of PRB. The results of research can provide a decision-making basis for the optimal design plan of heavy metal contamination remediation in the groundwater for similar sites.