Fe0-PRB修复地下水硝酸盐污染数值模拟

基于地下水对流-弥散作用,采用数值分析方法,构建了GMS地下水渗流和硝酸盐污染物迁移三维耦合模型.在污染物迁移过程中,不考虑吸附降解和考虑吸附降解两种工况下,分析了污染物在地下水中的迁移特征.结果表明:地下水和土壤存在天然净化污染物的能力,但不显著,必须采取有效措施控制污染.以零价铁作为PRB墙体介质,并用GMS软件模拟Fe0-PRB修复地下水中硝酸盐的效果.PRB存在时能显著控制污染物的污染范围并降低污染物浓度.PRB厚度为4m时,污染物经过550d开始透过PRB墙,PRB运行10a后,1、2、3号观测井的浓度分别1.712,0.011,0.018mg/L,PRB下游污染羽拖尾明显;PRB厚度为6m时,污染物经过850d开始透过PRB墙,PRB运行10a后,1、2、3号观测井的浓度分别0.52,0.004,0.005mg/L,与4mPRB相比浓度分别降低69.6%、63.6%和72.2%,PRB下游污染羽拖尾仍存在但不明显.污染物迁移数值模拟是评价PRB修复污染地下水效果及确定PRB参数的重要手段.

Numerical simulation of Fe0-PRB in rehabilitating groundwater contaminated by nitrate

According to the theory of the advection-dispersion effect of groundwater, the coupled model of groundwater seepage and contaminant transport was established using GMS software. By numerical simulation method, the transport characteristics of the groundwater contaminant were analyzed. Under the two cases of sorption and dissolve or not, the contaminant laws were analyzed in the process of migration. The results showed that the groundwater and soil had natural ability of purifying contaminant, but it was not obvious. Zero-valence iron was choose as the PRB wall medium, the effects of decreasing nitrate concentration were simulated with GMS software by Fe0-PRB in rehabilitating groundwater contaminant. The pollution plume decreased significantly and pollution concentration reduced effectively. When the PRB thickness was 4meters, contaminant passed through the PRB wall after 550days. To the No.1, 2, 3observation well, the pollution concentration were 1.712, 0.011, 0.018mg/L respectively after PRB processed 10years. And there was a significant pollution plume tail under the PRB. When the thickness of PRB was added to 6meters, contaminant passed through the PRB wall after 850 days. The concentration of observation well was 0.52, 0.004, 0.005mg/L respectively after PRB processed 10 years, in the No.1, 2, 3. The pollution concentration have been reduced 9.6%, 63.6% and 72.2% respectively comparing with 4meters PRB. The pollution plume tail still existed but it was not significant. To the numerical simulation method, it was an important tool of evaluating the effect of PRB in rehabilitating groundwater pollution and defining the PRB parameters.