基于Visual MODFLOW对PRB原位治理酸性矿井水模拟

发布时间：2018-02-28 16:23

本文关键词： 硫酸盐还原菌数值模拟 Fluent Visual Modflow 溶质运移灵敏度分析　出处：《安徽工程大学》2015年硕士论文　论文类型：学位论文

【摘要】：酸性矿井水污染问题受到广泛关注,其危害在于低pH值、含有重金属离子和高浓度硫酸盐等其他污染物质。若不加以处理,直接排放到环境中,一方面会污染地表水,使得地表水中的浮游生物、藻类、鱼类等生物大量死亡,破坏区域内稳定的生态系统,另一方面若渗透到地下含水层等,污染物的扩散范围广、影响时间长。对该类污染学者提出利用可渗透反应墙固定化硫酸盐还原菌原位进行处理。前期试验研究表明,研究所提出的可渗透反应墙固定化硫酸盐还原菌原位对处理酸性矿井水效果良好。但是仍需要对反应墙中的降解机理进行更进一步的研究,因此本研究考虑对可渗透反应墙建立数值模型,包括水流运动模型和溶质运移模型,模拟研究可渗透反应墙降解高浓度硫酸盐。本研究主要实验及模拟结果如下：(1)本研究选取了一种填充可渗透反应墙介质,该填充介质均匀混合了四种物质,分别为直径5mm陶粒和玉米芯(按1：1配比),适量污泥和硫酸盐还原菌。对构建的柱体系统进行试验,得到有效孔隙度为0.305,渗透系数为1.12mm/s,纵向弥散度αL=0.01m,吸附分配系数Kd=8.89×10-4L/g。(2)实验室搭建可渗透反应墙水槽系统来处理模拟酸性矿井水,填充介质选用上述材料。采用蠕动泵进水和溢流出水,模拟水力停留时间为24h,硫酸盐入料浓度在3000mg/L左右。流体进入填充介质后pH迅速升高至中性,适宜硫酸盐还原菌生长。槽体内玉米芯软化为硫酸盐还原菌提供碳源,溶液电导率值持续稳定在5500～6000us/cm。根据4、5、6和7号取样点硫酸盐浓度值,线性拟合得到硫酸盐还原菌的一阶反应速率λ1=0.03(1/d),λ2=0.003(1/d)。(3)采用Fluent软件对自组装可渗透反应墙槽体进行水力学模拟研究发现：流体在进入多孔介质材料时存在涡流现象,多孔介质的宏观平均流速与实际流速相差不大。槽体内多孔介质材料的边界流量因受粘滞阻力作用比中心流量小,溢流出口下端存在死水区。陶粒介质间流速较大,能达到进水流速的3-4倍。(4)通过Visual Modflow软件核心方程,修正得到新型可渗透反应墙固定化硫酸盐还原菌水流运动方程和溶质运移方程。对比没有可渗透反应墙系统与有该系统得到,前者会导致污染区域将会扩散至很大范围,达到稳定状态(污染范围及浓度不增不减)需要的时间比较长,后者则随着污染物质的排放,填充介质将有效并迅速吸附降解污染物,改善下游环境,达到原位治理的效果。软件模拟显示其浓度衰减变化趋势较快,不向周围地质环境扩散。(5)基于对水流运动方程和溶质运移方程的敏感性因子分析,引入灵敏度分析方法。本文以渗透系数K、吸附分配系数Kd,固定相一阶反应速率λ2和流动相一阶反应速率λ1这4个参数为研究对象,分析这4个参数的灵敏度,得到λ1对可渗透反应墙处理酸性矿井水模型的影响最小,而λ2、K和Kd的影响相对较大,λ2与其他3个参数相关性不大。这4个参数在其他基本参数不变的情况下,增幅10%时分别为63.77mg/L、94.66mg/L和97.09mg/L,增幅20%分别为61.11mg/L、88.23mg/L和90.77mg/L。参数在增幅10%和20%时,总灵敏度变幅为63.45mg/L和60.54mg/L。
[Abstract]:Acid mine water pollution problem has attracted widespread attention, its harm is low pH, high concentration of sulfate containing heavy metal ions and other pollutants. If not treated and discharged directly to the environment, on the one hand will surface water pollution, makes the surface water plankton, algae, fish and other creatures of death, destruction of the ecological system stability in the region, on the other hand, if the seepage into underground aquifers, diffusion of pollutants, the effect time is long. The permeable reactive barrier in situ immobilization of sulfate reducing bacteria in the treatment for the pollution of scholars. Preliminary experimental study shows that the proposed permeable reactive barrier immobilized sulfate reduction bacteria in situ of acid mine water treatment effect is good. But still need to make further research on the degradation mechanism of reaction wall, so the study on permeable wall should be considered anti establishment The numerical model includes water flow model and solute transport model, simulation study on permeable reactive barrier degradation of high concentration sulfate. This research is experimental and simulation results are as follows: (1) this study selected a filled permeable reactive barrier medium, the medium mixed four kinds of materials were 5mm in diameter and ceramsite corncob (1:1 ratio), the amount of sludge and sulfate reducing bacteria. To test the column system, effective porosity is 0.305, the coefficient of permeability is 1.12mm/s, longitudinal dispersion of alpha L=0.01m, adsorption distribution coefficient Kd= 8.89 * 10-4L/g. (2) constructed the permeable reactive barrier tank system to deal with simulated acid mine water the material selection, filling medium. Using a peristaltic pump inlet and overflow outlet, simulate the hydraulic retention time was 24h, the sulfate feeding concentration at about 3000mg/L. The fluid into the filling medium after pH. The speed is increased to neutral, suitable for sulfate reducing bacteria growth. The trough of corncob softening provided the source of carbon for sulfate reducing bacteria, solution conductivity remained steady at 5500 ~ 6000us/cm. according to 4,5,6 and No. 7 sampling points of sulfate concentration by first-order reaction rate lambda 1=0.03 SRB linear fitting (1/d), 2=0.003 1/d (lambda). (3) the use of Fluent software for hydraulic simulation study found that the permeable reactive barrier tank self-assembly: eddy current phenomenon in fluid into the porous medium material, the macro average velocity of flow in porous medium and the actual flow rate had little difference. The boundary flow of porous material trough due to viscous resistance than the center flow is small, there are water overflow outlet end. Medium ceramsite high velocity, inlet velocity can reach 3-4 times. (4) by Visual Modflow software core equation, the corrected model can reverse osmosis The wall should be immobilized sulfate reducing bacteria flow equation and solute transport equation. Compared to the non permeable reactive barrier system and the system, the former lead pollution area will spread to a large extent, to reach a steady state (the scope of pollution and the concentration decrease) it takes a long time, the latter with pollution discharge, filling medium will be effective and rapid adsorption and degradation of pollutants, improve the downstream environment, achieve in-situ treatment effect. Software simulation shows the concentration attenuation trend is fast, does not spread to the surrounding geological environment. (5) the sensitivity analysis of factors on the flow equation and solute transport equation based on using sensitivity analysis method. Based on the penetration K coefficient, partition coefficient Kd, the first-order reaction rate of stationary phase and mobile phase lambda 2 lambda 1 first-order reaction rate of these 4 parameters as the research object, analysis of the 4 parameters of the spirit Get a sensitivity, the permeable reactive barrier effect of acid mine water model of minimum 1, and lambda 2, effect of K and Kd is relatively large, lambda 2 and the other 3 parameters are not relevant. The 4 parameters in the same basic parameters, an increase of 10% respectively 63.77mg/L, 94.66mg/L and 97.09mg/L, an increase of 20% respectively 61.11mg/L, 88.23mg/L and 90.77mg/L. parameters in the growth of 10% and 20%, the total sensitivity range of 63.45mg/L and 60.54mg/L.

【学位授予单位】：安徽工程大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X751;X172

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