表面活性剂强化曝气修复MTBE污染饱和砂土室内试验研究

发布时间：2018-01-14 10:00

本文关键词：表面活性剂强化曝气修复MTBE污染饱和砂土室内试验研究　出处：《东南大学》2015年硕士论文　论文类型：学位论文

【摘要】：地下水原位曝气是一种经济、有效的饱和带挥发性有机物污染修复技术,但常规曝气条件下受污染物特性及场地地质条件限制,导致曝气影响范围小、污染物去除效果不佳。因此,开展实用有效的强化曝气修复方法机理与效果研究具有重要的科学和工程意义。本文以国家自然科学基金项目(41330641,41272311)为依托,针对挥发性有机物甲基叔丁基醚(MTBE)污染饱和砂土,基于地下水曝气修复物理化学机制及一维与二维模型试验,对十二烷基苯磺酸钠(SDBS)表面活性剂强化曝气修复机理、气相运动规律与修复效果进行了系统的研究。取得了以下主要研究成果：1) 通过表面活性剂强化曝气修复的物理化学机理试验,研究了地下水pH值及盐度对SDBS溶液表面张力影响以及SDBS对MTBE的增溶与解吸附作用规律。结果表明,当SDBS浓度低于临界胶束浓度时,表面张力随溶液pH值增大略有升高;在较低盐度时(小于15‰),SDBS溶液的表面张力随盐度增大明显减小；SDBS浓度较低时,对于有机污染物MTBE的增溶和解吸附作用都不明显,当SDBS浓度分别达到200 mg/L和500 mg/L后其增溶和解吸附特性才开始发挥作用。2) 通过一维与二维室内模型试验,对表面活性剂强化地下水曝气过程气相运动规律包括压力流量关系、气相饱和度、气流形态、影响半径、通道数目等进行了系统研究。结果表明,表面活性剂的引入降低了最小曝气压力；相同曝气压力下泡沫化表面活性剂曝气流量较常规曝气和表面活性剂预饱和曝气小；表面活性剂的引入能显著增大曝气过程中的气相饱和度和影响半径,气流通道数量也有一定程度增加,并且以上强化效果粗颗粒砂土(2.0-4.0mm)优于细颗粒砂土(0.5-1.0mm)；表面活性剂引入对气流形态基本没有影响,但2.0-4.0 mm砂土中气泡的尺寸有所减小,且出现较多微型气泡；表面活性剂溶液预饱和方式气相运动规律较泡沫化表面活性剂方式好,但后者更适于现场应用。3) 通过表面活性剂SDBS强化曝气修复MTBE污染饱和砂土室内模型试验,研究了污染物的去除规律与效果。结果表明,一维和二维模型试验条件下,泡沫化表面活性剂曝气较常规曝气对污染物的去除速率均有明显提高;表面活性剂强化修复效果粗颗粒砂土(2.0-4.0 mm)优于细颗粒砂土(0.5-1.0 mm)；一维模型试验条件下,无论何种曝气方式模型柱从底部到顶部各点的集总参数KLa均逐渐减小,泡沫化SDBS曝气情况下相同位置表面活性剂影响区KLa值高于常规曝气法；在二维模型试验条件下,由于单井曝气影响范围有限以及空气注入对地下水的扰动作用,可引起MTBE污染物向周围未污染区的扩散。4) 基于多相流理论,考虑表面活性剂强化作用,利用TOUGH2软件对污染物苯的泄漏迁移与地下水污染曝气修复过程进行了数值模拟。研究表明,表面张力的减小将增大曝气影响半径、气相饱和度及污染物去除速率,使得污染物苯的去除率得到显著提高。
[Abstract]:In situ groundwater aeration is a kind of economy, saturated with volatile organic compounds pollution remediation technology, but the conventional aeration conditions restricted pollutant characteristics and geological conditions of the site, resulting in aeration influence area, the pollutant removal effect. Therefore, it has important scientific and engineering significance to research the mechanism and effect of strengthening the practical and effective method to repair the aeration in this paper the project of National Natural Science Fund (4133064141272311) as the basis, the volatile organic compounds of methyl tert butyl ether (MTBE) contamination of saturated sand, groundwater aeration repair the physical and chemical mechanism and 1D and 2D model test based on twelve sodium dodecyl benzene sulfonate (SDBS) surfactant enhanced air sparging mechanism, gas motion and the repair effect was studied. The main results are as follows: 1) by surfactant enhanced air sparging Test the physical and chemical mechanism, study the adsorption law of groundwater pH value and salinity on surface tension of SDBS solution and SDBS MTBE on the solubilization and solution. The results show that when the SDBS concentration is lower than the critical micelle concentration, surface tension with the pH value of the solution increased slightly increased; in the low salinity (less than 15 per thousand) the surface tension of SDBS solution, with the increase of salinity decreases; when the SDBS concentration is relatively low, is not obvious for the solubilization of organic pollutants MTBE settlement adsorption, when the concentration of SDBS was 200 mg/L and 500 mg/L after the solubilization and desorption properties began to play a role in.2) by 1D and 2D model test, movement the law of groundwater aeration process including gas pressure flow relationship enhancement of surfactant, gas saturation, airflow pattern, radius of influence, the number of channels were studied. The results show that the surface active agent The introduction of reduced minimum aeration pressure; pressure activated aeration bubbles of the same surfactant aeration volume than conventional aeration and surfactant saturated aeration; introducing surfactant can significantly increase the aeration process in gas phase saturation and radius of influence, the number of flow channel also increased to some degree, and the above strengthening effect coarse sand (2.0-4.0mm) is better than that of fine sand (0.5-1.0mm); the introduction of surfactant has no effect on the air bubbles form, but 2.0-4.0 mm in sand size decreased, and the more micro bubble; surfactant solution saturated vapor movement is active mode of bubble surface agent mode, but the latter more suitable for field application of.3) by surfactant SDBS aeration MTBE contaminated sand model test, studied the pollutant removal efficiency and the law Results. The results show that a two-dimensional model under the experimental conditions, the activity of bubble surface aeration agent than conventional aeration on pollutant removal rate were significantly improved; surfactant enhanced remediation effect of coarse sand (2.0-4.0 mm) is better than that of fine sand (0.5-1.0 mm); test condition of one-dimensional model, no matter what kind of aeration model column from the bottom to the top of the lumped parameter KLa are reduced gradually. The effect of SDBS foam under the same aeration position of surfactant KLa value is higher than that of the conventional aeration method; in the 2D model under the experimental conditions, due to the limited scope of the single well aeration and air injection on groundwater disturbance, pollutants can cause MTBE to spread around.4 not polluted area) based on the multiphase flow theory, considering the effect of surfactant enhanced migration and underground water pollution, leakage of pollutants benzene exposure by using TOUGH2 software Numerical simulation of gas recovery process shows that decreasing the surface tension will increase the influence radius of aeration, gas phase saturation and pollutant removal rate, and increase the removal rate of benzene.

【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU441

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