基于流固耦合的垃圾污染物运移模型及模拟

基于流固耦合和溶质运移理论,建立了垃圾渗滤液有机污染物运移耦合模型,用SOM法对所建的模型进行数值求解,利用该数值模型对垃圾渗滤液在地下水中迁移行为进行模拟,预测了污染物浓度的时空分布特征,对耦合、非耦合模拟结果结合实际监测数据进行对比,并对污染晕的大小、分布范围进行了数值模拟分析.结果表明,耦合模型模拟的污染物浓度变化趋势与监测值基本吻合,从而验证了耦合模型的可靠性和实用性.     

垃圾渗滤液污染物在土壤中迁移规律试验及模拟

为全面系统地研究垃圾渗滤液迁移规律,科学地分析污染物运移规律和预测污染物浓度分布情况,通过垃圾渗滤液的动态淋溶试验,研究了垃圾渗滤液主要污染物包括有机物(CODcr,)、Cl-、SO42-、总硬度等在土壤水环境中的运移机理,试验结果表明迁移速度最快和最慢的分别为Cl-与有机物(CODCr);并对建立的一维数学模型求解表明·模型曲线与COD试验曲线较好的吻合,说明所建数学模型模拟有机污染物的有效性.     

某垃圾填埋场氯化物运移的不确定性分析

实际污染物的运移浓度和污染范围受水文地质参数的数值不确定性和空间分布随机性的影响,常规数值模型不能有效地模拟污染物运移。分别将水文地质参数的数值不确定性和空间分布随机性考虑到常规数值模型中,以某垃圾填埋场氯化物渗滤液运移为例,计算了该垃圾填埋场1940-2000年60 a氯化物的运移浓度和运移范围变化情况。以第43年计算结果为例,结果表明:考虑了不确定性因素的随机模型多次模拟结果平均值与实际值吻合更好,说明随机模拟法较常规数值模拟更具有优势;当自变量变化范围为20%时,考虑数值不确定性的随机模型计算结果比同等条件下考虑空间随机性模型计算结果的平均偏差值和平均方差值大25.04%和26.95%; 60 a内氯化物浓度和污染范围的计算结果不确定性大小存在变化,两种不确定性模型计算得到的结果大小变化趋势一致,即呈现出先增大后减少的趋势。通过不确定性分析可以掌握该地区氯化物浓度的变化范围,在划分不同浓度置信区间的基础上进行风险分析,为地下水的污染防治提供数据参考。     

垃圾渗滤液污染物层状砂箱模拟试验

通过自制的二维砂箱模拟垃圾渗滤液污染物在层状含水层中的运移,得出了渗滤液中Cl-,SO2-4、总硬度(CaCO2)在地下环境中的迁移和时空分布规律,该实验模型较好地反映了层状层中污染物渗漏的基本特征,对预测、控制渗滤液污染地下水提供了一种试验方法.     

基于GMS的云南德厚水库下游废弃砒霜厂地下水溶质运移模拟

地下水溶质运移模拟是找出污染物迁移规律、确定污染范围及污染物浓度分布的重要手段,可以为合理开发地下水资源、优化设计地下水开采方案及地下水污染修复提供定量依据。在分析德厚水库咪哩河流域裂隙岩溶含水层的水力性质和污染物运移特征的基础上,运用GMS软件建立地下水流场模型和溶质运移模型,对裂隙岩溶水的流场和污染物进行了数值研究,判断出了污染源分布及污染羽扩展范围,分析了砒霜厂污染物运移对水库建设的影响。     

基于降雨条件的垃圾污染物释放规律实验研究

为全面系统地研究垃圾污染物释放规律,科学地分析污染物运移规律和预测污染物浓度分布情况。根据阜新市的实际降雨状况,通过垃圾柱的动态淋溶试验,研究了垃圾渗滤液主要污染物:有机物(CODCr)、Cl-、SO42-、总硬度等释放机理。试验结果表明:(CODCr)的衰减曲线方程为:c=9 792.7e-0.103 t,在垃圾中释放速度最快和最慢的分别为Cl-与有机物(CODCr),该试验成果将为阜新垃圾填埋场污染防治提供一定的理论依据。     

垃圾填埋场渗滤液特征及其治理

介绍了垃圾渗滤液对水体产生污染的实例，通过讨论和总结揭示了垃圾填埋场渗滤液特征，即垃圾渗滤液污染物浓度高、持续时间长、流量极不均匀、水质变化大。根据垃圾渗滤液特征提出了治理垃圾渗滤液的有效措施。     

冬小麦生长与土壤-植物-大气连续体水热运移的耦合研究Ⅰ:模型

本文开展了冬小麦生长与土壤-植物-大气连续体(简称SPAC)水热运移的耦合研究，建立了可以同时动态模拟冬小麦生长过程与SPAC水热运移过程的动力学模型-WheatSPAC模型。模型中，采用有限元差分格式进行土壤水热运移的数值模拟；采用双层模型进行冠层水热运移的模拟；采用改进的Feddes根系吸水模型及负指数分布形式的根系密度模型，实现土壤与冠层的耦合；通过生育阶段、干物质生产、干物质分配等过程的模拟，建立了冬小麦生长的机理性模型；通过对冬小麦叶面积指数、株高、根系分布的模拟，实现冬小麦生长与SPAC水热运移的耦合。     

考虑固结、扩散和降解耦合作用下污染物在黏土中的运移解析模型

为了研究在固结、扩散和降解耦合作用下污染物通过黏土衬垫的运移规律,建立了有机物在其中的运移模型,并获得了零通量和零浓度下边界条件的解析解。本文模型计算结果与数值分析程序Comsol获得的结果较为一致。结果表明有机污染物的降解作用能有效地减少其在黏土衬垫中的浓度和底部通量。针对2 m黏土衬垫,半衰期为10年工况的底部通量仅为半衰期100年的24%;半衰期为10年的工况底部浓度分别是无降解和半衰期为100年的11.78%和15.8%。本文解析模型相对简单,可用于验证复杂数值模型,以及评价扩散、固结和降解耦合作用对污染物运移的影响等。     

地下水数值模拟研究与应用进展

工农业的快速发展,使得大量污染物随着降雨径流入渗进入地下水,对地下水资源产生了严重威胁。由于对地下水污染物的实时监测具有一定难度和较高的经济成本,地下水模拟软件应运而生。系统分析了GMS、FEFLOW、Visual MODFLOW、Visual groundwater、MT3DMS、TOUGH2等地下水模拟软件的结构、模型求解方法、功能及优缺点等,总结了软件在水流、地下水水位和污染物运移数值模拟的应用进展。最后,进行了展望,提出地下水数值模拟软件与3S技术集成、与人工神经网络等系统预测方法结合、气候变化模型与多相模型及地表水-地下水模型等耦合开发以及结构优化等发展趋势。以期为地下水动力学和污染物运移模拟及海绵城市建设提供参考。     

Modeling Leachate Contamination and Remediation of Groundwater at a Landfill Site

Leachate contamination of an aquifer from a landfill site was simulated using the groundwater flow and transport model SUTRA developed by the U.S. Geological Survey. The model calibration was performed by spatially adjusting the hydraulic conductivity in order to capture the measured hydraulic head spatial variation and then by adjusting the dispersivity and porosity match the measured chloride plume. Based on the simulations it was found that without remedial action the contaminants in the existing leachate plume would remain above acceptable regulatory concentration levels for longer than 2010. The chloride loading of an adjacent stream exceeds acceptable levels under Ontario's Reasonable Use Guidelines. Simulations indicate that a pump-and-treat system using additional two purge wells could remediate the leachate contamination within approximately 10 years from now.     

Enhancing waste decomposition and methane production in simulated landfill using combined anaerobic reactors.

The design of leachate recirculation to enhance municipal solid waste decomposition, methane production and microbial activities was taken into account in this study by using the combined anaerobic reactors of a simulated high organic content landfill reactor and a stabilized fixed film anaerobic reactor. The latter aimed to treat high strength leachate from the simulated landfill reactor before recirculation back to the former reactor. The results showed the possibility to apply this technique to high organic waste landfill where rapid and accumulative acids formed in the leachate were removed and treated by a fixed film anaerobic reactor. In addition, the treated leachate when circulated back to the simulated bioreactor landfill helps accelerate waste decomposition and methane production by providing buffer capacity as well as diluting organic content in the leachate to achieve the favourable conditions for acidogen and methanogen, respectively, to rapidly enter into the methanogenesis phase.     

Identification of Groundwater Contamination Sources Using Meshfree RPCM Simulation and Particle Swarm Optimization

In this study, a simulation-optimization (SO) model is presented by coupling a meshfree based simulator using radial point collocation method (RPCM) and particle swarm optimization (PSO) as optimizer to identify the unknown groundwater contaminant sources from the measured/simulated contaminant concentration data in the aquifer. To demonstrate the approach, two case studies have been presented. The first example is a hypothetical case which simulates the contaminant releases from several disposal sites in an aquifer during four years release period. The second case considered is a field study where leaching of contaminant, during their storage, from disposal sites at several locations in the aquifer leads to contamination of the groundwater. The goal in both cases was to reconstruct the contaminant release history from the disposal sites and their magnitudes from the given historical concentration data at a few observation wells in the aquifer. It was observed that the source identification model could reconstruct the release histories from the waste disposal sites in both the cases accurately. This study demonstrated that PSO based optimization model with a meshfree flow and transport simulator can be effectively used for groundwater contaminant source identification problems.     

A NEW NUMERICAL METHOD FOR GROUNDWATER FIOW AND SOLUTE TRANSPORT USING VELOCITY FIELD

A new numerical method for groundwater flow analysis was introduced to estimate simultaneously velocity vectors and water pressure head. The method could be employed to handle the vertical flow under variably saturated conditions and for horizontal flow as well. The method allows for better estimation of velocities at the element nodes which can be used as direct input to transport models. The advection-dispersion process was treated by the Eulerian-Lagrangian approach with particle tracking technique using the velocities at FEM nodes. The method was verified with the classical one dimensional model and applied to simulate contaminant transport process through a slurry wall as a barrier to prevent leachate pollution from a sanitary landfill.     

A NEW NUMERICAL METHOD FOR GROUNDWATER FlOW AND SOLUTE TRANSPORT USING VELOCITY FIELD

A new numerical method for groundwater flow analysis was introduced to estimate simultaneously velocity vectors and water pressure head. The method could be employed to handle the vertical flow under variably saturated conditions and for horizontal flow as well. The method allows for better estimation of velocities at the element nodes which can be used as direct input to transport models. The advection-dispersion process was treated by the Eulerian-Lagrangian approach with particle tracking technique using the velocities at FEM nodes. The method was verified with the classical one dimensional model and applied to simulate contaminant transport process through a slurry wall as a barrier to prevent leachate pollution from a sanitary landfill.     

模拟渗滤液和压力对压实黏土衬垫渗透性影响的试验研究

衬垫材料防渗性能的好坏是决定填埋场有效性的关键,而渗滤液和受力条件是影响衬垫渗透系数的重要因素。从填埋场衬垫实际渗滤液和受力状态分析出发,选择CaCl2溶液为模拟渗滤液,研究模拟渗滤液和竖向压力对压实黏土衬垫渗透系数的影响。结果表明:当以模拟渗滤液代替水进行试验时,渗透系数增加约2倍;当竖向压力增大2倍时(从200 kPa增至400 kPa),渗透系数减小约1个数量级。双因素方差分析表明:相对于竖向压力,模拟渗滤液对渗透系数的影响较小;在衬垫设计与评价时,考虑竖向应力的影响是非常必要的。     

Degradation of recalcitrant organic contaminants by solar photocatalysis.

Biological pre-treated landfill leachates of Djebel Chakir contains some macromolecular organic substances that are resistant to biological degradation. The aim of the present work is to assess the feasibility of removing refractory organic pollutants in biological pre-treated landfill leachate by solar photocatalyse process. Leachate pollutant contents are studied to assess their contribution to leachate pollution and their treatability by solar photocatalyse process. Phenol is chosen as model of pollutants, to evaluate its removal and the efficiency of the photocatalytic system. The experiments were carried out in suspended photocatalytic reactor, using TiO2 Degussa P25, under sunlight illumination (UV-A: 15-31 W/cm2). Under optimum operational conditions, applied to single reactant (phenol), the system presents a TOC removal of 90% (the degradation follows a first-order kinetic). Based on the TOC removal, the results shows that the degradation of biological pre-treated leachate follows a zero-order kinetic. After 5 h of sunlight exposure, 74% of COT is removed. The TOC removal is the best without any correction of the pH and at the TiO2 concentration of 2.5 g/L. The photocatalytic degradation of organic contaminants as well as the formation and disappearance of the by-products were followed by GC/MS. The solar photocatalysis processes induce several modifications of the matrix leading to more biodegradable forms: all the remaining and new compounds generated after the biological pre-treatment of leachate are degraded and other types of organics appear, mainly carboxylic acid, aliphatic hydrocarbons and phtalic acids.     

南水北调工程北京市受水区非正规垃圾填埋场控高水位研究

近年来北京市平原区地下水污染范围已呈现从城区向郊区延伸、从浅层向深层扩散的趋势.地下水污染源调查评价研究表明,垃圾填埋堆放场是造成地下水污染的主要污染源之一.以北京市南水北调工程受水区内存在被浸泡可能的27个非正规垃圾填埋场为研究对象,在垃圾填埋场基本特征的基础上,对典型非正规垃圾填埋场进行水文地质勘察和水、土、垃圾样...