地下水环境修复工艺优化设计研究进展

介绍了3种应用相对广泛的地下水修复技术,即抽出处理法、可渗透反应墙和自然降解法,重点回顾和评述了地下水修复系统优化设计的方法,探讨了结合健康风险评价体系和不确定性研究的地下水修复系统优化设计,旨在为地下水资源的修复和管理提供理论依据。     

基于可变环境标准约束的地下水修复优化模型

提出了一个集成的模拟-优化方法用于设计不确定条件下受石油污染的地下水最优修复方法。该方法有以下4个优点:1通过建立的代理回归模型给修复策略(井的抽注速率)和修复性能(污染物浓度)之间提供了直接且响应迅速的桥梁;2减轻优化过程中产生的计算工作量;3提供一个能够揭示满足环境质量标准程度大小的满意度水平;4防止过于乐观或悲观的优化策略的制定。将该方法应用于位于安徽省某发电厂受石油污染的地下水含水层区域,用来识别最佳的修复策略。结果表明:在较宽松的、对修复效果影响不是很大的环境标准或者较长的修复周期条件下,大多数抽注修复井的抽注速率将会减小,伸缩指数的增加对修复优化结果并没有产生严重影响。     

A Multiobjective Optimisation Model for Groundwater Remediation Design at Petroleum Contaminated Sites

This study proposes a fuzzy multi-objective model for groundwater remediation in petroleum-contaminated aquifers. The optimisation system is designed based on the PAT technology, and includes two objectives (i.e. total pumping rate and average post-remedial contaminant concentration). The relationship between pumping rates and contamination concentrations at all monitoring wells after remediation are determined by a proxy model, which integrates simulation, inference, and optimisation technologies and is composed of intercept, linear, interactive, and quadratic options. Fuzzy algorithms are used to solve the formulated multi-objective optimisation problem to find optimal solutions. The model is then applied to a petroleum-contaminated aquifer in western Canada. The trade-off and λ analyses of the results indicate that the fuzzy multi-objective model has great potential in groundwater remediation applications as it can: (1) provide reliable groundwater remediation strategies, (2) reduce computational costs in the optimization processes, and (3) balance the trade-off between remediation costs and remediation outcomes.     

In situ source zone sediment mixing coupled to groundwater biostimulation to enhance phenol natural attenuation

Phenol is an industrially key compound that has a wide range of applications and also one of the most commonly found toxic pollutants in wastewaters and groundwater. This paper demonstrates the applicability of in situ remediation at a deactivated industrial site using source zone excavation and sediment mixing associated with nutrients delivery into groundwater. Sediment excavation and mixing displaced the entrapped source zone enhancing mass transfer into groundwater and contaminant bioavailability. A nutrient solution prepared with nitrate, phosphate, sodium hydroxide and hydrogen peroxide was continuously delivered into groundwater to stimulate biodegradation and restrict plume migration. The observed correlation between phenol-dependent Enterobacteriaceae concentrations throughout the remediation time frame supported circumstantial evidence of biodegradation. Phenol concentration in groundwater (up to 1,300 mg/L) was reduced >99% after 5 months following remediation and remained under the established site specific target level (4 mg/L). Nitrate and phosphate concentrations returned to background concentrations levels at the end of the remediation. Overall, the proposed in situ remediation scheme was effective to remediate this particular aquifer contaminated with phenol for over 20 years.     

Artificial Neural Network and Grey Wolf Optimizer Based Surrogate Simulation-Optimization Model for Groundwater Remediation

We herein propose a simulation-optimization model for groundwater remediation, using PAT (pump and treat), by coupling artificial neural network (ANN) with the grey wolf optimizer (GWO). The input and output datasets to train and validate the ANN model are generated by repetitively simulating the groundwater flow and solute transport processes using the analytic element method (AEM) and random walk particle tracking (RWPT). The input dataset is the different realization of the pumping strategy and output dataset are hydraulic head and contaminant concentration at predefined locations. The ANN model is used to approximate the flow and transport processes of two unconfined aquifer case studies. The performance evaluation of the ANN model showed that the value of mean squared error (MSE) is close to zero and the value of the correlation coefficient (R) is close to 0.99. These results certainly depict high accuracy of the ANN model in approximating the AEM-RWPT model. Further, the ANN model is coupled with the GWO and it is used for remediation design using PAT. A comparison of the results of the ANN-GWO model with solutions of ANN-PSO (ANN-Particle Swarm Optimization) and ANN-DE (ANN-Differential Evolution) models illustrates the better stability and convergence behaviour of the proposed methodology for groundwater remediation.

     

纳米零价铁用于地下水污染修复时存在的问题与对策

介绍了纳米零价铁(Nanoscale Zero-Valent Iron,NZVI))用于地下水污染修复时存在的问题及改进技术。NZVI可以去除水体中的各种卤代烃(主要是氯代烃)以及Cr、Pb、As等重金属,但NZVI在水体中会由于团聚、沉淀和钝化等而降低其修复效率。将超声波技术和添加微生物方法与NZVI技术进行协同,以及对NZVI进行固体负载和表面改性是解决NZVI修复地下水时存在问题的有效途径。今后,探讨地下复杂环境因素对应用NZVI进行地下水修复的影响,以及改进NZVI水污染修复技术是利用NZVI修复地下水污染的重要研究方向。     

双井抽灌处理地下水污染的回收率理论公式

采用抽出处理法修复地下水污染场地需要有一定的回收率,以达到充分净化的目标。当地下水存在侧向径流时,抽出处理法的回收率不一定能够达到100%。对于"一抽一灌"双井单元,井孔扰动下的地下水稳定流场可分为内循环区、外循环区和非循环区,某些情况下内循环区或外循环区不存在。由内循环区的水动力学特性得到回收率的理论公式和变化曲线。回收率取决于地下水侧向径流的方向和相对强度,随抽水流量的增大而增加。回收率公式可用于抽出处理法的井孔设计,地下水污染物的目标去除率越高,所需要的回收率越大。针对北京某试验场,应用该方法进行了回收率优化评估。     

地下水硝酸盐原位修复技术研究进展

介绍了地下水硝酸盐原位修复技术,对目前使用较多的渗透反应墙与注射井引入工程实例加以说明。指出原位修复技术不同的适用条件,同时提出浅层地下水系统本身的自然净化机制对大范围的地下水硝酸盐的防治更具经济优势。     

铬污染土壤动态浸出特征及对地下水影响的模拟

以原长沙铬盐厂污染土壤为研究对象,利用动态淋溶试验,研究不同淋溶模式下土壤六价铬[Cr(VI)]淋出特征及其对地下水的影响。结果显示,淋溶流速会影响土柱中Cr(VI)达到解吸稳定所需要的时间,即在连续淋溶模式的高、中、低3种流速条件下,达到平衡的时间分别为1 、4 、15 d,而间歇淋溶模式的Cr(VI)浸出效率略低于连续淋溶模式,这主要是受到土壤中孔隙水更新效率的控制。利用COMSOL Multiphysics?5.6构建试验中Cr(VI)迁移的模型,计算连续、间歇2种淋溶模式下6种不同情景中Cr(VI)的质量浓度变化及累积浸出质量,结合模型计算与柱实验结果分析发现,当土壤中Cr(VI)质量分数达到二类用地筛选值（5.7 mg/kg）后,淋出液中Cr(VI)质量浓度仍为地下水V类水标准（0.1 mg/L）,此时淋出液中Cr(VI)质量浓度仍对地下水环境造成威胁;同一时间段内,间歇淋溶柱高流速情景下有最小淋出率（33.67 %）,连续淋溶柱高流速情景有最大浸出率（83.99 %）。研究表明,在场地地下水污染治理过程中,需要考虑土壤修复标准对地下水的影响,即水土共治。研究成果可为重金属污染场地修复工程提供参考。     

Defining Groundwater Remediation Objectives with Cost-benefit Analysis: Does It Work?

The use of cost-benefit analysis (CBA) is increasingly advocated as a tool for supporting water planning decisions, in particular at the local (site) level. This paper questions whether CBA is relevant for evaluating groundwater management options at the scale of large regional aquifers. It highlights the difficulties related to estimating the cost of groundwater protection and remediation measures at the regional (water body) level. It also identifies methodological challenges in estimating the economic value of the benefits of groundwater protection. The paper is based on an original case study carried out on the upper Rhine valley aquifer in eastern France. The methodology deployed combines engineering approaches to assess the cost of remediation and economic methods (contingent valuation) to estimate the benefits associated with groundwater improvement.     

铀矿区地下水污染治理与修复技术研究进展

在总结近年来国内外铀矿区地下水污染治理与修复技术最新进展和已有成果的基础上,评述物理化学修复 技术,生物修复技术及可渗透反应墙技术基本理论、实际案例和未来发展前景。当前铀矿区地下水污染的原位治 理与修复技术以实验室研究为主,缺乏对实际铀矿区地下水污染治理与修复的工程实践,如何结合实际铀矿区水 文地质条件和污染特征开发绿色、高效、低碳的治理与修复技术,是未来铀矿区地下水污染治理修复的重要发展 方向。     

Integration of Optimal Dynamic Control and Neural Network for Groundwater Quality Management

This study integrates an artificial neural network (ANN) and constrained differential dynamic programming (CDDP) to search for optimal solutions to a nonlinear time-varying groundwater remediation-planning problem. The proposed model (ANN-CDDP) determines optimal dynamic pumping schemes to minimize operating costs and meet water quality requirements. The model uses two embedded ANNs, including groundwater flow and contaminant transport models, as transition functions to predict groundwater levels and contaminant concentrations under time-varying pumping. Results demonstrate that ANN-CDDP is a simplified management model that requires considerably less computation time to solve a fine mesh problem. For example, the ANN-CDDP computing time for a case involving 364 nodes is 1/26.5 that of the conventional optimization model.     

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。     

Water Quality Zoning Using Probabilistic Support Vector Machines and Self-Organizing Maps

Water quality zoning is an important step for studying and evaluating surface and groundwater quality variations with time and space. It can also provide important information for developing efficient water quality management strategies. Most common methods for water quality zoning do not consider the uncertainties associated with water resources systems. Also, these methods only categorize the water quality monitoring stations into some classes based on existing water quality but do not provide any information about the quality of water which is categorized in a class. In this paper, a new methodology for probabilistic water quality zoning is developed which utilizes the capabilities of Probabilistic Support Vector Machines (PSVMs) and Fuzzy Inference System (FIS). The required data for training the PSVM is generated by using the FIS in a Monte Carlo Analysis. The trained PSVM-based water quality index provides the probabilities of belonging quality of water to different water quality classes. The applicability of the proposed methodology is investigated by applying it to two surface and groundwater resources systems in Iran. Also, for more evaluating the efficiency of the methodology, the results are compared with those obtained from two clustering techniques, namely Fuzzy Clustering Technique (FCT) and Self-Organizing Map (SOM). The results of surface and ground water quality zoning are depicted in maps by utilizing the Geographic Information System (GIS).     

Optimal Groundwater Remediation Under Uncertainty Using Multi-objective Optimization

A methodology is developed for optimal remediation of groundwater aquifers under hydraulic conductivity uncertainty. A multi-objective management method based on a pump-and-treat remediation technology, is proposed. The pumping rates and well locations are the decision variables and two objectives are chosen: minimization of contaminated groundwater in the aquifer and minimization of remediation cost. A Monte Carlo simulation method is used to cope with hydraulic conductivity uncertainty. A number of equally probable realizations of hydraulic conductivity are created and a Pareto front is obtained using a modified multi-objective Genetic Algorithm. A penalty function is utilized to maintain the algebraic sum of pumping and recharging rates equal to zero. Since Monte Carlo simulations are CPU time consuming, a method is proposed to identify the few significant realizations which have an effect on the optimal solution (critical realizations). A Pareto front with an assigned probability is derived, so that the decision maker can make decisions with specified reliability. In a case study with 100 realizations, only 11 realizations were found critical and need be considered. The remaining 89 realizations consistently obtain low ranks for all designs considered and do not affect decisions at 95% reliability level. Thus these realizations need not be considered which implies a 89% savings in computer time. The designs obtained using the critical realizations, retain a similar reliability for new realizations not considered in the design process.     

Cost efficiency of subsurface remediation using soil vapor extraction and groundwater extraction

The groundwater pollution due to volatile organochlorines like trichloroethylene and tetrachloroethylene has been a great environmental issue in Japan. Thc nation wide survey revealed on the basis of up to fifty-nine thousand samples collected until 1995 that 1.5% for trichloroethylene and 2.3% for tetrachloroethylene cannot meet the drinking water standard. In order to repair subsurface pollution and to establish the integrated procedure for cost-benefit remediation measure, physical remediation technologies of soil vapor extraction and groundwater extraction were applied to a study site contaminated with trichloroethylene. The results showed that the trichloroethylene amounts of 472 kg by soil vapor extraction and 1764 kg by groundwater extraction were removed during three-year operation. In addition experience with both technologies has demonstrated that the soil vapor extraction has been successful in removing 1 kg hr^-1 of trichloroethylene at the initial stage of remediation, which shows one order as high as the groundwater extraction. However, the removal rate due to soil vapor extraction declines much earlier than groundwater extraction, and consequently the removal rates of both technologies develop inversely with the progress of remediation. Such remediation behavior of technologies raised the relative cost for soil vapor extraction 15 times as high as groundwater extraction.     

Importance Analysis of Groundwater Remediation Systems

This paper aims to investigate the importance levels of the components in two groundwater remediation systems and examine the impact of each component on the whole system. Four measures are introduced including structural importance (SI), Birnbaum importance (BI), criticality importance (CI), and modification importance (MI). In the first system, four measures are simply applied on the components importance analysis. In the second one, operational time, components number and component position changes are considered. It is found that different measures may lead to variations in importance levels even for the same system mainly due to the definitions and algorithms of the measures; importance level would be reduced with the increase in the number of the identical components used in parallel. In general, SI just depends on system structure, BI and CI are not significantly affected by failure rate except when the component and the changing component are in the same part, and MI is sensitive to modification of failure. The information obtained through importance analysis can effectively support design of groundwater remediation systems by pre-checking the reasonability of factors such as operational time, number of components, and configuration of components.     

地下水污染曝气修复技术进展

从曝气流型和组分反应传质两方面总结了地下水污染曝气修复技术的研究进展,提出已有研究在地下水流及土壤介质特性与曝气流型相互影响、脉冲曝气机理、曝气-抽提技术联用研究、生物降解作用等方面存在的问题,并探讨该技术未来可能的研究方向,指出该技术在技术改良、工程优化设计及机理研究三方面存在深入研究的空间,为进一步研究和应用推广提供参考依据。     

地下水污染修复技术综合评价

结合当前国内外地下水修复研究现状,针对地下水污染修复的三种典型技术(抽出处理技术、监测天然衰减技术、原位修复技术)进行概要介绍,分别论述各种修复技术的修复机理、修复对象及其技术特点,并就基于以上修复技术的工程投资、运行成本及治理时间等方面进行综合对比评价,为开展实施地下水污染修复提供必要的理论依据。最后展望了地下水污染修复技术的发展方向。     

地下水资源管理新技术与新方法

近年,随着科学技术的飞速发展,地下水资源管理新技术与新方法不断涌现．地下水资源管理进入了一个新阶段,为了进一步提高我国地下水管理水平,更好地指导我国地下水管理工作,在综合分析国内外地下水管理技术现状的基础上,重点介绍了在地下水资源调查评价、地下水管理模型与软件、地下水勘查物探新技术、地下水监测技术与设备、地下水修复技术、地下水补源等领域出现的新技术与新方法。