共查询到20条相似文献，搜索用时 93 毫秒
1.
One of the most cost-effective in situ technologies for soil and groundwater (i.e., aquifer) remediation is electrokinetic remediation. In electrokinetic remediation, electromigration due to electric field is combined with hydromigration due to hydraulic flow by purge water to remove pollutants from aquifers through the pore water. This study aims at investigating theoretically the role of electromigration (as active movement) of pollutants and the role of hydromigration (as passive movement) of pollutants in electrokinetic remediation, and making it clear that the control variables for electrokinetic remediation are the applied voltage and the hydraulic flow rate. These aims are pursued by construction of a mathematical model based on physico-chemical considerations and by model simulations of the electrokinetic remediation applied to the virtual aquifer polluted by heavy metals of copper sulfate. According to numerical simulations with the model: (1) heavy metal (nonanionic copper) is removed from the upstream anode region and accumulated in the downstream cathode region; (2) to carry away the heavy metal outside the aquifer (global removal), hydromigration by purge water flow is essential; and (3) electromigration contributes mainly to the redistribution of heavy metals within the aquifer (local removal and local accumulation). 相似文献
2.
Surfactant-enhanced remediation of contaminated soil: a review 总被引：48，自引：0，他引：48
Extracting aqueous solutions with or without additives are employed to solubilize contaminants in soil. Since water solubility is the controlling removing mechanism, additives are used to enhance efficiencies. These additives can reduce the time to treat a site compared to the use of water alone. Additives must be of low toxicity and biodegradable. The research in this area has focussed mainly on halogenated volatile organic compounds (VOCs) and is still quite limited for metal removal. Additives include surfactants, organic and inorganic acids, sodium hydroxide, which can dissolve organic soil matter, water-soluble solvents such as methanol, displacement of cations with nontoxic ones, complexing agents such as EDTA, acids in combination with complexing agents or oxidizing/reducing agents. Cationic, anionic and nonionic surfactants are particularly used for soil washing or flushing. They contain both hydrophobic and hydrophilic portions, making them ideal for solubilization of hydrophobic compounds. Numerous studies have indicated that surfactants enhance recoveries of non-aqueous phase liquids (NAPLs). There have also been indications that pretreatment of soil with surfactant washing to solubilize hydrophobic compounds such as PAHs enhances biodegradation of these contaminants. A few in situ field studies have been performed with surfactants. Large-scale treatment has been done mostly for organic removal. Soil pH, soil type, cation exchange capacity (CEC), particle size, permeabilities and contaminants all affect removal efficiencies. High clay and organic matter contents are particularly detrimental. Understanding the chemistry of the binding of the contaminant and the hydrogeology of the site are very important. Once the water is pumped from the soil, it must be extracted and then treated to remove the hydrocarbons and metals. Several technologies exist such as sodium hydroxide or sodium sulfide precipitation, ion exchange, activated carbon adsorption, ultrafiltration, reverse osmosis, electrodialysis and biological processes. Recycling of the surfactants is desired to decrease treatment costs.
This paper will provide an overview of the laboratory research, field demonstration and full-scale application of surfactants for the remediation of contaminated soil. The majority of pilot scale in situ flushing tests, particularly in the United States, have involved the use of surfactants and co-solvents. There are only a few full-scale projects however. Recent laboratory scale efforts by the authors concerning the use of biosurfactants, biologically produced surfactants, to enhance the removal of copper, cadmium and zinc from contaminated soils and sediments are discussed. Three types of biosurfactants were evaluated for their effectiveness. They included a lipopeptide called surfactin from Bacillus subtilis, a rhamnolipid from Pseudomonas aeruginosa and a sophorolipid from Torulopsis bombicola. The results indicated the feasibility of removing the metals with the anionic biosurfactants even though the exchangeable fractions were not significant. 相似文献
3.
针对铬污染软土,自行设计了电动淋洗试验装置,开展了铬污染软土室内土柱淋洗试验,分析了试验过程中电流、电解质溶液pH的变化以及淋洗液种类、外加电压、温度对重金属铬去除特性的影响。结果表明:电动淋洗试验可以有效去除土壤中的重金属铬;相对于单一淋洗试验,用10 V电压强化淋洗试验显著提高了重金属铬去除效果,淋洗液为十二烷基苯磺酸钠（SDS）时Cr（VI）和Cr（总）去除效率是单一淋洗法的2.79,3.12倍。当电压为10 V,温度升高至45 ℃时,淋洗液为柠檬酸（CA）和草酸（OA）的各组试验表明Cr（Ⅵ）与Cr（总）去除率均相应提高;而淋洗液为十二烷基苯磺酸钠时的试验组中Cr（VI）去除率提高了5.84%,Cr（总）去除率降低了4.25%,表明升高温度使部分Cr（VI）还原成不易迁移的Cr（III）;淋洗液为草酸的试验组中升高温度时Cr（Ⅵ）与Cr（总）去除率最高,分别达到了82.08%、77.57%,分别相应提高了27.65%、26.01%。电动淋洗试验后,铬污染软土土粒结构变得更紧密,土粒之间的孔隙减小且被填充的更加密实。 相似文献
4.
Electrokinetic remediation of metal contaminated glacial tills 总被引：2，自引：0，他引：2
This paper presents the results of an experimental investigation which studied the feasibility of using the electrokinetic process to remediate contaminated clays of glacial origin, otherwise known as glacial tills. An overview of the electrokinetic phenomena, as well as previously performed laboratory and field investigations, is first presented. The methodology of the electrokinetic experiments which were conducted to investigate the removal of metals from a glacial till is then described. A total of 16 experiments were conducted using glacial till samples obtained from a project site near Chicago. Sodium and calcium were used as the surrogate cationic metallic contaminants. These experiments demonstrated that ion transport during the electrokinetic process occurs due to both electro-osmosis and electromigration, but that due to electromigration is significantly higher than that due to electro-osmosis. Unlike other clays such as kaolinite, the glacial till used for this investigation possessed high buffering capacity because of its high carbonate content which prevented the acid front migration from the anode to the cathode during the electrokinetic process. The ion removal efficiency of the electrokinetic process was found to increase when: (1) the voltage gradient applied to the soil was increased, (2) the initial concentration of the contaminants was increased, and (3) the duration of the treatment process was increased. The ion removal efficiency was also greater for smaller ions which possess less ionic charge and when the ions existed independently in the soil as compared to when they coexisted. This investigation suggests that the electrokinetic process has significant potential for remediating glacial tills contaminated with metals. However, the properties of Na and Ca are not representative of contaminants, such as heavy metals, so further investigations are needed. 相似文献
5.
土壤修复过程中重金属形态的研究综述 总被引：4，自引：0，他引：4
重金属污染土壤的修复是现阶段污染土壤治理中的难点之一,在土壤修复过程中对重金属的形态研究已在多个领域中开展,并且在重金属形态及其与生物有效性和毒性等研究领域取得了一定的成果。本文综述了现阶段在污染土壤修复过程中对重金属形态研究的主要领域,分析研究重金属形态的必要性,总结出土壤修复过程中重金属形态方面应当从重金属在土壤与植物中的存在形态入手,研究重金属元素在不同界面间的迁移转化规律,通过阻断重金属元素在污染源、土壤、生物之间的传递链条,以阻止重金属对生物体造成危害,从而为土壤重金属污染的治理修复提供理论基础。 相似文献
6.
M. Gholami D. Yousefi Kebria M. Mahmudi 《International Journal of Environmental Science and Technology》2014,11(5):1433-1438
One large group of persistent and toxic contaminants is the hydrophobic organic contaminants. Among them, perchloroethylene (PCE) has been recognized as a representative group of these pollutants with low solubility. This study reports on the effects of electrokinetic remediation with non-ionic surfactant on PCE-contaminated soil. The performance of electrokinetic process was investigated in the treatment of clay soil that artificially contaminated with two levels: 10,000 and 30,000 mg/kg PCE and 0.33 g/kg Triton X-100. A DC power supply with electric voltage (1 V/cm) was used for 8–16 days. A negatively charged soil surface resulted in a more negative zeta potential and greater electroosmotic flow toward the cathode. The PCE was measured after extraction using n-hexane and analyzed by Fourier transform infrared spectroscopy instrument. The water content of soil was kept 25 % (w/w). Results were shown that PCE removal efficiency achieved was 74 and 89 % for 10,000 and 30,000 mg/kg PCE, respectively, for 16 days. Therefore, in this study, the integration of electrokinetic with non-ionic surfactant as a hybrid method was most effective for the remediation of PCE-contaminated soils. 相似文献
7.
8.
Bacterial biosurfactants can be an ecofriendly and advanced technology for remediation of heavy metals and co-contaminated soil 总被引：1，自引：0，他引：1
A. J. Das S. Lal R. Kumar C. Verma 《International Journal of Environmental Science and Technology》2017,14(6):1343-1354
Environmental pollution due to heavy metals has become a significant drawback as a result of their ecotoxicity. Hence, their remediation is of pressing concern. Many technologies are planned for their remediation; however, most of them are highly expensive and result in incomplete removal of contaminants. So, massive attention has paid to the event and application of the latest biologically techniques, that is effective in remedy and cost, not harming the prevailing surroundings. Hence, application of biosurfactant in heavy metal remediation is one among the recent ecofriendly technique. The present review critically highlights bacterial biosurfactants as a best alternative technique for heavy metals remediation. The review also emphasizes that bacterial biosurfactants can open up a new vista in remediation of metal-contaminated soil. 相似文献
9.
Sang Yong Chung Venkatramanan Senapathi Kye Hyun Park Joo Hyeong Son Selvam Sekar 《Arabian Journal of Geosciences》2018,11(24):769
Ulsan mine produced the iron ore minerals of magnetite, arsenopyrite, and scheelite in 1992, and serpentine was developed from 1977 to 2002. The soils of the mine were contaminated by heavy metals such as As, Zn, Ni, and Cd. Heavy metals of Ni and Zn came mostly from serpentinite, and As was derived mainly from arsenopyrite in the scan-type iron ore body. As, Zn, and Ni were major contaminants, but Cd was a minor contaminant on a basis of Korean standard. The heavy metals in the deep depth (>?5 m) came from the host rocks, and those in the shallow depth (<?5 m) were derived from the organic–mineral complexation soil. The remediation plan was a soil washing for highly contaminated soils and the containment of clay materials for less contaminated soils. Even though the remediation methods were successful, the continuous monitoring and the analysis of monitoring data are still necessary for the conservation of soil and groundwater around the study area. 相似文献
10.
AB-DTPA提取法在重金属污染土壤修复模拟试验中的应用可行性 总被引：2，自引：0，他引：2
将碳酸氢铵-二乙三胺五乙酸(AB-DTPA)提取重金属生物有效态的方法应用于重金属污染土壤修复的模拟试验中,该土壤的污染元素主要是铜、锌和镉,试验所用修复材料是钠化膨润土。研究表明,AB-DTPA提取法具有很好的稳定性,而且能准确指示铜、锌、镉元素在土壤中的有效态含量,同时AB-DTPA对土壤中铜、锌、镉元素的提取率也适用于模拟试验中修复效果的平行对比。AB-DTPA提取法在重金属污染土壤修复模拟试验中的应用是可行的。 相似文献
11.
Heavy metals are toxic elements that have hazardous effect on the environment. They cause soil pollution as a result of their toxicity, potential reactivity, and mobility in soils. There are so many methods for the measurement of heavy metal concentrations in soils and aquatic systems. The traditional methods used for detecting heavy metal distribution in soil involve laboratory analysis and raster sampling. Both of them are expensive and time-consuming for large areas. Remote sensing techniques are used for obtaining the earth’s surface information, and these techniques have been used in the investigations of heavy metal distributions in preliminary analysis of soils as a rapid method. Today, near-infrared reflectance spectroscopy (NIRS) of soil characteristics has been of interest as a significant object. The present investigation is focused on the detection of heavy metals in contaminated soils by the application of reflectance spectroscopy in the spectral range of 350 to 2500 nm. This study also discusses the circumstances of the applied current methods for the detection and estimation of arsenic (As), cadmium (Cd), nickel (Ni), and lead (Pb) in contaminated agricultural soils. In the first part of laboratory spectroscopy, estimations were done using heavy metal reflectance spectroscopy and partial least square regression (PLSR) approaches, while in the second part, the heavy metal estimations were done using soil organic carbon reflectance spectroscopy through the PLSR approaches. Similar to the tasks above, estimations of As, Cd, Ni, and Pb by using Landsat 8 images were done in the forms of direct and indirect methods and the distribution of heavy metals in the study area was determined. Finally, the results obtained using direct and indirect methods were compared with the wet chemical measurements of heavy metals and organic carbon. It was found that although the direct detection of heavy metals using the images of Landsat 8 produced more accurate results than the indirect detections, the results obtained from laboratory spectroscopy corresponded more with the results from atomic adsorption spectroscopy. On the other hand, based on the fact that the soil has a complex content, the use of nonlinear methods, such as artificial neural networks in predicting soil heavy metal contents, could be regarded as a trusted method. 相似文献
12.
13.
《Applied Geochemistry》2005,20(5):841-848
Electrokinetic remediation is an emerging technology that has generated considerable interest as a technique for the in situ remediation of clay-rich soils and sediments. Despite promising experimental results, however, at present there is no standardised universal electrokinetic soil/sediment remediation approach. Many of the current technologies are technically complex and energy intensive, and geared towards the removal of 90% or more of specific contaminants, under very specific field or laboratory-based conditions. However, in the real environment a low-tech, low-energy contaminant reduction/containment technique may be more appropriate and realistic. Such a technique, FIRS (Ferric Iron Remediation and Stabilisation), is discussed here. The FIRS technique involves the application of a low magnitude (typically less than 0.2 V/cm) direct electric potential between two or more sacrificial, Fe-rich, electrodes emplaced in, or either side of, a contaminated soil or sediment. The electric potential is used to generate a strong pH (and Eh) gradient within the soil column (pH 2–13), and force the precipitation of an Fe-rich barrier or “pan” in the soil between the electrodes. Geochemical and geotechnical data for FIRS-treated sediments from the Ravenglass estuary, Cumbria, UK indicate that the technique can significantly reduce contaminant concentration in treated soil, by remobilisation of contaminants and concentration on, or around, the Fe-rich barrier. Arsenic, in particular, seems highly amenable to the FIRS treatment, due to its solubility under the high pH conditions generated near to the cathode, and its marked geochemical affinity with the freshly precipitated Fe oxides and oxyhydroxides in the Fe barrier. Geotechnical tests indicate that the Fe barrier produced by the technique is practically impervious (permeability = 10−9 m/s or less), and has moderate mechanical strength (UCS ∼11 N/mm2). Notably, a large increase in shear strength in the treated soil near to the anode electrode (due to Fe cementation and/or dewatering) is also observed, without significant loss of porosity. The data indicate that the FIRS technique shows considerable promise as an in situ method for contaminated land remediation and soil water containment, and for improving the mechanical properties of soils (contaminated or otherwise) for civil engineering purposes. 相似文献
14.
中国农田土壤重金属污染防治现状与问题思考 总被引：7，自引：0，他引：7
土壤是农业可持续发展的基础。经过近40年的经济快速发展与农业高度集约化生产后,我国农田土壤污染与土壤环境质量下降问题逐渐凸显。当前,中国农田土壤重金属污染形势不容乐观,对农产品的安全生产和食品安全构成威胁。文章首先对我国农田土壤重金属污染现状与污染特点、农田重金属污染来源及修复技术研究现状等进行了总结。结果显示：(1)我国农田土壤重金属污染点位超标率相对较高,但以轻度污染为主;(2)污染土壤中主要以Cd、As、Hg、Pb和Cr这5种健康风险重金属元素为主,尤其以Cd风险最高,而以生态风险为主的Ni、Cu和Zn 3种重金属环境风险相对较小;(3)农田土壤污染分布总体表现为南方重于北方,东部重于西部;(4)农田土壤污染逐渐呈现由工业源向农业源、城郊向农村、土壤向食物链转移的发展趋势。基于文献计量方法对我国近30年来农田土壤污染防治研究的热点与趋势进行了分析。结果表明,我国农田土壤污染防治研究主要始于2000年前后,2009年后进入快速发展阶段,研究热点主要包括重金属污染监测、土壤环境环境质量评价、重金属污染土壤修复技术等,近10年来污染土壤修复技术表现为从单一修复技术向联合修复技术发展态势。此外,文章对我国农田重金属污染修复的一般程序、不同污染程度农田土壤的安全利用技术与高风险污染土壤的管控技术进行了评价,最后,对我国当前农田重金属污染防治过程中出现的问题进行了思考,同时针对我国今后农田重金属污染防治研究进行展望,提出了基于源头控制与风险管控措施相结合的农田重金属污染防治体系,以期为未来我国农田土壤重金属污染防治研究规划以及土壤重金属污染防治技术的创新提供参考与借鉴。 相似文献
15.
Feasibility of electrolyte conditioning with strong alkaline solution on electrokinetic remediation of fluorine-contaminated
field soil was investigated in the laboratory. The initial concentration of fluorine, pH and organic matter content in the
soil were 1,058 mg kg−1, 8.17 and 20.51 g kg−1, respectively. Electrokinetic experiments were conducted under two different concentrations of alkaline solution and three
different voltage gradients. The removal of fluorine increased with the concentration of the alkaline solution and applied
voltage and fluorine removed up to 73% within 10 days. Anolyte enhanced electrokinetic process could promote effectively the
migration of fluoride in soil. The electromigration was the main transport mechanism and the electroosmotic flow had an effect
on the migration of fluoride in soil. Appropriate anolyte enhanced electrokinetic method could be applied to remediate fluorine
from contaminated field soil and has significant potential for removing other anionic pollutants such as arsenate and chromate
from soil. 相似文献
16.
Yu Guo Yangrong Fu Sen Yan Yi Yang Yuepin Guo Zhengyu Bao 《Environmental Earth Sciences》2012,66(4):1083-1089
Consuming edible plants contaminated by heavy metals transferred from soil is an important pathway for human exposure to environmental contaminants. In the past several decades, heavy metal accumulation in contaminated soil has been widely studied; however, few researches investigated the background levels of metals in plants and evaluated the difference in plants grown in soils produced from different parent rocks. In this study, a systemic survey of heavy metal distribution and accumulation in the soil–pepper system was investigated in an unpolluted area, Hainan Island, China. Levels of Cu, Pb, Zn and Cd were measured in soils and pepper fruits from five representative pepper-growing areas with different soil parent rocks (i.e. basalt, granite, sedimentary rock, metamorphic rock and alluvial deposits). Average concentrations of Cu, Pb, Zn and Cd in pepper fruits were 11.52, 0.84, 8.77 and 0.05 mg/kg, respectively. The concentrations of heavy metals in soils are controlled by the parent materials and varied greatly from in different areas. Heavy metal contents in all pepper samples were lower than the Chinese maximum contaminant levels. The relationship between heavy metals in soils and biological absorption coefficient (BAC) of pepper fruits suggests that the uptake ability of pepper for soil metals depends mainly on the physiological mechanism, while in some cases, the soil types and supergene environment are also important. 相似文献
17.
With a rapid development of road systems and an associated drastic increase in number of automobiles, the traffic has induced more and more obvious environmental pollution such as noise, dust, emission and heavy metal contamination. Lead, as one of the most harmful heavy metal contaminants, can execute a significant impact on soil quality and plant growth, depending on its form, as well as its transport and accumulation in soil. This paper describes the source and characteristics of Pb contaminant in soil along a road, and reviews the results of research on remediation of Pb-contaminated soils, aiming at identifying promising approaches to soil remediation along roads. 相似文献
18.
Excessive heavy metal content in sandy soils poses risk to human health and the environment. The rapid expansion of urban areas makes it imperative to manage contaminated sites so that land can be reclaimed for beneficial purposes. Several methods have been proposed to control the leaching of heavy metals from contaminated soils. In this study, four techniques for mobilization and immobilization of metals in sandy soil were compared. The assessed mobilization techniques included chemical extraction using aqueous solutions of acids and chelating agents as well as biochemical extraction using sulfur-oxidizing microorganisms. The evaluated immobilization techniques included lime-cement-pozzolan stabilization and natural-zeolite stabilization. The immobilization techniques do not involve removing metals from soil and instead focus on addition of substances to the soil that alter its composition, volume, and properties. On the other hand, mobilization techniques entail the removal of metals from soil and changes in the soil properties. The findings confirmed that both mobilization and immobilization are effective in controlling the leaching of metals from sandy soils and thereby minimize the risk to the environment and human health. However, the appropriate technique for application at a given site should be chosen on a case-by-case basis, while accounting for the economic and technical feasibility, the necessary level of cleanup, and effect of residual metals on human health and the environment. 相似文献
19.
René van Herwijnen Tim Laverye Jane Poole Mark E. Hodson Tony R. Hutchings 《Applied Geochemistry》2007
Organic materials such as compost are often proposed as suitable materials for the remediation of contaminated brownfield sites intended for soft end-use. In addition to vitalising the soil, they are also believed to immobilise metals thereby breaking contaminant-receptor pathways and reducing the ecotoxicity of the contaminants. However, some research has demonstrated contradictory effects between composts on metal immobilisation. In the present study, four different composts and a liming product containing organic matter (LimeX70) were tested to examine both their metal retention and toxicity reduction capabilities on three different metal contaminated soils. Leaching tests, a plant growth test with Greek cress (Lepidium sativum), an earthworm (Eisenia fetida) survival and condition test and a bacterial toxicity test using Vibrio fischeri were carried out. The leaching test results showed that spent mushroom compost caused an increase in metal concentration in the leachates, while LimeX70 caused a decrease. The variation in behaviour between different amendments for each soil was high, so a generic conclusion could not be drawn. Toxicity tests showed significant reduction of metal bioavailability and toxicity for Greek cress, earthworms and bacteria. The results also suggest that more research should be undertaken to understand the mechanisms involved in metal complexation using different types of organic matter, in order to optimise the use of organic materials like compost for soil remediation. 相似文献
20.
水泥固化重金属污染土的强度特性试验研究 总被引：5，自引：0，他引：5
土体受到重金属离子污染后,会引起土的工程性质的改变,重金属离子的渗出也会给周围环境带来严重的危害。在国外,目前常采用水泥固化技术来处治重金属污染土;而在我国,这方面的研究成果还很少。主要通过系统的室内试验和理论分析,研究了在不同污染物掺量、污染物类型、水泥掺量以及养护龄期条件下固化污染土的强度特性。试验结果表明,金属污染物的存在会导致土体无侧限抗压强度较小幅度的降低,但随着水泥掺入量及养护龄期的增加,土体强度会有显著提高。试验结果还发现,不同的污染物类型及掺入量对固化污染土强度存在不同的影响,NaCl能促进水泥固化土早期强度的提高,而CuCl2和AlCl3则会阻碍水泥与土的固化反应。 相似文献