土壤重金属污染修复技术研究进展

近年来随着社会经济的快速发展,土壤受重金属污染问题日益显著,土壤污染不仅对整个土壤圈层造成危害,而且对其它各大圈层也造成一定的影响,如水体污染、空气污染等.其污染源主要分为自然源和人工源2大类,所涉及到的重金属元素主要有Hg、Cd、Pb、Cr、As、Zn、Cu、Ni等元素,如何有效地治理土壤重金属污染对农产品安全和人类健康发展具有重要意义.因此文中从土壤重金属污染来源,国内外土壤修复研究现状,土壤重金属污染修复技术的研究进展几个方面阐述,目前土壤重金属污染修复所采用的技术主要有物理修复、化学修复、生物修复、农业生态修复以及联合修复技术,阐述各修复技术的原理、适用条件、应用实例并分析其优点和不足,其中最为常用的修复手段为生物修复,而联合修复因具备其它单一修复技术所不具备的优越性,可以作为今后在土壤修复领域的重点发展方向,以期为我国受污染土壤的治理借鉴经验.      

有色金属矿山重金属污染土壤修复技术研究进展

我国有色金属种类与产量众多,有色金属矿区的土壤普遍存在重金属污染状况。介绍了有色金属矿区重金属污染的来源,重点对矿区重金属污染土壤的不同修复技术进行了阐述,客土法、换土法、玻璃固定化、热脱附技术适合小范围内的土壤修复。土壤淋洗、化学稳定化修复效率较快,但因为要外加药剂,处理不当很容易造成二次污染。相比于物理化学修复,生物修复更加具有经济性环保性,适合用于工程上大规模的修复,有利于矿区生态长久地发展。同时对矿区重金属污染土壤治理的发展方向进行了展望,以期为有色金属矿区土壤生态环境保护提供参考。     

重金属污染土壤修复技术及其修复探讨

近年来我国的土壤污染问题越来越严重,对人民群众的身体健康造成了巨大的威胁,所以土壤的防护成为了当下防治工作的重点。土壤污染中最严重的就是重金属污染。本文就从各个方面讲解重金属污染土壤的修复技术,对这些技术的原理和应用范围进行探讨。     

钝化材料修复土壤重金属污染研究进展

重金属污染土壤的修复是一项长期而艰巨的任务。作为化学修复的一种,钝化技术成本低、高效省时,而被广泛应用。从石灰性物质、含磷材料、黏土矿物、生物炭、其他材料五大方面归纳了钝化修复的种类,并介绍了钝化修复的作用机制,最后分析了钝化剂修复土壤中重金属的影响因素——钝化剂的投加量、pH、钝化剂的稳定性。基于目前研究现状以及钝化修复存在的问题,对钝化修复今后的发展趋势进行了展望。     

土壤重金属污染以及微生物修复技术探讨

重金属通过各种途径进入到环境中,对生态环境和人类的生存造成了潜在的威胁.文中对生态环境中重金属的来源、特征以及其在土壤中的环境行为特征研究成果进行分析,并对利用微生物修复技术修复土壤重金属污染的有效性和可行性做了相关探讨.     

重金属污染土壤修复原理与技术

重金属污染会导致土壤生态结构、功能、理化性质发生改变,极大地减少农作物产量,危害生态环境和人体健康,已经成为全球主要的环境污染之一。为修复土壤重金属污染,开发了数种土壤修复技术。探讨了各种修复技术的原理、优缺点、适用性,提出了未来土壤重金属污染的研究方向应该是联合修复技术。     

土壤重金属污染现状及植物修复研究进展

综述了我国土壤重金属的污染现状,总结了重金属污染土壤植物修复的类型、典型案例及局限性,重点概括了植物修复的核心--超富集植物的研究现状,并对植物修复的发展方向进行了展望.     

金属矿山重金属污染废弃地土壤修复技术分析

随着中国现代化产业的蓬勃发展,越来越多的金属矿被开发,也正是由于这些采矿活动形成了中国矿山土壤环境中污染土壤的重金属物质的主要源头,本研究重点阐述了目前中国经济越来越发达的金属矿所带来的土壤重金属污染情况,并对土壤重金属污染的主要源头和影响因素做出了剖析,并根据中国目前土地重金属物质恢复的物理性质、生化、物理化工、海洋生物等技术手段及其特征做出了概括。     

重金属污染土壤修复有新方法

中国地质科学研究院矿产资源研究所日前在昭山示范区选取有代表性的重金属污染场地作为“重金属污染修复科研示范基地”,并尝试以“电动修复重金属污染土壤技术”着手探索适合湖南污染状况的修复治理方案。     

金属矿区污染土壤的修复技术进展

在金属矿区开采后,重金属含量超标的情况时有发生,容易在植物、动物体内积累后危害人类的身体健康安全,说明要对金属矿区内的污染土壤开展治理修复工作。鉴于此,文章围绕有色金属矿区的实际情况,阐述了污染土壤修复的六项相关技术,以广西某有色金属选矿厂为例,分析了污染土壤修复工程的两方面内容。     

Integrated System for Remediation of Contaminated Soils

A pilot-scale study was conducted to evaluate an integrated system for the remediation of soils contaminated primarily with pentachlorophenol (PCP), a wood preserver. The integrated soil remediation system consisted of three unit processes: (1) Soil solvent washing; (2) solvent recovery; and (3) biotreatment of the contaminant residual. Pilot-scale countercurrent solvent washing was carried out using a 95% ethanol solution—a solvent that in an earlier bench-scale study was found to be effective in removing PCP and hydrocarbons (HCs) from soils. Three-stage countercurrent solvent washing of a field-contaminated soil was performed using batches of 7.5 kg of soil and 30 L of solvent (1 kg:4 L soil-to-solvent contact ratio). The washed soil was rinsed with water in a single stage after three countercurrent wash stages. Pilot-scale, three-stage countercurrent solvent washing with 95% ethanol reduced the PCP and HC contamination on the soil by 98 and 95%, respectively. The spent solvent and the spent rinse water were combined as the spent wash fluid for further treatment. A pilot-scale distillation unit was used to recover the ethanol from the spent wash fluid. The HC constituents of the spent wash fluid were removed by pH adjustment prior to feeding the spent wash fluid to a distillation unit. Greater than 96% of the ethanol in the spent wash fluid was recovered in the distillate stream, whereas PCP was captured in the bottoms stream. The bottoms stream was treated sequentially in anaerobic and aerobic granular-activated carbon fluidized-bed reactors. Complete mineralization of PCP was achieved using this treatment train.     

Cosolvent-Enhanced Electrokinetic Remediation of Soils Contaminated with Phenanthrene

This research was carried out to evaluate feasibility of using an electrokinetic technique to remove hydrophobic organic pollutants from soils, with the assistance of a cosolvent (n-butylamine, tetrahydrofuran, or acetone) added to the conducting fluid. The experiments were carried out on glacial till clay with phenanthrene as the test compound. Desorption equilibrium was investigated by batch tests. The electrokinetic experiments were conducted using a 19.1 cm long × 6.2 cm inside diameter column under controlled voltage. Water or 20% (volume) cosolvent solution was constantly supplied at the anode. The concentration of phenanthrene in the effluent collected at the cathode was monitored. Each experiment lasted for 100 to 145 days. Results showed that the presence of n-butylamine significantly enhanced the desorption and electrokinetic transport of phenanthrene; about 43% of the phenanthrene was removed after 127 days or 9 pore volumes. The effect of acetone was not as significant as butylamine. The effluent flow in the tetrahydrofuran experiments was minimal, and phenanthrene was not detected in the effluent. The use of water as the conducting solution did not cause observable phenanthrene migration.     

Cyclodextrin-Enhanced Electrokinetic Remediation of Soils Contaminated with 2,4-Dinitrotoluene

The removal of 2,4-dinitrotoluene (2,4-DNT), a munitions waste constituent and an industrial intermediate, from contaminated soils was evaluated using enhanced electrokinetic (EK) remediation. Two model soils were spiked with 480?mg of 2,4-DNT/kg of dry soil for the EK experiments. The spiked soils were kaolin, a low-buffering clayey soil, and glacial till, a high-buffering silty soil. The glacial till was obtained from a field site and contained 2.8% organic matter. Deionized (DI) water and cyclodextrin solutions were used as the EK purging solutions. Cyclodextrin was selected as a nonhazardous solubility enhancer for enhancing the desorption and removal of 2,4-DNT from soils in EK remediation. Two aqueous solutions of hydroxypropyl β-cyclodextrin (HPCD) at concentrations of 1 and 2% were selected for kaolin and glacial till, respectively, based on results for batch extraction of 2,4-DNT from the same soils. During the EK experiments, greater current and electro-osmotic flow were observed for HPCD solutions than for DI water. After the completion of the EK experiments, the soils in the EK cell were extruded and the residual 2,4-DNT in the soils was determined. Less 2,4-DNT remained in the kaolin soil (up to 94% transformed) than in the glacial till soil (20% transformed) due to strong retention of 2,4-DNT by the soil organic matter in glacial till. For kaolin, less 2,4-DNT remained in the soil using HPCD solutions than using DI water. For glacial till, comparable levels of 2,4-DNT remained in the soil for both EK solutions. Since no 2,4-DNT was detected in the effluents from the EK cells, the decrease in 2,4-DNT concentration in the kaolin and glacial till soils was attributed to electrochemical transformation of 2,4-DNT to other species.     

Citric Acid Enhanced Remediation of Soils Contaminated with Uranium by Soil Flushing and Soil Washing

Laboratory bench-scale soil washing (batch) and flushing (column flow) experiments were conducted to determine the efficiency of citric acid as an agent to extract uranium from a synthetically contaminated sandy soil. The results of soil washing and flushing experiments indicate that citric acid is highly effective in removing uranium, and that the extraction efficiency increases with increasing citric acid concentration, especially under slightly acidic to alkaline conditions in systems containing sand coated with secondary minerals (e.g., Fe). The enhanced U(VI) desorption in the presence of citrate may be explained through several processes, including the complexation of U(VI) with citrate and extraction of secondary coatings (e.g., Fe), which results in the liberation of Fe-citrate complexes into solution. In batch washing systems, the presence of 10?3?M citric acid enhances the extraction of uranium 2.8 times greater than water alone for the conditions of the experiment. A comparison of soil washing and flushing shows that the extraction efficiency is higher in bench-scale washing experiments. A removal efficiency of up to 98% was achieved with 10 mL of 10?3?M citric acid in batch systems, whereas it required 4 pore volumes (150 mL) of 0.1 M citric acid to accomplish similar extraction efficiencies in column soil flushing systems.     

Remediation of Contaminated Soils with PCBs Using an Integrated Treatment: Desorption and Oxidation

During most of the past century, large quantities of substances were produced and utilized that subsequently proved harmful. This is the case with polychlorinated biphenyls (PCBs) which only became prohibited by law in the 1970s. As a result of their physicochemical properties, these substances are now present everywhere, although they are mainly found in soils, since they are hydrophobic in character. The present study evaluates an innovatory treatment for the remediation ex situ of soils contaminated by PCBs. This treatment consists of a first stage of desorption using a surfactant agent, followed by a second stage of oxidation with the object of transforming the PCBs into innocuous substances through successive oxidations using the photo-Fenton process. The results obtained (87% remediation in the desorption and 100% in the oxidation stages) show this new treatment to be a highly effective alternative, which does not generate dangerous residues of any type.     

典型有色金属矿区Cd、Pb、As复合污染土壤稳定化修复试验研究

针对有色金属矿区多重金属复合污染土壤,研究了化学稳定化技术对土壤中Cd、Pb、As的修复效果。筛选、复配出了TMT-15-FeCl₃-熟石膏复配型重金属稳定化剂;对药剂用量、各药剂配比、用水量、药剂作用时间、药剂施用方式等影响因素进行了优化,得到最优试验条件为:TMT-15、熟石膏和FeCl₃的比例为3∶1∶1,药剂与土壤质量比6%,用水量为最大田间持水量70%,反应时间7d以上,施用方式:混匀、加水、搅拌、浸润、振荡、静置。在此条件下土壤中有效态Cd、Pb、As的稳定化率分别可达61.28%、73.62%,51.86%。     

铁负载生物炭对土壤中锑砷的稳定修复效果

我国锑矿区土壤锑与砷污染严重,化学稳定化是修复锑砷污染土壤的重要方法。以水稻秸秆为原材料,采用水热法制得比表面积高达33.11 m2/g的铁负载生物炭稳定材料,Fe3+的负载明显促进碳化过程,改善了生物炭的性能。铁负载生物炭对土壤中五价态锑、砷的稳定化效果明显高于三价态。水溶态As(Ⅴ)和Sb(Ⅴ)的稳定率分别为51.22%和58.33%,有效态As(Ⅴ)和Sb(Ⅴ)的稳定率分别为53.67%和52.33%。修复后土壤中非专性吸附态和专性吸附态锑、砷向弱结晶和结晶型铁铝氧化物结合态转化,从而实现锑砷稳定。     

Electroremediation of Contaminated Soils

This paper presents a comprehensive review of the literature on electroremediation of soils. Laboratory studies of the technique are outlined, mechanisms of contaminant transport discussed, and major factors affecting the decontamination process examined. Enhancement techniques and hybrid processes are considered and examples of field trials and commercial applications described.     

镉砷锌铜复合污染土壤的共钝化剂筛选试验

为探究镉砷锌铜复合污染土壤的原位共钝化工艺,以广西南丹县农田土样为研究对象,实施了生物炭、铁粉等几种材料的复合型钝化剂的共钝化试验。结果表明,不同复配钝化剂的钝化效果不尽相同。CaO与FeSO_4的复合物在钝化20d时,3%和6%两种配比均能实现4种金属共钝化。1#生物炭与铁粉混合物的共钝化效果最好,在6%配比钝化10d时,4种金属有效态含量与空白对照组相比分别下降50.22%、49.95%、41.40%和29.18%,对应的残渣态分别增加6%、13%、14%和1.8%。各组复配钝化剂的加入使土壤的有机质增加。     

施肥对潮土养分非匀衡化的土壤修复研究

[目的]研究施肥对不同处理的土壤修复作用.[方法]利用盆栽试验对长期不合理施肥导致土壤养分失衡及生产力下降的土壤进行施肥修复.[结果]试验结果表明:有机、无机肥配合施用是快速修复土壤养分和提高生产力的最佳方法;NP、NPK是既均衡土壤肥力又提高作物产量的无机肥施用方式;对土壤有效磷、氮极度缺乏的土壤,单施磷肥、氮肥效果极显著,其肥效在小麦上与NPK相同.[结论]长期施化肥的土壤对化肥的依赖性更强,停止施肥,玉米产量下降78.6%,小麦产量下降52.8%;而长期施NK和PK肥的土壤,停止施肥反而产量增加,NK处理玉米产量提高112%,小麦产量增加182%,PK处理中玉米产量增加15.1%,小麦产量增加59%;单施有机肥的当季效果不如化肥,但后效明显好于化肥.