地下水VOCs污染修复技术探讨

污染物事故性排放、工矿企业搬迁后遗留的污染场地修复面临各种问题,给地下水资源的使用带来严重威胁。地下水VOCs污染,具有易扩散迁移、毒性高、风险大的特点,修复难度较高。本文结合典型深层地下水修复案例,充分分析场地地质背景、水文地质条件等,根据污染物的特性、污染范围和分布特征,探讨各种修复技术的修复机理、修复对象和技术特点,针对VOCs污染修复进行性能比较及适用性分析。同时通过两个阶段的试验综合研究,原位和异位技术相结合,为开展类似地下水VOCs污染修复实践和管理提供了依据和思路。     

冻结技术在水土重金属污染净化与修复中的应用及进展

随着工业化进程的加快,水土重金属污染事件逐渐增多,对其治理与修复成为当前的迫切工作。冻结技术在治理修复污染水土时,其修复过程只向地层输入“冷量”,属于绿色修复技术,无二次污染风险,受到越来越多的关注。详细总结了冻结技术的修复机理,及其在污水、污泥、重金属污染土壤治理修复中的应用现状和最新研究进展。冻结修复机理是通过冰的自净作用和固-液相平衡原理来实现污染物的定向驱赶和富集,而黏性土壤颗粒的吸附和阻滞作用使单一技术对重金属污染土壤的修复难度增大,其他修复手段与冻结技术联合处理成为一种新的思路。利用冻结土体的低渗透性,还可有效降低污染物的迁移速度,封闭不同种类污染物,形成阻隔污染物扩散的冻结屏障。冻结修复技术在水土重金属污染净化及修复领域具有良好的应用前景。     

实验室与田间条件下骨炭粉与海藻肥对镉污染土壤修复效果评价

本研究基于小麦、玉米、高粱籽粒及烟草烟叶镉(Cd)消减率、修复边际效率及土壤中Cd有效态含量的变化等对比了实验室与田间条件下骨炭粉与海藻肥对Cd污染农田土壤的修复效果。研究结果表明：骨炭粉与海藻肥使玉米、小麦、高粱和烟草对Cd的吸收、转运均有显著(P<0.05)降低作用;在田间条件下,骨炭粉与海藻肥对不同作物籽粒或烟叶的Cd消减率为16.2%~39.8%,可增加作物产量12.3%~38.6%。钝化剂对不同作物增产效果有一定差异,对小麦籽粒增产作用最为有效。研究发现添加钝化剂改变了Cd在土壤团聚体中的分布,使得Cd在大粒径团聚体中负载量增加,并且与对照相比,显著提高土壤pH(提高0.43~0.77),降低土壤Cd的有效性,有利于控制Cd在土壤植物系统中的迁移。总体而言,不同钝化剂的Cd污染土壤修复边际效率为3.99%~14.74%,同海藻肥相比,骨炭粉的修复边际效率较高。不同钝化剂在盆栽实验的修复效果优于田间实验的效果,可能是因为相比于田间实验,盆栽实验条件下根系的作用范围有限,钝化剂的作用效果较高。     

冻融循环对多年冻土区石油迁移影响试验研究

多年冻土区石油污染物迁移过程和特点、污染定量评价、防治和治理措施研发,都是目前寒区经济发展和能源开发迫切需要解决的重要课题.通过室内试验对土体温度场分布、水分分布和石油总量分布的监测分析,研究了冻融循环作用对迁移过程的影响机制.试验结果表明,冻融循环作用通过影响石油污染物本身的物理性质、土颗粒对石油污染物的吸附作用和土体内水相的分布和相状态,影响了石油污染物的迁移过程.原油黏度随温度的降低逐渐增加,使得原油在土体中的迁移能力降低.冻融循环是油水迁移的主要驱动力之一,随着冻融循环的增加,石油污染物和水分向上迁移并聚集,石油随土样高度增加逐渐减小,而水分随高度增加而增加且在一定的位置聚集.研究成果可为多年冻土区石油污染迁移过程和定量评价及防治治理提供重要基础和参考.     

电动力学技术在受污染地下水和土壤修复中新进展

综述了电动力学技术的原理及其在受污染土壤和地下水修复方面的应用.电动力学技术利用电渗析、电迁移和电泳使土壤孔隙中的水和荷电离子或粒子发生迁移运动.大量研究表明,电动力学技术能够高效地去除土壤和地下水中的重金属离子.最新研究表明电动力学技术也能够直接去除有机污染物,其与生物修复优化组合有可能成为高效"绿色"修复技术.这种技术具有安装方便、操作简单和成本低廉的特点,而且不影响生态环境,是非常有发展前景的一种环境修复技术.     

微生物修复石油污染地下水的实验研究

为修复陕北黄土区石油污染地下水,采用优化土著微生物菌群的生物技术,进行了地下水中石油的降解与修复实验研究。在实验装置内加入了1.5%的优化菌群制剂,优化出的菌群初步鉴定主要有:假单胞菌属、微球菌属、放线菌属、真菌类的青霉属和曲霉属等。实验结果显示,在实验装置中人为添加石油含量为182.5 mg/l、862.5 mg/l、1695.0 mg/l时,经过28~37 d的微生物修复,地下水中石油的降解率为27.47%~92.46%,而无菌对照中的石油含量变化在5%以内,说明在无菌条件下地下水中石油降解缓慢。该实验过程验证了微生物修复技术在地下水石油污染修复中的有效性,探索了应用的可行性。     

Application research of enhanced in-situ micro-ecological remediation of petroleum contaminated soil

Experimental study of enhanced in-situ micro-ecological remediation of petroleum contaminated loess soil was carried out in Zhongyuan oil production areas, and the enhanced in-situ micro-ecological remediation technique includes optimistic in-situ microbial communities, physical chemistry methods, alfalfa planting and regulation of soil environmental elements. Experiments showed that the oil content in the contaminated soil with oil content about 2 898.25 mg/kg can be reduced about 98.61% after in-situ micro-ecological remediation for 99 days, which demonstrated the effectiveness of in-situ micro-ecological remediation methods for petroleum contaminated soil in central plains of China, and explored the practical and feasible application of these methods.     

Surfactant-enhanced remediation of contaminated soil: a review

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.     

铁矿物催化氧化技术在水处理中的应用

广泛存在于地下水中的各种有机污染物严重影响着水资源的安全利用,常见的水处理工艺对持久性有机污染物去除效果不够理想。近年来,天然含铁矿物作为催化剂,催化过氧化氢的化学治理方法对各种有机污染物去除效果显著。概述近年来主要含铁矿物、负载型矿物和纳米矿物材料催化过氧化氢在地下水有机污染去除中的应用,探讨了该领域的发展现状和存在问题,并对其应用前景进行展望。认为天然矿物材料具有成本低、在地壳中含量高、环境友好等特点,可用于多种有机污染物的去除与降解。但处理过程中,天然有机质的作用、纳米矿物材料的毒性和地球化学归宿问题应该做进一步研究。     

纳米材料在土壤重金属污染修复中的应用

重金属污染土壤的修复一直是国内外环境研究者关注的重点环境问题之一.近年来,纳米材料在土壤重金属污染修复中的应用也受到了越来越多的关注.综述了主要纳米材料及其改性材料修复土壤重金属的应用、纳米材料的组合技术应用以及影响纳米材料修复土壤重金属效果的主要因素,提出了今后该领域应重点加强研发新的纳米材料,同时提高其在土壤中的扩散能力,研究从室内实验到田间实验的应用;进一步深入探讨了纳米材料在土壤中的环境行为及相关机理等,以期充分理解并进一步推动纳米材料在土壤重金属污染修复中的应用.      

中国地下水污染修复方法和技术应用展望

[研究目的]:中国地下水污染调查和修复日益受到科学界的重视,了解和掌握地下水污染修复方法和技术有助于对污染场地进行科学修复.[研究方法]:本文在系统分析国内外地下水污染修复案例的基础上,对中国地下水污染修复现场实施的技术方法进行总结.[研究结果]:结合中国区域经济发展特征和地下水污染调查评价成果认为,复杂的水文地质条件...     

有机物污染的土壤治理方法及研究进展

污染土壤的修复已成为环境保护研究的一个重点。本基干有机物污染土壤治理的最新进展,介绍有机物污染土壤的物理、化学、生物、植物治理方法。并讨论了各种治理方法的最新动态与存在问题。     

Influence Factors on the In-situ Remediation of Halogenated Organic Compounds by Nanoscale Zerovalent Iron

The pollution of soil and groundwater by halogenated organic compounds (HOCs) is more and more severe. HOCs are of strong toxicity and difficult to be biodegraded. Due to its unique advantages, nanoscale zerovalent iron (NZVI) has become a hot research topic in the field of in situ remediation around the world. In this paper, basic reaction theories and kinetics of HOCs degradation by NZVI are briefly summarized. The influence factors on the in situ remediation of HOCs by NZVI are comprehensively discussed. The influence factors include the intrinsic properties of NZVI due to its different preparation and modification methods, and environment factors, such as pH, dissolved oxygen, ionic species, metals, nonreactive hydrophobic and natural organic compounds, concentrations and components of HOCs, microorganisms and subsurface heterogeneity. The effects of all these factors on NZVI stability, deliverability, targeting ability, and reactivity during in situ remediation are emphasized. Finally, the practical application of this technology are summarized and prospected.     

Advances in Moisture Migration in Vadose Zone of Dryland and Recharge Effects on Groundwater Dynamics

The vadose zone is the zone in between the land surface and above the groundwater table at vertical profile with partial water saturation and under the unsaturation condition, which constitutes the connections among atmospheric water, surface water and groundwater. Soil moisture migration in the vadose zone is a rather complicate process, which controls the rates of groundwater depletion and recharge, and has close hydraulic connections with highly frequent water transfers on the interfaces among the irrigation farmland, sand dunes, wetlands, lakes, and other landscape types. Recent development on soil moisture migration simulations and the application of tracer techniques, geophysical techniques and other geological methods in the vadose zone research, the factors affecting soil moisture migration and groundwater recharge,and soil moisture migration effects on moisture exchange between different landscapes were reviewed in this paper. Several suggestions on the future research were presented here: ① An intense field observation and research database should be initiated and constructed to determine the soil hydraulic parameters, and quantify the influence of moisture migration in vadose zone on the groundwater recharge; ② The proposed observations and researches should learn from the “Critical Zone Observatory”, and focus on the coupling of the soil moisture migration, solute transport and groundwater recharge.     

环境介质中高氯酸盐污染及微生物修复技术研究进展

高氯酸盐(ClO4-)是一种有毒的无机阴离子,其环境污染问题引起了广泛关注,控制与修复高氯酸盐污染环境成为新的研究热点,其中微生物修复技术最具应用前景。国外已开展环境中高氯酸盐污染现状的调查工作,利用微生物修复技术去除高氯酸盐取得了一定的成果,但我国的相关研究较少。文章综述了近年来国内外高氯酸盐的污染现状及微生物修复高氯酸盐的最新研究进展。由于高氯酸盐的高水溶性和低吸附性,当前研究最多的是高氯酸盐水体污染,这些水体通过饮用水(源水)或食物链直接或间接地对人类健康造成影响。在微生物修复方面,从有机电子供体,无机电子供体(H2、Fe0等),电子受体(O2、NO3-、SO24-)及微生物的生长环境因素(pH值、温度、氧化还原电位、盐度)等方面总结了各因素对微生物修复技术去除高氯酸盐效果的影响,以期为我国开展微生物处理技术在高氯酸盐污染修复领域的实践应用提供参考。     

缅甸翡翠研究进展

翡翠是一种重要的宝玉石资源。近年来我国学者对翡翠的研究成果丰硕,在翡翠矿物学、翡翠致色机理及颜色检测技术、翡翠成因研究、翡翠合成技术研究和翡翠鉴定技术领域,都有了很大的进展。文章讨论了上述诸方面的发展概况。     

Electrokinetic remediation of an electroplating site: design and scale-up for an in-situ application in the unsaturated zone

In-situ electrokinetic remediation of contaminated soils requires integrated approaches and adequately engineered setups to control relevant mass fluxes. Based on laboratory findings, this study presents the design of a pilot-scale remediation at an operating electroplating site. The fine-textured soil developed from Jurassic limestone exhibits a chromium, copper, nickel, and zinc contamination down to depths of more than 4 m. The feasibility of an electrokinetic remediation in the unsaturated zone was tested in a lab-scale experiment with subsoil material sampled at the site. The electrodes were placed in water-impermeable, ion-selective membrane wells. This construction allows the necessary watering of the electrodes, maintains unsaturated conditions in the soil compartment, and enables the transfer of contaminant ions into the wells. In addition, the soil is protected from pH changes caused by water electrolysis at the electrodes. The setup includes a watering and drainage system to compensate the electroosmotic water flux and impede desiccation of the anodic region. With a direct current of 70 V and an electric field strength of 2.2 V cm⁻¹, contaminant removal rates amounted up to 27% and 66% (w/w) of the initial zinc/copper and chromium/nickel concentrations. Copper, nickel, and zinc accumulated in the cathode well, while chromate species were enriched in the anode well. Given the successful lab-scale remediation, the pilot plant was designed for the in-situ treatment of a soil volume of 12 m³ below a production hall. A power of 500 V DC at a maximum current of 30 A is supplied by a transformer rectifier. This yields an electric field strength comparable to the lab-scale experiment and thereby similar contaminant transport velocities. A vacuum distillation unit is employed for process water reuse and to control electrolyte conductivity. To cope with chlorine gas generation at the anodes a gas absorber unit is employed. According to the lab-scale results, about 2, 9, 9, and 15 kg zinc, chromium, copper, and nickel, respectively, are expected to be removed from the field plot during an operation time of 10 months.     

含单裂隙非饱和带中轻非水相流体修复的数值模拟

针对非饱和带中油类污染物时空分布的研究,室内实验很难定量分析运移机理,野外检测成本高且破坏地层。数值模拟法作为一种应用广且成熟的方法,可以用来分析油类污染物在非饱和带中的运移规律。为了研究单井抽提及原位冲洗修复时,含单裂隙非饱和带中轻非水相流体（Light non-aqueous phase liquids,LNAPL）的时空变化规律,建立了数值模型,分析不同条件下LNAPL的修复效果及时空变化规律。模拟结果发现,LNAPL注入时优先流入裂隙,停止注入时优先流出裂隙。单井抽提修复模拟表明,抽提流量越大,修复效率越高。原位冲洗技术能有效补充地下水,防止产生新的环境问题;注水井起到“冲洗”及稀释污染物的作用,模拟最优方案修复面积达到96%,修复率达到75%,LNAPL饱和度控制在约0.05;对比分析发现,注水井布设在污染物范围的上边界时修复效果最好,能有效“冲洗”污染物并携带至抽提井中抽出地表。该研究为受轻油污染的土壤及地下水修复提供了科学的理论依据及有效的评估方法。     

Removal of fluorine from contaminated field soil by anolyte enhanced electrokinetic remediation

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.     

A modified EK method with an I<Superscript>−</Superscript>/I<Subscript>2</Subscript> lixiviant assisted and approaching cathodes to remedy mercury contaminated field soils

Wanshan mercury mine is the largest cinnabar deposit in Guizhou, China. Few effective methods had been achieved to remedy Hg heavily contaminated field soils. In this paper, a modified EK method with approaching cathodes (AC-EK) and an I⁻/I₂ lixiviant was described to remedy mercury-contaminated field soils near Wanshan mercury mine. Paddy Soil I and Paddy Soil II were sampled and contained 576.73 ± 45.50 and 491.35 ± 4.73 mg/kg Hg, respectively. Although they contained 6.9 and 9.4% organic matter respectively, more than 92 and 89% Hg were removed by AC-EK within 5 days. Removal ratio increased by 0.21 and 0.68 times using EK process with ACs over that with one single cathode (SC-EK). AC-EK method saved nearly 26.4–28.1% electric power as compared to SC-EK method. As an I⁻/I₂ lixiviant solution was used to solubilize HgS(HgO) during EK process, the bonding of Hg to organic functional S groups should be less important than the binding to inner sites of organic matter in soil. The relationship between EK remediation effect and soil organic matter content was fitted to a linear model. It turned out that when soil OM increased by 1.0%, EK removal ratio (%) of Hg would decrease by 2.63%.