共查询到18条相似文献，搜索用时 187 毫秒
1.
零价纳米铁(NZVI)具有较高活性,近年受到人们关注并将其应用于地下水污染原位修复,但在实际应用中NZVI易发生氧化与团聚,容易失活。因此尝试运用环境友好型材料对NZVI进行表面改性,选择羧甲基纤维素(CMC)对纳米铁进行表面包覆获得CNZVI,研究不同CMC含量包覆NZVI的分散稳定性和CNZVI对水中六价铬的去除效果。结果表明：经过改性后的CNZVI分散稳定性要明显优于商用纳米铁RNIP,包覆CMC的比例越高,CNZVI的稳定性越好,在较高的CMC包覆比例下,纳米铁不易失活并具有良好的反应活性,对溶液中六价铬有很好的去除效果。 相似文献
2.
监测式自然衰减（MNA）能够高效低耗地原位修复石油污染地下水的场地,微生物对污染物的降解对MNA过程起到了重要作用。在分析东北石油污染场地地下水中总石油烃（TPH）、电子受体的质量浓度分布和变化规律基础上,划分了微生物功能区。采用溶质通量计算法,对MNA原位修复的潜能及其微生物降解效果进行了评估。结果显示,场地微生物降解正在发生,利用的电子受体不同,划分为Mn、Fe和SO2-4还原区。污染通量模型计算显示：上游地区微生物降解强度不断增强,下游地区微生物降解强度不断降低。监测期内石油烃总量降低了394 kg,微生物降解为自然衰减过程中的主要作用,其贡献率为64%~93%,每个通量断面内微生物降解率为0.18~0.73 kg/d。由此可以证明,MNA可以有效地修复地下水中的石油污染。 相似文献
3.
为使含水层中苯胺污染的原位修复过程高效安全且不产生二次污染,提出了一种电化学-水动力循环下的井内生物反应器修复地下水中苯胺的方法.在水动力循环系统的驱动下,评价了苯胺在水动力循环系统的挥发情况并且通过电化学手段提供氧气,井内生物反应器提供修复载体,在砂槽模拟的含水层体系中开展井内生物反应器降解苯胺的修复实验,并对生长曲线及含水层中苯胺修复进行了模拟.289 h的修复使体系内苯胺平均浓度从298 mg/L降低到132 mg/L,去除率为56.5%.运行过程中,监测点苯胺平均浓度在48 h内去除速率为1.10 mg/（L·h）,48~72 h内去除速率为0.85 mg/（L·h）,72 h到289 h内苯胺去除速率维持在0.65 mg/（L·h）,氧化降解逐步减弱.该过程符合Michaelis-Menten方程,反应速率为:-6.71×10-7/（15+t）2.该修复系统是基于地下水动力循环技术的改进,有望应用于有机污染地下水修复. 相似文献
4.
可渗透反应墙（Permeable Reactive Barrier,PRB）技术是原位地下水或者土壤修复中最受瞩目的技术之一,该技术设计和安装的首要关键问题就是反应墙的厚度计算.现有的反应墙设计方法大部分只考虑了单一污染物或者反应墙本身,很少考虑多种污染物的存在以及含水层水力性质的实际情况.聚焦于可渗透反应墙中的PCE（四氯乙烯）链式降解过程,基于可渗透反应墙-含水层的多域多组分污染物的体系建立了一维条件下的对流弥散方程,通过借鉴相关文献提出的转换算法得出方程解析解,并由此推导出适合多组分污染物体系的反应墙厚度公式,利用软件COMSOL建立了数值模型验证了其正确性.对比已有的Rabideau模型发现:计算反应墙厚度时不能完全忽略含水层的自然衰减反应,尤其当达标面远离反应墙出口处时;对于多种组分皆来源于同一种母源反应物的污染物,计算反应墙厚度时边界条件十分关键.本文模型的解析解可以为可渗透反应墙的设计和安装提供建设性的意见,还可以快速分析多组分污染物的分布和预测,为地下水的修复工程、风险评估、后期监测控制提供了计算的支撑. 相似文献
5.
三氯乙烯（TCE）是一种地下水中常见的有机污染物,传统的地下水循环井修复技术虽然有效但耗时长,且需配套地面处理。文章研发了一种电化学循环井耦合修复体系,以期通过顺序化学氧化 -还原作用高效快速降解地下水中TCE。以地下水循环井为基础,通过抽水井中的地下水电解,原位提供O2和H2,投加Fe（Ⅱ） -EDTA络合物活化O2产生羟基自由基氧化降解TCE,进而利用钯催化剂催化剩余的H2还原降解TCE。在二维砂槽模拟含水层中评价了该体系的运行效果,含水层中初始TCE浓度为7.50 mg/L,经过13天的连续通电处理后,TCE浓度降低到1.65 mg/L,降解率达到78%。处理后Cl-浓度相应增加118.20 μmol/L,接近于TCE降解量（44.50 μmol/L）的3倍,证明TCE近乎完全脱氯。运行过程中,TCE平均降解速率由0~5 d的0.90 mg/(L·d) 降低到9~13 d的0.10 mg/(L·d),氧化降解主要发生在前期阶段,钯催化还原效率较为稳定,后期两种过程降解效率都逐渐下降,主要原因是溶解态Fe（Ⅱ）浓度减少以及钯催化剂活性降低。该耦合修复体系是基于地下水循环井技术的改进,其氧化 -还原作用机理有望实现地下水中多种不同有机污染物的降解。 相似文献
6.
膨润土负载纳米铁去除地下水中六价铬研究 总被引：4，自引：1，他引：3
随着人民生活水平的提高和城市化进程的加快,有机污染物及重金属高强度场地污染对人类健康、生态环境及社会安全构成了严重威胁。地下水中的重金属Cr(Ⅵ)污染逐渐受到重视,纳米零价铁可以有效地将六价铬还原成三价铬,使其沉淀固定下来,从而将污染源区的污染物消减固定,防止其向周围扩散。然而由于纳米铁颗粒微小,易被氧化,极易团聚,自身活性受到限制,因此,纳米铁的分散性、稳定性、良好活性研究至关重要。采用低成本环境友好型粘土矿膨润土作为负载材料制备膨润土负载纳米铁（B-NZVI）,批实验和柱实验研究B NZVI去除模拟地下水中Cr(Ⅵ)。结果表明：(1)自制的膨润土负载纳米铁个体呈球形,呈分散状负载于膨润土;(2)相同铁含量的B-NZVI处理Cr(Ⅵ)的效率远大于纳米铁,还原反应符合伪一级反应动力学模型,表观速率常数K随着B NZVI初始浓度的减小而减小;(3)B NZVI在石英砂柱中基本无迁移,适用于点源污染,Cr(Ⅵ)穿透曲线为B-NZVI的实际应用提供了理论和实验基础。 相似文献
7.
传统原位化学氧化地下水修复技术存在氧化剂迁移距离短和利用率低等问题。本研究在双井循环模式促进传质的基础上,通过注水井中的地下水电解原位提供O2和H2,配合乙二胺四乙酸(ethylenediamine tetraacetic acid,EDTA)络合溶解出含水层Fe(Ⅱ),活化O2产生羟基自由基(•OH),实现地下水三氯乙烯(TCE)的氧化降解。在填充了砂土和黏土互层的二维砂槽中,设置电流为0.2 A、流速为72 cm/d、初始TCE浓度为3 mg/L,经过9 d的连续通电处理后,TCE浓度降低到1 mg/L,降解率达到67%。通电前投加0.5 mmol/L EDTA,经过1 d水流循环后含水层中溶解态Fe(Ⅱ)浓度从02 mg/L增加到414 mg/L,黏土区域较高。通电过程中,循环井促进O2、Fe(Ⅱ)-EDTA和TCE的有效接触与反应,使TCE氧化降解。通电初期,黏土区域Fe(Ⅱ)氧化速率、TCE降解速率较周围慢,后期差异逐渐减小。未通电时加入醋酸钠可促进Fe(Ⅲ)还原,使含水层中铁循环利用。该修复过程通过循环井提升了氧化剂迁移距离,使用源于含水层的Fe(Ⅱ)-EDTA和稳定性较好的O2提高了氧化剂利用率,有望应用于有机污染地下水修复。 相似文献
8.
微生物参与铁氧化物矿物的还原性溶解是高砷地下水形成的关键过程,其中具有砷还原功能的微生物如何参与含水层砷释放的生物地球化学过程亟待研究.利用从江汉平原典型高砷含水层中厌氧条件下分离出的四株细菌(Citrobacter sp.JH-1、Clostridium sp.JH-6、Exiguobacterium sp.JH-13、Paenibacillus sp.JH-33),通过室内厌氧模拟培养实验,查明其砷、铁还原能力,并通过分别与铁氧化物矿物及原位沉积物共同培养,探究原位含水层微生物参与的砷释放机理.结果表明:四株细菌均具有厌氧条件下砷、铁还原功能,Citrobacter sp.JH-1砷还原能力最强,96 h内还原的As(Ⅴ)浓度为2.22 μmol/L.其中Citrobacter sp.JH-1不仅可在厌氧和有氧条件下还原溶液中的As(Ⅴ),还可在厌氧条件下还原溶液中的Fe(Ⅲ)和无定型的水铁矿,在与含水层沉积物共培养12 d后,沉积物中铁与砷的释放量分别为510 mg/kg及1 150 μg/kg.江汉平原含水层中的原位微生物兼具砷/铁还原功能,在厌氧条件下可还原沉积物中的铁氧化物矿物并促进砷的释放,为深入揭示高砷地下水成因机理与地下水砷污染的防控提供重要科学依据. 相似文献
9.
当地下水邂逅DNA:石油类有机污染及其生物降解 总被引：1，自引：0，他引：1
地下水科学与工程研究发展到今日,已经成为一门涉及多个领域的综合性学科。地下水污染的控制和修复研究更需要跨学科的技术和知识支持,而生物修复作为一种高效低耗修复的技术成为环境领域的研究热点。微生物因其自身特性及其对污染的降解主导特征对确定有机物污染场地的永续修复具有重要意义。简要地综述了地下水有机污染及其原位修复、有机污染物和地下环境微生物的交互作用,进一步聚焦生物降解机制、生物修复和细菌研究。在此基础上以某石油污染场地地下水为例,进行了地下水中分离微生物菌株及其降解特征的实验研究。结果表明:放线菌降解效果最好,细菌和真菌次之;两两组合降解效果好于单菌,表明存在协同作用;不同菌株混合降解率较低,表明具有拮抗作用。通过动力学实验得出对TPH的降解符合一级反应动力学方程及其降解速度和降解半衰期。就微生物对有机组分降解而言,烷烃和总石油烃降解规律相似;难降解组分降解率低,后期因烷烃转化使其浓度升高;苯浓度变化不大。微生物活性实验表明:活菌总数和脱氢酶活性与降解率呈正相关变化。运用生理生化及分子生物学方法鉴定得出了具体的菌种。 相似文献
10.
岩溶含水层的极不均一性特征使岩溶水溶质运移受构造、裂隙空间及其发育方向控制;因环境条件复杂,开展岩溶水污染原位修复技术难度较大,截止目前,国内尚未系统地开展岩溶含水层水污染原位修复研究工作。文章选择鲁中南山区典型岩溶发育及硝酸盐污染地段,施工组合钻孔建设修复试验工程,采用“乙醇+葡萄糖”液态碳源和“聚乙烯醇+淀粉颗粒”固态反应器分别进行岩溶水硝酸盐污染原位修复试验。结果表明:浓度500 mg?L－1、1 000 mg?L－1的“乙醇+葡萄糖”反硝化溶液对硝酸盐浓度的降解率分别为6.45 %和21.52 %;单位长度组成材料“聚乙烯醇3 kg+淀粉颗粒3 kg”、“聚乙烯醇2 kg+淀粉颗粒4 kg”的两种反硝化固态反应器对硝酸盐浓度的降解率分为33.91%和34.96%。试验证明在裂隙型岩溶地区采用孔组方案进行地下水污染原位修复技术可行、且能取得较显著效果。修复工程布设方式和试验成果对类似地区开展岩溶地下水污染原位修复具一定借鉴意义。 相似文献
11.
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. 相似文献
12.
地下水中三氯乙烯(TCE)严重威胁公众健康和环境安全,纳米零价铁原位注射技术可以还原降解TCE,但是应用中,纳米零价铁存在易氧化团聚而失活、迁移性差等问题。为此,利用天然高分子壳聚糖作包覆剂增强分散性和稳定性,镍作催化剂增强反应活性,成功制备获得壳聚糖包覆纳米铁镍双金属颗粒(CS Fe Ni)。沉降光谱实验表明包覆壳聚糖后纳米铁的分散稳定性得到增强,Zeta电位测试进一步证实颗粒表面负电荷增加,提高了静电排斥力,使得CS Fe Ni分散稳定性明显改善。柱迁移实验表明改性后的CS Fe Ni迁移能力得到提高。批实验表明CS Fe Ni能够高效降解TCE并能完全脱氯,研究结果为纳米铁原位注射技术的实际应用提供了理论基础和实验参考。 相似文献
13.
Assessing the effectiveness of nanoscale zero-valent iron particles produced by green tea for Cr(VI)-contaminated groundwater remediation 
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下载免费PDF全文 Nanoscale zero-valent iron particles (NZVI) produced by using green tea (GT) extract as a reductant can remove Cr(VI) from water effectively, which can be utilized in groundwater remediation. In order to define the reaction mechanism and removal effect in the aquifer, in this study, GT-NZVI particles were prepared and measured by some characterization methods to define their surface performance, and then batch and one-dimensional experiments were carried out to reveal the reaction properties of GT-NZVI and Cr(VI) in groundwater. The results showed that the prepared GT-NZVI particles were regular spherical with a diameter of 10–20 nm, which could disperse in water stably. The main component of GT-NZVI was α-Fe with superficial polyphenols as a stabilizer. GT-NZVI suspension had good ability to reduce the Cr(VI) to Cr(III) in water. When the concentration of GT-NZVI was 1 g/L, the removal efficiency of Cr(VI) with an initial concentration of 100 mg/L reached 92.8% in 1 h reaction. In column tests, GT-NZVI passed through the natural sand column successfully with an average outflow percentage of 71.2%. The simulated in-situ reaction zone (IRZ) with GT-NZVI was used to remediate Cr(VI) contaminated groundwater. The outflow concentration of Cr(VI) kept in 0.14–0.32 mg/L corresponding to the outflow rate below 0.32% within 15 days, and the removal efficiency of Cr(VI) by IRZ with GT-NZVI decreased with the increase of aquifer medium particle size, groundwater flow rate and ionic strength. Most of Cr(III) as reduzate was adsorbed or immobilized on the surface or in the lattice of GT-NZVI, which indicated effective immobilization for chromium. 相似文献
14.
地下水污染场地风险管理与修复技术筛选 总被引：4，自引：0，他引：4
赵勇胜 《吉林大学学报(地球科学版)》2012,42(5):1426-1433
国际上对于地下水污染场地的控制与修复研究已经取得了许多成果,已有成功的修复实例。我国虽然起步晚,但非常重视地下水污染的防治,开展了全国范围的地下水污染调查,并进行了地下水污染的防治规划。地下水污染的控制与修复已经逐渐进入示范性研究阶段。面对地下水污染场地风险管理的不同方法,以及众多的污染修复技术,如何制定风险管理策略,如何在各种各样的修复技术中筛选合适的技术或技术组合,对于地下水污染场地的防治具有非常重要的意义。笔者分析了发达国家地下水污染风险管理策略,结合在地下水污染场地研究方面的经验,对一些主要的地下水污染修复技术进行了分析论述,提出了考虑污染物特征、场地水文地质条件的地下水污染修复技术的筛选过程和方法。 相似文献
15.
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. 相似文献
16.
Nanoscale zero-valent iron flakes for groundwater treatment 总被引：1，自引：0，他引：1
R. Köber H. Hollert G. Hornbruch M. Jekel A. Kamptner N. Klaas H. Maes K.-M. Mangold E. Martac A. Matheis H. Paar A. Schäffer H. Schell A. Schiwy K. R. Schmidt T. J. Strutz S. Thümmler A. Tiehm J. Braun 《Environmental Earth Sciences》2014,72(9):3339-3352
Even today the remediation of organic contaminant source zones poses significant technical and economic challenges. Nanoscale zero-valent iron (NZVI) injections have proved to be a promising approach especially for source zone treatment. We present the development and the characterization of a new kind of NZVI with several advantages on the basis of laboratory experiments, model simulations and a field test. The developed NZVI particles are manufactured by milling, consist of 85 % Fe(0) and exhibit a flake-like shape with a thickness of <100 nm. The mass normalized perchloroethylene (PCE) dechlorination rate constant was 4.1 × 10?3 L/g h compared to 4.0 × 10?4 L/g h for a commercially available reference product. A transport distance of at least 190 cm in quartz sand with a grain size of 0.2–0.8 mm and Fe(0) concentrations between 6 and 160 g/kg (sand) were achieved without significant indications of clogging. The particles showed only a low acute toxicity and had no longterm inhibitory effects on dechlorinating microorganisms. During a field test 280 kg of the iron flakes was injected to a depth of 10–12 m into quaternary sand layers with hydraulic conductivities ranging between 10?4 and 10?5 m/s. Fe(0) concentrations of 1 g/kg (sand) or more [up to 100 g/kg (sand)] were achieved in 80 % of the targeted area. The iron flakes have so far remained reactive for more than 1 year and caused a PCE concentration decrease from 20.000–30.000 to 100–200 µg/L. Integration of particle transport processes into the OpenGeoSys model code proved suitable for site-specific 3D prediction and optimization of iron flake injections. 相似文献
17.
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
18.
Retention of surface-modified nanoscale zero-valent iron (NZVI) particles in the porous media near the point of injection has been reported in the recent studies. Retention of excess particles in porous media can alter the media properties. The main objectives of this study are, therefore, to evaluate the effect of particle retention on the porous media properties and its implication on further NZVI particle transport under different flow conditions. To achieve the objectives, a one-dimensional transport model is developed by considering particle deposition, detachment, and straining mechanisms along with the effect of changes in porosity resulting from retention of NZVI particles. Two different flow conditions are considered for simulations. The first is a constant Darcy’s flow rate condition, which assumes a change in porosity, causes a change in pore water velocity and the second, is a constant head condition, which assumes the change in porosity, influence the permeability and hydraulic conductivity (thus Darcy’s flow rate). Overall a rapid decrease in porosity was observed as a result of high particle retention near the injection points resulting in a spatial distribution of deposition rate coefficient. In the case of constant head condition, the spatial distribution of Darcy’s velocities is predicted due to variation in porosity and hydraulic conductivity. The simulation results are compared with the data reported from the field studies; which suggests straining is likely to happen in the real field condition. 相似文献