铁碳复合纳米材料活化过硫酸盐降解土壤中对羟基联苯的机制研究

本文发展了一种高效、低成本的有机污染土壤修复技术,以生物炭和工业铁粉作为原料,采用工业球磨技术制备出了铁碳复合纳米材料,其能够高效活化过硫酸盐降解对羟基联苯。通过高分辨透射电子显微镜和元素扫描发现,球磨法制备的铁碳复合材料粒径为5-30 nm,平均粒径为15 nm,铁颗粒均匀分布于碳材料中；铁碳复合纳米材料的投加量为0.1 g/L、过硫酸钠的投加浓度为0.50 mmol/L,120 min内对水中对羟基联苯的去除率可达100%,而对土壤中的对羟基联苯的降解率也可达85%；利用电子顺磁共振技术发现铁碳材料活化过硫酸盐的主要机制是铁碳材料催化分解过硫酸盐产生具有强氧化能力的羟基自由基(.OH)和硫酸根自由基(SO_4^?-),从而快速降解有机污染物；该反应体系作用pH范围广、不受氯离子和硝酸盐干扰,将为有机污染土壤的修复提供了新的技术。     

高级氧化技术修复萘污染土壤和地下水研究进展

多环芳烃是土壤和地下水中普遍存在的持久性有机污染物。其中，萘是结构最简单的多环芳烃，具有迁移性强的特点，可通过多种途径在土壤和地下水中富集，是焦化、化工等历史遗留地块重点关注的污染物之一。高级氧化技术高效、安全且经济，因此，基于高级氧化的萘污染土壤和地下水修复技术受到越来越多的关注。本文综述了芬顿和类芬顿氧化、臭氧氧化和过硫酸盐氧化的反应机理，重点阐述了二价铁、微纳级零价铁、铁矿物、铁螯合物等均相及非均相活化剂活化的氧化技术在修复萘污染土壤和地下水方面取得的研究进展，介绍了多种高级氧化技术联合修复以及高级氧化技术与生物降解技术协同修复的研究现状，指出了目前萘的高级氧化技术研究存在的问题，并对研究做出了展望。     

微纳铁活化过硫酸钠降解污染土壤中DDTs的效果研究

作为典型的持久性有机污染物,DDTS尽管已被禁止使用,但由于其稳定的结构,土壤中仍然残留大量的DDTs,亟需开发快速高效的DDTs降解技术。基于此,本文研究了微米尺寸具有纳米单元的铁粉(微纳铁,micro/nano-Fe~Ⅱ)活化过硫酸钠(sodium persulfate,PS)降解场地污染土壤中DDTs的效果,并考察了微纳铁负载量、过硫酸钠浓度、反应时间及氧化-洗脱耦合对DDTs去除效率的影响。研究结果表明:微纳铁能有效活化Ps降解土壤中的DDTs,在Ps浓度为100mmol/L时,DDTs的降解率随着微纳铁负载量增加而增加,当微纳铁升高到44.8g/L时,p,p'-DDT和o,p'-DDT的降解率高达92.2%和95.1%。洗脱-氧化耦合实验中,3种表面活性剂Tween80、Brij35和SDBS,其中Brij35土壤洗脱液中DDTs的降解效率最高,微纳铁和Ps的摩尔比为4:1时,对DDTs有最佳的降解效果。以上研究结果为DDTs的去除提供了一种新的途径,也为其他有机污染场地的修复提供了一类新技术。     

土壤中有机复合污染物微生物组转化机制与调控原理：进展与展望

实际污染土壤中有机污染物通常以复合污染状态存在,有机复合污染物的微生物降解过程及其作用机制显得更为复杂。土壤微生物类群多样,具有丰富的功能多样性。而有机复合污染物的降解通常由微生物组操控,通过微生物群落代谢网络完成污染物的去除。近年来,研究者逐渐关注有机复合污染土壤中微生物群落适应机制-微生物组转化过程-合成微生物组设计-原位微生物组修复等方面的研究,对认知污染土壤治理和修复具有重要的科学意义。本文以具有代谢协同性及功能互补性的微生物组为切入点,系统阐述土壤中有机复合污染物的微生物组转化机制与调控原理等,探讨微生物组在复合污染土壤绿色可持续原位生物修复中的发展前景。     

持久性有机污染场地土壤淋洗法修复研究进展

持久性有机污染场地土壤淋洗法是污染场地土壤物化修复方法中一种常用的技术。淋洗法是指运用特定淋洗剂对污染土壤进行深度洗涤,通过分离净化淋洗剂,实现回用集成,达到去除土壤中污染物的目的,并最终安全化处置污染物和修复土壤的过程。本文根据污染场地土壤处理位置、淋洗剂种类和淋洗剂施用方式的差异,将持久性有机污染场地土壤淋洗法划分为不同的种类;总结了为达到高效去除土壤中污染物质,可运用多级淋洗方式、超声方式、电动力方式和化学氧化等方式实现强化修复效率;阐述了污染场地土壤质地、污染物性质、淋洗剂性质、淋洗条件优化以及淋洗剂回用效率等因素对淋洗修复整体效用的显著影响;同时指出了目前持久性有机污染场地土壤淋洗法存在的问题和今后国内外研究和应用的方向。综合考虑土壤淋洗修复技术适用范围和成本因素,认为淋洗法是一种较符合我国持久性有机污染场地土壤实情的修复技术,具有较强的针对性和较广泛的运用前景。     

土壤有机污染物电化学修复技术研究进展

综述了有机污染土壤的电动力修复和微生物电化学修复的最新研究进展。分析了电动力修复中电极材料、运行条件等因素对污染物去除效果的影响,总结了添加表面活性剂、引入具有降解能力的基质、与化学或生物联合等方式对土壤修复效果的强化作用,阐述了微生物电化学修复的效果、影响因素和微生物群落演变的规律。电化学技术能够有效去除土壤中的有机污染物,且电动力较微生物电化学具有更好的去除效果。为了实现电化学技术在污染土壤修复中的应用,未来需要从土壤导电性、电极材料以及反应器构型等方面优化以提高修复效果;此外,电化学修复技术的机理、功能微生物的群落特征研究等也是下一步研究的重点。     

土壤中有机农药的自然降解行为

有机农药是一类典型的环境污染物,自然降解是其在土壤中消除的主要过程。本文阐述了土壤中有机农药生物降解、光解、水解和化学氧化等自然降解机制,综述了土壤中有机农药自然降解的研究方法及研究现状,指出了目前自然降解研究中存在的一些问题并展望了今后的研究方向。     

土壤环境中多环芳烃的微生物降解及联合生物修复

研究土壤环境中持久性有机污染物的生物降解及其生物修复技术是当今国际环境修复科学技术前沿领域的重要课题。本文重点论述了土壤环境中持久性有机污染物多环芳烃的微生物降解机理及其在生物修复中的应用等,并结合当前研究进展,展望了基于多种修复措施相结合的多环芳烃污染土壤联合生物修复工程技术的开发与应用前景。     

阳离子表面活性剂增强固定土壤中的苯酚和对硝基苯酚

当前,对有机物污染土壤进行修复成为环境科学研究热点之一[1],常用的修复方法有化学修复、生物修复、化学与生物相结合的修复;但迄今仍没有经济有效的有机污染土壤修复的实用技术.因此,利用在土壤中注入阳离子表面活性剂形成吸附区,截留有机污染物,阻止有机物迁移,并对固定污染物进行修复,无论对土壤及地下水有机物污染防治,还是生产优质农产品都具有现实意义.近年来,相关研究主要集中在截留非极性有机污染物[2～7],而对溶解度较大且易于迁移的极性有机物截留研究较少;并且认为表面活性剂增强土壤截留有机物的机理由土壤表观有机碳含量增大所致.对硝基苯酚、苯酚是环境中优先控制有机物,它们是重要化工原料,也是农药的降解产物.本文以极性化合物对硝基苯酚、苯酚为目标污染物,探讨阳离子表面活性剂增强固定作用及机理,为有效防治土壤有机污染提供理论依据.     

多环芳烃污染土壤生物联合强化修复研究进展

多环芳烃(polycyclic aromatic hydrocarbons,PAHs)是广泛存在于环境中的一类有毒有机污染物。在PAHs污染土壤修复领域中,运用一些生物化学的方式来强化生物联合修复技术可以有效缩短生物修复的时间,大大提高修复效率,最具发展前景和应用价值。本文主要以植物-微生物、植物-微生物-土壤动物两种生物联合修复方式为对象,结合各自的特点、机理和实例,推断了其修复机制的内在原因,总结了影响土壤中PAHs降解效率的主要因素(包括:PAHs的浓度水平、根系分泌物的种类、外源添加降解菌和土壤动物的数量和种类、菌属或土壤动物之间的种间竞争和部分环境因素等);同时通过综述近年来国内外强化生物联合修复PAHs污染土壤的技术原理、应用成果和存在的一些问题,指出了不同情况下制约PAHs强化降解进程的潜在限制因子(包括:表面活性剂和固定化微生物的添加量、不同表面活性剂的适度混合、载体材料的性质、固定化方式的选取、土壤养分和水分含量等);并强调在进行强化修复的过程中,要注重现场应用和安全性评价,为多环芳烃污染土壤的生物联合强化修复研究提供了理论依据和技术参考。     

Biodegradation combined with ozone for the remediation of contaminated soils

The effectiveness of the SS-SBR (Soil Slurry – Sequencing Batch Reactor) process for the remediation of soils contaminated by several organic pollutants has been evaluated. Experimental tests have been performed on two different soils, a spiked one and an industrial aged soil. The spiked soil, artificially contaminated, has been prepared trying to simulate the pollution of an industrial aged soil in terms of number and kind of contaminants. PAHs (Polycyclic Aromatic Hydrocarbons) and phenols degradation has been particularly investigated because they are considered persistent and recalcitrant. Concerning the spiked soil, removal efficiencies higher than 95% in 6 to 9 weeks have been found for all the pollutants, except for five-rings PAHs; however, these compounds were partly removed in 11 to 13 weeks. Good results have been achieved also for the industrial aged soil with a maximum removal of about 80% in 7–8 weeks. To enhance the pollutants degradation, trying to obtain a faster remediation, the biological treatment has been combined with a chemical oxidation with ozone. The best degradation effectiveness of the combined process has been obtained applying the ozonation after few days of the biological treatment. Therefore, a combined biological and chemical treatment allowed to markedly improve the remediation of contaminated soils.     

固定/稳定化土壤修复技术的应用与优化分析

固定/稳定化技术是污染土壤修复的常用方法之一,具有费用低、无毒、综合效益好等优点,非常适合我国典型土壤污染区的修复。本文介绍了固定/稳定化方法的作用原理与修复材料,分析了此技术的适用范围及优缺点。文章归纳了近年来固定/稳定化技术在污染土壤修复中的应用成功案例,并结合我国土壤污染的实际状况和修复需求,从加强工程技术与装备研发、优化费用结构和发展环境友好型固定/稳定化技术等角度,提出了固定/稳定化技术应用的优化建议。     

Comparison of Fenton's Reagent and Ozone Oxidation of Polycyclic Aromatic Hydrocarbons in Aged Contaminated Soils (7 pp)

Background, Aim and Scope   Polycyclic aromatic hydrocarbons (PAHs) are formed as a result of incomplete combustion and are among the most frequently occurring contaminants in soils and sediments. PAHs are of great environmental concern due to their ubiquitous nature and toxicological properties. Consequently, extensive research has been conducted into the development of methods to remediate soils contaminated with PAHs. Fenton's reagent or ozone is the most commonly studied chemical oxidation methods. However, the majority of remediation studies use soils that have been artificially contaminated with either one or a limited number of PAH compounds in the laboratory. Hence, it is essential to extend such studies to soils contaminated with multiple PAHs under field conditions. Objectives   The objective of this study is to investigate the capacity of Fenton's reagent and ozone to degrade PAHs in soils. The soils have been collected from a number of different industrial sites and, therefore, will have been exposed to different PAH compounds in varying concentrations over a range of time periods. The capacity of Fenton's reagent and ozone to degrade PAHs in industrially contaminated soils is compared to results obtained in studies using soils artificially contaminated with PAHs in the laboratory. Materials and Methods: Nine soil samples, contaminated with PAHs, were collected from five different industrial sites in Sweden. For the Fenton's reagent procedure, the pH of the soil slurry samples was adjusted to pH 3 and they were kept at a constant temperature of 70oC whilst H2O2 was added. For the ozone procedure, soil samples were mixed with 50% water and 50% ethanol and kept at a constant temperature of 45 oC. Ozone was then continually introduced to each soil sample over a period of four hours. Following the Fenton's reagent and ozone oxidation procedures, the samples were filtered to isolate the solid phase, which was then extracted using pressurized liquid extraction (PLE). The sample extracts were cleaned up using open columns and then analysed by gas chromatography-mass spectrometry (GC-MS). Results: The relative abundance of the detected PAHs varied between soils, associated with different industries. For example, low molecular weight (LMW) PAHs were more abundant in soil samples collected from wood impregnation sites and high overall PAH degradation efficiencies were observed in soils originating from these sites. In the contaminated soils studied, PAHs were more effectively degraded using Fenton's reagent (PAH degradation efficiency of 40-86%) as opposed to ozone (PAH degradation efficiency of 10-70%). LMW PAHs were more efficiently degraded, using ozone as the oxidizing agent, whereas the use of Fenton's reagent resulted in a more even degradation pattern for PAHs with two through six fused aromatic rings. Discussion: The degradation efficiency for both methods was largely dependent on the initial PAH concentration in the soil sample, with higher degradation observed in highly polluted soils. LMW PAHs are more susceptible to degradation than high molecular weight (HMW) PAHs. As a result of this the relative abundance of large (often carcinogenic) PAHs increased after chemical oxidation treatment, particularly after ozone treatment. Repeated Fenton's reagent treatment did not result in any further degradation of soil PAHs, indicating that residual soil PAHs are strongly sorbed. The effectiveness of the two oxidation treatment approaches differed between industrial sites, thus highlighting the importance of further research into the influence of soil properties on the sorption capacity of PAHs. Conclusions: This study demonstrates that the degree to which chemical oxidation techniques can degrade soil bound PAHs chemical degradation is highly dependent on both the concentration of PAHs in the soils and the compounds present, i.e. the various PAH profiles. Therefore, similarities in the PAH degradation efficiencies in the nine soil samples studied were observed with the two chemical oxidation methods used. However, the degradation performance of Fenton's reagent and ozone differed between the two methods. Overall, Fenton's reagent achieved the highest total PAH degradation due to stronger oxidation conditions. LMW PAHs showed higher susceptibility to oxidation, whereas high molecular weight (HMW) PAHs appear to be strongly sorbed to the soils and therefore less chemically available for oxidation. This study highlights the importance of including soils collected from a range of contaminated sites in remediation studies. Such soil samples will contain PAH contaminants of varying concentrations, chemical and physical properties, and have been aged under field conditions. In addition to the chemical and physical properties of the soils, these factors will all influence the chemical availability of PAHs to oxidation. Recommendations and Perspectives: We recommend including aged contaminated soils in chemical degradation studies. In future chemical remediation work, we intend to investigate the potential influence of the chemical and physical properties of PAHs and soil parameters potential influence on the chemical oxidation efficiency in aged contaminated soils. Due to the vast number of contaminated sites there is a great need of efficient remediation methods throughout the world. This study shows the difficulties which may be experienced when applying remediation methods to a variation of contaminated sites.     

高锰酸钾氧化修复污染土壤中菲和芘的研究

利用人工污染土壤,研究了高锰酸钾对4种不同土壤中菲和芘的氧化修复效果。结果表明,当高锰酸钾浓度为33.33mmol·L^-1时,土壤中菲和芘的氧化去除率达到最大。高锰酸钾氧化去除率不仅与高锰酸钾浓度有关,还与土壤性质和老化时间有关。土壤有机质含量的增加会降低高锰酸钾对土壤中菲和芘的氧化去除率;随着老化时间的增加,高锰酸钾的氧化去除率逐渐降低。老化40d后,4种土壤中菲和芘的氧化去除率显著降低,菲的氧化去除率在14%～67%之间,芘的氧化去除率在61%～84%之间。高锰酸钾氧化前后,4种土壤中有机质含量下降范围为0.77%～9.21%。从土壤有机质含量来看,高锰酸钾氧化修复多环芳烃污染土壤对土壤质量影响较小,具有较好的应用前景。     

植物修复多环芳烃污染土壤的根际效应机制研究进展

多环芳烃类有机污染物在土壤中可长期存在,进而通过食物链对人类健康产生重大潜在风险。对多环芳烃污染土壤进行植物修复是一种环境友好且经济有效的污染补救策略。进行植物根际效应机制研究对于开发可持续性多环芳烃污染土壤的植物修复技术具有重要指导意义。对近年来的相关研究工作进行了总结,结果表明:多种禾本科植物具有较强的多环芳烃污染耐受性和较好的修复效能,利用多植物混植的联合修复方式表现出优于单一植物的修复优势。低分子量有机酸类根系分泌物通过与土壤中多环芳烃污染物形成反馈回路决定植物修复体系中多环芳烃的命运。修复植物根系分泌物可塑造特定的根际微生物区系,根际微生物可通过多种机制来降解土壤环境中的多环芳烃。针对在植物修复多环芳烃污染土壤研究过程中尚存在一些问题,提出了未来植物修复根际效应机理研究中应该关注的重点和方向,旨在为优化多环芳烃污染土壤植物修复技术提供科学依据与理论参考。