Nanosized magnetite in low cost materials for remediation of water polluted with toxic metals,azo- and antraquinonic dyes

Nanosized magnetite has emerged as an adsorbent of pollutants in water remediation. Nanoadsorbents include magnetic iron oxide and its modifiers/stabilizers, such as carbon, silica, clay, organic moieties (polymers, aminoacids, and fatty acids) and other inorganic oxides. This review is focused on the recent developments on the synthesis and use of magnetic nanoparticles and nanocomposites in the treatment of contaminated water. The emphasis is on the influence of the iron oxide modifiers on some properties of interest such as size, BET area, and magnetization. The characteristics of these nanomaterials are related to their ability to eliminate heavy metal ions and dyes from wastewater. Comparative analysis of the actual literature was performed aiming to present the magnetic material, its preparation methodology and performance in the elimination of the selected pollutants. Vast information has been properly summarized according to the materials, their properties and preferential affinity for selected contaminants. The mechanisms governing nanomaterial’s formation as well as the interactions with heavy metals and dyes have been carefully analyzed and associated to their efficiency.     

Acid mine-drainage toxicity testing

The BOD inhibition test, the activated sludge respiration inhibition test, and the Microtox® Bioassay procedure were examined for their potential as rapid toxicity screening methods for acid mine drainage (AMD) and for setting toxicity threshold levels in receiving waters. The BOD inhibition test proved to be unsuitable due to the high chemical oxygen demand of the toxicant. The long incubation time (minimum 5 d at 20°C) allowed growth of chemo-autotrophic bacteria and resulted in excessive flocculation and precipitation of metals, making accurate and meaningful measurements of inhibition impossible. The activated sludge respiration inhibition test was successful in measuring AMD toxicity, and for deriving toxicity threshold levels for the basic heterotrophic community in surface waters. However, it is a very time-consuming technique and is not sensitive enough to be used as a routine screening technique. The variability in toxicity was found to be due to the availability of metals as well as the effect of pH on metabolism. Simple linear models were derived to estimate inhibition within surface waters. Prediction of the inhibition caused by AMD can be made as long as the pH of the river water after mixing and the dilution of the AMD are known. Most accurate predictions are made using equations for specific pH ranges, but a useful estimation of inhibition can be obtained using the general equation: inhibition (%) = -2.34 pH + 6.41 AMD (%) + 22.1. The Microtox® Bioassay method, although expensive, was rapid and simple to use. It was the most sensitive test of the three, with the toxic response of marine bacteria increasing notably from 5 to 15 min due to the presence of bivalent metals in the toxicant. The problem of repeatability and reproducibility encountered with the activated sludge inhibition test was overcome with the highly standardised Microtox® method, making it an ideal screening method for AMD. However, the advantage of the activated sludge inhibition test is that the types of heterotrophic micro-organisms found in activated sludge are similar to those found in receiving waters such as the Avoca River and so more meaningful toxicity threshold values can be obtained.     

Mitigation and remediation technologies for organic contaminated soils

Organic contaminated soils have become a widespread environmental problem, which may lead to a great threat to the quality of agricultural production and to human health. Physical, chemical, and biological technologies have been employed for the mitigation and remediation of organic contaminated soils. This paper reviews the progress of mitigation and remediation technologies for organic contaminated soils and suggests two different strategies for the mitigation of ’slightly-contaminated’ agricultural soils and the remediation of ‘heavily-contaminated’ soils/sites, respectively. On this basis, directions for future research in this field are suggested.     

In situ immobilisation remediation of cadmium in artificially contaminated soil: a chemical and ecotoxicological evaluation

A pot experiment was conducted to evaluate the effectiveness of sepiolite-induced immobilisation remediation of Cd contaminated soil. The results demonstrated that adding sepiolite significantly increased the soil pH and resulted in 35.1–66.0%, 30.3–48.9%, and 31.6–51.6% reduction in toxicity characteristic leaching procedure of Cd (TCLP-Cd), respectively, for the Cd levels of 1.25, 2.5, and 5?mg/kg compared with the no-sepiolite controls. These decreases in TCLP-Cd were associated with reductions in plant phyotoxicity and Cd absorption, and sepiolite-treated soils resulted in increases of 3.2–38.0%, 34.2–52.3%, and 8.4–51.5% in shoot biomass, respectively, and in decreases of 26.7–39.6%, 17.3–28.5%, and 6.1–21.8% in shoot Cd contents, respectively, under soil Cd concentration of 1.25, 2.5 and 5?mg/kg compared to the unamended soils. The greater microbial biomass and catalase and urease activities after applying sepiolite implied a certain degree of recovery in metabolic function recovery during soil remediation. These results demonstrated that the application of sepiolite not only was effective at reducing Cd bioavailability and the rate of Cd accumulation in plants, but also improved soil environmental quality.     

三氯乙烯环境污染修复技术研究进展

三氯乙烯(TCE)是一种挥发性的有机溶剂,具有较强的环境毒性,对人体有很大危害,被列为"优先控制化合物"及"疑似致癌物质".近年来,许多研究者采用各类技术对TCE的降解进行了系统研究,并取得一定成效,为TCE环境污染的修复提供了多种方法.本文综述了物理修复、化学修复、植物修复及微生物修复等TCE原位修复方法的原理、效能、优缺点及各方法的影响因素,并展望了今后TCE修复技术的发展趋势.     

监测水体重金属污染的分子生物标志物研究进展

水体重金属污染具有持久性、高度危害性和难治理性,如何快速、准确监测并对其进行科学评价,成为当今环境科学关心的热点问题。大量研究表明,水生生物体内某些生理指标的变化可以反映水体重金属的污染程度。综述了乙酰胆碱酯酶、抗氧化防御系统、腺苷三磷酸、DNA损伤以及金属硫蛋白等几种分子水平上的生物标志物监测重金属污染的原理、国内外研究进展以及应用现状。认为分子生物标志物具有特异性、敏感性等优势,可以较快指示水体重金属污染对生物体的影响,在实际应用中需注意各种干扰因素。在进行野外研究时,要注重混合重金属与多途径暴露下,分子生物标志物的变化规律。生物体之间差异性会导致标志物在同样暴露条件下产生不同的变化规律,需要加强＂离体＂标志物和＂标准化＂标志物的研究,确保监测结果的可靠性和可重复性。生物标志物较为敏感,容易受到外界环境及体内生理因素影响,可考虑综合运用多种生物标志物指示重金属污染。目前,有关重金属对水生生物毒性效应的研究较多,但重金属对生物体的致毒机理方面研究并不深入,这将是今后研究的重点问题之一。     

Some aspects of heavy metals contamination remediation and role of biosurfactants

Contamination by heavy metals is the result of different industrial activities. The presence of heavy metals in soil and water causes serious problems, as these materials are not biodegradable and do contaminate both biological systems and the subsoil. Biological surface-active compounds otherwise known as biosurfactants in general and rhamnolipids biosurfactants in particular have been successfully employed in the remediation of environments contaminated with heavy metal ions. The aim of the present review is to highlight potential applications of these tensioactive compounds for use in environmental heavy metals removal and bioremediation and processes involved.     

菌根技术在环境修复领域中的应用及展望

菌根作为植物根系和真菌所建立的共生体,是生物界最为广泛的一种互惠共生现象。这一系统的形成能够有效增强植物的物质生产和抗病能力,全面改善宿主植物的生长状况,因此在新兴生态农业生产领域受到广泛重视。与此同时,菌根系统的形成可有效促进植物对污染或胁迫环境的适应能力,以及对环境污染物的去除能力,并能联合其它根际微生物共同发挥效能,在受损和污染环境生态修复领域具有巨大的潜力。近年来,菌根技术在环境修复领域中的应用正成为环境工作者关注的新兴方向,但目前仍处于起步阶段。文章在前人研究结果的基础上,对菌根技术在重要的环境修复领域,如面源污染综合防治领域、污染场地生物修复领域、受损和胁迫环境恢复重建中的试验研究和应用进展进行了综述,并结合其发展现状探讨了当前菌根技术在环境修复治理工程应用以及大规模工业化生产中的瓶颈问题,提出应在菌根真菌对异质环境的适应性、菌根系统的复杂性解析、以及内生菌根真菌分离纯化等关键理论与技术方面加大力度,尽早实现广适性功能菌种的工业化生产和多元＂生物制剂＂的开发,从而在环境修复领域发挥更大的作用。     

利用新型可渗透反应格栅技术对垃圾渗滤液污染地下水过程作用研究

以垃圾渗滤液污染地下水为研究对象,选择沸石、无烟煤、陶粒、活性炭、炉渣、粉煤灰、零价铁、石英砂作为填充材料,设计7种地下可渗透反应格栅（PRB）,分别为反应器1、2、3、4、5、6和7。通过连续实验模拟,对PRB技术治理污染地下水的可行性和有效性进行研究,监测反应器处理效果,分别7种反应器内流速、EC、Cl-的变化及对污染物去除效果及其影响进行分析,探索污染物去除机理。结果显示,反应器水渗流速度在80-150 cm.d-1情况下,对COD去除率为82.22%-88.88%,对Cl-去除率为-0.20%-1.68%,对色度去除率为36.38%-71.86%,表明利用新型PRB技术防控渗滤液污染地下水是可行的,但仍有些技术问题有待深入研究。     

Nanomaterials for water pollution monitoring and remediation

Water shortage and pollution are serious challenges for many countries. Nanomaterials are promising new tools for water quality management due to unique physicochemical properties, high economic benefit, high removal efficiency and environmental friendliness. Here we describe four types of nanomaterials used for water treatment: nanofiltration membranes, photocatalytic nanomaterials, adsorption nanomaterials and reducing nanomaterials. We discuss their properties, applications and mechanisms for pollutant removal. We also review nanomaterials used for water quality monitoring, notably nanomaterials used for the detection of trace pollutants and pathogens. These nanomaterials include carbon nanotubes, magnetic nanoparticles, noble metal nanomaterials and quantum dots.     

土壤石油污染物生物通风修复的研究进展

生物通风是一种去污效果好、操作费用低的土壤原位修复技术。文章概述了生物通风系统的结构、设计目的、适用范围和优缺点，详细论述了生物通风的国内外研究现状，包括现场应用、影响因素和强化技术及理论研究，并展望了生物通风在我国的应用前景。     

基于土壤酶活性变化的铅污染土壤修复基准

近年来,污染土壤修复技术发展很快,而污染土壤修复标准的建立则相对迟缓。为了推进我国该领域的工作,对铅胁迫下土壤酶活性（如过氧化氢酶,磷酸酶,脲酶）随时间的变化进行了研究,以确定棕壤土中铅的土壤修复基准。结果表明：土壤中的铅能够刺激土壤中过氧化氢酶活性的增加,但随着土壤铅浓度的增加,这种刺激作用逐渐减小。土壤过氧化氢酶活性不宜作为铅污染土壤的生物标记物。土壤磷酸酶活性没有一致的变化规律,土壤磷酸酶活性不能作为铅污染土壤的生物标记物。在整个实验时间范围内,土壤脲酶活性与土壤中铅的浓度具有明显的剂量-效应关系（P〈0.01）,土壤脲酶活性可以作为铅污染土壤生物标记物。以土壤脲酶抑制率降低25%为依据,确定棕壤中铅的土壤修复基准为94mg·kg-1,以土壤脲酶抑制率降低45%为依据,确定棕壤中铅的土壤修复基准为178mg·kg-1。     

扰动对水体富营养化的改善作用

利用人工构建的模拟水体系统,观察搅拌和曝气条件下水体中氮磷含量和形态的变化规律,研究和探讨了扰动对水体富营养化的改善。结果表明：（1）扰动对上覆水体氮的去除效果不明显,但是能够有效促进底泥中氨氮向水体扩散,从而使底泥中氮含量明显降低,运行99 d后,曝气反应器中底泥总氮含量从初始3.46 g.kg-1降至0.68 g.kg-1,仅为对照反应器的1/4;（2）搅拌对上覆水中磷的去除效果最佳,反应器运行期间,总磷的平均去除率为37%左右;（3）扰动能增加底泥中微生物的数量和多样性,为污染物的生物降解提供了良好的基础。合理运用扰动能够提高水中溶解氧含量,改善微生态环境,增加微生物的数量和种类,有利于水体富营养化的改善。     

农田土壤重金属污染状况及修复技术研究

重金属污染因具有毒性、易通过食物链在植物,动物和人体内累积,对生态环境和人体健康构成严重威胁。随着工业快速发展、农药及化肥的广泛使用,农田土壤重金属污染越来越严重,研究农田土壤重金属污染现状及修复技术对农产品安全具有重要意义。综合国内外农田土壤重金属污染状况,农田土壤重金属污染主要来源于固体废弃物堆放及处置、工业废物大气沉降、污水农灌和农用物质的不合理施用。该文综述了国内外有关农田重金属污染土壤修复技术（物理修复、化学修复、生物修复、农业生态和联合修复）的研究进展,并针对各种修复方法,阐述了其原理、修复条件、应用实例及其优缺点,重点论述了植物修复的机理和应用,提出了草本与木本联合修复可有效提高农田土壤重金属复合污染的修复效率,为农田土壤土壤重金属复合污染修复提出了新的途径。最后在对已有研究分析的基础上,提出了联合修复技术（如生物联合技术、物理化学联合技术和物理化学-生物联合技术）可以在一定程度上克服使用单一修复手段存在的缺点,可提高复合污染的修复效率、降低修复成本,未来应深入探索联合修复技术间的相互作用机理,以期为农田土壤重金属综合治理与污染修复提供科学依据。     

An emerging market for groundwater remediation in China: Policies,statistics, and future outlook

There is a rapidly emerging and potentially huge market for the remediation of contaminated groundwater in China. The Chinese government published a Water Action Plan in April 2015, a Soil Action Plan in May 2016, and a draft Soil Pollution Prevention and Control Law in June 2017. All of these new policies and regulations put pressures on local governments and contaminated site owners, obliging them to conduct site investigation and to cleanup contaminated groundwater. The Chinese population in northern regions heavily depend on groundwater, with nearly 70% of water supply coming from aquifer sources in the Beijing-Tianjin-Hebei region. However, poor groundwater quality due to natural geochemical background and anthropogeic pollution is a serious concern, with poor or very poor quality water observed in nearly 80% of groundwater monitoring wells in 17 northern provinces. Shallow groundwater in many areas has been contaminated by toxic pollutants such as heavy metals and chlorinated organic compounds. There is an urgent need to better understand the situation and to conduct groundwater remediation at contaminated sites. The Chinese government is investing heavily in the research and development for groundwater remediation, which is expected to greatly add to the quality and quantity of groundwater remediation projects in the near future.     

Applications of hollow nanomaterials in environmental remediation and monitoring: A review

Hollow nanomaterials have attracted significant attention because of their high chemical and thermal stability, high specific surface area, high porosity, low density, and good biocompatibility. These state-of-the-art nanomaterials have been shown to efficiently adsorb heavy metals, and volatile hazardous substances, photodegrade persistent organic pollutants, and other compounds, and inactivate bacteria. Such properties have enabled the use of these materials for environmental remediation, such as in water/wastewater treatment, soil remediation, air purification, and substance monitoring, etc. Hollow nanomaterials showed higher photocatalytic activity than those without hollow structure owing to their high active surface area, reduced diffusion resistance, and improved accessibility. And, the Doping method could improve the photocatalytic performance of hollow nanomaterials further under visible light. Moreover, the synthetic mechanisms and methods of these materials are important because their size and morphology help to determine their precise properties. This article reviews the environmental applications and potential risks of these materials, in addition to their syntheses. Finally, an outlook into the development of these materials is provided.     

Acute toxicity assessment of drinking water source with luminescent bacteria: Impact of environmental conditions and a case study in Luoma Lake,East China

• Acute toxicity assessment was conducted in Luoma lake watershed, East China. • Impacts of environmental factors on the toxicity testing was fully evaluated. • Dissolve oxygen had a weak positive correlation with luminescence inhibition rate. Protecting the quality of lake watersheds by preventing and reducing their contamination is an effective approach to ensure the sustainability of the drinking water supply. In this study, acute toxicity assessment was conducted on the basis of acute bioluminescence inhibition assay using the marine bacterium Vibrio fischeri as the test organism and Luoma Lake drinking water source in East China as the research target. The suitable ranges of environmental factors, including pH value, organic matter, turbidity, hardness, and dissolved oxygen of water samples were evaluated for the toxicity testing of bioluminescent bacteria. The physicochemical characteristics of water samples at the selected 43 sites of Luoma Lake watershed were measured. Results showed that the variations in pH value (7.31–8.41), hardness (5–20 °d) and dissolved oxygen (4.44–11.03 mg/L) of Luoma Lake and its main inflow and outflow rivers had negligible impacts on the acute toxicity testing of V. fischeri. The luminescence inhibition rates ranged from -11.21% to 10.80% at the 43 sites. Pearson’s correlation analysis in the experiment revealed that temperature, pH value, hardness, and turbidity had no correlation with luminescence inhibition rate, whereas dissolved oxygen showed a weak statistically positive correlation with a Pearson correlation coefficient of 0.455 (p<0.05).     

Improved nitrogen removal in dual-contaminated surface water by photocatalysis

River waters in China have dual contamination by nutrients and recalcitrant organic compounds. In principle, the organic compounds could be used to drive denitrification of nitrate, thus arresting eutrophication potential, if the recalcitrant organics could be made bioavailable. This study investigated the potential to make the recalcitrant organics bioavailable through photocatalysis. Batch denitrification tests in a biofilm reactor demonstrated that dual-contaminated river water was short of available electron donor, which resulted in low total nitrogen (TN) removal by denitrification. However, the denitrification rate was increased significantly by adding glucose or by making the organic matters of the river water more bioavailable through photocatalysis. Photocatalysis for 15 min increased the Chemical Oxygen Demand (COD) of the river water from 53 to 84 mg·L^-1 and led to a 4-fold increase in TN removal. The increase in TN removal gave the same effect as adding 92 mg·L^-1 of glucose. During the photocatalysis experiments, the COD increased because photocatalysis transformed organic molecules from those that are resistant to dichromate oxidation in the COD test to those that can be oxidized by dichromate. This phenomenon was verified by testing photocatalysis of pyridine added to the river water. These findings point to the potential for N removal via denitrification after photocatalysis, and they also suggest that the rivers in China may be far more polluted than indicated by COD assays.     

水生维管束植物在水污染中的应用

随着水污染的加剧，高效低耗的水污染处理技术逐渐受到人们的重视，水生维管束植物以其特有的组织和生态功能及易于人工操纵等原因而在净化水体污染、防治富营养化方面发挥了重要的作用。文章对水生维管束植物在水质净化中的作用、影响因素、水生植物的综合利用及其在水污染监测中的作用等方面进行了系统分析，提出多种植物组合比单种植物能更好地实现对水体的净化，通过温度、水深的调控措施可以加强水生维管束植物对水质的净化效果，温度、水深、水质状况以及水生植物的经济价值等是水生植物选择的重要因素。指出了当前水生维管束植物研究中存在的一些问题，认为在人为操纵下，对于水生植物的长效管理是其在水污染应用中的一个重要内容。     

江苏省夏季浮萍种类及其生长水环境调查

对江苏省多个县（市）分布有浮萍的工业区、生活区、农田水体进行调查与采样,观测各地浮萍种类及其生长水体的富营养化状况,探讨水体pH值,铵态氮、硝态氮、总氮、总磷含量与浮萍分布的关系。调查结果表明,浮萍适宜生长在静止的水体中,流动的河流中较为少见;此外,浮萍适宜生长在农田和生活区水体中,工业区附近样本数较少。江苏省夏季浮萍的主要品种为紫萍（Spirodelapolyrrhiza）、青萍（Lemmaminor）、芜萍（Wolffiaarrhiza）和少根紫萍（Spirodelaoligorrhiza）,调查期间未发现稀脉浮萍（Lemmaperpusilla）与品藻（Lemmatrisulca）。紫萍和青萍在所调查的每个采样点均有分布,其生长水体的pH值变化范围（4．5～7．5）较大。浮萍生长水环境的氮、磷养分浓度范围很广,铵态氮、硝态氮、总氮、总磷质量浓度范围分别为0～42、0．2—2．0、0．2～45和0．02～13mg·L-1,尚未发现浮萍分布与水体氮、磷含量之间的必然联系。工业区附近水体中常见紫萍与青萍以共生形式存在,偶尔还伴有芜萍。在利用浮萍去除水中氮、磷营养物质时,应优先考虑利用各地当季优势浮萍品种及不同品种浮萍的共生复合系统,保障浮萍的最大生长量以及对水体氮、磷的最大去除率。