Pollution source identification methods and remediation technologies of groundwater: A review

Groundwater is an important source of drinking water.Groundwater pollution severely endangers drinking water safety and sustainable social development.In the case of groundwater pollution,the top priority is to identify pollution sources,and accurate information on pollution sources is the premise of efficient remediation.Then,an appropriate pollution remediation scheme should be developed according to information on pollution sources,site conditions,and economic costs.The methods for identifying pollution sources mainly include geophysical exploration,geochemistry,isotopic tracing,and numerical modeling.Among these identification methods,only the numerical modeling can recognize various information on pollution sources,while other methods can only identify a certain aspect of pollution sources.The remediation technologies of groundwater can be divided into in-situ and ex-situ remediation technologies according to the remediation location.The in-situ remediation technologies enjoy low costs and a wide remediation range,but their remediation performance is prone to be affected by environmental conditions and cause secondary pollution.The ex-situ remediation technologies boast high remediation efficiency,high processing capacity,and high treatment concentration but suffer high costs.Different methods for pollution source identification and remediation technologies are applicable to different conditions.To achieve the expected identification and remediation results,it is feasible to combine several methods and technologies according to the actual hydrogeological conditions of contaminated sites and the nature of pollutants.Additionally,detailed knowledge about the hydrogeological conditions and stratigraphic structure of the contaminated site is the basis of all work regardless of the adopted identification methods or remediation technologies.

Source,migration,distribution,toxicological effects and remediation technologies of arsenic in groundwater in China

Groundwater with high arsenic(As) content seriously threatens human life and health. Drinking high-As groundwater for a long time will lead to various pathological changes such as skin cancer, liver cancer,and kidney cancer. High-As groundwater has become one of the most serious environmental geological problems in China and even internationally. This paper aims to systematically summarize the sources,migration, distribution, toxicological effects, and treatment techniques of As in natural groundwater in China based on a large number of literature surveys. High-As groundwater in China is mainly distributed in the inland basins in arid and semi-arid environments and the alluvial and lacustrine aquifers in river deltas in humid environments, which are in neutral to weakly alkaline and strongly reducing environments.The content of As in groundwater varies widely, and As(Ⅲ) is the main form. The main mechanism of the formation of high-As groundwater in China is the reduced dissolution of Fe and Mn oxides under the action of organic matter and primary microorganisms, alkaline environment, intense evaporation and concentration, long-term water-rock interaction, and slow groundwater velocity, which promote the continuous migration and enrichment of As in groundwater. There are obvious differences in the toxicity of different forms of As. The toxic of As(Ⅲ) is far more than As(V), which is considered to be more toxic than methyl arsenate(MMA) and dimethyl arsenate(DMA). Inorganic As entering the body is metabolized through a combination of methylation(detoxification) and reduction(activation) and catalyzed by a series of methyltransferases and reductases. At present, remediation methods for high-As groundwater mainly include ion exchange technology, membrane filtration technology, biological treatment technology, nanocomposite adsorption technology, electrochemical technology, and so on. All the above remediation methods still have certain limitations, and it is urgent to develop treatment materials and technical means with stronger As removal performance and sustainability. With the joint efforts of scientists and governments of various countries in the future, this worldwide problem of drinking-water As poisoning will be solved as soon as possible. This paper systematically summarizes and discusses the hot research results of natural high-As groundwater, which could provide a reference for the related research of high-As groundwater in China and even the world.

Remediation Technologies for Cadmium Contamination in Greenhouse Vegetable Fields

Based on the literature and experimental results, three kinds of soil amendments, namely rice biochar, hydroxyapatite and potassium dihydrogen phosphate(KH2PO4), and deeper ploughing were selected to evaluate the field application effect of soil amendments and agronomic measures on the remediation of Cd contamination in greenhouse vegetable fields. Cd-contaminated greenhouse screening was conducted from 2015 to 2017. In September 2017, comparative tests of eight treatments were performed, and a preferred test was performed in September 2018. The screening results of the contaminated areas indicated that the distribution of over-standard sites was uneven, and Cd content was significantly different. Over-standard rate of No.4 greenhouse was 83.33% and was the highest, and the average content of Cd in soil was 0.535 mg/kg. It was used as a comparative test greenhouse for eight treatments. No.1 greenhouse was selected as the preferred test greenhouse, with three over-standard plots having average Cd concentrations of 0.530, 0.568 and 0.792 mg/kg. The comparative test results showed that after 8 months of remediation, the content of available Cd in the treatment of hydroxyapatite+rice biochar+deeper ploughing(T6) was reduced by 32.55% compared with CK(the control) and 24.96% than 2 months of remediation. The content of available Cd using the treatment of potassium dihydrogen phosphate+rice biochar+deeper ploughing(T7) decreased by 47.88% compared with CK and 31.00% than 2 months of remediation. The preferred remediation test results showed that in the treatment of hydroxyapatite+rice biochar+deeper ploughing: the mean Cd content decreased from 0.489 to 0.372 mg/kg, reducing by 23.86%, and the mean did not exceed the standard. Compared with CK, the mean content of available Cd decreased by 10.71% after 8 months, and the lowest content of available Cd in three treatments was 0.133 mg/kg. In addition, the Cd content, bioconcentration factor(BCF) and translocation coefficient(TF) of bean aboveground plants were decreased by 15.86%, 23.68% and 25.77%, respectively when compared with CK. Rice biochar+hydroxyapatite +deeper ploughing is a favoured technology for the remediation of Cd-contaminated greenhouse vegetable fields.

Study on Obstacles to Continuous Cropping of Vegetables and Soil Remediation Technology

Firstly,this paper analyzes the cause of obstacles to continuous cropping of vegetables,and then introduces the soil ecological remediation technology used for overcoming obstacles to continuous cropping of vegetables. Finally,this paper analyzes the effect of applying soil ecological remediation technology in overcoming obstacles to continuous cropping of vegetables.

Remediation Technology for Combined Pollution of Lead and Cadmium in Farmland Soil

At present,the problem of heavy metal pollution in farmland in southern China is serious. Especially,the cadmium and lead are two heavy metal elements with serious pollution and great harm to human body. This paper reviewed some common methods and materials used in the control of cadmium and lead pollution in farmland soil. Then,it discussed the problems in the repair of cadmium and lead pollution in farmland soil. It came up with the future research direction,to provide references for remediation of lead and cadmium pollution in farmland soil.

The Research Progress and Status of In-Situ Remediation Technology of Groundwater

The characteristics and application of the in-situ remediation technology of groundwater,including air sparing,electro kinetic remediation,in-situ chemical oxidation,in-situ groundwater bioremediation and permeable reactive barriers,were compared and evaluated.The results show that over 90%of

The Analysis and Remediation Technology of the Pollution of the Groundwater Environment in Longkou Plain, China

In order to study the groundwater environment in the Longkou plain,48 groups of water samples are collected,consisting of 7 groups of surface water samples and 41 groups of groundwater samples.The quality of groundwater in the Longkou Plain is poor,with class V water quality accounting for more than 90%,and no class I,II water quality,sporadic distribution of Class III and IV water quality.The influencing factors of water quality are mainly inorganic indicators such as nitrate,total hardness,chloride,salinity and sulfate,the detection rate of heavy metals is low.Nitrate is the main pollution index in this area,and the increase of nitrate content is closely related to the construction of underground reservoir.Based on the characteristics of groundwater pollution in the Longkou Plain,the in-situ chemical remediation of groundwater pollution is proposed.

Analysis of Soil Remediation Technology for Heavy Metalcontaminated Sites in Electroplating Enterprises

The advantages and disadvantages of chemical leaching,phytoremediation,in-situ/ex-situ solidification and stabilization,cement kiln co-disposal and safe landfill remediation are analyzed.In addition,the application of chemical leaching and in-situ/ex-situ solidification and stabilization technology in the treatment of heavy metal-contaminated soil in electroplating enterprises in China is introduced in detail to provide reference for the remediation of heavy metal-contaminated soil around electroplating enterprises in China.

Site Pollution Remediation and Its Technology

This paper summarized the connotation of contaminated site remediation,the differences between contaminated site and brownfield,the differences between contaminated site and soil pollution and land pollution,clarified the relationship between the concepts,and introduced the remediation technology of contaminated site.

Overview of Patented Technologies for Remediation of Soil Pollution

Soil, an important material basis for human activities, is an indispensable natural rasource that is difficult to regenerate. It is also an important part of human ecological environment. Currently, soil pollution has affected China＇s agricultural production and threatened human health and ecological safety, so it has been paid more attention to by the people and has become a hot spot in environmental field. Through continuous research, a variety of soil remediation patents and technologies also emerge. Here, by retrieving the main words through the website （www. soopat. corn） and Chinese patent net, types of soil pollution and remediation technologies under the authorization status of the patents were analyzed, and the major species of soil pollutants and soil remediation technologies were reviewed.

Study of polluted soil remediation based on freezing and thawing cycles

It is generally known that soil pollution poses a terrible hazard to the environment, but the present techniques of contaminated soil remediation cannot control this growing threat. This paper compares the pollutant extraction efficiency of traditional pumping and treating, which is a typical washing technology for the remediation of contaminated soils, with methods that utilize freeze-thaw cycles. In the soil freezing process, water shifts from unfrozen soils to the freezing front, and the permeability of soil will be enhanced under certain temperature gradients and water conditions. Therefore, this paper discusses the purification of contaminated soil through freeze-thaw action. We conducted a cleansing experiment on clay and silica sand infused with NaCl（simulation of heavy metals） and found that the efficiency of purification was enhanced remarkably in the latter by the freeze-thaw action. To assess the effective extraction of DNAPLs in soil, we conducted an experiment on suction by freezing, predicated on the different freezing points of moisture and pollutants. We found that the permeability coefficient was significantly increased by the freezing-thawing action, enabling the DNAPL contaminants to be extracted selectively and effectively.

Current Research and Strategy on the Biosurfactants Used in the Remediation of Petrochemical Polluted Environment

Biosurfactants are biologically active metabolites, and the efficiency of direct screening of new biosurfactants from nature using traditional methods is low, which should be enhanced in the following studies by adopting advanced biotechnologies. Rapid development and wide application of microbial culture independent methods, such as metagenomics, metatranscriptomics, metaproteomics and metabonomics, etc., contributes to quickly and precisely screening of novel biological surfactants. We mainly represented the current status of research and applications of biosurfactants in the remediation of petrochemical polluted environment, and also prospected avenues for future research.

Research Progress on the Remediation Benefits of Mineral Passivators on Heavy Metal Contaminated Soil

With the continuous development of society,the development of agricultural economy is also accelerating.Meanwhile,a large amount of sludge and waste materials enter the farmland system,and the state of soil heavy metal pollution is becoming more and more serious.In order to ensure food security and the health of people’s lives,a large number of experts and scholars have begun to look for remediation methods for heavy metal contaminated soil.At present,the use of mineral passivators in the remediation technology of heavy metal contaminated soil is a new and healthy recovery method,and has received extensive attention.

电动力耦合循环井技术修复低渗透含水层污染

提出一种电动力耦合循环井修复技术,以铬酸盐为典型目标污染物,研究该技术对低渗透含水层中地下水污染的修复效果及去除规律.结果表明:电动力耦合循环井技术相比循环井技术,修复半径扩大为原来的1.25倍,修复盲区面积占比从35.56%降为0,污染物的去除率从76.01%提高到了90.56%,相较于电动力修复技术电动力能耗降低了3个数量级,污染物去除率更高,可提升2~3倍.该技术耦合电动力方法实现了低渗透含水层中带电离子组分的强化定向迁移,解决了循环井在低渗透含水层中传质效率低、修复范围小、存在水力循环盲区等问题,修复效果显著提升.

黑臭水体底泥处理技术发展现状

我国河湖黑臭水体问题极大地影响了生态环境系统,并对人体健康和经济发展构成威胁。目前随着我国大力推进黑臭水体治理,截污系统逐渐完善,底泥中污染物释放及在厌氧环境下发酵产生的嗅味物质引发的内源污染成为了河湖黑臭的重要原因。因此,黑臭水体底泥治理成为了水环境治理领域的热点和难点,目前针对黑臭水体底泥的主要处理方法有异位修复和原位修复两大类。本文针对黑臭水体底泥的成因、组成及危害做出分析,系统阐述了异位修复技术和原位修复技术的分类、原理及各处理技术的利弊,并对底泥修复技术的发展做出展望,明确了原位修复技术的巨大发展空间。

地下水污染修复技术及其国内工程应用进展

地下水污染具有长期性、隐蔽性、难恢复性等特点,开展地下水污染场地的修复工作是一项巨大的挑战。对此,国内外研究团队提出了多种修复技术,但如何选择适用于我国地下水污染场地的技术或技术组合,对我国地下水污染治理具有重要意义。本文对常用修复技术在我国的工程应用情况进行调查整合,并从技术原理、场地水文地质条件的适用范围及工程应用效果等方面对其进行具体探讨,综述了地下水污染场地修复技术筛选常用方法,希望为我国地下水污染场地修复提供些许参考。

场地污染地下水抽出处理系统井群加权优化方法研究

井群布设是地下水修复抽出处理技术的关键环节之一。为提高抽出处理技术的修复效率,以某污染场为研究对象,建立非线性-动态-多目标的模拟-优化模型,以污染物去除率最高、修复达标时间最短、资金成本最低为优化目标,设定单井、双井、三井模式下不同的抽出流量,采用加权优化方法对井群布设方案进行对比计算。结果表明:整体而言单井模式修复效果较差,侧重资金成本时双井模式抽出方案修复效果整体较优,侧重达标时间成本时三井模式抽出方案修复效果整体较优;单井模式恒定流量抽出修复效果较优,多井模式下后期若适当降低抽出流量,可减少总抽出量,节省资金成本,井群动态管理可提高修复效率。研究验证了加权优化方法在井群优化应用中的灵活性和实用性,可为加权优化方法结合数值模拟方法在抽出处理技术的井群布设优化中应用提供参考。

我国土壤中抗生素抗性基因污染的消减策略

近年来,土壤环境的抗生素耐药性问题日益严重并逐渐成为威胁人类和动植物健康的全球性挑战。抗生素抗性基因(ARGs)是耐药性在土壤中传播的重要载体和指示物质,寻找合适的策略以降低其在土壤中的丰度及传播风险是当前和今后一个时期深入推进生命-生态一体化健康的主攻方向。ARGs进入土壤的途径主要包括粪肥施用和废水灌溉。针对不同来源,利用好氧堆肥和厌氧消化等阻控技术可从源头有效阻止ARGs进入土壤。当ARGs不可避免地进入土壤后,则仍需前瞻性研究和使用噬菌体、生物炭等ARGs污染土壤原位修复技术并深入开发植物间作等调控技术以构建免疫型土壤微生态环境。该文从阻控、修复和调控3个技术层面对ARGs去除效果和技术优劣势进行归纳,以期为土壤ARGs消减的技术开发和实际应用提供参考。

长江经济带工业区污染场地特征及修复技术选择分析

掌握工业场地污染特征及修复技术选择信息,明确场地污染防治需求,对长江经济带工业区污染场地土壤污染防治及再开发安全利用具有重要意义.本文对长江经济带工业区621个污染场地修复治理的案例数据进行调研,采用相关性分析等方法,对工业场地的污染特征及修复技术的优先选择进行了综合解析.结果表明:砷、镍、汞、铅、铬、锌、镉、苯、1,2-二氯乙烷、氯仿、苯并[a]芘和石油烃是长江经济带工业区的主要目标污染物,也是引起下游地区以复合型污染为主(48%)的主要因子,而砷、铅、镉、铬等的普遍存在是造成中上游地区以无机型污染为主(上游无机型污染占48%,中游占67%)的主要原因;化学原料和化学制品制造业污染场地中涉及污染物种类(116种)最多,占据长江经济带工业区污染场地中发现污染物种类的85%;调研的案例中污染深度较大的场地(污染深度>10 m)多集中于下游地区,可能受场地土层结构、污染物本身性质以及企业的生产年限等因素影响;目前长江经济带工业区污染场地修复技术多选择异位修复,主导因素为场地污染类型、用地规划以及修复效果和工期.研究显示,长江经济带工业区场地污染特征具有区域性,以异位固化/稳定化、水泥窑协同处置和异位化学氧化为主的异位修复技术应用广泛,未来需要进一步加强引导土壤污染防治向绿色低碳发展.

过碳酸钠-过硫酸钠双氧化体系降解地下水中三氯乙烯

为了解决单一氧化体系降解地下水中三氯乙烯的效率不高的问题,采用柠檬酸螯合Fe^(2+)催化过碳酸钠与过硫酸钠协同降解地下水中的三氯乙烯,考察过碳酸钠和过硫酸钠的配比、水质条件(pH、典型阴离子)以及三氯乙烯的初始浓度对三氯乙烯降解效率的影响。结果表明,当三氯乙烯的初始浓度为0.16 mmol/L时,在中性条件下,柠檬酸螯合Fe^(2+)催化过碳酸钠-过硫酸钠双氧化体系可以显著提高地下水中三氯乙烯的降解速率;三氯乙烯的降解受过碳酸钠与过硫酸钠的配比的影响,过碳酸钠、过硫酸钠、柠檬酸、 Fe^(2+)、三氯乙烯的物质的量比为10∶8∶5∶10∶1时,反应180 min后三氯乙烯的降解率为98.5%;随着反应体系pH增大,三氯乙烯的降解率逐渐降低;地下水中常见的阴离子SO_(4)^(2-)、 NO_(3)^(-)对该双氧化体系去除地下水中三氯乙烯的影响较小,但较高浓度的HCO_(3)^(-)、 Cl^(-)显著抑制三氯乙烯的降解;自由基清扫实验确定双氧化体系中存在氢氧自由基HO·、硫酸根自由基SO_(4)^(-)·、超氧自由基O_(2)^(-)·等自由基,且HO·对三氯乙烯的降解起主导作用。