石油污染土中微生物的分离鉴定及降解特性

为了为汽油污染土的微生物修复提供优良菌种,以LB培养基为基质,从石油污染土中对汽油降解菌进行了分离鉴定,以降油培养基为基质对分离得到的菌株进行汽油降解率的测定,以培养温度、培养基pH值及培养时间为参数对5种具有优良汽油降解性能的菌株进行单因素试验,基于单因素试验结果进行三因素三水平的正交试验后,以汽油降解率为响应值对试验结果进行响应面分析,筛选出具有优良降解性能的菌株,并确定了菌株降解汽油的最佳条件。结果表明:从石油污染土中分离出了9种具有汽油降解性能的菌株,其中,铜绿假单胞菌、假单胞菌属、苍白杆菌属、博得特氏菌属以及戈登氏菌属具有优良降解性能,这5种菌降解汽油的最优条件为:铜绿假单胞菌、假单胞菌属、苍白杆菌属、博得特氏菌以及戈登氏菌的最佳培养温度均为32℃,培养基pH值均为7.0,培养时间均为20 h,降油培养基中的汽油降解率分别为70.12%、76.42%、75.66%、77.50%和73.22%。

受污染地块的深基坑土方开挖及污染土验收流程探究

大城市中受污染场地的土壤修复工程逐渐增多。土壤修复的同时,地块内深基坑的安全也必须引起高度重视。根据传统的污染土效果评估方式,很难在满足土壤修复诸多要求的同时保证深基坑的安全。因此,介绍了一种改进的土壤效果评估方式,在满足深基坑安全的同时兼顾了土壤修复相关要求。该改进方法简化了土壤的验收流程与深基坑中土方开挖流程,从而减少了由于深基坑长时间暴露而带来的潜在风险。实践证明,改进的土壤效果评估方案,可带来巨大的时间效益、经济效益和社会效益。

常州市某污染土深基坑开挖有限元分析

为探究土壤修复工程中污染土“换土”处理对再次开挖基坑产生的影响,以常州市某污染土修复项目为例,运用有限元数值计算方法,对污染土基坑的“换土”、回填及再次开挖过程做了模拟分析;并结合理论分析,探究了污染土基坑回填后对周边环境的影响,比较了污染土基坑再次开挖与直接在原状土场地开挖两种情况下支护桩水平位移的区别。结果表明,污染土基坑回填后其边界处有较为明显的变形,再次开挖后支护桩桩顶位置处有更大的水平位移。并基于此给出了一些建议以确保基坑的安全性,对于实施类似的土壤修复工程有一定的借鉴意义和参考价值。

微生物岩土技术及其应用研究新进展

微生物岩土技术主要是利用自然界广泛存在的微生物的代谢功能,与环境中其他物质发生一系列生物化学反应,改变土体的物理力学及工程性质,从而实现环境净化、土壤修复、地基处理等目的。微生物岩土技术作为岩土工程领域新的分支逐渐成为一个热门研究方向,近年来,许多学者已经开展了相关研究。为了促进该领域更加全面深入的基础研究,指导微生物技术在岩土工程中更切合实际的推广与应用,对环境岩土工程领域涉及的几种主要微生物种类、相关生物化学反应过程以及微生物作用机理进行详细的介绍与总结,并对微生物岩土技术在土体加固、岩土体抗渗封堵、金属污染土修复等方面的相关研究及应用进行了总结与评述。

Effects of Red Mud on the Remediation of Pb, Zn and Cd in Heavy Metal Contaminated Paddy Soil

[Objective] To study the remediation efficiency of red mud on Pb, Zn and Cd in the heavy metal contaminated paddy soil of mine area, to clarify its remediation mechanism and fertilizer efficiency on heavy metal contaminated soil. [Method] The soil incubation experiment was conducted to study the effect of red mud on the pH values and electrical conductivity （EC）, and the remediation efficiency of red mud on lead （Pb）, zinc （Zn） and cadmium （Cd） in heavy metal contaminated soil. [Result] Red mud addition reduced the content of exchangeable Pb, Zn and Cd in the soil significantly. Compared with the control, when incubated for 30, 60 and 90 d with the red mud dosage of 4% （W/W）, the exchangeable Pb content was decreased by 39.25%, 41.38% and 50.19%; exchangeable Zn content was decreased by 49.26%, 57.32% and 47.16%; and exchangeable Cd content was decreased by 19.53%, 24.06% and 25.70%, respectively. The application of red mud had significant impact on the share of Pb, Zn and Cd contents in five forms, and different amounts of red mud application all reduced the proportion of exchangeable Pb, Zn and Cd to the total Pb, Zn and Cd. In addition, the proportion of exchangeable Pb, Zn and Cd to total Pb, Zn and Cd decreased with the increasing amount of red mud addition. [Conclusion] The study provided references for reasonable application of red mud and reduction of heavy metal pollution in paddy soil.

Research Progress of Phytoremediation Technology on Soils Polluted by Heavy Metals in Mining Areas

Phytoremediation is an efficient and economic ecological technology. It includes phytostabilization, phytovolatilization, and plant absorption. In the research, status quo and progress of Phytostabilization and plant absorption in soils polluted with heavy metals in metal mines were summarized, including the characteristics and status quo of phytoremediation and selection method of hyperaccumulator. In addition, further research was proposed as well.

Study Progress in Remediation of Soil Contaminated by Heavy Metals and Its Application Prospect

Flax is an ideal crop for remedying soil contaminated by heavy metals. It has high tolerance to heavy metals and strong adsorption to heavy metals. Through properly using or adjusting external conditions such as regulator, moisture, fertilizer, microorganisms, and pH value, it is able to improve ability of flax to absorb, trans- fer, and accumulate heavy metals. To improve the ability of flax in remediating heavy metal contaminated soil, it is recommended to strengthen cultivation of flax varieties and screening of germplasm resources, actively carry out studies on tech- nologies of fax remedying heavy metal contaminated soil, implement large-scale and mechanized planting of flax, and promote control of heavy metal contaminated soil.

Improvement in electrokinetic remediation of Pb-contaminated soil near lead acid battery factory

To improve the conventional electrokinetic remediation of Pb-contaminated soil,the Pb-contaminated soil near a lead acid battery factory in the Pearl River Delta region of China was electrokinetically remedied with polarity exchange technique.The variations in Pb removal efficiency and the soil p H value with the treatment time and the exchange polarity interval were determined.It is found that the removal efficiency of Pb reaches a maximum of 87.7% when the voltage gradient is 1 V/cm and the exchange polarity interval is 48 h.This value is far higher than that obtained with conventional electrokinetic remediation（61.8%）.Additionally,the ＂focusing effect＂ which appears in the conventional electrokinetic remediation can be avoided,and thus additional chemicals are not needed for the polarity exchange technique.The mechanism of Pb electromigration behavior in soil during the treatment with the polarity exchange technique was described.

浅析环保工程的全过程控制管理

环保工程在当今社会越来越被人们所关注,环保工程的全过程控制管理是为了保证工程实施的规范、工程质量的合格、资金使用的合理有效,来达到环保效果的控制手段。但是现阶段由于环保工程全过程控制管理的基础比较薄弱,为改善这一现状,该文结合污染土修复工程谈了几点体会,可供类似工程参考。

Study on the Remediation of Cd-contaminated Soil

[Objective] The remediation effect of the plant to Cd-contaminated soil was studied. [Method] By taking simulation test and field test, the ryegrass （Lolium perenne L.） was planted, and the remediation effect of the plant to contaminated sites was studied. [Result] The ryegrass was planted in the eluotropic soil for 0-60 d, Cd content in the soil showed a rapid decreasing trend; after 60 d, the enrich- ment ability of the plant to Cd gradually weakened over time; after 75 d of phytore- mediation, the Cd content in the soil decreased greatly, and the remediation effi- ciency was 90.66%. [Conclusion] Ryegrass remediation technology had good reme- diation effect to Cd-contaminated soil.

Degradation of TCP in Soil Planted with Alfalfa(Medicago sativa L.)

[Objective] The research aimed to study the degradation of 2,4,6-trichlorophenol （TCP） in soil planted with alfalfa （Medicago sativa L.）,as well as to provide references for the Chlorophenols phytoremediation technology in the practical application.[Method] By the use of pot culture experiment in greenhouse,the phytoremediation effect of alfalfa on TCP-contaminated soil,the growth conditions of alfalfa,as well as the effect of TCP on the activity of soil polyphenol oxidase,dehydrogenase and catalase were studied.[Result] After the alfalfa was grown for 75 d,the TCP content in soil of three different concentrations treatments （low,middle and high） decreased dramatically within 15 d,and then the decreasing rate was gradually slow; on the 30^th d of cultivation,the fresh weight of treated alfalfa showed no significant difference with the control （P〈0.05）,indicating that TCP in soil had inhibition effect on the growth of alfalfa; alfalfa could significantly enhance the activities of polyphenol oxidase,dehydrogenase and catalase,thus raising the degradation capability of soil plants and microorganisms on pollutants in soil.[Conclusion] There results indicated that alfalfa could enhance the degradation rate of organics in the contaminated soil and enhance soil enzyme activity,so the alfalfa could be used for the bioremediation of TCP contaminated soil.

浅析环保工程的全过程控制管理

随着改革开放和社会的发展,环保工程在当今社会越来越被人们所关注,环保工程的全过程控制管理可以保证工程实施能够符合规范,是一种能够达到环保效果的控制手段。现在,我国对于环保工程全过程控制的管理方面相对薄弱,为改善这一现状,本文通过分析总结我国环保工程全过程控制管理工作中存在的问题,结合污染土修复工程,探讨应对全过程控制管理基础薄弱问题的对策,以期为我国环保工程的健康持续发展提供借鉴。

Surfactant-Enhanced Phytoremediation of Soils Contaminated with Hydrophobic Organic Contaminants:Potential and Assessment

Phytoremediation is becoming a cost-effective technology for the in-situ clean up of sites polluted with hydrophobic organic contaminants （HOCs）. The major factors limiting phytoremediation are the mass transfer, rate of plant uptake, and microbial biodegradation of HOCs. This article discusses the potential of surfactants to enhance desorption, plant uptake, and biodegradation of HOCs in the contaminated sites. Positive effects of surfactants on phytoremediation have been recently observed in greenhouse studies. The presence of some nonionic surfactants including polyoxyethylene sorbltan monooleate （Tween 80） and polyoxyethylene（23）dodecanol （Brij35） at relatively low concentrations resulted in significant positive effects on phytoremediation for pyrene-contaminated soil. However, the anionic surfactant （sodium dodecyl sulfate, SDS） and the cationic surfactant （cetyltrimethylammonium bromide, CTMAB） were not useful because of their phytotoxicity or low efficiency for surfactant-enhanced phytoremediation （SEPR）. The mechanisms of SEPR for HOC-contaminated sites were evaluated by considering experimental observations. In view of concerns about the cost effectiveness and toxicity of surfactants to plants, more research is needed to enhance the use of SEPR technology.

Application of polymeric aluminum salts in remediation of soil contaminated by Pb,Cd,Cu,and Zn

Soil contaminated with typical heavy metals (Pb,Cd,Cu,and Zn) was remedied by using the polymeric aluminum salt coagulants including polyaluminum chloride (PAC) and polyaluminum sulfate (PAS).The remediation efficiencies are influenced by reaction time,water amount,and dosage of remediation agent.The optimal remediation conditions are as follows:6 h of reaction time,1 kg/kg of water addition amount,and 0.25 kg/kg of remediation agent dosage.After PAC addition,the remediation efficiencies of diethylenetriamine-pentaacetic acid (DTPA)-extractable Pb,Cd,Cu,and Zn reach 88.3%,85.1%,85.4%,and 73.7%,respectively;and those for PAS are 89.7%,88.7%,83.5%,and 72.6%,respectively.The main remediation mechanism of the polymeric aluminum salt may contribute to the ionization and hydrolysis of PAC and PAS.H + released from ionization of polymeric aluminum salt can cause the leaching of heavy metals,while the multinuclear complex produced from hydrolysis may result in the immobilization of heavy metals.For PAC,the immobilization of heavy metals is the main remediation process.For PAS,both leaching and immobilization are involved in the remediation process of heavy metals.

Study on electrokinetic remediation of cadmium contaminated soils

Kaolinite from a lead-zinc mining district,which was spiked with cadmium,has been treated by electrokinetics to investigate effects of treatment time and applied voltage gradient.The results showed that the increased test duration had induced a higher removal rate of cadmium.Being treated for 7 days,cadmium was removed from kaolinite dramatically.It was also found that higher removal rate happened when a higher voltage gradient was applied and cadmium accumulated near the cathode because pH increased.Increase of pH near the cathode caused accumulation of cadmium.Moreover,it was observed that cation exchange membrane which was placed between kaolinite and cathode could make pH lower than the initial value and avoid the higher pH near the cathode.As a result,the high concentration accumulation of cadmium near the cathode was avoided.

Influence of Phosphate on Transformation and Plant Uptake of Cadmium in Cd-amended Soils

Phosphate was found to have neither influence on Cd transformation nor effect on plant Cd uptake in three Cd-amended upland soils.However,on submerged red earth,high phosphate dressing inhibited the transformation of Cd from exchangeable fraction to other lower-available ones.Cadmium uptake by rice plants increased simultaneously with increasing phosphate supply though plant resistance to Cd also increased at high phosphate level.Application of phosphate as an amendment for Cd-contaminated soil was therefore not recommended in view of the increasing influx of Cd into food chain especially on flooded soils.

Mathematical Modei of In-situ Ozonation for the Remediation of 2-Chlorophenol Contaminated Soil

A microscopic diffusion-reaction modei was developed to simulate in-situ ozonation for the remediation of contaminated soil, i.e., to predict the temporal and spatial distribution of target contaminant in the subsurface. The sequential strategy was employed to obtain the numerical solution of the modei using finite difference method. A non-uniform grid of discretization points was emploved to increase the accuracy of the numerical solution by means of coordinate transformation. One-dimensional column tests were conducted to verify the modei. The column was packed with simulated soils that were spiked with 2-chlorophenol. Ozone gas passed through the column at a flow rate of 100ml·min-1. The residual 2-chlorophenol content at different depths of the column was determined at fixed time intervals. Compared the experimental data with the simulated values, it was found that the mathematical modei fitted data well during most time of the experiment.

Modeling for Volatilization and Bioremediation of Toluene-contaminated Soil by Bioventing

A two-dimensional numerical model is developed to simulate the flow,transport and biodegradation of toluene during bioventing （BV） processes in the unsaturated zones.The simulation for a single well BV system is used to illustrate the effect of air injection rate on remediation efficiency.The air is injected into the vadose zone to create a positive pressure.Simulation results show that air injection rate is a primary parameter governing the dispersal,redistribution and surface loss of contaminant.At injection rates of 81.504 m3·d-1 （Run 1） and 407.52 m3·d-1 （Run 2）,the total removed mass of toluene is 169.14 kg and 170.59 kg respectively.Ratios of volatilization to bio-degradation in Run 1 and Run 2 are 0.57︰1 and 0.89︰1,respectively,indicating that lower air injection rate enhances the biodegradation efficiency greatly.Air injection rate should be optimized to meet oxygen demand and to minimize the operational cost.

Microbial Remediation of Heavy Metal(loid)Contaminated Soil: A Review

Because of the rapid development of industrial processes, increased urban pollution and agricultural chemicals applied in recent years, heavy metal(loid) pollution in soil has been very serious, and there is an urgent need for fast and efficient removal of heavy metal(loid) pollution. Currently, environmental microorganisms are always used to perform biological alteration or improvement of soils and sewage. Using functional microorganisms that are resistant to toxic heavy metal(loid) ions for alteration and transformation of heavy metal(loid)s in ionic form is an effective measure for microbial remediation of heavy metal(loid)contaminated soil. This paper reviewed the microbial remediation mechanism of heavy metal(loid) contaminated soils, and the approaches for breeding bacteria those can be used for highly efficient removal of heavy metal(loid)s, as well as the application examples of microbial remediation and transformation of heavy metal(loid) contaminated soil, and finally described the future trends and further research work of heavy metal(loid) contaminated soils by microbial remediation.

Phytoremediation of Cd Contaminated Soil through Certain Weed and Crop Species

Phytoremediation is a relatively new approach in remediating ecosystems contaminated by ecotoxic pollutants such as herbicides or heavy metals and especially cadmium （Cd）. Certain indicators of phytoremediation, as plant growth, tolerance to Cd, and uptake, transfer factor （TF） and percent removal of Cd, were studied for 11 crops and 8 weed species in soil with varying levels of Cd （0-240 mg Cd kg＂ soil） under controlled environment. Cadmium accumulated mainly in roots （51%-86%, depending on the species）, while a 14%-49% was transferred to shoots （except for four species） the concentration being positively related to Cd level in soil. Highest concentration in the above ground plant part was measured in sugarbeets （41-101 mg Cd kg-1 DW） followed by Bromus sterilis （75）, Eruca sativa （32-82）, Cichorium intibus （35-80）, and maize （60 mg Cd kgl）. Based on the results it is concluded that sugarbeets, maize, C. intibus, B. sterilis, E. sativa, Apium graveolens, and Vicia sativa seem to have a potential in remediating Cd contaminated soils.