Remediation of in-situ Leach Mining Contaminated Soil by Amendment-plant Synergism

This study aimed to remediate in-situ leach mining contaminated soil by amendment-plant synergism. The results showed that plant species exhibited ex-tremely significant effects on the concentration of nitrate nitrogen; to be specific, the concentration of nitrate nitrogen in soil planted with wheat was reduced from 692.19 mg/kg to lower than 100 mg/kg; when the mass ratio of amendment to soil reached 3：50 and the amendment particle size was 1-2 mm, the concentration of nitrate ni-trogen in soil planted with wheat was reduced to 43 mg/kg. The amendment type exhibited extremely significant effects on the concentration of ammonium nitrogen; to be specific, when the mass ratio of amendment to soil reached 10：50, the concen-tration of ammonium nitrogen in soil added with 2-3 mm zeolite was reduced from 23 593.75 to 3 300 mg/kg on day 15. Amendments and plants mainly exhibited desorption performance for sulfate radical in soil, and the amendment type extreme-ly significantly affected the concentration of sulfate radical; to be specific, the con-centration of sulfate radical in soil added with limestone increased from 370 mg/kg to 900 mg/kg on day 7.

Application research of enhanced in-situ micro-ecological remediation of petroleum contaminated soil

Experimental study of enhanced in-situ micro-ecological remediation of petroleum contaminated loess soil was carried out in Zhongyuan oil production areas, and the enhanced in-situ micro-ecological remediation technique includes optimistic in-situ microbial communities, physical chemistry methods, alfalfa planting and regulation of soil environmental elements. Experiments showed that the oil content in the contaminated soil with oil content about 2 898.25 mg/kg can be reduced about 98.61% after in-situ micro-ecological remediation for 99 days, which demonstrated the effectiveness of in-situ micro-ecological remediation methods for petroleum contaminated soil in central plains of China, and explored the practical and feasible application of these methods.

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.

In-situ remediation of deep petroleum-contaminated soil injection

A computational fluid dynamics(CFD)numerical simulation and field experiment were used to investigate optimal operating parameters of high-pressure jet grouting equipment and clarify the boundary law of the injection area in the remediation process.The response surface optimization design results show that the optimal injection pressure is 30 MPa,rotation speed is 23 r/min,commission speed is 30 cm/min,and the optimal injection diameter is 147.3 cm.Based on the CFD numerical simulation,the ratio of the injection core,turbulent zone,and seepage zone is approximately 1∶4∶2.The distribution law of jet core,turbulence zone and seepage zone at different cross-sections under 30 MPa operating conditions is as follows:The jet core radius is approximately 100 mm,the turbulence zone is mainly distributed at 100 to 500 mm,the seepage zone is mainly distributed at 500 to 700 mm,the seepage zone could be completed within 2 h,and the proportion of the three boundary zones in the injection zone is similar to that of the numerical simulation.This study provides theoretical parameters and practical reference for the remediation of deep pollution via in-situ chemical oxidation in the Loess Plateau soil environment.

Enhanced remediation of chlorpyrifos-contaminated soil by immobilized strain Bacillus H27

Chlorpyrifos is a pesticide widely used in agricultural production with a relatively long residual half-life in soil.Addressing the problem of residual chlorpyrifos is of universal concern.In this study,rice hull biochar was used as an immobilized carrier to prepare the immobilized strain H27 for the remediation of chlorpyrifos-contamination soil.Soil microorganisms after remediation were investigated by ecotoxicological methods.The immobilized strain H27 had the highest removal rate of chlorpyrifos when 10%bacterial solution was added to the liquid medium containing 0.075-0.109 mm diameter biochar cultured for 22 hr.This study on the removal of chlorpyrifos by immobilized strain H27 showed that the initial concentration of chlorpyrifos in solution was 25mg/L,and the removal rate reached 97.4%after 7 days of culture.In the soil,the removal rate of the immobilized bacteria group increased throughout the experiment,which was significantly higher than that of the free bacteria and biochar treatment groups.The Biolog-ECO test,T-RFLP and RT-RCR were used to study the effects of the soil microbial community and nitrogen cycling functional genes during chlorpyrifos degradation.It was found that ICP group had the highest diversity index among the four treatment groups.The microflora of segment containing 114 bp was the dominant bacterial community,and the dominant microflora of the immobilized bacteria group was more evenly distributed.The influence of each treatment group on ammonia-oxidizing bacteria(AOB)was greater than on ammonia-oxidizing archaea(AOA).This study offers a sound scientific basis for the practical application of immobilized bacteria to reduce residual soil pesticides.

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.

Immobilization of Cd and Pb in soils by polymeric hydroxyl ferric phosphate

A polymeric hydroxyl ferric phosphate(PHFP)was prepared by using a byproduct of titanium dioxide containing ferrous sulfate and phosphates under alkaline condition.The PHFP was used to immobilize lead(Pb)and cadmium(Cd)in soils.Fourier transform infrared spectra,X-ray diffraction were applied to revealing the characteristics of PHFP,and the modified Tessier sequential extraction and column leaching experiment with simulated acid rain were used to assess the effectiveness of immobilization of Cd and Pb in soils by PHFP.The results showed that PHFP was indeed a polymer with complicated OH-Fe-P structure and consisted of Fe6(OH)5(H2O)4(PO4)4(H2O)2and Fe25(PO4)14(OH)24.Moreover,the removal rates of DTPA-extractable Cd and Pb in soils reached up to33%and45%,and the water-soluble Cd and Pb decreased by56%and58%,respectively,when PHFP was added in soils at4%dosage.In addition,the immobilization of Cd and Pb contributed to transforming water soluble,exchangeable and carbonate-bonded fractions to Fe and Mn oxides-bonded,organic-bonded and residual fractions.Under leaching with simulated acid rain,Cd and Pb release amount in PHFP amended soil declined by53%and52%,respectively,as compared with non-treated soil.The result implied that PHFP had a potential application for the remediation of Cd-and Pb-contaminated soils.

Advances in Microbial Fuel Cells in the Field of Environmental Remediation

In order to protect ecological environment,it is urgent to restore the polluted environment. Among traditional methods of environmental remediation,it is common to add excessive electron donors or electron acceptors to the polluted environment,but these methods have a high cost and can cause secondary pollution easily. Microbial fuel cells( MFCs) can realize the transformation of pollutants and collection of electric energy by using microorganisms as a catalyst; they are clean,efficient and controlled easily and have a wide range of application,so MFCs have wide application prospects in the field of environmental remediation. In this study,MFCs and their applications in the field of environmental remediation were summarized.

高效烃降解菌群的驯化、降解特性及初步应用

微生物技术在石油污染土壤的修复中具有广阔的应用前景,而获得具有高降解效率的菌(菌群)是保证高效修复的关键。该研究从4种不同含油土壤中驯化、培养获得稳定、高效降解石油烃的1号菌群,对其进行高通量测序,确定菌群组成;研究不同环境因素对该菌群石油烃降解能力的影响,确定了最佳降解条件;对菌群降解石油烃的特性和降解动力学进行了分析;探究了该菌群在较高浓度含油土壤中的应用潜力,以及以破碎荞麦壳为载体,将菌群固定化后修复石油烃-镉复合污染土壤的能力。结果表明,该菌群主要由寡养单胞菌属(Stenotrophomonas)、假单胞菌属(Pseudomonas)、苍白杆菌属(Ochrobactrum)、乳杆菌属(Lactobacillus)和无色杆菌属(Achromobacter)等组成;在原油质量浓度为0.5%,p H为8,盐度为1%,温度为35℃,C∶N∶P为100∶2∶1,以硝酸铵为氮源的最佳条件下,培养10 d后,菌群对石油的降解率由52.1%提高至76.6%;GC-MS分析结果显示,培养9 d和24 d后菌群对C13~C26烷烃平均降解率分别为90.3%和97%,说明该菌群能够快速高效降解中长链烷烃。菌群对原油初始浓度为0.5%和4%的降解符合一级反应动力学模型。将菌群接种于石油含量为4 631 mg/kg、8 591 mg/kg的土壤中,40 d后降解率分别为47.7%、26.4%;固定化后的菌群用于修复石油烃-镉复合污染土壤,石油烃降解率、土壤脱氢酶活性和过氧化氢酶活性高于其他组,可交换态镉的浓度低于其他组。以上结果充分显示了该菌群在石油浓度较高的土壤以及石油烃-镉复合污染土壤修复中的应用潜力。

高温活化磷尾矿钝化矿区污染土壤中阳离子态重金属研究

矿冶场地土壤重金属污染是重要的环境问题,亟需研发低成本的高效修复技术。化学钝化是常用修复技术,但现有钝化材料仍存在效率较低、成本较高等问题。本研究采用900℃高温处理制备活化磷尾矿材料,研究不同处理下材料对土壤重金属的钝化效果。结果表明:高温处理将磷尾矿中的白云石分解为方解石、MgO和CaO,活化材料可显著提升土壤pH,降低土壤可交换态重金属含量;添加0.8%的高温活化磷尾矿钝化30天后,土壤可交换态Zn、Cd和Pb含量分别降低97%、46%和95%。重金属由可交换态向碳酸盐结合态转化,部分Cd转化为铁锰氧化物结合态。主要钝化机理为MgO与水反应生成氢氧化物提升土壤pH,促使重金属形成氧化物、氢氧化物沉淀,同时增加铁锰氧化物对Cd的吸附固定。研究结果可为矿区土壤原位钝化和磷尾矿资源化利用提供参考。

固定化微生物技术在多环芳烃污染土壤修复中的应用

固定化微生物技术是修复多环芳烃(PAHs)污染土壤有效且环保的方法之一。该技术通过保护微生物免受周围恶劣环境的影响,在PAHs污染场地修复中长时间保持功能微生物活性,克服传统微生物修复效率低、周期长等问题。主要介绍了我国土壤PAHs污染现状及常见的PAHs污染土壤微生物修复技术;从载体材料、降解菌及固定条件3个方面综述固定化微生物技术的研究现状以及影响固定化效果的重要因素;从土壤环境、微生物群落和吸附-降解过程分析PAHs污染土壤固定化微生物修复的作用机制;最后从载体材料、功能微生物、固定方法、评价体系、生态风险和实际应用6个方面,对固定化微生物技术在PAHs污染土壤修复中存在的问题进行总结并提出展望。

磁性炭基菌球降解土壤阿特拉津性能的研究

本研究通过海藻酸钠包埋磁性生物炭与降解菌DNS32形成磁性炭基菌球(DMBC-P),并将其用于阿特拉津(ATZ)污染土壤的修复,探讨其去除ATZ的效能及促进大豆幼苗生长的能力。研究表明,当海藻酸钠与氯化钙的浓度为2%时,DMBC-P对ATZ的去除能力最强。在DMBC-P投加量为2%、温度为30℃、pH=7.3时,其对水体中ATZ的去除率可达到99.99%;并且在pH为3.3~7.3、温度为10~50℃以及ATZ浓度为30~140 mg·L^(-1)的环境中,DMBC-P对ATZ的去除性能仍然十分优异且其可以被有效回收。盆栽试验结果表明,施用DMBC-P进行修复后,该处理下大豆幼苗的生理指标显著高于空白对照处理,叶绿素a、叶绿素b、类胡萝卜素和总叶绿素含量分别提高79.14%、45.48%、67.87%和110.78%。研究表明,DMBC-P施用于污染土壤中能够实现ATZ的高效去除和材料有效回收,是一种极具潜力的污染土壤修复材料。

天然矿物修复剂筛选及其对镉固持性能研究

对湖南省14个产地、4类矿物材料的镉固持性能进行对比,优选出4种天然高效镉修复材料(宁乡县喻家坳的石灰石、湘潭县楠木冲的低品位锰矿石、桃源县马宗岭的膨润土和石门县新岗的海泡石)。4种天然矿物材料对镉的固持动力学速率从快到慢排序为:膨润土>石灰石>海泡石>锰矿石。各矿物材料对镉的吸附量随着镉初始质量浓度增大而增大,镉质量浓度不高于10.0 mg/L时,各矿物材料对镉的吸附量从大到小排序为:石灰石>膨润土>锰矿石>海泡石;镉质量浓度高于10.0 mg/L时,各矿物材料对镉的吸附量从大到小排序为:膨润土>石灰石>锰矿石>海泡石。吸附行为均符合Langmuir吸附模型,膨润土、石灰石、锰矿石、海泡石对镉的最大吸附容量分别为29.38、14.51、9.67、5.27 mg/g。溶液pH=6~9时,各矿物材料对镉的去除效率排序为:石灰石>膨润土>锰矿石>海泡石。天然矿物材料对镉的固持效果与矿物的化学组分、初始镉质量浓度、pH值有关。

固定化微生物技术修复镉污染红黏土的室内试验研究

为了探究固定化微生物技术对镉(Cd)污染红黏土物理力学性质和环境污染的修复效应,以活性炭为载体,菌种选取巴氏芽孢杆菌,开展基本物理试验、无侧限抗压强度试验、毒性浸出试验和重金属形态提取试验。试验结果表明:巴氏芽孢杆菌对镉离子有较强的耐受性;对比单加微生物或活性炭,固定化微生物技术的修复效果更显著;14%活性炭微生物土样的无侧限抗压强度为229.7 kPa,较镉污染土提升174.7%;修复21 d后,10%活性炭微生物土样的镉离子浸出浓度降低到0.002 mg/L,较镉污染土样降低99.8%;修复后,土中的镉从弱酸态向可还原态和残渣态转化。总的来说,固定化微生物技术对镉污染红黏土具有良好的修复效果,活性炭的掺量以10%为宜。研究成果可为贵州省镉污染红黏土的治理提供参考。

生物炭-壳聚糖复合材料对镉污染土壤的修复效果研究

[目的]探讨生物炭-壳聚糖复合材料(CBC)对镉(Cd)污染土壤的修复效果。[方法]以黑麦草为供试植物进行盆栽试验,探究向酸性低镉土壤、中性高镉土壤和碱性高镉土壤中分别添加0、0.5%、1.0%和3.0%(W/W)的CBC时,土壤pH、全镉含量、有效态镉含量、黑麦草根和茎叶的生物量以及其中的全镉含量变化情况。[结果]施用CBC可以提高酸性和中性土壤的pH。随着CBC施用量的增加,土壤中有效态镉含量降低,当施加量至3.0%时达到显著水平。CBC可以钝化土壤中的镉活性,其钝化效果与土壤污染程度、酸碱性密切相关。随着CBC施加量的增加,黑麦草根和茎叶中镉含量降低,尤其植物地上部分降低效果明显,也证明了CBC对土壤中镉具有钝化作用;黑麦草的富集系数(BCF)和转运系数(TF)随CBC施用量的增加而减小,表明施用CBC能够减弱土壤中的镉向植株体内的迁移,从而达到缓解镉毒害的作用。[结论]CBC可以用于镉污染土壤的修复,尤其是在污染程度严重的酸性土壤中效果更加显著。

固定化微生物技术在小秦岭金矿区农田土壤修复中的应用

为积极探索土壤污染防治新路径,开展固定化微生物技术在土壤原位生态修复方面的应用研究。选取豫西小秦岭金矿矿区及周边农田土壤进行重金属含量测定及分析评价,发现该地区土壤中Pb^(2+)元素污染风险较大。将侧孢芽孢杆菌、放线菌及酵母菌株进行固定化混合菌制备并开展土壤原位生物修复。发现经固定化混合菌处理后土壤脲酶活性显著高于CK。以Pb^(2+)钝化效率及去除率提高为目的,分别采用单因素试验及响应面法对影响土壤修复效果各因素进行分析,最终确定Pb^(2+)最佳去除条件为固定化混合菌投加量10.496%,处理温度30.784℃,pH值6.242,Pb^(2+)去除率理论值为72.754%。对此模型进行试验验证,结果与理论值接近,说明响应面分析可起到优化土壤原位修复试验参数的目的。

比较三种稳定剂对FeS纳米颗粒的稳定效果及对水土中镉的固定与去除性能的影响

本研究评估了三种多糖稳定剂(羧甲基纤维素钠(CMC)、羧甲基淀粉钠(CMS)和一种水溶性淀粉)用于稳定FeS纳米颗粒的有效性,并测试了相应稳定化纳米颗粒在水和土壤中固定Cd^(2+)的性能。使用0.010 wt%CMC、0.025 wt%CMS或0.065 wt%淀粉可获得完全稳定的FeS纳米颗粒(100 mg/L FeS)。CMC-FeS表现出较高的zeta负电位,淀粉-FeS保持中性,而CMS-FeS则表现出中等负电位。CMCFeS对Cd^(2+)的吸附速率最快,吸附容量也最高。当用100 mg/L CMC-FeS或CMS-FeS处理一种含Cd土壤(58.3 mg/kg Cd)后,Cd的TCLP浸出率分别降低了88.4%和68.0%。CMC-FeS和CMS-FeS均可在模型土壤中运移,显示出其在土壤中原位固定Cd^(2+)方面的潜力。土壤穿透曲线实验表明,CMC-FeS在4.5个孔体积,CMS-FeS在约25个孔体积处几乎完全穿透。柱实验结果表明,当用55个孔体积的CMC-FeS或CMS-FeS悬浮液(100 mg/L)处理该含Cd土壤后,Cd的水浸出率分别降低了98.2%和98.0%。根据目标污染物、材料在土壤中的传输特性和材料成本,可找到这三种稳定剂在土壤修复中的最佳应用。

黑臭水体底泥修复中载体微生物技术的应用研究

载体微生物技术具有高效、环保和经济等优点,可应用于黑臭水体底泥修复。以江苏省常州市黑臭河道整治工程为例,探讨载体微生物技术在城市黑臭水体底泥修复中的应用效果。试验选取十字河为场地,持续150 d,使用沸石作为载体固定光合细菌,并实时监控底泥和上覆水。结果显示,底泥中有机质及Cu、Zn、Ni、Pb、Cd、Cr等重金属含量显著降低,上覆水中化学需氧量(Chemical Oxygen Demand,COD)、氨氮(NH_(3)-N)、总氮(Total Nitrogen,TN)、总磷(Total Phosphorus,TP)的去除率显著提升,证明该技术能有效改善水质并增强水体自净能力。研究表明,载体微生物技术可以提高菌体密度,避免菌体流失,为城市黑臭水体底泥治理提供一种长效的方法。

风化煤固定化微生物材料对铅的吸附特性及机理

风化煤固定化微生物材料较游离微生物能更好地钝化重金属。研究旨在探究风化煤固定化微生物材料的铅吸附性能及机理,为其污染场地应用提供理论指导和依据。以风化煤固定化微生物材料为对象,通过批量吸附试验系统研究材料的用量、pH、吸附时间和铅溶液质量浓度对其吸附性能的影响,并采用动力学、热力学模型拟合的方式描述铅吸附过程,结合扫描电镜和红外光谱技术对吸附机理进行探究。结果表明,风化煤固定化微生物材料用量为0.4 g/L、pH值为4、吸附时间大于12 h时,在200 mg/L铅溶液中吸附性能最优,最大吸附量达到338 mg/g;拟二级动力学模型和Langmuir模型显示,该吸附过程以化学吸附为主,且铅离子以单分子层的形式排列;热力学分析表明,该反应是自发的吸热反应,温度升高会促进反应的发生。材料表面钙、钠等元素的离子交换作用及羟基、羧基、羰基、酰胺基等活性基团的络合沉淀作用,促进了风化煤固定化微生物材料的铅吸附作用。在铅质量浓度为200 mg/L,材料用量为0.4 g/L、pH值为4、吸附时间大于12 h时,可实现材料吸附性能的最大化。材料表面的Ca、Na等元素与铅的离子交换作用以及羟基、羧基、羰基、酰胺基与铅的络合沉淀作用是其主要作用机制。

Generation of color-controllable room-temperature phosphorescence via luminescent center engineering and in-situ immobilization

Materials with controllable luminescence colors are highly desirable for numerous promising applications, however, the preparation of such materials, particularly with color-controllable room-temperature phosphorescence(RTP), remains a formidable challenge. In this work, we reported on a facile strategy to prepare color-controllable RTP materials via the pyrolysis of a mixture containing 1-(2-hydroxyethyl)-urea(H-urea) and boric acid(BA). By controlling the pyrolysis temperatures, the as-prepared materials exhibited ultralong RTP with emission colors ranging from cyan, green, to yellow. Further studies revealed that multiple luminescent centers formed from H-urea, which were in-situ embedded in the B2O3matrix(produced from BA) during the pyrolysis process. The contents of the different luminescent centers could be regulated by the pyrolysis temperatures, resulting in color-tunable RTP. Significantly, the luminescent center engineering and in-situ immobilization strategy not only provided a facile method for conveniently preparing color-controllable RTP materials, but also endowed the materials prepared at relatively lower temperatures with color-changeable RTP features under thermal stimulus. Considering their unique properties, the potential applications of the as-obtained materials for advanced anti-counterfeiting and information encryption were preliminarily demonstrated.