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.

Remediation of Pb-contaminated port sediment by biosurfactant from Bacillus sp.G1

The remediation of Pb-contaminated port sediment by biosurfactant from a new isolated Bacillus sp.G1was studied.ThePb removal efficiencies were investigated under multi-levels of water-solid ratio,pH and ionic strength.Result showed thatexchangeable speciation of Pb could be removed by maximum removal capacity of76.8mg/g after leaching.The Langmuir isothermreflected the adsorption process best to fit the experimental adsorption equilibrium data.Fourier transform infrared spectra(FTIR)indicated that C=O and-CH3may be the functional groups.Scanning electron microscopy(SEM)analysis showed that thesurface of the port sediment became much smoother after adsorption interaction,which reflected that the complexation between Pbions and biosurfactant was more stable.The results indicated that the biosurfactant of Bacillus sp.G1could remove Pb effectivelyfrom the Pb-contaminated port sediment(PCPS)and suggested a novel method for PCPS remediation.

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.

Monitoring Re-Suspension and Transport of Dioxin Contaminated Sediment to Evaluate the Recovery of a Shallow Urban Creek Post Sediment Remediation

Pringle Creek, identified as the source of dioxin/furan (PCDD/F) contamination to a Lake Ontario harbour was remediated in 2008. Surface sediment collected in 2013 near the floodplain remediation was no longer contaminated (∑17PCDD\Fs < 60 pg/g dw), but residual contamination extended downstream to the creek mouth (surface sediment maximum: ∑17PCDD\Fs 2900 pg/g dw). Nevertheless, sediment ∑17PCDD/F concentrations were lower in 2013 than pre-remediation suggesting that cleaner sediment was being deposited in the creek. Core data confirmed the decrease in sediment contamination through time since the most contaminated sediment was buried. Prior to the development of a remediation strategy for the harbour, the transport of bed-load and suspended sediment contaminated with PCDD/F was assessed. The challenge was the shallow water depth (0.6 m) throughout the creek thereby requiring non-standard sediment traps designed for this study. Suspended sediment collected in traps in 2014 showed residual contamination at the remediated site (∑17PCDD\Fs: 380 pg/g dw;TEQ (TEF fish) < 0.6 pg/g), with concentrations increasing with distance downstream mirroring surface sediment: mean ∑17PCDD\Fs concentration for suspended sediment at the creek mouth was 2200 pg/g (SD 260 pg/g dw) indicating PCDD/F contributions to the harbour. However, congener patterns in bottom sediment and suspended sediment near the remediated site and extending about 100 m downstream were similar to background upstream patterns consistent with atmospheric deposition as the source rather than the historical source which indicated that floodplain remedial actions were successful.

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.

Sedimentation in the Submarine Outfall and in the Mixing Zones （Avoiding, Diagnosis and Remediation）

Some practical design tips and important recommendations are given to minimize the negative effect of discharge of wastewater laden with solid particles via submarine outfall. This study emphasizes the role of respecting the hydraulic conditions in the outfall to prevent sedimentation in the outfall or their accumulation in adjacent areas; also it includes the ways used to improve the outfall hydraulic capacity that decreases with time. The diagnostics and remediation procedures of mixing zones are discussed, especially in the case of previous toxic discharge that results in toxic sediments at the bed load. A literature review of techniques used to assess sediment quality near discharge points and locate effluent-affected sediment deposit is presented that include using acoustic profiles and images, chemical analysis, toxicity tests and multivariate indicators.

Development of in-situ Marine Sediment Geo-Acoustic Measurement System with Real-Time and Multi Frequencies (the Second Generation)

Compared with the laboratory acoustic measurement of sediment samples, the in-situ acoustic measurement in marine sediment is considered more accurate and rehable, because it covers all of the surrounding environment factors and avoids the disturbance during the course of sampling and transporting of sediment samples. A new multi-frequency in-situ geoacoustic measurement system （MFIS^AMS） has been developed. The system can provide acoustic vdocity （compressional wave） and attenuation profiles of the uppermost 4 - 8 m sediment in the seafloor. It consists of 8 channels with 12 frequencies （multi-frequencies） and 0.5 - 2 MHz sampling rates. The data collected can be transmiuted in real-time. Associated with inclinometer and altimeter, it can provide the data for depth emendation. Acoustic velocity and attenuation data have been obtained from two in-situ experiments conducted in the Hangzhou Bay.

In-situ stabilisation followed by ex-situ composting for treatment and disposal of heavy metals polluted sediments

An innovative in-situ stabilisation treatment followed by ex-situ sediment composting was tested for its ability to treat and dispose of heavy-metal-polluted sediments in a river near the Chinese Pearl Delta. First, polluted sediments were treated in-situ to stabilise the heavy metals. Then the treated sediments were dredged, dewatered and sent for high temperature aerobic composting （HTAC） treatment. Finally, the compost products were used as a fertiliser for fiver bank plants. The stabilisation efficiency of heavy metals during the process was investigated and the results are as follows： （1） using in-situ stabilisation, the extraction concentrations of Cu, Zn and Pb were reduced by 65.0%, 82.2% and 90.0%, respectively, which are much lower than the national standard given in the Identification Standard for Hazardous Waste （GB5085.3-1996）; （2） chemical fraction analysis showed that heavy metals were further stabilized during the HTAC treatment; （3） the concentrations of Cu, Zn and Pb in rainwater leachate through the river bank met the level of class V in the Environmental Quality Standards for Surface Water in China （GB3838-2002）. Therefore, using this new process, the toxicities of heavy metals in sediments were reduced markedly.

Experimental investigation on the effective thermal conductivities of different hydrate-bearing sediments

The natural gas hydrate has been regarded as an important future green energy.Significant progress on the hydrate exploitation has been made,but some challenges are still remaining.In order to enhance the hydrate exploitation efficiency,a significant understanding of the effective thermal conductivity(ETC)of the hydrate-bearing sediment has become essential,since it directly controls the heat and mass transfer behaviors,and thereby determines the stability of hydrate reservoir and production rate.In this study,the effective thermal conductivities of various hydrate-bearing sediments were in-situ measured and studied.The impacts of temperature,particle size and type of sediment were investigated.The effective thermal conductivities of the quartz sand sediments before and after hydrate formation were in-situ measured.The results show the weak negative correlation of effective thermal conductivity of the quartz sand sediment on the temperature before and after the hydrate formation.The effective thermal conductivity of the hydrate-bearing sediment decreases with the increase of particle size of the sediment.The dominant effect of the type of porous medium on the characteristics of the effective thermal conductivity of hydrate-bearing sediment was highlighted.The results indicate that both the effective thermal conductivities of hydrate-bearing quartz sand sediment and hydrate-bearing silicon carbide sediment are weakly negatively correlated with temperature,but the effective thermal conductivity of hydrate-bearing clay sediment is weakly positively dependent on the temperature.In addition,the values of the effective thermal conductivities of various hydrate-bearing sediments are in the order of hydrate-bearing silicon carbide sediment>hydrate-bearing quartz sand sediment>hydrate-bearing clay sediment.These findings could suggest that the intrinsic thermal conductivity of porous medium could control the characteristics of effective thermal conductivity of hydrate-bearing sediment.

Effect of Different Remediators on the Control of Phosphorus Release from Landscape River Sediments

In this paper,different chemicals were added to sediments to control phosphorus release from river sediments by means of different dosing methods,thus reducing the concentration of organic pollutants in overlying water.Two remediators,aluminum sulfate and ferric chloride,were respectively added to six groups of experimental samples in three different covering methods,namely injection,mixing and tiling,and a control group was set up.The results showed that at the initially stationary phase of the experiment,the control effect of phosphorus release from sediments of mixing of aluminum sulfate was the most obvious,followed by tiling and injection into the mud;at the finally stationary phase of the experiment,the control effect of phosphorus release from sediments of injection of aluminum sulfate was the most obvious,followed by mixing and tiling.Under the same coverage,the inhibition effect of aluminum sulfate was more obvious than that of ferric chloride.This paper undertook research into the control effect of phosphorus release from sediments to provide a reference point for the control of water eutrophication in the days to come.

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.

生物淋滤电动修复湖泊底泥中的铬

该文采用生物淋滤电动复合技术修复底泥,经生物淋滤后底泥中铬形态发生了改变,可交换离子态、碳酸盐结合态的铬含量比例明显增加,而铁锰氧化物结合态、硫化物及有机结合态以及残渣态的比例含量明显下降(可为电动修复底泥时铬的迁移提供有利条件)。单纯电动修复铬的去除率为32.6%,单纯生物淋滤铬的去除率为25.1%,淋滤去除率与底泥的pH值和氧化还原电位紧密相关。经生物淋滤电动复合处理后,铬的去除总量可达53.4%。生物淋滤电动复合技术对可交换的离子态、碳酸盐结合态、硫化物及有机结合态的铬去除率较高,特别是对碳酸盐结合态的铬去除率达到61.1%。实验表明电动生物淋滤技术具有协同作用,适合湖泊底泥铬污染治理。

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。

不同载体固定活性污泥原位修复轻度淤积底泥的效能

底泥修复是黑臭水体治理中的重要环节,原位修复操作简便且对河道的破坏小。利用固定化菌剂原位修复实验装置,探究了活性炭、沸石、陶粒3种载体固定活性污泥修复轻度淤积底泥的效能。载体物理特性及载体对微生物的吸附特性实验结果表明,活性炭相对于沸石和陶粒具有更丰富的孔隙结构和更强的活性污泥吸附能力,沸石的吸附能力强于陶粒。不同载体固定活性污泥原位修复轻度淤积底泥实验结果表明,3种载体固定活性污泥均能有效降低底泥中有机质含量,其中活性炭固定活性污泥对底泥中有机质的降解效果最佳,60 d内有机质含量可降低45.2%;3种载体固定活性污泥均能促进底泥中重金属离子转移,其中沸石固定活性污泥对重金属离子的去除效果最佳,60 d内对铜离子、铬离子、铅离子的去除率分别达到了28.8%、27.2%、37.2%;此外,3种载体固定活性污泥均能有效去除上覆水中的CODCr、NH3-N、TN、TP,60 d内CODCr去除率基本超过50%,NH3-N、TN、TP去除率基本超过80%。综合底泥和上覆水处理效果可知,活性炭固定活性污泥的表现最优,其次为沸石固定活性污泥。

高岭土改性丝瓜络生物炭修复PAHs污染沉积物及微生物响应

采用高岭土改性生物炭或者使用三维立体,如丝瓜络生物炭(LSBC)修复PAHs污染沉积物,制备了三维立体LSBC(3D-LSBC)、改性三维立体LSBC(3D-K-LSBC)、颗粒LSBC(G-LSBC)和改性颗粒LSBC(G-K-LSBC)四种材料.结果表明:G-K-LSBC修复PAHs污染沉积物效果显著,沉积物PAHs去除率达21.76%,PAHs的修复效率提高了1个数量级.各组下层沉积物PAHs生物有效性明显高于上层沉积物(P<0.05);添加G-LSBC和G-K-LSBC有效降低了沉积物PAHs生物有效性,分别为对照组的43.99%~78.48%和39.08%~72.01%.经过150d修复,沉积物PAHs含量未出现明显垂向分布特征(P>0.05).然而,沉积物微生物群落组成发生了明显变化(P<0.05).在3D-K-LSBC和G-LSBC作用下,沉积物微生物物种丰富度和多样性明显提高;其中,在G-K-LSBC作用下,沉积物群落中具有芳香烃降解和芳香化合物降解功能菌属呈显著富集.G-K-LSBC表现出更高的PAHs污染沉积物修复潜力.此外,高岭土改性显著提高了LSBC材料的稳定性.

基于低水位运行的城市河流污染底泥中微生物群落特征及影响因素

针对低水位运行修复城市河流污染底泥微生物机制不清的问题,基于高、低水位下不同城市河流的底泥理化性质检测分析、宏基因组高通量测序及生物信息学分析等手段,开展了低水位运行的城市河流污染底泥中微生物群落特征及影响因素研究。结果表明:变形菌门、放线菌门、厚壁菌门和广古菌门分别是不同水位运行条件下相对丰度最高的细菌门类和古菌门类;高水位运行条件下底泥中细菌的香农指数显著高于低水位运行条件下的指数值(p<0.001),古菌则相反,说明古菌群落可能主导了低水位运行过程中底泥污染物降解过程;低水位运行时变形菌门可能是参与底泥中含氮污染物降解以及氮循环过程的主要微生物门类,α-变形菌纲则可能对底泥中氨氮的去除发挥了重要作用;TOC,TN和NH_(3)-N是影响城市河流底泥中微生物群落变化的主要环境驱动因子;低水位运行不仅能够有效降低底泥中常规污染指标的污染程度,解决底泥内源污染问题,还能显著降低底泥中致病菌的潜在危害,构建更为安全的亲水城市河流生态系统。

矿物基活性覆盖材料对富营养化湖泊沉积物磷的控制研究进展

论述了内源磷释放对湖泊富营养化造成的影响,根据不同的性质对黏土矿物进行了系统分类,归纳了国内外关于黏土矿物对控制沉积物磷释放的研究和应用进展,分析了黏土矿物控制沉积物磷释放的应用效果和作用机理,并对未来应用黏土矿物治理与修复湖泊沉积物的发展方向进行了展望。

沉水植物苦草及其微生物对沉积物中多环芳烃修复作用

沉水植物苦草(Vallisneria natans)可以有效地修复受多环芳烃(PAHs)污染沉积物,但其微生物作用机制有待进一步阐明。本研究选取东太湖大水港这一典型的苦草生长及PAHs污染区域为研究对象,考察不同灭菌处理条件下,苦草对PAHs的修复效果。结果表明,经过15 d的苦草修复试验,沉积物灭菌处理组PAHs去除率最高(41.81%),苦草根表灭菌处理组次之(31.81%),二者均灭菌处理组去除率较低(25.19%)。微生物群落结构表明,苦草的根际与非根际沉积物中微生物主要由变形菌门(Proteobacteria)、绿弯菌门(Chloroflexi)、酸杆菌门(Acidobacteria)、拟杆菌门(Bacteroidetes)以及放线菌门(Actinobacteria)等组成,而苦草的根表及根内同样富集了显著不同微生物,苦草根表及根内主要为变形菌门(Proteobacteria),其丰度分别为88.5%、67.7%。进一步分析显示富集的优势菌属主要为不动杆菌属(Acinetobacter)、假单胞菌属(Pseudomonas)以及草螺菌属(Herbaspirillum)。由此表明,大水港地区沉积物中微生物及苦草根系微生物均对促进沉积物中PAHs去除有效果。在保持苦草根系活性情况下,苦草生长可能促进了灭菌沉积物中微生物降解潜力的部分恢复,并协同苦草根表根内微生物加速降解沉积物中PAHs。

不同改底剂与改性麦饭石协同作用下对苦草生长的影响研究

该文从调节富营养化水体底质环境和沉水植物生态恢复的角度出发,系统研究并探索针对城市浅水湖泊沉水植物恢复的高效复合底泥改良剂。实验选取水环境治理常用的4种改底剂:氧化钙、过氧化钙、硝酸钙、过硫酸氢钾,联合镁元素负载改性麦饭石对污染底泥进行复合改良处理,同时结合沉水植物苦草种植生长效果综合评价不同改底剂与镁改性麦饭石组合对于苦草的生长效果的影响。结果表明,在与镁改性麦饭石复合处理过程中,氧化钙对于上覆水体中总磷及底泥氨氮的固定作用最好,但处理后水体环境对于苦草的生长具有一定抑制效果;硝酸钙处理后的水体富营养化风险较高,处理后苦草生长效果较差;过氧化钙和过硫酸氢钾进行底泥复合改良后植物生长状态较好,其中过氧化钙实验组沉水植物净重增长倍数最大,同时过氧化钙对于将富营养状态下的显著影响环境因子(底泥中氨氮、总磷、总有机碳)含量控制在适宜沉水植物苦草生长的范围内的效果优于过硫酸氢钾。过氧化钙+镁改性麦饭石复合改良底泥的措施较其他改底剂组合更适合水环境治理过程中沉水植物生态修复的底泥改良。