黄土体对重金属（Cd、Pb、Zn、Cu）吸附试验研究

本文主要研究了土壤环境ｐＨ值的变化对黄土吸附重金属的影响，得出随着ｐＨ值增大土壤对重金属吸附量增大；随着重金属离子浓度的增大，水溶液的ｐＨ值降低；随着重金属离子浓度的增大，黄土对重金属的吸附量增大；黄土对重金属（Ｃｄ、Ｐｂ、Ｚｎ、Ｃｕ）吸附力亲和顺序为：Ｐｂ２＋＞Ｃｄ２＋＞Ｃｕ２＋＞Ｚｎ２＋。     

掺绿砂改良土中铅离子浸出浓度影响因素分析

利用不同pH值的渗滤液对掺绿砂改良土进行注渗试验,通过试验数据分析,得出改良土中铅离子的浸出浓度受渗滤液p H值、掺砂率和浸出时间等因素影响的结论,其中渗滤液pH值越低,改良土中铅离子浸出浓度越大,当掺绿砂率为30%～40%时铅离子浸出浓度最小,铅离子浸出浓度随时间变化呈指数函数衰减。     

pH值对铜、铅的淋滤特性影响——以某铜矿尾矿料为例

矿山开采引起的重金属排放是一个全球性的环境问题.随着国民经济的发展,这一问题显得越来越突出,应该引起更大的关注.以某铜矿尾矿料为研究对象,采用不同pH值的淋滤液对其进行间断淋滤,研究其尾矿库中典型重金属离子铜、铅的淋滤释放规律.结果表明:淋滤过程分为快速释放和缓慢释放两个过程;重金属的淋滤浓度随着pH值的降低而增加.     

建筑垃圾骨料浸出重金属对环境影响研究

为了探究建筑垃圾骨料作为渗透性路面底基层替代材料的适用性,必须考虑建筑垃圾对地下水的污染问题。选取2种常见的建筑垃圾再生骨料:再生砖骨料(CB)和再生混凝土骨料(RCA),探究其浸出重金属浓度含量及其污染物的释放特征及规律,分析建筑垃圾试样配比、液固比、pH 值等因素对重金属浓度的影响。结果表明:在纯砖块条件下时,重金属Cd、Cu、Ni和Zn含量最小;在纯混凝土条件下时,重金属Cr和Pb含量最小。Cd和Zn的含量随着液固比的变化上下起伏不大,浸出浓度基本保持不变,可见Cd和Zn达到了溶解平衡;Cr和Pb的浸出率随着液固比的增加而增加,浸出量也在不断增加;Cu和Ni的浸出率随着液固比的增加而减小。Cd、Ni和Pb在不同pH值时的浸出浓度随时间变化趋势也基本相似,随着pH值的升高,Cd、Ni和Pb的平衡浓度降低;Cr的浸出浓度与pH值的增高呈正相关;Cu和Zn具有两性浸出,形成U形曲线,在极端的酸性和碱性pH值时浓度升高。建筑垃圾再生骨料浸出后的重金属浓度低于我国相关标准,可作为路面填料。     

不同浊度下的泥沙对水体镉、铅、砷去除的影响分析

针对流域突发性重金属污染,不同浊度下的泥沙对重金属有一定的去除效果。以浊度为指示指标,通过试验研究了常温(25 ℃)和低温(5 ℃)条件下浊度50～650 NTU(Nephelometric Turbidity Unit)范围内泥沙对重金属镉、铅、砷吸附去除的影响。试验结果表明:泥沙对重金属镉、铅、砷的去除效果为铅＞镉＞砷,其中铅的去除率达到99%。浊度与能处理达标的最高重金属浓度呈线性关系,常温下浊度与能处理达标的最高镉、铅、砷浓度关系曲线的相关系数分别为0.996、0.998、0.999,低温下其相关系数分别为0.999、0.996、0.998。常温较低温更利于泥沙对重金属镉、铅、砷的去除,能去除更高浓度的重金属,达到生活饮用水卫生标准。     

黄河泥沙与重金属污染物相互作用研究现状

20世纪80年代以来,国内外学者对重金属在泥沙颗粒上的吸附、解吸研究都很活跃,且取得了不少成果,研究内容包括吸附动力学方程、泥沙和水环境特征(泥沙粒度、矿物成分、pH值、温度等)对吸附的影响、水体中重金属的化学稳定性等。粗细不同的泥沙对重金属污染物的吸附能力差异很大,泥沙颗粒越细,比表面积越大,吸附能力越强;在同一重金属初始浓度下,重金属从溶液中的去除量随pH值的升高而增加;水体中含沙量增加时,单位泥沙对重金属的吸附量先增加后降低。     

重金属污染物在土壤中的扩散规律及埋置策略研究

为了探索重金属污染物在土壤中的扩散规律,本文基于三维扩散方程,推导出了空间、时间和扩散系数等因素对埋置点周围重金属污染物浓度的影响规律。在此基础上,分析比较了集中埋置和分散埋置方法对重金属污染物浓度分布影响的异同。结果表明:在其他条件相同时,某一空间位置的浓度随扩散时间和扩散系数的增大先增大后逐渐减小,最后曲线趋于平缓;相同扩散时间情况下,浓度随着扩散半径的增大而减小,当扩散半径大于一定值时,浓度趋于零。对同量的污染物的三种不同的埋置方案进行分析发现:埋置点越少,其附近的浓度越高,而埋置点越多,远处的浓度越低。     

不同pH值条件下重金属捕集剂有效性的研究

采用高分子有机捕集剂与废水中的多种重金属离子发生螯合反应,生成稳定且不溶于水的金属螯合物来去除废水中的重金属离子。对4种捕集剂在不同pH值的条件下对含有汞、铜、镉、铅等重金属污水的去除效果进行了试验研究。结果表明,利用重金属捕集剂方法处理重金属废水的效率较高,有很好的应用前景。     

含锌重金属废水藻类吸附处理技术

以小球藻为吸附剂,研究藻类吸附剂对重金属废水中Zn2+的吸附过程,分析吸附时间、温度、pH值、Zn2+起始浓度以及预处理过程等因素对小球藻吸附Zn2+性能的影响。结果表明:预处理能提高小球藻的吸附性能,其吸附过程符合Langmuir吸附特征,对废水的pH值适应范围广。对于ρ(Zn2+)=100 mg/L的重金属废水经小球藻一次处理,去除率达到98%。小球藻吸附处理废水中Zn2+的较佳工艺条件为pH值6.5、温度25℃、吸附时间60 min、小球藻用量2 g/L。     

负载纳米水合氧化铁活性炭去除水中铅的实验研究

通过共沉淀法制备一种负载纳米水合氧化铁活性炭,研究其对铅的吸附性能、负载前后活性炭的结构的影响,并进行TEM和XRD表征分析。利用动态小柱实验探究不同p H值、进水浓度和空床接触时间对铅吸附能力的影响,同时比较负载前后活性炭处理实际河道水中铅的吸附穿透曲线。结果表明:无定型的纳米水合氧化铁成功负载于活性炭上,负载后的活性炭显著提高了铅的吸附性能,其对铅的吸附容量随p H值、空床接触时间的增大而增加,进水浓度的变化基本不影响铅的吸附容量。以实际河道水为处理对象,得出负载前后的活性炭穿透点运行的床体积分别为1233和11004,显著提高了9倍,表明负载纳米水合氧化铁活性炭可以有效去除实际水体中的铅,具有良好的应用前景。     

城市地表径流胶体对重金属下渗迁移行为的影响

为了解城市地表径流胶体对重金属在下渗设施中迁移行为的影响,提取道路雨水径流中的胶体,采用下渗柱试验研究了存在径流胶体时Cu~(2+)、Pb~(2+)和Cd~(2+)的下渗迁移出流质量浓度变化,分析进水流速、pH值、Na~+浓度、重金属离子共存和胶体粒径对胶体携带重金属迁移行为的影响。结果表明:径流胶体能够促进重金属离子的下渗迁移;进水流速越高,径流胶体对重金属离子的携带迁移作用越明显;弱酸性条件更有利于径流胶体对重金属离子的携带迁移;雨水径流中存在Na~+或多种重金属离子共存时,胶体携带重金属离子的下渗迁移过程会受到抑制,且离子浓度越大,其受抑制作用越明显;胶体粒径会显著影响径流胶体对重金属离子的携带迁移能力,胶体粒径越小,越容易携带重金属离子下渗迁移。     

电浮选法净化含高浓度Cu2+和Zn2+的废水研究

以自制的间歇式电浮选柱为反应容器,采用电浮选方法对含高浓度Zn^2+和Cu^2+混合离子废水进行了净化试验研究,浮选过程中考察了pH值、电流密度、初步浮选时间、离子强度4个主要因素对浮选效率的影响。试验选用混合离子的整体去除效率为评价指标,优化了电浮选方法净化含混合重金属Zn^2+和Cu^2+的实验条件,得到了较好的浮选条件。该方法操作简单,处理效果较理想,对实际利用电浮选法处理重金属离子废水工程具有一定的参考价值。     

水生植物去除重金属机制及生理响应研究综述

重金属是水环境中的典型污染物,存在着潜在的生态风险。利用水生植物去除重金属的处理方法具有高效、环保、经济等特点,成为当前研究的热点领域。阐述了植物对重金属的去除机制主要有植物吸收、根际微生物活动、植物根系微环境作用及植物富集,综述了植物在重金属胁迫下发生的生理响应,包括植物生长、细胞结构、酶活性等方面的生理变化。并讨论分析了pH、温度、底泥性质等对水生植物去除重金属过程的影响。同时,提出了植物去除重金属及响应机理方面还需深入研究的几个问题。     

Biological treatment of heavy metals in acid mine drainage using sulfate reducing bioreactors.

The uncontrolled release of acid mine drainage (AMD) from abandoned mines and tailing piles threatens water resources in many sites worldwide. AMD introduces elevated concentrations of sulfate ions and dissolved heavy metals as well as high acidity levels to groundwater and receiving surface water. Anaerobic biological processes relying on the activity of sulfate reducing bacteria are being considered for the treatment of AMD and other heavy metal containing effluents. Biogenic sulfides form insoluble complexes with heavy metals resulting in their precipitation. The objective of this study was to investigate the remediation of AMD in sulfate reducing bioreactors inoculated with anaerobic granular sludge and fed with an influent containing ethanol. Biological treatment of an acidic (pH 4.0) synthetic AMD containing high concentrations of heavy metals (100 mg Cu(2+)l(-1); 10 mg Ni(2+)l(-1), 10 mg Zn(2+)l(-1)) increased the effluent pH level to 7.0-7.2 and resulted in metal removal efficiencies exceeding 99.2%. The highest metal precipitation rates attained for Cu, Ni and Zn averaged 92.5, 14.6 and 15.8 mg metal l(-1) of reactor d(-1). The results of this work demonstrate that an ethanol-fed sulfidogenic reactor was highly effective to remove heavy metal contamination and neutralized the acidity of the synthetic wastewater.     

Surfactant enhanced remediation of cadmium contaminated soils

An investigation involving the addition of surfactant to remediate cadmium-contaminated soils was perfoemed to determine the optimal surfactant enhanced remediation system. Anionic (sodium dodecyl sulfate, SOS), nonionic (Triton X-100, TX100) and cationic (cetyltrimethylammonium bromide, CTAB) surfactants were used to elucidate the extraction efficiency of surfactant. EDTA and diphenylthiocarbazone (DPC) were also added to enhance the extraction efficiencies of surfactants. Moreover, the pH effect was examined to determine the optimal surfactant systems. The addition of anionic and nonionic surfactants can enhance the desorption rates of cadmium, lead and zinc, whereas the addition of cationic surfactant decreased the desorption efficiency of heavy metals. The desorption efficiency was found to increase linearly with the increasing surfactant concentration below critical micelle concentration (CMC) and remained relatively constant above the CMC. Moreover, the addition of EDTA can significantly enhance the desorption efficiency of heavy metals. Cationic surfactant was shown to be a more effective surfactant than nonionic and anionic surfactants in extracting heavy metals under acidic environment. The desorption efficiency of heavy metal in the surfactant/EDTA mixture system was in the order of Cd > Pb> Zn. However, the addition of DPC lowered the heavy metal removals by 2 to 4 times. Also, increasing pH value can decrease the extraction capabilities of nonionic and anionic surfactants. The results of this study demonstrate that surfactant in combination with complexing agents can be effectively used as chemical amendments to flush cadmium-contaminated soil by proper selection of type and concentration of surfactant and complexing agent at different pH values.     

Landfill leachate treatment by an experimental subsurface flow constructed wetland in tropical climate countries.

Municipal leachate was treated in an experimental unit of constructed wetlands of subsurface flow type. The parameters studied were organics (BOD and COD), solids and heavy metals (Zn, Ni, Cu, Cr and Pb). Using two types of emergent plants of Scirpus globulosus and Eriocaulon sexangulare, more than 80% removal was achieved for all the parameters. E. sexangulare removed organics and heavy metals better than Scirpus globulosus. A higher concentration of heavy metals in the influent did not change the removal efficiency.     

Analysis of build-up of heavy metals and volatile organics on urban roads in gold coast, Australia

Urban water quality can be significantly impaired by the build-up of pollutants such as heavy metals and volatile organics on urban road surfaces due to vehicular traffic. Any control strategy for the mitigation of traffic related build-up of heavy metals and volatile organic pollutants should be based on the knowledge of their build-up processes. In the study discussed in this paper, the outcomes of a detailed experimental investigation into build-up processes of heavy metals and volatile organics are presented. It was found that traffic parameters such as average daily traffic, volume over capacity ratio and surface texture depth had similar strong correlations with the build-up of heavy metals and volatile organics. Multicriteria decision analyses revealed that that the 1-74 microm particulate fraction of total suspended solids (TSS) could be regarded as a surrogate indicator for particulate heavy metals in build-up and this same fraction of total organic carbon could be regarded as a surrogate indicator for particulate volatile organics build-up. In terms of pollutants affinity, TSS was found to be the predominant parameter for particulate heavy metals build-up and total dissolved solids was found to be the predominant parameter for the potential dissolved particulate fraction in heavy metals buildup. It was also found that land use did not play a significant role in the build-up of traffic generated heavy metals and volatile organics.     

两种絮凝工艺去除污水中金属元素的对比试验

分别采用化学生物絮凝与化学絮凝两种工艺处理同一低浓度城市污水,对比分析污水中金属元素的去除效果。试验结果表明,在相同加药量的条件下,化学生物絮凝工艺在增加絮凝产物中铝元素含量的同时,对部分有害重金属的控制也优于化学絮凝工艺。但该工艺在处理高浓度污水时,处理效果会受重金属浓度的制约。