化学方法降低城市污泥的重金属含量及其前景分析

城市污泥含有丰富的氛、磷、河和有机质,农用前景广阔。但其中重金属含量常超标而受到限制。利用化学试剂如酸、有机物、表面活性剂等与污泥中的重金属发生作用,形成溶解性的金属离子或金属－试剂络合物,再通过淋滤．可以剔除污泥中大量的重金属,使其降低到符合农用标准。本文介绍了化学方法去除污泥事金属的原理和效果,分析了影响因素,包括重金属种类、污泥特性、操作方法、剔除时间等。并对该法的应用前景进行了讨论。     

Metallic wastewater treatment by sulfate reduction using anaerobic rotating biological contactor reactor under high metal loading conditions

An-RBC reactor is highly suited to treat metallic wastewater. Metal removal is due to sulfide precipitation via sulfate reduction by SRB. Cu(II) removal was the best among the different heavy metals. Maximum metal removal is achieved at low metal loading condition. Metal removal matched well with the solubility product values of respective metal sulfide salts. This study was aimed at investigating the performance of anaerobic rotating biological contactor reactor treating synthetic wastewater containing a mixture of heavy metals under sulfate reducing condition. Statistically valid factorial design of experiments was carried out to understand the dynamics of metal removal using this bioreactor system. Copper removal was maximum (>98%), followed by other heavy metals at their respective low inlet concentrations. Metal loading rates less than 3.7 mg/L?h in case of Cu(II); less than 1.69 mg/L?h for Ni(II), Pb(II), Zn(II), Fe(III) and Cd(II) are favorable to the performance of the An-RBC reactor. Removal efficiency of the heavy metals from mixture depended on the metal species and their inlet loading concentrations. Analysis of metal precipitates formed in the sulfidogenic bioreactor by field emission scanning electron microscopy along with energy dispersive X-ray spectroscopy (FESEM-EDX) confirmed metal sulfide precipitation by SRB. All these results clearly revealed that the attached growth biofilm bioreactor is well suited for heavy metal removal from complex mixture.     

Some aspects of heavy metals contamination remediation and role of biosurfactants

Contamination by heavy metals is the result of different industrial activities. The presence of heavy metals in soil and water causes serious problems, as these materials are not biodegradable and do contaminate both biological systems and the subsoil. Biological surface-active compounds otherwise known as biosurfactants in general and rhamnolipids biosurfactants in particular have been successfully employed in the remediation of environments contaminated with heavy metal ions. The aim of the present review is to highlight potential applications of these tensioactive compounds for use in environmental heavy metals removal and bioremediation and processes involved.     

The adsorption of lead and copper from aqueous solution on modified peat-resin particles

Raw peat was modified with sulfuric acid, then mixed modified with resin to prepare the modified peat-resin particles. Using the batch experimental systems, the removal of heavy metals (copper and lead) on the modified peat-resin particles was investigated. The data of the adsorption isotherm could be fitted by the Langmuir equation well. The adsorption rate of heavy metals on modified peat-resin particles was very swift. The removal processes of heavy metals on modified peat-resin particles could be well described by pseudo-second order model. The adsorption rate of lead was affected by the initial heavy metal concentration, initial pH, particle size, agitation speed and particle mass. In the adsorption of heavy metals (lead and copper) on the modified peat-resin particles, ion exchange was the major reaction mechanism. Desorption data showed that the lead adsorbed by modified peat-resin particle could be desorbed by 0.5 N or 1.0 N HNO3. The desorption rate was swift. The experiments indicated that the modified peat-resin particles have great potential for the removal of heavy metals from wastewater.     

酸阻滞技术的研究与应用

本文提出酸阻滞法从废液中分离，回收重金属和酸的新技术工艺，从十多种国产树脂中成功地筛选出两种可作为酸阻滞剂，有较好的分离效果。但洗脱时酸脱尾严重，当选择穿透比在０．６左右时，可以解决酸脱尾现象，使脱尾酸损失由３０％降到７％，而酸的回收率由６０％提高到９０％，采用该工艺对几种废液进行处理，重金属回收液中酸去除率大于９５％，而回用酸中金属去除率大于７０％，该工艺既可回收重金属，同时也可回收酸。     

利用非活体生物质去除废水中重金属的研究

为了解非活体牛物质去除废水中重金属的效果，选择了玉米芯、水稻谷壳、花生壳、松树树皮和茶叶等5种非活体生物质，州室内模拟方法比较研究了它们对重金属的吸附能力。结果表明，生物质对重金属的吸附是一个快速反应，可在20-30min内达到平衡。pH值对牛物质吸附阳离子型重金属有很大的影响，吸附量随pH值上升而增加，pH值在4．5以上时可达到较高水平。5种生物质对重金属都有较高吸附能力，它们吸附重金属的能力依次为：花生壳〉松树树皮〉玉米芯〉水稻谷壳〉茶叶。生物质去除废水中重金属的效果一般为：Cu、Pb〉Cd〉Zn。用碱、柠檬酸和磷酸对生物质进行改性处理可显著增强其对重金属的去除能力。生物质是一种廉价、有效的吸附剂，可替代商品吸附剂用于废水中重金属的去除，主要重金属的移除率在85％以上。     

贵、重金属的生物吸附

采矿业和工业废水中常含有大量的重金属离子 ,严重污染环境 ,危害人类健康 .因此 ,治理重金属污染的技术受到极大重视 .贵金属是指钌 (Ｒｕ)、铑 (Ｒｈ)、钯 (Ｐｄ)、银 (Ａｇ)、锇 (Ｏｓ)、铱(Ｉｒ)、铂 (Ｐｔ)、金 (Ａｕ)等 8种金属 ,由于其特殊性能 ,广泛应用于航天航空、电子和石油化工等工业 .随着工业的发展 ,贵金属的应用愈加广泛 ,但贵金属资源稀少 ,冶炼困难 .因此 ,从含贵金属的废料、废液和废水等“二次资源”中回收贵金属具有重要的经济和社会意义 .从废液、废水中去除重金属或回收贵金属 ,传统的方法有化学沉淀法、电解法、离…     

The Adsorption of Lead and Copper from Aqueous Solution on Modified Peat–Resin Particles

Raw peat was modified with sulfuric acid, then mixed modified with resin to prepare the modified peat–resin particles. Using the batch experimental systems, the removal of heavy metals (copper and lead) on the modified peat–resin particles was investigated. The data of the adsorption isotherm could be fitted by the Langmuir equation well. The adsorption rate of heavy metals on modified peat–resin particles was very swift. The removal processes of heavy metals on modified peat–resin particles could be well described by pseudo-second order model. The adsorption rate of lead was affected by the initial heavy metal concentration, initial pH, particle size, agitation speed and particle mass. In the adsorption of heavy metals (lead and copper) on the modified peat–resin particles, ion exchange was the major reaction mechanism. Desorption data showed that the lead adsorbed by modified peat–resin particle could be desorbed by 0.5 N or 1.0 N HNO₃. The desorption rate was swift. The experiments indicated that the modified peat–resin particles have great potential for the removal of heavy metals from wastewater.     

Heavy metal phyto-technologies from Ramsar wetland plants: green approach

Side effects of chemical technologies to remediate hazardous heavy metals paved the way to green phyto-technologies. The present research investigated the effectiveness of wetland plants Lemna minor (duckweed), Azolla pinnata (water fern), and Eichhornia crassipes (water hyacinth) pertaining to synchronised removal of heavy metals (Fe, Zn, Cu, Cr, and Cd) from a Ramsar site of an Indo-Burma global biodiversity hot spot region. These plants were grown at different concentrations (1.0, 2.0, and 5.0?mg/L) of metals in microcosm investigation. To this end, the result indicated high removal (>90%) of different metals during 15 days of the experiment. Furthermore, maximum removal was noted on the 12th day of the experiment. Also, results revealed that E. crassipes was the most efficient for the removal of heavy metals followed by L. minor and A. pinnata. Results from analysis confirmed the accumulation of metals within the macrophytes and a corresponding decrease of metals in the wastewater. Significant correlations between metal concentration, water, and wetland plants were obtained. To this end, wetland plants accumulated heavy metals within their tissues, leading to physiological/biochemical alterations. Selected plants exhibited a wide range of stress tolerance to all of the metals and therefore might be utilised for eco-removal of heavy metals from contaminated water. Finally, issues of phytosynthesis of nanoparticles, phytomining, and bioenergy have been critically discussed to attain a sustainability paradigm in the use of phyto-technologies for a green future in the environment sector.     

Combined Fenton process and sulfide precipitation for removal of heavy metals from industrial wastewater: Bench and pilot scale studies focusing on in-depth thallium removal

Addition of alkali to pH 10 is effective for precipitation of precipitable metals. Fenton treatment is effective for substantial removal of Tl, Cd, Cu, Pb, and Zn. Sulfide precipitation is a final step for removal of trace Tl, Cd, Cu, Pb, and Zn. Bench and pilot studies demonstrated the effectiveness of this combined technique. Thallium (Tl) in industrial wastewater is a public health concern due to its extremely high toxicity. However, there has been limited research regarding Tl removal techniques and engineering practices to date. In this investigation, bench and pilot studies on advanced treatment of industrial wastewater to remove Tl to a trace level were conducted. The treatment process involved a combination of hydroxide precipitation, Fenton oxidation, and sulfide precipitation. While hydroxide precipitation was ineffective for Tl+ removal, it enabled the recovery of approximately 70%–80% of Zn as Zn hydroxide in alkaline conditions. The Fenton process provided good Tl removal (>95%) through oxidation and precipitation. Tl was then removed to trace levels (<1.0 µg/L) via sulfide precipitation. Effective removal of other heavy metals was also achieved, with Cd<13.4 µg/L, Cu<39.6 µg/L, Pb<5.32 µg/L, and Zn<357 µg/L detected in the effluent. X-ray photoelectron spectroscopy indicated that Tl2S precipitate formed due to sulfide precipitation. Other heavy metals were removed via the formation of metal hydroxides during hydroxide precipitation and Fenton treatment, as well as via the formation of metal sulfides during sulfide precipitation. This combined process provides a scalable approach for the in-depth removal of Tl and other heavy metals from industrial wastewater.     

花生壳吸附Pb^2＋、Cu^2＋、Cr^3＋、Cd^2＋、Ni^2＋的动力学和热力学研究

以花生壳为生物吸附剂,通过序批式实验研究了吸附剂投量、吸附时间、金属离子初始质量浓度、吸附温度对吸附金属离子的影响,探讨了花生壳吸附的动力学及热力学特性。结果表明,准二级动力学方程能很好地描述花生壳对Pb^2＋、Cu^2＋、Cr^3＋、Cd^2＋、Ni^2＋的吸附过程。Langmuir模型和Freundlich模型均能较好地描述花生壳对5种重金属离子的等温吸附过程,而Langmuir模型拟合的线性更好。Pb2＋、Cu2＋、Cr3＋、Cd2＋、Ni2＋5种金属离子的最大吸附量分别是32.25、7.09、3.82、2.95、2.22 mg.g-1,花生壳可用于处理低质量浓度多种重金属混合的废水。热力学研究表明,花生壳对5种金属离子的吸附具有自发、吸热和熵增的特性。     

微生物方法降低城市污泥的重金属含量研究进展

城市污泥 (简称污泥 )是城市污水净化处理过程中产生的沉积物 ,数量巨大 ,增长迅速 ,是亟待解决的城市固体废物 ,其处置方式主要有填埋、焚烧、倒海和农业利用等 .前 3种方式由于场地的限制、费用昂贵、造成二次污染等原因而难以为继或被禁止 .污泥通常含有丰富的Ｎ、Ｐ、Ｋ和有机质 ,是良好的有机肥料资源 .实践证明 ,农业利用是污泥最有前景的处置方法 ,有利于城市和农业的可持续发展[1 ] .虽然我国污泥的农用率较低(<10 % ) ,但英、美、法、荷兰和瑞士等国也仅为 6 0 %左右 ,主要是因为污泥中重金属的含量超标 .因此 ,解决污泥农业利用的…     

纳米零价铁颗粒去除水中重金属的研究进展

重金属是毒性大、难降解、易累积的环境污染物,纳米零价铁作为一种新型功能修复材料在去除水体和土壤中重金属方面有着广阔的应用前景.本文综述了纳米零价铁颗粒去除水中重金属的研究进展,包括纳米零价铁的常用制备方法及特性、去除效能、对不同重金属的去除机理以及发展前景和今后的研究方向,以期为该领域的深入研究提供借鉴并拓展新的思路.     

长三角和珠三角农业土壤对Pb、Cu、Cd的吸附解吸特性

研究了长江三角州和珠江三角州10种代表性农业土壤对重金属Pb、Cu和Cd的吸附与解吸特性。结果表明:大多数土壤对重金属有较强吸附能力,土壤性质对重金属吸附与解吸行为有很大影响。其中,pH值是影响土壤对重金属吸附与解吸的最重要因素,土壤重金属吸附量随pH值增加而增加。土壤pH值和有机质或粘粒含量较高的土壤(如乌栅土、青紫泥田、黄斑田),其对重金属吸附能力高于pH值和有机质或粘粒含量较低的土壤(如黄筋泥、粉泥田)。重金属解吸量随重金属吸附量和土壤重金属饱和度增加呈指数增加趋势;土壤对重金属的吸附能力从强至弱依次为Pb、Cu、Cd;当3种重金属共存时,重金属之间竞争能力强弱顺序与吸附能力顺序相同。重金属之间竞争作用随土壤酸度和重金属污染程度的增加而增强。     

Degradation of Ni–EDTA complex by Fenton reaction and ultrasonic treatment for the removal of Ni<Superscript>2+</Superscript> ions

It is difficult to meet the increasingly stringent environmental regulations by the application of conventional precipitation processes treating complex heavy metal wastewaters. We studied the potential of a new method for removing heavy metals from metal–EDTA wastewater by Fenton reaction followed by hydroxide precipitation. This process is referred to as Fenton reaction-hydroxide precipitation (FR-HP) process. This study investigated the use of FR-HP and ultrasonic/FR-HP processes for the removal of Ni(II) from Ni–EDTA wastewater. The results indicate that ultrasonic/FR-HP process is more effective for the removal of nickel ions than FR-HP process.     

Treatment of metal-chloride-enriched wastewater by simulated constructed wetlands

The ability of surface flow and subsurface flow simulated wetlands to remove heavy metals from a NaCI-enriched wastewater was examined, employing bulrush (Scirpus validus) and cattail (Typha angustifolia) plants, and two organically amended substrates (mixtures of mushroom compost and leaf litter,with topsoil) with a limestone liner. A simulated wastewater solution containing Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn as chloride salts was added to the wetlands at a rate of 0.3 l h^–1. During 12 weeks of surface flow, Fe was retained most efficiently (74%), and Mn the least (24%). Most metal retention occurred in residual forms, primarily in the upper 5 cm of the substrate. A subsequent 10 week subsurface flow treatment exhibited greater removal efficiencies for all metals, probably due to increased contact with the highly buffered lower substrate. During both treatments, bioaccumulation occurred in plants, but accounted for a very small portion of the total metal removal. Plant species did not significantly influence wetland performance with respect to metal retention. Substrate type did not affect removal efficiency for most metals, but did influence the forms of the metals retained in the wetland.To whom correspondence should be addressed.     

钢铁工业遗留场地土壤重金属洗脱剂筛选研究

土壤重金属污染限制了工业遗留场地再利用,通过振荡试验考察了HCl、HNO3和EDTA对工业遗留场地土壤中超标重金属Pb、Zn、Cd和As的洗脱效果。结果表明：土壤Pb、Zn、Cd、As的脱除效果均随洗脱剂浓度增加而增加;HCl、HNO3和EDTA等3种洗脱剂浓度分别为0.5、0.5和0.1 mol.L-1时,土壤Pb、Cd质量分数可降低至场地安全再利用的控制标准以内（分别为140 mg.kg-1、1mg.kg-1）;洗脱剂浓度分别增至2、2和0.2 mol.L-1时,土壤Pb、Cd质量分数继续降低,Zn、As质量分数有大幅降低但没有达到其相应的场地安全控制标准（分别为200、20 mg.kg-1）;与EDTA相比,HCl在低浓度时的重金属脱除效果较差,但HCl浓度增加对重金属脱除率的提高效果更为明显;洗脱液pH值（7.88~0.15）与重金属脱除率均呈显著负相关且与As的负相关系数最小,说明洗脱液pH值变化对As去除的影响相对较小;与HCl和HNO3相比,EDTA洗脱液pH值与Pb脱除率之间的负相关系数较大,与Zn、Cd、As脱除率之间的负相关系数较较小,说明EDTA洗脱液pH值变化更易对Pb的去除产生影响。     

鼠李糖脂对沉积物中Cd和Pb的去除作用

用铜绿假单胞菌(Pseudomonas aeruginosa)产生的鼠李糖脂生物表面活性剂对沉积物中重金属的去除作用进行了研究．研究表明,鼠李糖脂对沉积物中的Cd和Pb有明显的去除作用,在鼠李糖脂溶液的pH值为10．0的条件下对重金属的去除效率最好,而且当鼠李糖脂在沉积物上的吸附达到饱和时去除效率达到最大．通过连续萃取对提取前和提取后沉积物样品中重金属的形态进行分析,发现可交换态和有机结合态的重金属较容易去除．通过4次连续的提取,使cd和Pb的去除效率分别达到80．1％和36．5％．     

Ludwigia stolonifera for remediation of toxic metals from simulated wastewater

The present study investigated the phytoremediation of simulated wastewater, mimicking wastewater generated by industrial processes containing significant amounts of toxic heavy metal ions. The wetland plant Ludwigia stolonifera was used to study its efficiency in the removal of the three toxic metals Pb, Cd and Cr. Survivability of the plant has been studied in solutions at different concentrations of three metals separately or as a mixture, and the accumulation of these toxic metals for a prolonged period has been evaluated. The plant performed very successful in eliminating Cd, Cr and Pb as single metals of up to 65%, 97% and 99%, respectively, within four days. In addition, the trend of metal uptake revealed negligible dependence on different masses of plant and on various pH-values. L. stolonifera has high potential in eliminating various toxic pollutants from aquatic environments.     

Heavy metals uptake from aqueous solutions using marine algae (Colpomenia sinuosa): kinetics and isotherms

The adsorption of copper, zinc, cobalt, lead and cadmium ions onto Colpomenia sinuosa was studied as a function of contact time, initial metal ion concentration and initial pH. In addition, desorption studies were performed. Characterisation of this adsorbent was also confirmed by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis. Batch adsorption experimental data were analysed using Langmuir, Freundlich and Dubinin–Raduschkevich (D–R) adsorption isotherms. The results indicated that the biosorption equilibrium was well described by both the Freudlich and D–R isotherms. Moreover, sorption kinetics was performed and it was observed that equilibrium was reached in<60 min, which could be described by the pseudo-second-order kinetic model for all heavy metals. The sorption of heavy metals onto the biomass was largely dependent on the initial solution pH. The elution efficiency for heavy metal ions desorption from C. sinuosa was determined for 0.1 M HCl, 1.0 M HCl and 1.0 M HNO₃. Desorption efficiency and also adsorption capacity were highest for Pb(II). The results indicate that C. sinuosa has great potential for the removal of heavy metals in an ecofriendly process.