堆肥对城市污泥重金属的影响

城市污泥的土地利用是其资源化利用的有效途径之一,但该利用方式的推广受限于对城市污泥中重金属引起的土壤二次污染问题的担忧。由城市污泥中重金属引起的土壤污染不仅与重金属的总量有关,更大程度上决定于重金属的化学形态。本文对城市污泥及其堆肥产品中重金属的含量和形态进行了分析研究,并讨论了污泥及堆肥产品的土地利用造成的土壤和农作...     

城市污泥中重金属去除技术研究

重金属污染是目前城市污水处理厂污泥农用的主要障碍之一。综述了城市污泥中重金属去除的常用四种技术：化学浸提、生物淋滤、动电技术和固化-稳定化,同时分析了污泥中重金属去除技术的发展方向。     

Agricultural use of sewage sludge and its regulation

Sewage sludge is waste for which the most positive outlet must be sought whilst, at the same time, making use of its qualities. In view of its organic matter and other nutrients content, it may be thought that the best system is to use it for agricultural purposes, although the load of heavy metals it may bear with it proves to be the main obstacle involved. Since it is a heterogeneous material whose composition depends on various factors, the content of such metals in sewage sludge will be highly variable. Thus it becomes necessary to always analyze sewage sludge before directing it towards agricultural use and also to know the heavy metal content of the soil where it is applied already so as to adjust this agronomical practice to the limits as set by current legislation in force. The provisions of law must also be complied with when certain substances deemed toxic or dangerous are present in sewage sludge. The purpose of all this is to prevent possible soil pollution and other kinds of risk involved in accumulation in the food chain.     

Soil effects due to sewage sludge application in agriculture

Field trials show that increased nutrients (mainly P) and heavy metals in soil due to agricultural use of sewage sludge have mainly to be expected when sludge is applied in too high amounts. The biological effects of heavy metals on plants are determined by their solubility which is increased by pH decrease and degradation of organic matter. Normally, it should be expected that the microbial activity in soil would increase with the application of organic matter in sewage sludge. But, also negative effects on the microflora by simultaneous enrichment of organic matter or inorganic and organic pollutants were found. The most important deleterious effects on soil microorganisms are the reduction in size of the total biomass, a reduced nitrogen fixing activity and changes in the composition of microbial populations of the soil. At what stage heavy metal toxicity to soil microorganisms or to microbial processes in soil is likely to become evident is unfortunately still uncertain. Again, the soluble fraction of heavy metals (also of organic pollutants) is a determing factor. To minimize the shown environmental risks an adequate sludge management is proposed.     

城镇污水处理厂污泥中重金属去除方法研究进展

城镇污水处理厂污泥中的重金属是污泥资源化利用的潜在危害之一,因此如何有效去除污泥中的重金属是当前亟待解决的问题。在分析我国污泥重金属含量现状的基础上,对动电技术、生物沥滤法、化学浸提法和植物提取法等重金属去除方法进行了比较。通过比较可知,这四种方法的主要优势分别为去除效率高、适用范围广、操作简单、费用低廉。在分析这些技术与方法各自特点的基础上,指出了这些去除方法各自存在的问题及其研究进展。     

污泥堆肥及其复合肥对草坪生物效应和环境效应的影响

研究了污泥堆肥及复合肥对草坪草的生物效应、土壤效应的影响.试验结果表明,污泥堆肥及草坪专用复合肥对草坪草的生长具有良好的生物效应.污泥堆肥及复合肥的施用使草坪草的叶绿素含量增加,污泥堆肥施用量高的叶绿素含量明显高于其它处理,达到了一级水平.试验结果还表明,污泥堆肥及复合肥的施用促进了草坪草叶片对氮素的吸收,使草坪草在成坪期获得了充足的养分.并保持了肥料的持续性.污泥堆肥及复合肥对草坪草具有较好的培肥效应,污泥堆肥及复合肥处理可提高土壤全量及有效N,P和K含量,且明显高于对照组.     

城市污泥中重金属存在形态、去除及稳定化研究进展

城市污水处理厂污泥产生量大,含有丰富的有机质、氮、磷、钾等农作物所需营养物质,但由于受重金属的污染使污泥无法直接农用。本文简述了城市污泥重金属的来源、特点及危害。重点论述了城市污泥中重金属去除和稳定方法,包括化学法（电化学法、化学试剂法）、生物法（微生物法、植物法、低等动物法）、物理法（超临界流体萃取、微波和超声）及联合技术。分析了各种方法处理污泥重金属过程中重金属的形态变化及其对处理效果的影响,对比各种方法的优缺点、影响因素及适用范围。指出污泥中重金属形态分布是影响去除效果的关键因素,污泥中重金属形态分布差异性大,且大部分重金属以稳定或相对稳定的状态存在,导致物理法和生物法去除效率较低,微生物和低等动物处理法相比植物法（备受时空限制）则表现出更好的适应性;电化学法对可氧化、可还原态分布的重金属都能起到较好的转化去除作用,但往往受由污泥向污泥液相中转移过程的控制,电损耗较突出;化学试剂浸提剂是目前效率较高的方法,但强酸环境常导致污泥营养物质流失和酸根离子累积,农用时容易板结而不利于污泥土地利用。因此,以土地利用为前提的条件下,将各种处理技术联合运用以提高污泥重金属去除率有待于进一步研究。     

污泥焚烧底灰的理化性质及再利用技术

污泥焚烧底灰的处理处置与资源化利用是污泥焚烧过程中必须解决的难题。该文通过对两种不同的污泥焚烧底灰的粒径、抗剪、压缩固结性、渗透性以及重金属含量等理化性质进行了研究,并将其与原生污泥性质进行对比,分析焚烧处理对污泥理化性质的影响,并进一步根据焚烧底灰性质,探索其再利用途径。结果表明污泥焚烧底灰属于砂土,且抗剪强度较污泥焚烧前有明显增大,可达76．23～80．03kPa;重金属含量有所超标,但重金属浸出量均小于相应标准限定值,可进行路基材料、cO2捕集、填海造陆等再利用。     

市政污泥生物质炭在废水吸附处理中的应用

随着经济全球化的飞速发展,城市污水处理中排放的污泥量日益增加,预计到2025年我国市政污泥年产量将超过9000万吨。市政污泥中含有的病原微生物、有机物及重金属,会对环境和人体健康造成严重危害。污泥衍生的生物炭材料因其较大的比表面积、优良的孔隙结构以及丰富的含氧基团,被广泛应用于废水吸附处理领域,实现了固体废物再利用和去除污染的双重目的,做到以废治废,达到生态与发展的双赢。本文系统总结了污泥生物质炭的制备及改性方法、综述了其对废水中重金属、染料、无机盐、抗生素、酚类等的应用及其吸附机理,指出未来污泥生物炭的发展方向和需攻克的难题,努力形成绿色低碳的资源化处理体系。     

污泥土地利用需注意的问题

污泥是城市污水处理厂不可避免的产物。随着工业的发展和城市化进程的加快,城市污泥的产量急剧增加。城市污泥中含有丰富的有机质及氮、磷等营养元素,但同时也含有种类较多含量不等的重金属、微量的有机污染物和病原物。所以将产生量巨大、成分复杂的污泥经过科学处理后,使其减量化、无害化、资源化,已成为我国乃至全世界环境界深为关注的课题之一。目前,国内外主要的污泥处置方法有填埋、焚烧和土地利用等。污泥土地利用是城市污水污泥资源化利用的一个重要技术途径,为了保证污泥土地利用更加安全有效,本文提出了污泥土地利用应注意的问题。     

城市垃圾焚烧飞灰中重金属形态及生物有效性研究

随着集中焚烧法逐渐成为我国城市生活垃圾处理的主要方式,焚烧飞灰的安全处置与利用也成为学者普遍关注的问题。由于在填埋过程中受到各种环境要素的影响,垃圾焚烧飞灰中的重金属有可能会发生迁移和转化,重金属形态、毒性也会随之变化。本文对不同粒径城市垃圾焚烧飞灰中重金属的总量、形态及生物有效性进行了研究,为其在安全填埋及资源化利用过程中预测重金属的环境风险提供参考。     

重金属污泥磨细粉对硅酸盐水泥基材料性能的影响

为了更好地实现对重金属污泥的资源化利用,研究了高温无害化处理重金属污泥与建筑渣土混合渣料磨细粉对硅酸盐水泥基材料工作性、力学性能、早期收缩变形、抗氯离子渗透性能及重金属浸出的影响及机理。研究结果表明,随着磨细粉掺量的增加,硅酸盐水泥基材料的工作性没有降低,但其力学性能均有一定程度下降,这说明磨细粉与硅酸盐水泥的需水比相差不大,但其掺量越大水泥基材料中水泥的量越低,其强度均会有一定程度下降。磨细粉不会引起硅酸盐水泥基材料的体积安定性问题,可以提高早期抗裂性,但会降低其抗氯离子渗透性能。含磨细粉试件中重金属的浸出浓度、水胶比的下降与龄期的上升呈负相关,且在28 d龄期下含40%(质量分数)磨细粉的硅酸盐水泥基材料中重金属Cu、Ni、Zn和Cr的浸出量均低于GB 30760—2014《水泥窑协同处置固体废弃物技术规范》规定的浸出浓度限值。     

柠檬酸和谷氨酸N，N-二乙酸优化处理污泥重金属

采用柠檬酸（CA）和谷氨酸N,N-二乙酸（GLDA）处理污泥重金属,研究了试剂浓度、pH和反应时间对重金属去除效果的影响,并以重金属去除率为表征,通过正交试验获得CA和GLDA处理重金属的最佳条件。结果表明,增加试剂用量、降低体系pH均有利于重金属的去除,但延长反应时间对重金属的去除效果影响不明显。CA和GLDA处理污泥重金属的最佳条件分别为：CA 0.3 mol·L^-1、pH 4、反应时间2 h和GLDA 0.05 mol·L^-1、pH 4、反应时间3 h。最佳反应条件下,对于CA和GLDA,重金属Cd、Cu、Pb和Ni的去除率可分别达80.25%、77.75%、64.66%和75.16%,及78.57%、78.48%、64.84%和76.71%。CA和GLDA对重金属的去除效果大小顺序均为：Cd>Cu> Ni>Pb,但GLDA的处理效果优于CA。污泥经CA和GLDA处理后,污泥固相酸溶态重金属含量下降幅度最大,平均达81%,残渣态重金属含量下降52.1%,而污泥液相中重金属含量则增加了17.54倍,说明重金属从污泥固相向液相转移。SEM镜检发现,污泥由处理前表面分散的絮状结构,变成更为明显的团块结构和片层结构,污泥的吸附能力下降,且体积缩小。研究结果表明,CA和GLDA处理污泥能有效降低污泥重金属含量并提高污泥固相重金属的化学稳定性,有利于污泥脱水及脱水后的进一步处理及其资源化。     

超声协同硝酸提取城市污泥重金属的研究

主要通过超声技术协同硝酸提取城市污泥重金属,以研究重金属的去除效果。文章阐明了超声波技术在不同pH、酸化时间时对城市污泥重金属去除的影响。     

垃圾焚烧飞灰重金属药剂稳定化研究进展

生活垃圾焚烧飞灰中存有大量高毒性的重金属物质,若不规范处置容易对土壤、地下水造成严重污染,目前通常采用添加化学药剂的方法来稳定飞灰中的重金属。本文在梳理国内外文献的基础上,归纳评述了飞灰重金属的性质、固化稳定化填埋工艺以及目前已被研究或应用的飞灰重金属稳定药剂,包括硫化钠、磷酸、无定形硅材料、铁化合物等无机药剂以及硫脲、EDTA接聚体、壳聚糖、氨基硫代羧酸盐等有机螯合剂,阐明了药剂作用机制和存在的问题,总结了不同药剂作用下的重金属稳定效果,同时针对新形势下的飞灰重金属稳定化要求进行了探讨,提出今后的研究方向为：选择特征性重金属药剂复配稳定飞灰;以改性、成环方式改良氨基硫代羧酸盐类物质（DTC）物质或以交联接枝等方式开发新型螯合剂。     

Heavy Metals Precipitation in Sewage Sludge

Abstract

There is a great need for heavy metal removal from strongly metal‐polluted sewage sludges. One of the advantages of heavy metal removal from this type of sludge is the possibility of the sludge disposal to landfill with reduced risk of metals being leached to the surface and groundwater. Another advantage is the application of the sludge as soil improver. The use of chemical precipitation to remove dissolved heavy metals from sewage sludge implies a high cost for chemicals. This work shows, for real sewage sludge for the first time that the addition of NaOH as first precipitating agent considerably saves the addition of Na₂S, that is one of the most effective metal precipitating agents and also expensive. After solubilization of heavy metals by chemical leaching with previous aeration, the next step was the separation of the sludge solids from the metal‐rich acidic liquid (leachate) by centrifugation and filtration. Afterwards, the filtered leachate was submitted to the application of NaOH and Na₂S, separately and in combination, followed by filtration. The results showed that when iron and aluminium are present in the leachate, adsorption and/or coprecipitation of Cr, Pb, and Zn with Fe(OH)₃ and Al(OH)₃ might occur at increasing pH conditions. The combination of hydroxide and sulfide precipitation was able to promote an effective removal of heavy metals from leachate. Applying NaOH at a pH of 4–5 as a first precipitation step, followed by filtration and further addition of Na₂S to the filtered liquid at pH of 7–8 as a second precipitation step, decreased considerably the dosage of the second precipitant (almost 200 times), compared to when it was solely applied. This has practical applications, as the claimed costs drawbacks of H₂S addition is considerably reduced by the addition of the less expensive NaOH. The best removal efficiencies obtained were: Pb: ～100%, Cr: 99.9%, Cu: 99.7%, and Zn: 99.9%.     

Comparison of the characteristics of bottom ash and fly ash from a medium-size (32 MW) municipal district heating plant incinerating forest residues and peat in a fluidized-bed boiler

In this study, the physical and chemical properties of bottom ash and fly ash originating from the co-combustion of biomass-derived fuels (i.e. wood chips, sawdust, bark, and peat) from a 32 MW fluidized bed boiler at a municipal district heating plant were investigated. Silicate minerals were predominant in the bottom ash and calcium minerals in the fly ash, with most of the inorganic nutrients and heavy metals being enriched in the fly ash. The enrichment factors for heavy metals in the fly ash varied between 0.2 for silicon and 16.3 for lead, and for plant nutrients, between 1.5 for phosphorous and 108 for potassium. However, all heavy metal concentrations in both the bottom ash and fly ash were significantly lower than the current Finnish limit for maximum allowable heavy metal concentrations for forest fertilizers, which came into force in March 2007. According to the particle size distribution, the mass loadings of heavy metals in the fly ash were more than 90% contributed by the smallest particle size fraction lower than 0.074 mm. In the bottom ash, between 83.6 and 91.9% of the mass loadings of heavy metals were contributed by the particle size fraction between 0.5 and 2.0 mm.     

污泥中重金属去除的技术

介绍了污泥中重金属存在的形态,综述了污泥中重金属去除的常用的四种技术化学浸出、生物浸出、电分离和超临界流体萃取,重点介绍了化学浸取技术的原理和特点,并对诸项技术的优点以及存在的问题进行了评述。     

城市生活垃圾成分及其波动对水泥窑的影响分析

就水泥窑处置生活垃圾时,垃圾灰渣成分及其波动对熟料质量的影响进行了分析研究,结果表明:生活垃圾焚烧产生的灰渣可以作为水泥替代原料;垃圾灰渣作为替代原料会带入一些干扰元素,为保证垃圾处置量及熟料质量,需要对垃圾进行均化等处理。     

Thermal plasma vitrification process as an effective technology for fly ash and chromium‐rich sewage sludge utilization

The main goal of the vitrification process for environmental research is the destruction of hazardous waste. This study proposes the use of a thermal plasma treatment process to transform fly ash and chromium‐rich sewage sludge into glassy products called vitrificates that can be stored on the land without harmful environmental effects. This is achieved by: (i) decreasing the temperature and energy used to adjust process cost minimization; and (ii) stabilization of vitrificates for different compositions of waste mixture. The chemical stabilization of final products was examined by heavy metals leachability tests. Hardness tests were done to verify the physical stabilization of vitrificates. The most stable vitrificates were obtained from a sample consisting of 90 wt% fly ash and 10 wt% chromium sludge. The thermal plasma treatment is an effective method which can be used to convert hazardous waste mixtures into less toxic or inert glassy products. The chemical composition of raw materials influenced the chemical and physical properties of the vitrificates and determined their internal structures. Mixtures of two different hazardous wastes reduces the process cost without negative environmental impact, which is an innovation in thermal plasma treatment technology. © 2013 Society of Chemical Industry