The Cement Solidification of Municipal Solid Waste Incineration Fly Ash

The chemical composition, the content and the leachability of heavy metals in municipal solid waste incineration （ MSWI） fly ash were tested and analyzed. It is shown that the leachability of Pb and Cr exceeds the leaching toxicity standard, and so the MSWI fly ash is considered as hazardous waste and must be solidifled. The effect of solidifying the MSWI fly ash by cement was studied, and it is indicated that the heavy metals can be well immobilized if the mass fraction of the fly ash is appropriate. The heavy metals were immobilized within cement hydration products through either physical fixation, substhtaion, deposition or adsorption mechanisms.     

MSWI fly ash based novel solidification/stabilization matrices for heavy metals

The possibilities of MSWI fly ash as a major constituent of novel solidification/stabilization matrices for secure landfill were investigated by mixing MSWI fly ash with rich aluminum components, which was added as bauxite cement or metakaolinite instead, to form Friedel and Ettringite phases with high fixing capacities for heavy metals. The physical properties, heavy metals-fixing capacity, mineral phases and its vibration bands in the novel matrices were characterized by compressive strength, TCLP（toxic characteristic leaching procedure）, XRD （x-ray diffraction） , DTG （derivative thermogravimetry）, and FTIR （fourier transform infrared spectroscopy）, respectively. The Tessier＇s five-step sequential extraction procedure was used to analyze the fractions of chemical speciation for Pb, Cd and Zn ions. The experimental results indicate that Friedel-Ettringite based novel solidification/stabilization matrices can incorporate Pb, Cd and Zn ions effectively by physical encapsulation and chemical fixation, and it exhibits a great potential in co-landfill treatment of MSWI fly ash with some heavy metals-bearing hazardous wastes.     

高钙粉煤灰地聚合物固化/稳定重金属的试验研究

利用高钙粉煤灰研制地聚合物来固化/稳定重金属,采用静态和动态浸出试验研究了高钙粉煤灰地聚合物对重金属的固化/稳定效果,并进一步探索了重金属的迁移机制和长期安全性.研究表明:高钙粉煤灰地聚合物分别固化/稳定0.025％的铅,0.025％的铬和0.01％的汞后,经静态浸出试验,重金属浸出浓度远低于规定的上限值,且固化率均在98％以上.经动态浸出试验,重金属的实时浸出浓度低于规定的上限值,累积浸出浓度在72 h后趋于稳定;固化体中重金属的径向分布相似;重金属的有效扩散系数和浸出率非常低,长期安全性优良.     

废弃粗粉煤灰-水泥系统固化重金属废弃物的探讨

利用强度发展、毒性浸出试验(TCLP)和动态浸出试验(DLT)等手段探讨了废弃粗粉煤灰-水泥系统固化/稳定含铅、铜和锌的重金属废弃物的可能性。研究发现废弃粗粉煤灰-水泥系统养护28d后符合固化/稳定的指标要求，而且长期效果优于细粉煤灰-水泥系统。另外试验还发现，固化/稳定系统的酸中和能力是决定样品中重金属浸出能力的主要指标。     

生活垃圾焚烧飞灰的处理处置方法

随着生活垃圾焚烧技术在中国城市生活垃圾处理中的推广，对生活垃圾焚烧残余物，主要是飞灰的处理、处置已成为困扰人们生产生活的重要问题之一。介绍了飞灰处理的固化方法、药剂稳定化、飞灰中重金属的提取及最终处置。     

粉煤灰处理北京石油化工学院生活污水的研究

用固体废弃物粉煤灰处理污水，从而达到以废治废的目的，是当前研究的热点问题。以一定粒径的粉煤灰作为吸附剂，采用固定床连续流动的方法对校园生活污水进行吸附处理，实验研究了污水初始COD、进料速度以及pH等实验条件对污水处理效果的影响。研究表明，所用粉煤灰可以较好地脱除校园生活污水的颜色和臭味，能有效地降低污水的COD值。在实验条件范围内，污水初始COD越高，其脱除率越高；随着流速的增加，污水COD的脱除率先升高再下降，当流速为10mL／min时，COD的脱除率最大；较低的pH值有利于粉煤灰对污水COD的脱除。     

纯化粉煤灰的改性及应用研究

为了提高粉煤灰的利用率,扩大应用领域,在Ca（OH）2-H2O-CO2系统,利用化学沉积方法成功地实现了粉煤灰颗粒的表面包覆,包覆后粉煤灰具有较高的白度和表面粗糙度.描述了复合粉煤灰的制备过程,研究了粉煤灰表面的包覆机理,借助SEM,BET,XRD等先进检测技术分析了粉煤灰改性前后的性能变化.试验结果表明：复合粉煤灰的白度由入料的33.54提高到73.13,比表面积由入料的3.07 m^2/g增加到9.77 m^2/g.在25%相同填充量的情况下,PP-复合粉煤灰的力学性能均优于未包覆粉煤灰、重质碳酸钙或轻质碳酸钙作填料的性能.     

重金属铅对硫铝酸盐水泥水化及其浸出毒性的影响

研究了硫铝酸盐水泥体系下重金属铅对水泥水化进程的影响,以及硫铝酸盐水泥对重金属铅的固化/稳定效果分析.研究表明,重金属铅掺量达到一定阀值（本试验条件下为2.0%）时,才会对硫铝酸盐水泥水化产生明显影响.用硫铝酸盐水泥对重金属铅进行固化效果良好,重金属铅通过物理固封、替代或吸附等形式可固化入水化产物结构中,且2.0%硝酸铅掺量浸出毒性试验结果控制在国家标准要求之内.     

生活垃圾焚烧飞灰重金属特性分析

对国内四个不同的垃圾焚烧厂产生的飞灰进行物理及化学特性分析.四种飞灰在颗粒尺寸分布上有相似的规律,飞灰中重金属的质量分数分析结果表明采用纯垃圾焚烧的炉排炉飞灰中的质量分数高于掺煤混烧的流化床焚烧飞灰中的质量分数.随着飞灰颗粒尺寸的减小,飞灰中重金属的浓度呈现增加的趋势.飞灰的渗滤特性表明,飞灰中Ca质量分数越高,飞灰的酸中合能力越强,且重金属的渗出率受飞灰渗滤液的pH影响大,而在碱性渗滤条件下受飞灰中重金属质量分数的影响小.     

Characteristics of MSWI fly ash during vitrification

The vitrification characteristics of municipal solid waste incinerator (MSWI) fly ash were investigated. Effects of temperature on the binding efficiency of heavy metals, the change of chemical compositions and the weight loss of fly ash in the range of 800-1350 ℃ were studied. Toxicity Characteristic Leaching Procedure (TCLP) of the United States was used to analyze the leaching characteristics of heavy metals in fly ash and molten slag. Results indicate that chemical compositions, the weight loss of fly ash and the binding efficiency of heavy metals in fly ash have a tremendous change in the range of 1150-1260 ℃. The percentage of CaO, SiO2 and Al2O3 increases with the increasing temperature, whereas it is contrary for SO3, K2O, Na2O and Cl; especially when the temperature is 1260 ℃, the percentage of these four elements decreases sharply from 43.72% to 0.71%. The weight loss occurs obviously in the range of 1150-1260 ℃. Heavy metals of Pb and Cd are almost vaporized above 1000 ℃. Cr is not volatile and its binding efficiency can reach 100% below 1000 ℃. Results of TCLP indicate that the heavy metal content of molten slag is beyond stipulated limit values.     

焚烧飞灰熔融特性与熔渣利用技术研究进展

垃圾焚烧飞灰中含有高浸出浓度的Pb,Cd,Cu,Zn等重金属,属于危险废物。高温熔融技术可以有效地控制焚烧飞灰中的重金属污染物。从飞灰无害化和资源化2个角度介绍了熔融技术的研究进展,分析了熔融技术的优缺点,在综述国内外研究成果的基础上,为今后焚烧飞灰的热处理技术提出了研究方向。     

粉煤灰改性及钝化污泥实验研究

以粉煤灰和石灰石为原料,加入一定量矿化剂,在微波辐照下进行改性,得到吸附材料粉煤灰沸石（FZ）,通过X射线衍射和电镜扫描等方式对粉煤灰辐照改性原理及产物结构等进行了分析,通过添加不同比例的粉煤灰对城市污泥进行了钝化实验研究,并对钝化作用机理进行了分析,对钝化污泥中重金属含量变化及养分含量进行了测试,实验结果表明,改性粉煤灰对污泥中含重金属Zn、Cu、Mn具有明显钝化作用,对污泥中养分具有良好的滞留效果,经钝化处理后,污泥中重金属Zn、Cu、Mn含量都显著低于国家农用标准,污泥渗滤液中全氮含量低于中国地面水环境质量标准（10mg·L^-1）,全磷含量低于污水排入城市下水道水质标准（1mg·L^-1）。     

Solidification of Municipal Solid Waste Incineration Fly Ash with Cement and Its Leaching Behaviors of Heavy Metals

The solidifying qffect of cement addition on municipal solid waste incineration fly ash ( MSWFA for short, collected from the gas exhaust system of MSW incinerator), the interaction of MSWFA with cement and water and the leaching of heavy metals from cement-solidified MSWFA are investigated. The main results show that : ( 1 ) when MSWFA is mixed with cement and water, 112 evolution, the formation and volume expansion of AFt will take place, the volume expansion can be reduced by ground rice husk ash addition ; (2) heavy metals do leach from cement-solidified MSWFA and at lower pH more leaching will occur; (3) compared with cement - so-lidified fly ash, the leachate of solidified MSWFA is with higher heavy metal contents ; (4) with the increment of cement addition leached heavy metals are decreased ; and (5) concentrations of Zn , Mn , Cu and Cd in all the leachates can meet the relevant Standards of Japan, but as the regulations for soil and groundwater protection of Japan are concerned, precautions against the leaching of Pb , Cl^- and Cr^6 and so on are needed.     

Solidification Efficiency and Mechanism of Conventional Curing Agents for Sewage Sludge Stabilization and Dewatering

One of the challenges faced by sewage sludge treatment and disposal is its higher water content, and how to efficient dewater those hazardous materials properly is welcome in practice. This study stabilized the sewage sludge via the using of conventional curing agents and calcined aluminum salts, and the corresponding dewatering mechanisms and structural changes of the stabilized sludge were further comparable analyzed. Experimental results showed that wollastonite and kaolin exhibit a relative higher dewatering efficiency as compared to other conventional curing agents; however the releasing rate of heavy metals of Cu, Cr, Ni for kaolin solidification and Zn, Pb for wollastonite solidification is higher than the sludge samples solidified by other curing agents. For comparison, the sludge samples solidified by calcined aluminum salts (AS), calcium ash, Mg-based curing agent, tricalcium aluminate (C₃A) show a lower heavy metals leaching potential and unconfined compressive strength. In addition, the economic characteristics and local availability of AS, calcium ash, C₃A and CaO makes it have a broad prospect in extension and application. These findings are of great significance for stabilization and dewatering of sewage sludge.     

Hydrothermal synthesis of zeolites-calcium silicate hydrate composite from coal fly ash with co-activation of Ca(OH)2-NaOH for aqueous heavy metals removalOA

Coal fly ash is a typical secondary aluminum/silicon resource. The preparation of zeolite-type absorbent is a potential way for its value-added utilization, while the purity and adsorption property of zeolite are limited due to the occurrence of side reactions in the synthesis process. In this study, a designated composite consisted of crystalline zeolites and amorphous calcium silicate hydrate was selected, which was direct synthesized from fly ash under conditions of a Ca/Si molar ratio of 0.8...     

Removal of Pb^2＋ and Cd^2＋ by adsorption on clay-solidified grouting curtain for waste landfills

Pb^2＋ and Cd^2＋ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of heavy metal cations in leachate was determined with atomic absorption spectrophotometer. Their equilibrium isotherms were measured, and the experimental isotherm data were analyzed by using Freundlich and Langmuir models. The results show that the adsorption capacities of the heavy metal cations are closely related to the compositions of clay-solidified grouting curtain, and the maximum adsorption appears at the ratio of cement to clay of 2 ： 4 in the experimental conditions. At their maximum adsorption and pH 5.0, the adsorption capacities of Pb^2＋ and Cd^2＋ are 16.19 mg/g and 1.21 mg/g. The competitive adsorption coefficients indicate that the adsorption of clay-solidified grouting curtain for Pb^2＋ is stronger than that for Cd^2＋. The adsorption process conforms to Freundlich＇s model with related coefficient higher than 0. 996.     

垃圾焚烧飞灰电弧炉熔渣微晶玻璃的晶化行为

将垃圾焚烧飞灰与适量废玻璃粉混合后用电弧炉熔融处理,产生的水冷熔渣进一步粉碎、压型并在750～1 050℃间热处理制取微晶玻璃,运用同步热分析仪、X射线衍射仪、扫描电镜等测试设备对微晶玻璃的晶化行为及性能进行分析测试.研究表明:微晶玻璃主晶相为硅灰石CaSiO3和少量透辉石Ca(Mg,Al)(Si,Al)2O6,其衍射峰随处理温度升高呈增加趋势,850℃热处理时所得微晶玻璃具有较佳的微观结构和物理、机械及化学性能,其密度为2.62 g/cm3、抗弯强度达90.44 MPa,耐酸碱性分别为2.7％、0.9％,重金属浸出浓度非常低.     

利用热等离子体熔融垃圾焚烧飞灰

为了评价垃圾焚烧飞灰的热等离子体熔融处理效果, 研究SiO2和CaO对重金属固化效果和重金属毒性浸出特性的影响. 在飞灰中添加一定比例的SiO2和CaO, 配置成不同的配灰样品, 利用纯氩热等离子体在1 400～1 500 ℃下, 对飞灰及配灰进行熔融玻璃化的实验研究, 分别利用X射线能量色散谱仪(EDX)、场发射扫描电子显微镜(FSEM)、X射线衍射仪(XRD)和毒性浸出方法(TCLP)分析飞灰和熔渣的化学组成、微观结构、晶相组成和重金属毒性浸出特性. 结果表明, 热等离子体熔融所得熔渣为无定形的玻璃体, 重金属浸出质量浓度均远低于毒性标准. SiO2和CaO的添加都可以改善重金属固化效果, CaO比SiO2对Cu、Zn、Cd和Pb挥发的抑制效果更好. SiO2的添加可以改善熔渣中重金属的浸出特性, 而CaO的作用与之相反.     

PAA-硅胶净水剂对重金属的吸附性能研究

为了解PAA-硅胶对重金属的吸附能力,对其静态吸附性能进行了测定,包括pH对吸附性能的影响、吸附平衡、重金属离子浓度对吸附性能的影响和温度对吸附性能的影响等实验．实验结果表明:PAA-硅胶使吸附达到最佳的pH分别为:Cu2+,4．0;Zn2+,5．0;Ni2+,5．5;Co2+,5．0;pb2+,4．0;在适合的pH条件下,PAA-硅胶对重金属具有良好的选择吸附性能,适用于含重金属水体的处理,对水中微量重金属的去除效率较高;温度升高有利于吸附．     

Microstructures and thermal properties of municipal solid waste incineration fly ash

To analyze the feasibility of utilization of thermal technology in fly ash treatment, thermal properties and microstructures of municipal solid waste incineration (MSWI) fly ash were studied by measuring the chemical element composition, specific surface area, pore sizes, functional groups, TEM image, mineralogy and DSC-TG curves of raw and sintered fly ash specimens. The results show that MSWI fly ash particles mostly have irregular shapes and non-typical pore structure, and the supersonic treatment improves the pore structure; MSWI fly ash consists of such crystals as SiO₂, CaSO₄ and silica-aluminates, and some soluble salts like KCl and NaCl. During the sintering process, mineralogy changes largely and novel solid solutions are produced gradually with the rise of temperature. Therefore, the utilization of a proper thermal technology not only destructs those persistent organic toxicants but also stabilizes hazardous heavy metals in MSWI fly ash.