硅铝系固体废弃物合成Sialon材料的研究进展

以硅铝系固体废弃物为原料合成Sialon环境材料,不仅为固体废弃物的深度利用提供了一条新的思路,而且为Sialon材料的廉价合成提供了一条新的绿色工艺.简单介绍了冶金-高炉钙硅铝(钛)废渣、大宗能源系富含硅铝矸石尾矿、电厂铝硅铁灰渣、高硅多杂江河淤泥沙、稀土及贵金属伴生硅酸盐选矿后尾矿等硅铝系固体废弃物的概况,详细阐述了硅铝系固体废弃物合成Sialon材料的国内外发展现状,并对其发展前景进行了展望.

基于稳健优化的固体废弃物逆向物流网络设计

研究了不确定性环境下的固体废弃物回收问题。针对如何确定回收站和处理站的地址和数量,废弃物产生点的分配以及废弃物的存储和运输问题,建立了一个随机规划模型,并运用稳健优化将随机问题转换为线性规划问题;最后用算例证明了模型的有效性。

固体废弃物膏体充填料浆质量的神经网络研究

固体废弃物膏体充填在我国煤炭系统是一种新的胶结充填模式.充填料浆质量的研究至关重要.它是一典型的多输入、多输出、非线性的模糊模型.一方面,运用神经网络结合遗传算法构造了膏体充填料浆质量的隐式模型,建立该模型的方法以神经网络为基础,用遗传算法来学习神经网络的权系数,既保留了遗传算法的强全局随机搜索能力,又具有神经网络的鲁棒性和自学习能力.该模型具有较强预测能力,为优化固体废弃物膏体充填料浆质量的影响因素提供了理论依据.另一方面,利用已训练好的膏体充填料浆质量模型获得遗传算法,对充填料浆质量的影响因素进行优化,该法在配比设计时,可在较少的试验次数下获得较好的配比.

基于GRA—BP神经网络的固体废弃物充填体强度预测

为解决煤矿采空区充填材料不足和固体废弃物引起的生态环境问题,研究分析了膏体充填体强度的影响因素,采用正交试验测定了充填体样本强度,通过灰关联分析法确定了各影响因素与充填体强度之间的关联度,用改进的BP神经网络建立了以固体废弃物膏体充填体强度影响因素为输入层节点,充填体强度为输出层节点的强度预测模型;基于正交试验获得的强度试验数据作为网络的训练样本和测试样本,通过对建立的网络进行仿真模拟,检验了网络数据拟合能力和泛化能力。检验结果表明:建立的预测模型收敛速度快而且精度高,网络预测精度达到了93.75%,能够实现对充填体强度的准确预测。

农业垃圾:放错位置的资源——呈贡县对滇池沿岸农田固体废弃物资源化利用的探索与思考

一种应用高效生物菌使农作物秸秆、废弃菜叶子等迅速发酵制成有机肥的试验,不久前在云南滇池边上的呈贡县获得成功,目前,该县正在扩大示范和逐步推开.这项工作对改善当地生产条件,提高群众生活水平和质量,促进农业的持续健康发展,尤其是改善和保护好著名风景区滇池的环境,具有非常重要的意义.

煤炭开采区废弃物堆置体坡面侵蚀特征研究

通过野外布设坡面径流小区观测点量测，采用多年平均侵蚀模数来定量描述煤炭开采区废弃物堆置体坡面侵蚀强度，并通过模拟径流冲刷试验研究了煤矸石、自燃煤矸石、煤矸石覆土三种堆置形式坡面产流和产沙过程、侵蚀特征及抗冲性能。结果表明，在小流量冲刷下，煤矸石抗冲刷性能最大，坡面侵蚀轻微，几乎不产沙。以此为依据，提出了煤矸石排放工艺和废弃物堆置体坡面侵蚀防治的一些见解。

煤炭开采区废弃物堆置体坡面侵蚀特征的研究

本研究通过野外布设坡面径流小区观测点量测，采用多年平均侵蚀模数来定量描述煤炭开采区废弃物堆置体坡面侵蚀强度。并通过模拟径流冲刷实验研究了煤矸石、自燃煤矸石、煤矸石覆土三种堆置形式坡面产流和产沙过程、侵蚀特征及抗冲性能。以此为依据，提出了煤矸石排放工艺和废弃物堆置体坡面侵蚀防治的一些见解。

Experimental study on the properties of CMTs-incorporated geopolymers prepared at low temperatures

Considering that copper mine tailings(CMTs)are commonly mixed with ordinary Portland cement,fly ash(FA),and kaolin to produce geopolymers,to make full use of CMTs,the properties of geopolymers manufactured under different material mass ratios and curing methods(standard curing,water bath curing,and 60℃curing)are evaluated with significantly increased dosage of CMTs.Porosity and unconfined compressive strength tests,X-ray diffraction,field emission scanning electron microscopy,and energy dispersive spectroscopy are used to determine the physical and mechanical properties,microstructure,and mineral composition of geopolymers.Finally,costs and CO 2 emissions of specimens with different material mass ratios during the preparation processes are compared.The results show that during the geopolymerization of low-calcium materials,various geopolymer gels,including calcium silicate,calcium silicoaluminate,and mainly sodium silicoaluminate gels,coexist.The solid waste,cost,and carbon dioxide emission reductions can reach 100%,166.3 yuan/t,and 73.3 kg/t,respectively.Under a curing condition of 60℃,the sample with a CMTs mass fraction of 70%and an FA mass fraction of 30%meets the requirements of porosity,compressive strength.The resource utilization of CMT and FA is realized in a more economical way.

Catalytic effect of silver-bearing solid waste on chalcopyrite bioleaching:A kinetic study

Silver ion can be useful in improving chalcopyrite bioleaching efficiency.In this work,leaching kinetics of this process was investigated using silver-bearing solid waste under different chalcopyrite/solid waste ratios.Bioleaching behavior indicates that silver-bearing solid waste can enhance the bioleaching process,and the redox potential is much higher than the proposed appropriate range(380−480 mV vs Ag/AgCl)with the solid waste added.There is a positive correlation between temperature and copper extraction rate.The kinetics data fit well with the shrinking-core model.Under these leaching conditions,the bioleaching of chalcopyrite is controlled by internal diffusion with calculated apparent activation energy(Ea)of 28.24 kJ/mol.This work is possible benificial to promote the industrial application of silver catalyst in leaching of chalcopyrite.

Variation of Coenzyme F_(420) Activity and Methane Yield in Landfill Simulation of Organic Waste

A simulated landfill anaerobic bioreactor was used to characterize the anaerobic biodegradation and biogas generation of organic waste which was mainly composed of residuals of vegetables and foods. We investigated the dynamics of the coenzyme F420 activity and determined correlations between biogas yields, methane yields, methane concentration and coenzyme F420 activity. The experiment was carded out under different conditions from control without any treatment, addition of Fe^3＋, microorganism inoculation to a combination of Fe3＋ addition and inoculation at a temperature of 36±2℃. The experiment was lasted 120 d and coenzyme F420 activity was analyzed using ultraviolet spectrophotornetry. Experimental results indicated that activity of the coenzyme F420 treated by Fe and microorganism inoculation increased substantially. The waste treated by inoculation had the greatest increase. When the waste was treated by Fe^3＋, inoculation and the combination of Fe^3＋ and inoculation, biogas yields increased by 46.9%, 132.6% and 153.1%, respectively; while the methane yields increased 4, 97 and 98 times. Methane concentration varied between 0 and 6% in the control reactor, from 0 to 14% for waste treated by the addition of Fe^3＋, from 0 to 59% for waste treated by inoculation and from 0 to 63% for waste treated by Fe^3＋ addition and inoculation. Correlations between coenzyme F420 activity and biogas production, methane production and methane concentration proved to be positively significant （p〈0.05）, except for the control. Consequently, coenzyme F420 activity could be used as an index for monitoring the activity of methanogens during anaerobic biodegradation of the organic fraction of municipal solid waste.

Retention of clay-solidified grouting curtain to Cd^(2+), Pb^(2+) and Hg^(2+) in landfill of municipal solid waste

The effects of components and their ratio of grouts on anti-seepage capability of clay-solidified grouting curtain and its permeability of heavy metal cations were investigated by permeating experiments, using reactive solute transport model to study the permeation of heavy metals (Cd2+, Pb2+ and Hg2+). The study of permeating for different mixture ratios of cement and clay indicates that hydraulic conductivity of clay-solidified grouting curtain with different ratios of solid to liquid or with the same ratio of solid to liquid but with different ratios of cement to clay is changed. The laboratory simulation test results also show that precipitates produced in heavy metal cation migration process in curtain block up water flowing passage which makes the hydraulic conductivity of the solution-permeated curtain decrease with the leakage time. The permeation velocities for different heavy metal cations vary with ionic concentration, exchange capacity and ion radius etc. The test results indicate that the permeation rapidity order of heavy metals cations in clay-solidified grouting curtain is Hg2+>Pb2+ in the same experimental circumstance. In addition, permeability for different mixture ratios and antisepsis capabilities of clay-solidified grouting curtain were studied in tests.

Performance and mechanism of solid waste coking sulfur paste modified asphalt mixture before and after curing

For the resource utilization of the solid waste coking sulfur paste and the improvement of performance of the asphalt mixture,a method for preparing modified asphalt mixture with coking sulfur paste modifier(CSPM)is herein proposed.Compared with the matrix asphalt mixture,the Marshall stability of the 30%CSPM modified asphalt mixture increased by 38.3%,the dynamic stability increased by nearly one time(reaching 1847.5 times/mm),the splitting strength ratio increased by 39.3%while the splitting tensile strength decreased by 11.7%.After curing,the performance of the CSPM modified asphalt mixture was further improved.The results show that CSPM improved the high temperature stability and water damage resistance of the asphalt mixture,and the low-temperature anti-cracking performance of that was slightly reduced.Chemical analysis of asphalt binders shows that a little sulfur reacted with asphalt to produce polysulfide compounds(R-Sx-R′),and a part of sulfur existed in the form of crystalline sulfur which was further increased after curing.The presence of crystalline sulfur as an inorganic filler is the key point for improving the high temperature stability and water resistance performance of modified asphalt mixture.

Oxygen Gasification of Municipal Solid Waste in a Fixed-bed Gasifier

Four waste materials, paper, wood, textile and kitchen garbage, in municipal solid waste were gasified separately with oxygen in a fixed bed reactor. The yields of products char. tar and gas, the composition of gas components H2, CO, CO2 and CH4, and the lower heating value （LHV） were examined at temperatures between 700 and 900 ℃ and equivalence ratio （ER） between 0.14 and 0.32. Characteristics of gas evolution during gasification were inves- tigated. Results show that a higher temperature improves the formation of H2 and CO while lowers the yield of CO2 and CH4. The LHV of syngas increases with temperature and varies in the range of 6-10 MJ. m-3 reaching the maximum at 800 ℃ or above. As ER increases, both combustible gas component and LHV of syngas decrease while the yield of CO2 rises linearly. The appropriate ER for obtaining high quality gas is in the range of 0.18-0.23. Temperature and ER have significant effects on the product distribution. Higher temperature and ER are favorable for higher gas yield and lower yield of char and tar in the gasification of textile and kitchen garbage. At 800 ℃, the gas evolution may be divided into two regions. In the first region, the flow rate of gas increases and then de- creases ranidlv, while in the second reuion the flow rate decreases monotonically to lower level.

Laboratory testing of a densified municipal solid waste in Beijing

Municipal solid waste （MSW） and its disposal are gaining significant importance in geotechnical and geoenvironmental engineering. However, conventional research is primarily focused on fresh MSW or MSW that is compacted under its own weight in the landfill. In this work, a series of tests to study the properties of a densified MSW after ground treatment were presented. The tests involved oedometer test, simple shear test, triaxial shear test, and permeability test, which were conducted to investigate the compressibility, shear strength, creep behavior and permeability of the MSW. The results show that the compressibility modulus of the MSW increases as the dry density increases. However, the influence of density on modulus decreases once the density reaches a certain value. Like most soils, the stress-strain curve of the densified MSW can be approximated by a hyperbola in the triaxial shear test. Fibrous components provide additional cohesion for MSW, but have a relatively smaller effect on friction angle. Permeability is also found to be closely related to the dry density of the MSW, i.e., MSW with a higher dry density has a smaller permeability. The permeability coefficient may be less than 10 7 cm/s if the density is high enough.

Design and fabrication of a large-scale oedometer

The most common apparatus used to investigate the load-deformation parameters of homogeneous fine-grained soils is a Casagrande-type oedometer. A typical Casagrande oedometer cell has an internal diameter of 76 mm and a height of 19 mm.However, the dimensions of this kind of apparatus do not meet the requirements of some civil engineering applications like studying load-deformation characteristics of specimens with large-diameter particles such as granular materials or municipal solid waste materials. Therefore, it is decided to design and develop a large-scale oedometer with an internal diameter of 490 mm. The new apparatus provides the possibility to evaluate the load-deformation characteristics of soil specimens with different diameter to height ratios. The designed apparatus is able to measure the coefficient of lateral earth pressure at rest. The details and capabilities of the developed oedometer are provided and discussed. To study the performance and efficiency, a number of consolidation tests were performed on Firoozkoh No. 161 sand using the newly developed large scale oedometer made and also the 50 mm diameter Casagrande oedometer. Benchmark test results show that measured consolidation parameters by large scale oedometer are comparable to values measured by Casagrande type oedometer.

Optimal scenario balance of reduction in costs and greenhouse gas emissions for municipal solid waste management

To reduce carbon intensity, an improved management method balancing the reduction in costs and greenhouse gas(GHG)emissions is required for Tianjin's waste management system. Firstly, six objective functions, namely, cost minimization, GHG minimization, eco-efficiency minimization, cost maximization, GHG maximization and eco-efficiency maximization, are built and subjected to the same constraints with each objective function corresponding to one scenario. Secondly, GHG emissions and costs are derived from the waste flow of each scenario. Thirdly, the range of GHG emissions and costs of other potential scenarios are obtained and plotted through adjusting waste flow with infinitely possible step sizes according to the correlation among the above six scenarios. And the optimal scenario is determined based on this range. The results suggest the following conclusions. 1) The scenarios located on the border between scenario cost minimization and GHG minimization create an optimum curve, and scenario GHG minimization has the smallest eco-efficiency on the curve; 2) Simple pursuit of eco-efficiency minimization using fractional programming may be unreasonable; 3) Balancing GHG emissions from incineration and landfills benefits Tianjin's waste management system as it reduces GHG emissions and costs.

Municipal solid waste degradation and landfill gas resources characteristics in self-recirculating sequencing batch bioreactor landfill

Based on the degradation characteristics of municipal solid waste(MSW)in China,the traditional anaerobic sequencing batch bioreactor landfill(ASBRL)was optimized,and an improved anaerobic sequencing batch bioreactor landfill(IASBRL)was put forward on the basis of leachate self-recirculation.By monitoring MSW composition,leachate characteristics variation and landfill gas(LFG)generation,the effect of IASBRL was comparatively studied by simulation landfill.Based on the adjusting,scouring and carrying effects of leachate self-recirculation,IASBRL can rapidly decrease Eh value to about-500mV and form a suitable biochemical environment for methanogens,which provides a precondition for stable cooperation between non-methanogens and methanogens.IASBRL can avoid the accumulation of organic acids,make VFA(volatile fatty acid)concentration and CODCr decrease along with the small range fluctuations,and form a stable decomposition-consumption synergy during MSW degradation,therefore,the hydrolysis rate of easy hydrolyze material reaches 71.2% in IASBRL.From the viewpoint of LFG resources in IASBRL,the cumulative LFG production increases to 2327.0L,CH4 mass fraction stabilizes at about 50%,and these provide a favorable precondition for LFG development.

Geotechnical behavior of the MSW in Tianziling landfill

The valley shaped Tianziling landfill of Hangzhou in China built in 1991 to dispose of municipal solid waste (MSW) was designed for a service life of 13 years. The problem of waste landfill slope stability and expansion must be considered from the geotechnical engineering point of view, for which purpose, it is necessary to understand the geotechnical properties of the MSW in the landfill, some of whose physical properties were measured by common geotechnical tests, such as those on unit weight, water content, organic matter content, specific gravity, coefficient of permeability, compressibility, etc. The mechanical properties were studied by direct shear test, triaxial compression test, and static and dynamic penetration tests. Some strength parameters for engineering analysis were obtained.

Probe into Environmental Kuznets Characteristics and Causes of Wastewater, Waste Gas, and Solid Wastes in Wuhan City

Environmental Kuznets characteristics and causes of waste water, waste gas, and solid wastes in Wuhan city was researched; By comparing the variation of “three wastes”, i.e. waste water, waste gas, and solid wastes, the model between standardized per capita GDP and values of “three wastes” discharge was established and the causes were analyzed based on the theory of environmental economics. The results show that 1) the total amount is fluctuantly increasing, but the discharges of the three kinds are temporarily different, 2) the curve conforms to the three-power function, in which the curve descends from 1985 to 1994, and the curve preliminary shows the environmental Kuznets characteristics from 1995 to 2001, 3) the simulated calculation illustrates that the turning point of this environmental Kuznets curve would be over 25007.25 Yuan per caprta, and 4) the economic development, changing of industry structure, energy resource structure, and environmental policies are the main factors leading to the Environmental Kuznets Curve in Wuhan city.

Preparation and Characterization of Refuse Derived Fuel for Pyrolysis and Gasification by Bindless High Pressure Briquetting Technology

A new type of refuse derived fuel (RDF) for pyrolysis and gasification was prepared from municipal solid waste (MSW) in the presence of a small quantity of coal by bindless high pressure technology at room temperature. The physicochemical property of RDF was tested. Orthogonal experiment method was used to optimize the process parameters using dropping strength (mechanical strength) and thermal stability of the RDF as indices for quality of RDF. The result shows that the mixture of MSW and coal with a total moisture ranging from 5% to 17% can be easily compressed into RDF briquettes at a pressure above 70 MPa. When the briquetting pressure is higher than 100 kN and moisture content is about 10%, the qualified RDF can be obtained. The orthogonal experiment shows that the moisture can greatly affect the mechanical strength of RDF, while all the technique parameters have no obvious influence on thermal stability of RDF. The optimal parameters are a shaping pressure of 106 MPa, a moisture content of 10%, and a coal content of 20%.