Microstructural analysis of marl stabilized with municipal solid waste and nano-MgO

Municipal solid waste(MSW)is accumulating over elapsed time across the world,and it is observed in many projects associated with weak soils,such as marl.Therefore,effective solutions to the environmental problem are essential.Conventional techniques for stabilizing marl generally use substances such as lime and cement,which could exacerbate pollution.For this,some new stabilizers,e.g.nano-MgO,are used.There are large quantities of marls and MSW in Shiraz City,Iran.The present study aims to evaluate the feasibility of using nano-MgO as a green low-carbon binder to remove MSW from the environment and make construction projects more cost-effective.Consolidated drained shear tests were conducted to evaluate the mechanical behaviors of the nano-MgO treated marl specimens at high normal stresses.The marl specimens containing MSW percentages of 15%,25%,35%,and 45%and nano-MgO percentages of 0.25%,0.5%,0.75%,and 1%,were used.It is found that the marl containing 15%and 25%MSW and 0.5%nano-MgO at 28-d curing can perform cation exchange and form new cementitious products.The soils with merely MSW show good performance due to the removal of the kaolinite and the formation of brucite.However,the soil with 25%MSW and 0.5%nano-MgO shows the same strength enhancement as the specimen with the optimal nano-MgO(0.75%)through the formation of dolomite,with a 20.59%increase in strain energy(SE).

A perspective analysis on municipal solid waste(MSW) energy recovery in China

The paper analysed the current situation of municipal solid waste(MSW) quantity and quality in China and the changing tendencies of its composition. Further more, the energy value of MSW was discussed. To the point of the technical and economic aspects, the feasibility of the energy recovery from MSW was also analysed. The conclusion is that the energy can be effectively recovered through a landfill gas utilization process and the energy produced by an incineration process. Through a suitable energy recovery process, it is possible to improve the economic viability of a MSW treatment process.

Technology of comprehensive disposal and utilization of municipal solid waste (MSW)

The project for treating MSW of 200 tons each day was built in Yibin, Sichuan Province of China. The disposal processes are: separation and selection of usable resources; compost and fermentation of “heavy” organic waste (kitchen, garden composting rubbish); incineration of “light” waste (plastic, paper, wood and bamboo etc.) and landfill of inorganic waste. The thermal energy generated in the process can be used as 1/3 of the whole energy for drying fertilizers. In the process, there is no wastewater drainage, and air emissions can be effectively controlled by a series of measures. The sanitary and environmental indicators of disposal site meet the national standards. This project has worked well for two years. It not only disposes of and reduces the MSW, but also retrieves the resource effectively. The organic fertilizer has been applied in the ten thousand acres of fields, with productivity increase by more than 10%.

Environmental monitoring and fuzzy synthetic evaluation of municipal solid waste transfer stations in Beijing in 2001-2006

Transfer station(TS)is an integral part of present-day municipal solid waste(MSW)management systems.To provide information for the incorporation of waste facilities within the current integrated waste management system,the authors measured the existing environmental quality at five MSW TSs.Discharged wastewater,air,and noise were monitored and assayed at the five TSs in Beijing in 2001-2006 during rainy seasons(RSs)and dry seasons(DSs).Except Ammonia(NH_3)and hydrogen sulfide(H_2S),the analytical results of...

Engineering properties for high kitchen waste content municipal solid waste

Engineering properties of municipal solid waste （MSW） depend largely on the waste＇s initial compositionand degree of degradation. MSWs in developing countries usually have a high kitchen waste content（called HKWC MSW）. After comparing and analyzing the laboratory and field test results of physicalcomposition, hydraulic properties, gas generation and gas permeability, and mechanical properties forHKWC MSW and low kitchen waste content MSW （called LKWC MSW）, the following findings wereobtained： （1） HKWC MSW has a higher initial water content （IWC） than LKWC MSW, but the field capacitiesof decomposed HKWC and LKWC MSWs are similar; （2） the hydraulic conductivity and gaspermeability for HKWC MSW are both an order of magnitude smaller than those for LKWC MSW; （3）compared with LKWC MSW, HKWC MSW has a higher landfill gas （LFG） generation rate but a shorterduration and a lower potential capacity; （4） the primary compression feature for decomposed HKWCMSW is similar to that of decomposed LKWC MSW, but the compression induced by degradation ofHKWC MSW is greater than that of LKWC MSW; and （5） the shear strength of HKWC MSW changessignificantly with time and strain. Based on the differences of engineering properties between these twokinds of MSWs, the geo-environmental issues in HKWC MSW landfills were analyzed, including highleachate production, high leachate mounds, low LFG collection efficiency, large settlement and slopestability problem, and corresponding advice for the management and design of HKWC MSW landfills wasrecommended.

Impact of open dumping of municipal solid waste on soil properties in mountainous region

This paper presents the effect of open dumping of municipal solid waste(MSW) on soil characteristics in the mountainous region of Himachal Pradesh, India. The solid waste of dumpsite contains various complex characteristics with organic fractions of the highest proportions. As leachate percolates into the soil, it migrates contaminants into the soil and affects soil stability and strength. The study includes the geotechnical investigation of dump soil characteristics and its comparison with the natural soil samples taken from outside the proximity of dumpsites. The geochemical analysis of dumpsite soil samples was also carried out by scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS).Visual inspection revealed that the MSW consists of high fraction of organics, followed by paper. The soil samples were collected from five trial pits in the dumpsites at depths of 0.5 m, 1 m and 1.5 m. Then the collected soil samples were subjected to specific gravity test, grain size analysis, Atterberg’s limit test,compaction test, direct shear test, California bearing ratio(CBR) test and permeability analysis. The study indicated that the dumpsite soils from four study regions show decreasing trends in the values of maximum dry density(MDD), specific gravity, cohesion and CBR, and increasing permeability as compared to the natural soil. The results show that the geotechnical properties of the soils at all four study locations have been severely hampered due to contamination induced by open dumping of waste.

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.

CH4 emission and recovery from Municipal Solid Waste in China

Methane (CH 4) is an important greenhouse gas and a major environmental pollutant, second only to carbon dioxide (CO 2) in its contribution to potential global warming. In many cases, methane emission from landfills otherwise emitted to the atmosphere can be removed and utilized, or significantly reduced in quantity by using cost effective management methods. The gas can also be used as a residential, commercial, or industrial fuel. Therefore, emission reduction strategies have the potential to become low cost, or even profitable. The annual growth rate of Municipal Solid Waste (MSW) output in China is 6.24%, with the highest levels found in South China, Southwest China and East China. Cities and towns are developing quickly in these regions. MSW output was only 76.36 Mt in 1991 and increased to 109.82 Mt in 1997, registering an average increase of 43.8%. In China, methane emission from landfills also increased from 5.88 Mt in 1991 to 8.46 Mt in 1997; so the recovery of methane from landfills is a profitable project.

Impact of Municipal Solid Waste Disposal on Compaction Characteristics and Strength of Red Soil

The disposal of MSW （municipal solid waste）, in most of Indian cities, is to dump on nearby low laying lands. This investigation aims to characterize MSW and assess compaction characteristics and strength properties of contaminated soils at dumping sites in two cities Chickballapur and Kolar of Karnataka, India. Representative solid wastes from selected wards of the city were collected and analyzed. Substantial release of leachate form the dump yards occurred during past few years and the soil at the dump site experience extensive contamination. The test results of contaminated and uncontaminated soil show increase in optimum moisture content and decrease in maximum dry density. The unconfined compressive strength decreased considerably for soil samples obtained at 0.0 m, 0.5 m and 1.0 m depths below waste dump. At depths greater than 1.5 m, compaction characteristics and unconfined compressive strength closely match with the uncontaminated soil. Little variation in pH value, which makes soil slightly alkaline, was observed. From the study, it is inferred that, this investigation is very significant, as the foundation normally at these depths may be affected by this contamination.

基于Aspen Plus的MSW气化熔融工艺全流程模拟研究

城市固体废物(MSW)气化熔融工艺能够减少二噁英的生成和熔融固化重金属,是一种清洁高效的固体废物处理方式。已有研究多针对MSW的热解特性以及污染物的生成与排放,而对气化熔融工艺系统模块之间的影响和各反应器间物质流、能量流的联动变化过程研究不足。利用Aspen Plus模拟平台,基于吉布斯自由能最小化原理,对MSW气化熔融工艺进行了全流程模拟研究,分析了垃圾干燥温度、垃圾含水率、气化温度、气化介质以及灰熔点对工艺流程节点参数、物质流和能量流的影响,并提出了优化的工艺流程和运行参数。结果表明:在垃圾热解模拟时,垃圾含水率为9%,通过烟气循环能达到能量自给;在相同条件下,以水蒸气作为气化介质的气化效率最高,且在气化温度为850℃,水蒸气当量比为50%时,达到最佳工艺效果;当气化后产生的焦炭在熔融炉内燃烧刚满足灰熔点温度时,灰熔点的升高使气化剂比例、气化气有效气体摩尔流量和碳转化率不断降低。不同工况下的物质流、能量流的变化对实际工程具有指导意义。

水泥窑协同处置MSW环境负荷与性能耦合评价

基于中国某水泥厂2022~2023年生产数据及近3年国家/行业统计数据进行生命周期评价,核算水泥窑协同处置城市生活垃圾(MSW)生产不同品种水泥的环境负荷;联合数据质量指标评估和蒙特卡洛模拟来综合评估最终结果的不确定度.与常规工艺相比,水泥窑协同处置工艺生产每吨熟料的综合环境负荷降幅为7.82%;4种水泥中,P·O 52.5水泥的综合环境负荷最大,但其单位强度的环境负荷相对较小.综合考虑,采用水泥窑协同处置工艺生产P·C 42.5水泥与采用常规工艺生产P·O 42.5水泥相比,其综合环境负荷降幅为16.87%.

Exploring the development of municipal solid waste disposal facilities in Chinese cities:patterns and drivers

Rapid urbanization in Chinese cities has led to a surge in municipal solid waste(MSW)generation,necessitating the development of high-quality MSW disposal facilities.This study utilizes multi-source data and regression models to examine the status,development pathways,and driving forces of MSW disposal facilities in China.Our findings reveal an inverted U-shaped relationship between the capacities or numbers of MSW disposal facilities and GDP per capita of cities.Historical data show that cities in East and Southeast China preferred incineration,while cities in West and Central China developed landfills more,largely shaped by the imbalance of development levels and endowments among regions in China.The study also identifies mixed and differentiated influences of socio-economic factors on capacity expansion and increases in the number of MSW disposal facilities.The results suggest the need for updated construction guidelines and regulations,as well as enhanced technological and managerial capabilities for MSW infrastructure.These findings can inform policymakers and practitioners in their efforts to promote sustainable waste management practices in China.

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.

Recycling combustibles from aged municipal solid wastes(MSW)to improve fresh MSW incineration in Shanghai:Investigation of necessity and feasibility

Aged municipal solid wastes(MSW)excavated from landfills and dumpsites were characterized to analyze their fraction composition,moisture content,and lower heat value(LHV).The necessity and feasibility of recycling combustibles from aged MSW to improve the incineration of fresh MSW were investigated.The results showed that combustibles in aged MSW were easily separated from other components and than LHV of the separated combustibles are higher than 11000 kJ/kg.The fresh MSW are of high moisture contents with average LHV below 6500 kJ/kg,making their stable combustion difficult to maintain in MSW incinerators.For both fresh MSW and aged MSW,plastics are the main contributor to their LHV.To improve incineration of fresh MSW that are characterized with low LHV,combustibles separated from aged MSW were made into refuse derived fuel(RDF)pellets and were then added to fresh MSW by 2%wt.–5%wt.LHV variation and air supply resistance change of the MSW layer on the incinerator grate caused by the addition of RDF was checked,and no significant changes were found.No obvious difference was observed for the‘burn-out time’between RDF pellets and fresh MSW either.RDF made from aged MSW combustibles is found to be a promising auxiliary fuel to improve the incineration of fresh MSW,and aged MSW from old landfill cells and dumpsites can be finally disposed of jointly with fresh MSW by recycling combustible from the former to be coincinerated with the latter in the incineration plants.

A Life Cycle Comparison of Remote, Deployed Expeditionary Waste Management Scenarios

The current barrier to acquisition and utilization of viable waste-to-energy (WTE) technologies at remote or deployed expeditionary sites requires high capital and operation & maintenance costs. The impacts to environment and human health of differing expeditionary waste management strategies were compared using the Life Cycle Assessment software SimaPro 8.0. Emissions of individual waste management scenarios were compiled from peer-reviewed literature, converted to values compatible with SimaPro’s waste scenario inputs, and the calculated impacts compared using SimaPro’s pre-loaded methodologies. These calculated impacts and the economic impacts confirm that open-air burning of waste is not only dangerous to humans and the environment, but is also not cost-effective. Considering the economic effects and the mitigated human and environmental health impacts, WTE technologies may be a viable waste management strategy for the future.

2D Materials as Protective Coating against Low and Middle Temperature (100°C - 300°C) Corrosion-Erosion in Waste to Energy Plant: Case of Graphene

The combustion of MSW contains several species which if liberated into the flue gas will participate in erosion-corrosion reactions with the alloy surface and with the oxide layers. Actually with the evolution of material science and the discovery of 2D materials, we can handle that situation as well as possible. The graphene as 2D material presents a lot of advantage due to it physical properties such: melting point, boiling point and thermal conductivity, which can help to manage the problem of low and middle temperature (100°C - 300°C) erosion-corrosion into the boiler wall of waste to energy. The aim of the study was focused on analyzing the resistance at low and middle temperature (100°C - 300°C) in the enclosed environment and the corrosion-erosion resistance abilities of the graphene sheet as the 2D protective coating material. This paper analyzed the possibility of using the graphene in the aggressive environment which is waste to energy boiler. The results obtained from this study after simulation using ANSYS software which is one of the best software for simulations showed that Graphene protects the furnace walls against corrosion-erosion for temperatures lower than 400°C and that in the presence of certain impurities such as: sodium (Na), sulfur (S), chloride (Cl) and Phos- phorous (P), Sodium Chloride (NaCl), Hydrogen Chloride (HCl), Dioxide of Carbone (CO2) and Dioxide of Sulfur (SO2).

基于灰色系统的城市生活垃圾产生量预测研究

探究“无废城市”建设下城市生活垃圾产生量影响因素有助于指导城市制定有效的治理方案。基于灰色系统,以11个国内“无废城市”建设试点城市为对象,采用灰色关联分析法研究城市生活垃圾产生量的相关影响因素,并通过灰色预测模型预测城市未来9年的生活垃圾产生量。结果表明:1)城市的经济发展水平对生活垃圾产生量的影响最大,其相关影响因素的影响程度表现为地区生产总值>社会消费品零售总额>第三产业占比>人均GDP。2)GM(1,1)模型预测10个试点城市生活垃圾产生量的结果表明,2023—2030年重庆市和深圳市的生活垃圾产生量年增长率基本保持不变,威海市、盘锦市、三亚市等8个城市的生活垃圾产生量年增长率逐年降低,以铜陵市的降低幅度最大,绍兴市最小。3)加入5个相关影响因素的GM(1,N)模型预测6个试点城市生活垃圾产生量表明,2023—2030年盘锦市和重庆市的生活垃圾产生量年增长率呈下降趋势,深圳市、许昌市、三亚市、徐州市的年增长率逐年上升,增长幅度最大的是深圳市,最小的是徐州市。研究结果可为“无废城市”建设背景下城市的固废管理提供有效策略支撑。

Simulation analysis of municipal solid waste pyrolysis and gasification based on Aspen plus

To predict and analyze the municipal solid waste(MSW)pyrolysis and gasification process in an updraft fixed bed more veritably and appropriately,numerical modeling based on Gibbs energy minimization was executed using the Aspen plus software.The RYield module was combined with the RGibbs module to describe the pyrolysis section,while the RGibbs module was used for the gasification section individually.The proposed model was used to forecast and analyze the target performance parameters including syngas composition,lower heating value(LHV)and carbon conversion rate under different conditions of the gasification temperatures,and ratios and types of gasifying agents.The results indicate that there is a good agreement between the experimental data and the simulated data obtained using this model.The predicted optimum gasification temperature is approximately 750°C,and the best ratio of water vapor as gasifying agent is around 0.4.The mixture of flue gas and water vapor has an economical and recycled prospect among four commonly used gasifying agents.

Simulation of municipal solid waste gasification for syngas production in fixed bed reactors

This study proposes a model of syngas production from municipal solid waste (MSW) gasification with air in fixed bed reactors. The model (using Aspen plus simulator) is used to predict the results of MSW gasification and to provide some process fundamentals concerning syngas production from MSW gasification. The effects of gasification temperature, air equiva- lence ratio and moisture concentration on the composition of syngas, lower heating value (LHV) of syngas, heat conversion efficiency, and carbon conversion are discussed. The results indicate that higher temperature improves gasification, and higher air equivalence ratio increases the carbon conversion while decreasing syngas LHV. Heat conversion efficiency increases and reaches the maximum and then decreases with the increase of air equivalence ratio. Higher moisture concentration increases the carbon conversion and increases the heat conversion efficiency at lower ratios. Higher temperature and a lower equivalence ratio are favorable for obtaining a higher LHV of syngas at the same moisture concentration.

VOCs released from municipal solid waste at the initial decomposition stage: Emission characteristics and an odor impact assessment

The nuisance from odor caused by municipal solid waste(MSW) is resulting in a growing number of public complaints and concerns. Odor pollution occurs in the initial decomposition stage of MSW, including waste collection, transportation and early pre-treatment. Furthermore, decomposition takes place in waste facilities that are often close to living areas, which can result in odor impacts on local inhabitants. However, this aspect of odor impact from MSW has not been well studied. In the current study, lab-scale waste cells were designed to simulate MSW storage conditions in the early stage. The characteristics of VOCs emissions with different waste compositions were analyzed. The odor concentration( CO, non-dimensional) method and odor intensity were used for the assessment of odor. Ethanol was the substance with highest emission rate. The release rate of VOCs increased with the growth easily biodegradable waste(EBW). VOCs emissions was reduced by 25% when the proportion of EBW decreased from 60% to 45%. Methyl sulfide, ethanol, dimethyl disulfide and ethyl acetate were identified as typical odorants. The EBW proportion in waste is the main factor significantly influencing odor pollution. The CO was 244.51 for the 60% EBW condition, which was only 61.46 for 15% EBW condition. These study results provide important information for the implementation of a garbage sorting policy and the monitoring of odor pollution from waste management.