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).

Study on Rural Solid Waste Collection and Transportation Mode and Route Optimization Strategy in the Cold Regions of Northern China

Rural vitalization is a major strategy for reform and development of agriculture and rural areas in China,the key task of which is improving rural living environment.Imperfect rural solid waste(RSW)collection and transportation system exacerbates the pollution of RSW to rural living environment,while it has not been established and improved in the cold region of Northern China due to climate and economy.Through the analysis of the current situation of RSW source separation,collection,transportation and disposal in China,an RSW collection and transportation system suitable for the northern cold region was developed.Considering the low winter temperature in the northern cold region,different requirements for RSW collection,transportation and terminal disposal,scattered source points and single terminal disposal nodes in rural areas,the study focused on determining the number and location of transfer stations,established a model for transfer stations selection and RSW collection and transportation routes optimization for RSW collection and transportation system,and proposed the elite retention particle swarm optimization–genetic algorithm(ERPSO–GA).The rural area of Baiquan County was taken as a representative case,the collection and transportation scheme of which was given,and the feasibility of the scheme was clarified by simulation experiment.

Establishment and application of performance evaluation model for collection and transportation system of municipal solid waste

On the basis of analyzing the typical waste collection and transportation mode,the evaluation index system for performance of the waste collection and transportation system was proposed with three grades,which related to six factors,such as economic evaluation,high efficient evaluation,environmental impact assessment,resource evaluation,evaluation of security and emergency,evaluation of management and society. With the performance evaluation theory,the performance evaluation model of waste collection and transportation system was constructed,which quantified the grading standard of index and determined the index weight in analytic hierarchy process (AHP). After evaluating the waste collection and transportation system of the main districts of Chongqing city,the results show that the it has an excellent performance evaluation grade with very high performance level of three indices involving evaluation of management and society,environmental impact assessment,evaluation of security and emergency and quite low performance level of two indices that include high efficient evaluation and economic evaluation.

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.

Repercussions of Improved Municipal Solid Waste Management on Flood Risk Reduction: The Case of Dar es Salaam, Tanzania

Indisputably, flooding is one of the predicaments that have plagued many countries throughout the world. Consequently, Improvement of Municipal Solid Waste Management-(MSWM) has recently become one of the ways that is believed to help in reducing the impact of flooding. Following the fact that Dar es Salaam, the commercial capital, has nearly 5 million inhabitants and several of the wards are in flood-prone areas, the City authorities introduced new models of MSWM by incorporating public-private partnership as a deliberate action envisioned to improve MSWM. Nevertheless, the extent to which the strategy is effective in minimizing flood risks had not been adequately researched, which prompted a need to conduct a study. Specifically, the study sought to: assess the current practice of SWM in the settlement;examine the extent to which flood risk had been reduced given the application of the new models of SWM. This is primarily a case study which used Keko Machungwa in Dar es Salaam as the study area. Different forms of data collections tools were used for instance interviews of households and officials, photographs, spatial data etc. The findings indicated that Jukwaa la Wanawake in Keko Machungwa, a newly emerged community-driven organization was doing a fairly good job in handling SWM. This social entity was capable of collecting 40 tons of solid wastes per week and arranged for transportation. Overall, there was a marked decrease in haphazard dumping within the settlement. Despite the improvement, however, flooding was still persistent and was an alarming challenge. To that effect, this study recommends that improving solid waste collection could help overcome the problem of flooding particularly if integrated with other initiatives which include 1) Investment in robust flood control structures;2) Adherence to Urban planning and disaster management policies which prohibit development in hazardous areas, an instance of which being demolishing the existing building structures located in the water way in Keko Machungwa and;3) Initiate large scale flood risk reduction settlement schemes.

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.

Energy-Efficient Multi-Trip Routing for Municipal Solid Waste Collection by Contribution-Based Adaptive Particle Swarm Optimization

Waste collection is an important part of waste management system.Transportation costs and carbon emissions can be greatly reduced by proper vehicle routing.Meanwhile,each vehicle can work again after achieving its capacity limit and unloading the waste.For this,an energy-efficient multi-trip vehicle routing model is established for municipal solid waste collection,which incorporates practical factors like the limited capacity,maximum working hours,and multiple trips of each vehicle.Considering both economy and environment,fixed costs,fuel costs,and carbon emission costs are minimized together.To solve the formulated model effectively,contribution-based adaptive particle swarm optimization is proposed.Four strategies named greedy learning,multi-operator learning,exploring learning,and exploiting learning are specifically designed with their own searching priorities.By assessing the contribution of each learning strategy during the process of evolution,an appropriate one is selected and assigned to each individual adaptively to improve the searching efficiency of the algorithm.Moreover,an improved local search operator is performed on the trips with the largest number of waste sites so that both the exploiting ability and the convergence accuracy of the algorithm are improved.Performance of the proposed algorithm is tested on ten waste collection instances,which include one real-world case derived from the Green Ring Company of Jiangbei New District,Nanjing,China,and nine synthetic instances with increasing scales generated from the commonly-used capacitated vehicle routing problem benchmark datasets.Comparisons with five state-of-the-art algorithms show that the proposed algorithm can obtain a solution with a higher accuracy for the constructed model.

Investigation of Inhabitants' Wishes on Classified Collection of Waste in Wanghua District of Fushun

In order to disclose present situation and problem of classified collection of municipal solid waste in Wanghua District of Fushun and ana- lyze its practicability, questionnaire was designed in this paper, random research was adopted in Wanghua District, and statistic analysis of investi- gation result was conducted. This investigation could provide basis for popularizing classified collection of municipal solid waste in the whole nation.

Robust Optimization of Municipal Solid Waste Collection and Transportation with Uncertain Waste Output: A Case Study

Garbage collection is an important issue in urban environmental management.With the increased awareness of urban residents regarding safety,environmental protection,and health in recent years,it is necessary to logically organize municipal solid waste collection and transportation routes while also considering economic and social benefits.This article focuses on the optimization of the waste transportation routes of garbage trucks.With the objective of minimizing transportation costs and maximizing resident satisfaction,we establish a robust optimization model for the multi-trip collection and transportation of municipal solid waste in an uncertain environment.Resident satisfaction is defined as the penalty cost against a time window constraint.The Bertsimas robust optimization method is applied to characterize the uncertainty,and the decision-making scheme of the receiving route is used to adapt to waste volume changes.We conduct a case study based on real-world data for municipal solid waste collection and transportation in the Dongcheng District of Beijing,China.The solution is validated using the CPLEX program,and the validity of the model is verified.In addition,a sensitivity analysis of related parameters is conducted to study the impacts of variations in work hour limits and time windows on the total cost and service levels,as well as their relationships with the level of robustness.This could help decision-makers make reasonable choices based on actual conditions and to balance reductions in total cost with service level improvements.

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.