Properties Of Municipal Solid Waste Research Articles

Municipal solid waste as an alternative energy source

One of the main objectives in the field of waste management today is the implementation of waste-to-energy concept, because it decreases the amount of municipal solid waste landfilled and economizes the traditional hydrocarbon fuels. One of the main objectives of this study was to assess the global energetic potential of municipal solid waste and its potential contribution in energy balance. This evaluation was based on the analysis of main municipal solid waste properties such as component and chemical compositions, and heating value. The comparison of municipal solid waste properties and energetic potential with those for traditional solid fuels was also discussed. For comparison, the biomass samples and coals collected from Russian coal basins were considered. Study of municipal solid waste properties showed that municipal solid waste represents a well-flammable fuel with high carbon content (up to 50–60% for dry ash-free basis), and relatively high O/C atomic ratio. Total world energetic potential of municipal solid waste was estimated as 20 billion GJ that is 12.6% from energetic potential of coal mined. It was shown that by municipal solid waste incineration it is possible to produce 800 billion kWh of electrical energy that is about 3.5% of total world electricity generation. It was shown that in 2035 energetic potential of municipal solid waste may share up to 21.7% from energetic potential of coal. Executed estimations confirmed the urgency of municipal solid waste waste-to-energy implementation.

Thermotechnical properties of municipal solid waste depending upon component and fractional composition

Thermotechnical properties of municipal solid waste depending upon component and fractional composition

Effects of aging on dynamic properties of MSW: A case study from Kahrizak Landfill, Tehran, Iran

The eff ect of aging on dynamic properties of Municipal Solid Waste (MSW) including damping ratio and shear modulus was investigated in the current research. For this purpose, a series of cyclic Consolidated Undrained (CU) triaxial tests were performed on fresh and old reconstituted cylindrical specimens, taken from Mansoory Prototype Land ll (MPL) placed in Kahrizak Land ll, Tehran, Iran. The results showed that the shear modulus of old samples (7.5 years old) was more than that of the fresh ones. This trend can be attributed to decomposition of waste over time, which leads to reduction in organic content and, consequently, increment of brous waste particles (plastics) of the old samples. On the other hand, the results also indicated that the damping ratio was partially dependent on the composition of the specimen and it slightly decreased with increasing the age of MSW. The high percentage of organic content in fresh specimens can be consideredas the main reason for this behavior. Finally, the normalized shear modulus reduction and strain-dependent material damping curves were prepared for both ages of retrieved MSW from Kahrizak Center Land ll (KCL). The results of the current study are in the range reported in the technical literature and can be used as reliable data for seismic purposes.

Reliability assessment of bioreactor landfills using Monte Carlo simulation and coupled hydro-bio-mechanical model

The performance of a bioreactor landfill is highly influenced by the simultaneous interactions of several coupled processes that occur within the landfill. In addition, the high uncertainty and spatial variability in the geotechnical properties of municipal solid waste (MSW) poses significant challenge in accurately predicting the performance of bioreactor landfills. In this study, a 2D coupled hydro-bio-mechanical (CHBM) model was employed to predict the behavior of MSW in bioreactor landfills. The numerical model integrated a two-phase flow hydraulic model, a plane-strain formulation of Mohr-Coulomb constitutive model, and a first order decay biodegradation model. The statistical ranges (mean and standard deviation) of some of the major influential MSW properties were derived from the published studies. Random fields of spatially variable MSW properties were generated following the log-normal distribution. Reliability-based analysis was carried out by performing several realizations of Monte-Carlo simulations and the statistical response of the output results including the moisture distribution, pore fluid pressures, landfill settlement, and interface shear response of the composite liner system were quantified. The results clearly indicate the importance of considering spatial variability of the geotechnical MSW properties and its influence on the performance of bioreactor landfills during leachate injection operations. A comparison of the results with the deterministic analysis was performed to evaluate the relative benefits and to emphasize the need for reliability-based analysis for effective design of bioreactor landfills.

Torrefaction of Municipal Solid Waste in Malaysia

Municipal solid waste (MSW) disposal is one of the main issues towards sustainable development in Malaysia. Current practices for MSW disposal such as landfilling and incineration poses a serious problems on the environment and health. Therefore a significant efforts have been made to utilize MSW for energy source by employing gasification process. However, the MSW is characterized by its high moisture content and low high heating value (HHV) which lowering the energy efficiency. In order to overcome this problems, torrefaction can be used as pretreatment method to remove the moisture content and upgrading MSW properties. The objective of this work is to study the effects of torrefaction temperatures ranging from 240 to 330°C for residence time of 30 minutes on two types of MSW namely food waste and wood waste. The torrefied MSWs are characterized in terms of ultimate analysis, proximate analysis and HHV. The mass and energy yields are also performed for both MSW. Based on the torrefaction, it was found that both food waste and wood waste show an increment on the weight percentage of C contents and decrement on the weight percentage of H and O content which resulting into reduce O/C ratio as the temperature is increased. The HHV for both food waste and wood waste are also increased after torrefaction between 240 and 330°C. The mass yield and energy yield were found to decrease with an increase in the torrefaction temperature. This suggests that torrefaction can be used as an effective MSW pretreatment and the torrefied MSW is more suitable to be used as fuel in gasification process.

Investigation of Shear Strength Properties of Municipal Solid Waste and Slope Stability Analysis

Investigation of Shear Strength Properties of Municipal Solid Waste and Slope Stability Analysis

Effect of confining stress and loading frequency on dynamic behavior of municipal solid waste in Kahrizak landfill

In order to analyze the stability of a landfill site, it should analyze some properties of waste introducing the main structural elements. Up to now, it has not been done much research on the properties of municipal solid waste. In addition, due to the differences in waste properties from one country to another and even from one to another landfill site, it is impossible to generalize the results. These conditions caused local research on the evaluation of static and dynamic parameters of municipal solid waste to be done. Because Iran is a seismic country, the short-term behavior of waste controls landfill sites stability during seismic loads; so it is necessary to know the dynamic behavior of these materials. In this paper, about 18 cyclic tests were performed, and in addition to determining the dynamic parameters of municipal solid waste of Tehran Kahrizak Disposal Site using cyclic triaxial test, the effect of confining stress and loading frequency on dynamic properties of these materials was evaluated. The results have shown that with increasing the confining stress and loading frequency, shear modulus and damping ratio was increased and decreased, respectively, and it is related to the composition of the municipal solid waste materials.

Experimental study of the porosity and permeability of municipal solid waste

Permeability is a very important parameter to evaluate the landfill gas (LFG) transport properties of municipal solid waste (MSW). Waste permeability is largely dependent on pore structure, which is affected directly by compression stress and degradation. In this article, laboratory tests were conducted to determine the permeability of MSW under different stresses and degradation phases. Test results showed that porosity and permeability values were in the range of 0.11–0.65 and 8.7 × 10−14–7.29 × 10−12 m2, respectively. The porosity of waste samples declined exponentially with the increase of compacted density and linearly with the increase in water content. Permeability decreased significantly with stress and degradation because of the increase in compacted density and finer particles of the waste, which led to low porosity of the samples. The influence of stress on permeability was in the scope of 1.6 × 10−12–3.7 × 10−12 m2, whereas porosity was 0.23–0.34. However, the effect of coupled stress and degradation on permeability was reduced to more than an order of magnitude. The power model was found to be suitable for fresh and degradation wastes, whereas Kozeny–Carman model was only suitable for old wastes. This study provides theoretical and practical significance for environmental pollution control and resource utilization of LFG in landfills. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1694–1699, 2017

Modeling Coupled Processes in Municipal Solid Waste Landfills: An Overview with Key Engineering Challenges

Disposal of municipal solid waste (MSW) in engineered landfills is one of the most widely used waste management practices in the USA and worldwide. During its design life, landfilled MSW undergoes various complex mechanisms controlled by physical (hydraulic and mechanical), chemical, thermal, and biological processes and their interrelated behaviors. A thorough understanding of these coupled MSW interactions is critical in designing a stable, effective and well-operational landfill. However, to date, the current practices associated with mathematical modeling as well as long-term monitoring of landfill performance(s) are mostly empirical and limited to site-specific conditions. Moreover, they fail to substantially quantify the changes in the geotechnical properties of MSW that result from coupled processes, especially the highly uncertain biological processes that result in MSW degradation in landfills. Furthermore, the spatially and temporally varied waste composition, heterogeneous and anisotropic nature of field MSW together with leachate and landfill gas production due to biodegradation results in atypical differential MSW settlement and, therefore, can adversely impact the long-term performance of landfills. Over the years, numerous experimental studies, field studies and mathematical modeling studies that focus on these landfill processes have been performed to optimize MSW landfill performance. In this study, a critical review of the previous research efforts on coupled processes is provided to help landfill engineers understand, design and operate MSW landfills safely and efficiently. Moreover, key research issues and challenges related to numerical modeling of landfilled MSW undergoing coupled processes are presented.

Dynamic characterisation of municipal solid waste by SDMT

As documented after some recent earthquakes, landfills can be damaged by seismic loading. Thus, to analyse their stability, site-specific dynamic soil properties must be evaluated, and representative dynamic properties of the waste material need to be used. Dilatometer Marchetti tests (DMTs) are used widely for measuring soil properties, but little is found in the literature regarding their use for measuring the properties of municipal solid waste (MSW). To validate their applicability when estimating the properties of MSW, the results of an investigation carried out on MSW materials at the Cozzo Vuturo landfill in the Enna area (Sicily, Italy) are discussed. Seismic DMTs (SDMTs) are performed, and the test results are used to derive the dynamic properties of the waste materials in the deposit. A comparison among SDMTs, multichannel analysis of surface waves and seismic refraction tomography is reported. These preliminary results seem to be promising. The S-wave velocity distribution deduced by SDMT appears to be in very good agreement with the state of the art reported by the literature. The measured S-wave distribution confirms reliability in estimating the zones of the landfill with different compaction due to the age of the waste.

Influence of dynamic coupled hydro-bio-mechanical processes on response of municipal solid waste and liner system in bioreactor landfills

A two-dimensional (2-D) mathematical model is presented to predict the response of municipal solid waste (MSW) of conventional as well as bioreactor landfills undergoing coupled hydro-bio-mechanical processes. The newly developed and validated 2-D coupled mathematical modeling framework combines and simultaneously solves a two-phase flow model based on the unsaturated Richard’s equation, a plain-strain formulation of Mohr-Coulomb mechanical model and first-order decay kinetics biodegradation model. The performance of both conventional and bioreactor landfill was investigated holistically, by evaluating the mechanical settlement, extent of waste degradation with subsequent changes in geotechnical properties, landfill slope stability, and in-plane shear behavior (shear stress-displacement) of composite liner system and final cover system. It is concluded that for the given specific conditions considered, bioreactor landfill attained an overall stabilization after a continuous leachate injection of 16years, whereas the stabilization was observed after around 50years of post-closure in conventional landfills, with a total vertical strain of 36% and 37% for bioreactor and conventional landfills, respectively. The significant changes in landfill settlement, the extent of MSW degradation, MSW geotechnical properties, along with their influence on the in-plane shear response of composite liner and final cover system, between the conventional and bioreactor landfills, observed using the mathematical model proposed in this study, corroborates the importance of considering coupled hydro-bio-mechanical processes while designing and predicting the performance of engineered bioreactor landfills. The study underscores the importance of considering the effect of coupled processes while examining the stability and integrity of the liner and cover systems, which form the integral components of a landfill. Moreover, the spatial and temporal variations in the landfill settlement, the stability of landfill slope under pressurized leachate injection conditions and the rapid changes in the MSW properties with degradation emphasizes the complexity of the bioreactor landfill system and the need for understanding the interrelated processes to design and operate stable and effective bioreactor landfills. A detailed discussion on the results obtained from the numerical simulations along with limitations and key challenges in this study are also presented.

Состав и свойства твердых коммунальных отходов, учитываемые при выборе технических методов обращения с отходами

Состав и свойства твердых коммунальных отходов, учитываемые при выборе технических методов обращения с отходами

Constitutive model for municipal solid waste considering the effect of biodegradation

With large-scale construction of landfills, the study of the properties of municipal solid waste (MSW) has become an important subject. The objective of this study is to propose a new constitutive model for MSW considering the effect of biodegradation. The indicators representing the degree of biodegradation are first discussed, and the impact of biodegradation on the mechanical properties of MSW is then formulated in volumetric strain by introducing a biodegradation-induced void change parameter, which provides a fundamental understanding of the change in waste properties with long-term biodegradation. On the basis of this, a constitutive model is developed following the framework of critical state soil mechanics, and the proposed model is validated by comparing simulations and experimental data of triaxial tests and of a long-term settlement experiment. Finally, the effects of MSW composition and biodegradation are analysed by parametric studies.

Thermal and die electric properties of chemically modified municipal solid waste and banana fiber reinforced polymer composites

The thermal and dielectric properties of municipal solid waste (MSW)/banana fiber composites were investigated as a function of total volume fraction of filler (MSW+ banana fiber). The relative volume fraction of MSW/banana fiber and its chemical modification was also investigated. The total volume fraction (Vf) of filler is established by keeping the relative volume fraction of MSW and banana fiber as 50:50. The thermal conductivity of composites decreases with increase of filler ratio. Subsequently, composites with different volume ratios of MSW and banana fiber (100:0, 75:25, 50:50, 25:75, 0:100) were prepared by keeping total Vf of filler as 50%. Low thermal conductivity and diffusivity values were obtained in composites with an MSW and a banana fiber ratio as 50:50. Moreover, chemically modified filler composites show decrease in dielectric constant, dielectric loss factor and an increment in volume resistivity. Experimental dielectric constant values are correlated with theoretical models. © 2016 American Institute of Chemical Engineers Environ Prog, 2016

Geotechnical properties of municipal solid waste at Laogang Landfill, China

Landfills have been widely constructed all around the world in order to properly dispose municipal solid waste (MSW). Understanding geotechnical properties of MSW is essential for the design and operation of landfills. A comprehensive investigation of geotechnical properties of MSW at the largest landfill in China was conducted, including waste composition, unit weight, void ratio, water content, hydraulic conductivity, and shear behavior. A large-scale rigid-wall permeameter and a direct-shear apparatus were adopted to test the hydraulic conductivity and shear behavior of the MSW, respectively. The composition of the MSW varied with age. With the depth increasing from 0 to 16m, the unit weight increased from 7.2 to 12.5kN/m3, while the void ratio decreased from 2.5 to 1.76. The water content ranged between 30.0% and 68.9% but did not show a trend with depth. The hydraulic conductivity of the MSW ranged between 4.6×10−4 and 6.7×10−3cm/s. It decreased as the dry unit weight increased and was sensitive to changes in dry unit weight in deeper layers. Displacement-hardening was observed during the whole shearing process and the shear strength increased with the normal stress, the displacement rate, and the unit weight. The friction angle and cohesion varied from (15.7°, 29.1kPa) to (21.9°, 18.3kPa) with depth increasing from 4 to 16m. The shear strength of the MSW obtained in this study was lower than the reported values in other countries, which was caused by the less fibrous materials in the specimens in this study. The results in this study will provide guidance in the design and operation of the landfills in China.

Field and large scale laboratory studies on dynamic properties of emplaced municipal solid waste from two dump sites at Delhi, India

Dynamic properties of municipal solid waste (MSW) from two dump sites located at Delhi, India are evaluated from field and large scale laboratory tests. Shear wave velocity (Vs) profiles of MSW, measured at these two sites using surface wave techniques, are in range of Vs data reported for MSW landfills worldwide. Representative bulk MSW samples were collected from large test pits excavated at the two dump sites to determine the near surface unit weight. Large scale undrained cyclic triaxial (CTX) tests were conducted on reconstituted MSW specimens to investigate the effect of various parameters such as composition, confining pressure, number of loading cycles, loading frequency and saturation on the dynamic properties. Undrained CTX tests, conducted on the specimens with and without fibrous materials demonstrated the effect of fibrous waste constituents on the stiffness and damping behavior of MSW. Specimens consisting of fibrous waste constituents such as plastics and textiles exhibited significantly less modulus reduction compared to specimens with negligible amount of fibrous content. The modulus reduction (G/Gmax) and material damping ratio curves derived from the present study are in the range reported for MSW in the literature. The G/Gmax curves from present study are in good agreement with curves recommended for MSW at Tri-Cities landfill in USA and Tianziling landfill in China. Dynamic properties evaluated from the present study add to the growing database of the worldwide dataset and can be useful for evaluating the seismic stability and associated permanent deformations of the existing dumps in and around Delhi.

Engineering geological analysis of municipal solid waste landfill stability

Sanitary landfills are the main disposal method of municipal solid waste (MSW). There are multiple engineering issues in the construction and operation of landfills. Because the engineering properties of MSW are complicated and landfills can easily become unstable under the influence of external factors, landfill stability is the most significant engineering issue in landfill operation. This paper presents a review of engineering geological analyses of municipal solid waste landfill stability. Selected case histories involving instability of landfills are discussed based on published research, and the instabilities and their likely causes are examined. The concept of landfills as geologic bodies is introduced, and the factors that affect landfill stability are discussed, based on the engineering properties of the waste, the structural features of the landfill body, and dynamic engineering and geological process such as earthquakes, rainfall, and human engineering activity. Finally, suggestions for landfill operation based on the reviewed case studies and the analysis are presented and a summary of the factors influencing landfill instability is outlined.

The effect of temperature on the biodegradation properties of municipal solid waste.

The aim of this study is to analyse the effect of temperature on the biodegradation and settlement properties of municipal solid waste by using bioreactors. Three kinds of controlled temperature were performed during the biodegradation test; the variation of weight, leachate and biogas production were carefully monitored. The degradation test indicated that more leachate leaked out owing to the external compression and polymer hydrolysis reaction in the aerobic phase, which could lead to the decrease of biodegradation rate in the anaerobic phase. A proper temperature range in favour of enhancing biodegradation of refuse was obtained, which ranged from 22 °C to 45 °C. Finally, an empirical equation of biodegradation ratio was proposed, which incorporated the temperature effect. In the end, the validation of this proposed model is verified, and is proved to be reasonable for predicting degradation velocity in landfills.

Seismic characterization and dynamic site response of a municipal solid waste landfill in Bangalore, India.

Seismic design of landfills requires an understanding of the dynamic properties of municipal solid waste (MSW) and the dynamic site response of landfill waste during seismic events. The dynamic response of the Mavallipura landfill situated in Bangalore, India, is investigated using field measurements, laboratory studies and recorded ground motions from the intraplate region. The dynamic shear modulus values for the MSW were established on the basis of field measurements of shear wave velocities. Cyclic triaxial testing was performed on reconstituted MSW samples and the shear modulus reduction and damping characteristics of MSW were studied. Ten ground motions were selected based on regional seismicity and site response parameters have been obtained considering one-dimensional non-linear analysis in the DEEPSOIL program. The surface spectral response varied from 0.6 to 2 g and persisted only for a period of 1 s for most of the ground motions. The maximum peak ground acceleration (PGA) obtained was 0.5 g and the minimum and maximum amplifications are 1.35 and 4.05. Amplification of the base acceleration was observed at the top surface of the landfill underlined by a composite soil layer and bedrock for all ground motions. Dynamic seismic properties with amplification and site response parameters for MSW landfill in Bangalore, India, are presented in this paper. This study shows that MSW has less shear stiffness and more amplification due to loose filling and damping, which need to be accounted for seismic design of MSW landfills in India.

Axisymmetric gas flow model for bioreactor landfills incorporating MSW compression and leachate recirculation

To control the landfill gas (LFG) emission, LFG collection systems with vertical wells are extensively used in municipal solid waste (MSW) landfills. When investigating the LFG flow behavior, the solid–liquid–gas interactions cannot be neglected, especially in bioreactor landfills. In this study, an axisymmetric numerical model incorporating MSW compression and leachate recirculation was developed to describe the transient gas flow in bioreactor landfills. In the model, the porosity distribution was evaluated through circular computations, and the temporal and spatial changes in moisture were determined using the unsaturated–saturated seepage flow model. Based on these calculations, the governing equations of gas migration were solved using the finite element method. The influences of MSW properties, recirculation rate and well vacuum pressure were then investigated. The results show that the MSW compression and leachate recirculation have a significant impact on the distributions of gas generation, permeability and pressure. As the recirculation rate increases from 1 to 9 mm day−1, the gas permeability can decrease about 1 order of magnitude and thus the radius of influence decreases from 39 to 31 m. It is important to keep a balance between the acceleration of landfill stability and the recovery efficiency of LFG. These results provide helpful guidelines for the design of leachate recirculation and LFG control systems.