Content Of Municipal Solid Waste Research Articles

Assessment of pyrolysis potential of Indian municipal solid waste and legacy waste via physicochemical and thermochemical characterization

This study explores the viability of utilizing municipal solid waste (MSW) and legacy waste as a renewable energy source through pyrolysis, akin to solid fuels. The heating value of MSW and legacy waste were found to be 37737.89 and 40432.84 kJ/kg, respectively. Proximate analysis shows that MSW fits within Tanner diagram parameters, eliminating the need for auxiliary fuel in pyrolysis. With 47.6 % and 44.16 % lignin content in MSW and legacy waste were deemed suitable for char production. Thermal degradation resulted in mass losses of 68 % for MSW and 82 % for legacy waste. The kinetic and thermodynamic assessment indicates lower activation energy (Ea) and Gibbs free energy (ΔG) for MSW (5.72 kJ/mol and 170.37 kJ/mol, respectively) compared to fossil fuels, suggesting faster reactions without additional energy requirement. MSW emerges as a promising alternative to fossil fuels, aligning with the United Nations’ 2030 Sustainable Development Goals.

Biochemical, hydrological and mechanical behaviors of high food waste content MSW landfill: Numerical simulation analysis of a large-scale experiment

The complex process of thermal-hydro-mechanical-biochemical (THMBC) coupled degradation in high food waste content (HFWC) municipal solid waste (MSW) is the main cause of intense heat, gas, and leachate generation in the landfills, which could lead to environmental disasters. A large-scale indoor experiment on HFWC MSW has been done with operations of loading, heated mature leachate recharging to study the rules of degradation. A THMBC coupled degradation model is used to analyze the results in the first 400 days drawn from the experiments, to explain how recharge of heated mature leachate accelerated degradation process and how was the portion of settlement led by intraparticle water release. The numerical simulation also calculated the landfill gas that was not collected in the experiment due to operational defects. The results show that recharging the heated mature leachate allows the stabilization process to occur at least six months earlier and settlement due to intraparticle water release accounts for half of the settlement in the first 60 days. The research indicates highly coupled THMBC model can be used to analyze the complex process in MSW degradation, make up for the shortcomings of physical experiments, and provide theoretical support for the design, construction, and management of landfills.

Bioremediation of reverse osmosis concentrate generated from the treatment of landfill leachate.

The moisture content of municipal solid waste (MSW) and local precipitation events lead to the leachate generation from MSW landfills. The high concentration of organic pollutants in landfill leachate (LL) makes it hazardous, requiring treatment before disposal into the environment. LL is most commonly treated by reverse osmosis (RO), which generates large volumes of concentrate known as RO concentrate. This investigation aims to stabilize the RO concentrate through an inexpensive and effective bioremediation strategy. A bench-scale aerobic suspended growth reactor study was conducted using three commercial conversion agents, namely EM.1, Bokashi powder, and coir pith powder. Overall bench-scale efficiency of 63% was achieved in this study. The onsite studies were conducted in 7.5-m3 artificial ponds with 46% efficiency amid atmospheric influences and constraints. The overall efficiencies of both bench and field-scale studies were derived by ascertaining the arithmetic mean of the individual efficiency of the following parameters: chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total dissolved solids (TDS). In contrast, the control pond with no conversion agents showed an increase in pollution concentration over the 100 days of retention time. The findings revealed that the investigated technology had a marginally lower evaporation rate and performed relatively well compared to traditional solar evaporation ponds. Moreover, the technology can be easily scaled-up and readily applied for RO concentrate treatment in MSW landfills.

Development, exergoeconomic assessment and optimization of a novel municipal solid waste-incineration and solar thermal energy based integrated power plant: An effort to improve the performance of the power plant

Due to the growing population rate and increasing social activities, the content of municipal solid waste (MSW) production is increasing. Energy production from MSW is one of the promising ways to dispose of waste and reduce the limitations of fossil energies. However, this technology has a relatively low efficiency due to the high volume of moisture and inert materials in MSW and the lower heating value of waste. The integration of solar thermal collectors is one of the suggested solutions to increase the temperature of inlet steam to the power generation cycle in order to improve the power plant performance. In this regards, the present study develops a comprehensive thermodynamic-conceptual and exergoeconomic investigation of the performance of a MSW-incineration (MSWI) plant integrated with a parabolic trough collector (PTC)-based solar field. Accordingly, the temperature of the steam elevates by the solar field before entering the electric power generation cycle. Additionally, the solar unit is integrated with a phase change material (PCM)-based storage system. The use of storage tank at the delivery line of PTC can improve the power plant’s reliability. A comprehensive comparison of the developed power plant with the conventional MSWI power plant is presented. In addition, the technical and economic behaviors of the considered power plant have been optimized under two different single and multi-objective optimization scenarios. The outcomes indicated that the developed power plant can provide 15.75% and 15.68% higher energetic and exergetic efficiencies compared to MSWI power plant. In addition, the rate of electric power obtained from S-MSWI power plant is almost 16.1% more compared to MSWI power plant. However, the total cost rate of MSWI plant is almost 24.13% lower compared to the developed power plant. But, the value of LCOE in the developed power plant is approximately 8.93% lower than MSWI power plant. It was also found that, the multi-objective optimization can provide better and optimal results to energy engineers and decision makers compared the single-optimization. The conceptual design of the implementation of the solar field is also developed in a specific geographical condition. Additionally, this research comes from the key technology of the National Key Laboratory of Environmental Protection.

Estimating the chemical composition of municipal solid waste using the inverse method

This research aims to perform and implement an inverse solution method in waste-to-energy power plants for carrying out solid waste analysis without sampling. For this purpose, a simple simulated experiment is defined to evaluate the stability and accuracy of the method, which is investigated by adding random errors to the results of the direct problem conducted by the Monte Carlo method. The inverse problem solution procedure is solved by obtaining data categories for measuring parameters. In addition, the coefficient matrix is created and the linearization method is employed. By assuming a 0.5 percent nitrogen content in municipal solid waste, the number of unknown parameters is reduced, and the problem is solvable. The regularization method is applied to obtain the stability of the answer. The procedure is done for a municipal solid waste analysis with different regularization parameters. The mean value error and variance of the obtained solution from each analysis are evaluated and the acceptable range for regularization parameters is determined. Also, the identified matrix parameters between 1 and 100 are examined in the constant regularization parameter, and the acceptable parameters are determined. The error in validation by simulated experiment for carbon, oxygen, hydrogen, sulfur, moisture, and ash content of municipal solid waste is 1.47, 3.81, 0.91, 0.22, 7.32, and 1.57 percent, respectively. In the next step, the developed procedure is applied to the Aradkooh waste-to-energy power plant in Tehran, Iran. The operating data are gathered from the power plant, and the municipal solid waste composition is estimated. Results indicate the feasibility of the proposed method, and the municipal solid waste composition and mass flow rate can be predicted indirectly by the flue gas analysis and some other measurements without needing to sample the municipal solid waste. According to the results, the carbon, oxygen, hydrogen, sulfur, moisture, and ash content of municipal solid waste in the Aradkooh power plant is 21.13, 41.96, 5.70, 0.01, 25.06, and 5.63 percent, respectively. Further, the mass flow rate of municipal solid waste and air are 0.53 and 2.5 kg per second. Finally, the sensitivity of the estimated municipal solid waste composition to errors is evaluated by error analysis.

Municipal Solid Waste-to-Energy-Facility to Advance Circular Economy: A Case Study in the City of Spokane, Washington

The development of technologies for processing residual solid mixed waste has only become a focus of attention stimulated by the search for more efficient energy sources. The majority of municipal solid waste (MSW) is of biological origin (biogenic). Typically, half of the energy content in MSW is from biogenic material. Consequently, this energy is often considered renewable energy according to the waste input, and as a result, the energy yields and profit generated can be accounted for in the circular economy. Waste-to-Energy (WtE) processes can play a role in the transition to a “circular economy” provided that a country’s waste hierarchy is used as a guiding principle and that the choices made do encourage and reward higher levels of waste minimization, reuse, remanufacturing, refurbishing, and recycling. In conclusion, both Waste to Energy and landfill biogas recovery systems are credited for their respective recovered energy and revenue generation while managing MSW disposal using best management practices and in an environmentally sustainable manner.

Modeling energy content of municipal solid waste based on proximate analysis: R-k class estimator approach

Modeling energy content of municipal solid waste based on proximate analysis: <i>R-k</i> class estimator approach

BASIC: A Comprehensive Model for SO x Formation Mechanism and Optimization in Municipal Solid Waste (MSW) Combustion.

Municipal solid waste (MSW) incineration is one of the main techniques currently used for waste to energy (WTE) conversion in China. Although the sulfur content in MSW is lower than that in coal, its emission cannot be neglected due to environmental pollution, malodor, health problems, and global climate change. Therefore, it is particularly important to effectively predict and control the sulfur pollutants. In this study, a comprehensive model was developed and coupled with the full combustion process bed model bulk accumulated solids incineration code (BASIC) to investigate the formation and transformation processes of sulfur in MSW incineration. The submodels of the four stages in the MSW combustion processes; governing equations of mass, momentum, and energy conservation; and various chemical reactions were included in the model. Based on this model, the effects of different parameters on the formation of sulfur pollutants during the incineration process were studied under different operating conditions. The study finds that for SOX formation, initial temperature, primary air volume, and material particle size have significant impacts, whereas pressure shows a less significant effect. This article also considers H2S, COS, and CS2 formation under different conditions. An optimization study was performed to reduce SOX pollutants.

System design and thermo-economic analysis of municipal solid waste power system integrated with steam dryer

High moisture content of municipal solid waste (MSW) decreases the efficiency of power plant firing MSW directly. The MSW power system integrated with an external steam dryer and waste heat recovery system (WHRS) is proposed to enhance the MSW power plant (MSWP) efficiency. A reference case study with a 12 MW MSWP is carried out. The efficiency of MSWP integrated with a steam dryer can be enhanced by 1.07 percentage points (%-pts) and 0.36%-pts with 0.21 and 1.13 MPa steam extraction, respectively, as dryer heating source at a dryness degree of 0.25. Furthermore, when the WHRS is integrated, the power plant efficiency is enhanced by 1.79%-pts and 1.08%-pts. Then, economic analysis is carried out, and results show that the MSWP can bring profits with the integration of a steam dryer with steam 1.13 MPa steam as heat source at rated degree of dryness.

Estimation of energy content in municipal solid waste of Bhutan and its potential as alternate powers source

Conversion of Solid waste into energy is the most resourceful process to combat landfill saturation and environmental impression. Bhutan, with an exponential rise in the waste production, Waste to Energy (WTE) conversion is an alternative solution for municipal solid waste management (MSW). The study for MSW composition and its energy potential analysis for Memelakha (Thimphu) and Pekarshing (Phuntsholing) landfills was done to resolve the waste management challenges in the country. The standard number of samples from two dumpsites were used to analyze for the waste characterization (waste composition, proximate analysis, chemical analysis) and high heating value (HHV) of MSW. MSW of two landfills showed that the main elemental constituents were Carbon and Oxygen with 17.26% and 9.97% by mass respectively for Pekarshing and 16.52% (Carbon) and 11.07% (Oxygen) by mass for Memelakha landfill. Based on the physio-chemical analysis of MSW, the average calorific HHV of MSW obtained were 10.028 MJ/kg (26.04% of coal energy) for Pekarshing dumpsite and 9.6 MJ/kg (24.94% of coal energy) for Memelakha. The analysis showed that by the year 2050 Memelakha landfill has the potential to generate the power of 8.85 Megawatt (MW) and 1.44 Megawatt (MW) for Pekarshing. For (WTE) conversion, incineration, pyrolysis, and gasification technologies are found suitable based on the current composition MSW of Bhutan. Furthermore, in terms of energy efficiency and percentage of wastage, the gasification process was the most feasible method for WTE conversion at two locations with a waste volume reduction of 80 to 90 percent at the landfill.

Evaluation and Prediction of Energy Content of Municipal Solid Waste: A review

Researches in the literature have unveiled the potential of resource and energy recovery from waste, it can therefore no longer be regarded as trash. This study reviews the literature to evaluate and analyses studies which estimated the experimental heating value of waste and the theoretical energy potential recoverable from waste through thermochemical and biochemical routes at different case studies. It was observed in this study that most developing countries are not exploiting the full potential of energy recoverable from waste. Models developed to predict the energy content of municipal solid waste (MSW) based on the elemental analysis, proximate analysis and physical composition were evaluated. A comparative analysis of the energy prediction models was also done. Artificial neural network (ANN) and multiple linear regressions found more applications in energy prediction. Energy prediction based on ultimate analysis using the elemental composition of the waste was predominant and are the most accurate; while proximate analysis based predictions were the least. The prediction accuracy of ANN is greater than the linear regression in the forecast of the energy content of MSW. However, a major limitation in the use of these modelling techniques was identified. Most of the generalized models may not capture the peculiarity of the waste generated at a particular place or municipality and therefore may not be very accurate for specific applications at some municipalities.

Production of gasoline from municipal solid waste via steam gasification, methanol synthesis, and Methanol-to-Gasoline technologies: A techno-economic assessment

A techno-economic analysis of the process of producing gasoline via steam gasification of municipal solid waste (MSW) using dolomite catalysts, followed by a methanol synthesis and a methanol-to-gasoline process (SGMG) was conducted using an Aspen Plus model and an economic assessment. The process includes six steps: MSW pretreatment, steam gasification of MSW to produce syngas, gas purification through CO₂ and acid gas removal, methanol synthesis using syngas, conversion of methanol to gasoline, and gasoline separation. The Aspen Plus model used to estimate the energy and mass balance for sizing the equipment assumed that 2000 dry metric tonnes of MSW per day would be processed. Capital investment required and operating costs of gasoline production were estimated based on the Aspen Plus model's mass and energy balance and an nth plant. The minimum selling price (MSP) of gasoline was calculated using the capital investment and operating costs of the process. The total capital investment of the process was estimated to be ＄148 million, with an annual operational cost of ＄56 million. The minimum selling price was determined at ＄2.40/gal for a 20-year project life. The sensitivity analysis showed that the cost of feedstock has a direct impact on the MSP of gasoline, and MSP could decrease to ＄1.55/gal if the owners of the plant received disposal fees. Increasing the gasoline yield to 0.125 kg of gasoline/kg of MSW decreased the MSP to ＄1.86/gal. The ash content in MSW played a vital role in estimating the MSP. If the ash content in the feedstock increased, the MSP increased owing to a decrease in the gasoline yield and an increase in the cost of operations.

Comparative Biodrying Performance of Municipal Solid Waste in the Reactor under Greenhouse and Non-greenhouse Conditions

The high moisture content of municipal solid waste yields a lower energy content of solid fuel that affects the thermal conversion efficiency. Biodrying is an alternative drying method using bio-heat generated by microbial metabolism to reduce the moisture content of municipal solid waste. This research was conducted in three pilot-scale biodrying reactors, two under greenhouse conditions compared with one conventional non-greenhouse condition. Two bunkers with greenhouse cladding were connected with aerators, and airflow rates were set at 0.4 and 0.6 m3/(kgwaste·day), respectively. Meanwhile, a passive aeration method was applied to the non-greenhouse bunker. This study aims to investigate the effect of the greenhouse condition on the biodrying process and assess the performance of the drying process through different operating conditions. The result shows that the greenhouse mainly affects the air temperature rise in the reactor. The aeration rate is positively correlated with weight reduction (r = 0.93). At 0.6 m3/(kgwaste·day) airflow rate, the treatment can reach a moisture content less than 30% on average within ten days, while at 0.4 m3/(kgwaste·day) airflow rate, it takes 15 days to reduce the moisture content to less than 30%. Biodrying under the greenhouse condition with active aeration potentially achieves desirable moisture content reduction and heating value increase more efficiently than the common biodrying. However, the airflow rate is a crucial factor in determining the suitable drying time in biodrying under the greenhouse condition.

Seasonal Changes in the Composition and Thermal Properties of Municipal Solid Waste: A Case Study of the City of Perm, Russia

The paper presents experimental studies of municipal solid waste (MSW) composition and its thermal properties (moisture and ash content). Measurements were taken to track seasonal changes in the composition of MSW. For example, in spring, the content of organic waste was 17.0% and, in autumn, it reached 31.5% due to considerable consumption of seasonal vegetables and fruits. The share of paper in MSW changed from 21.4% in spring to 9.7% in autumn. More paper in spring is due to discarded student notebooks at the end of a school year, as well as spring household cleaning. These data indicate significant changes in waste composition during the year, which should be taken into account when planning technologies for waste management.&#x0D; Laboratory studies of moisture and ash content by season allowed the range of these changes to be determined. In autumn for instance, the moisture and ash content of organic waste was about 82% and 14%, respectively, while in winter, it was approximately 73% and 22%, respectively. These figures can be explained by the organic waste origin: autumn organic waste often comes from fruit pulp and, for example, watermelon peels, and winter organic waste tends to consist mostly of dry vegetable peels such as potato peelings.&#x0D; The low calorific value of certain components is based on their composition and the level of moisture and ash in different seasons. Therefore, it is important to take into account the moisture and ash content of individual components, not average values, in order to calculate the waste calorific value.&#x0D; MSW thermal characteristics change significantly over the seasons: the MSW moisture content is the highest in autumn (about 49%) and the lowest in winter (32%). The ash content in MSW ranges from 20% in spring and autumn to 27% in summer. The lowest calorific value per working mass in different seasons varies from 7 to 10 MJ/kg, which must be taken into consideration when developing waste management systems in general and when designing specific energy recovery facilities.

The Composition and Properties of Polish Waste Focused on Biostabilisation in MBT Plants during the Heating Season

This paper presents the morphological composition of fraction &lt;80 mm, being separated from municipal solid waste (MSW) and delivered in the winter season to the 21 mechanical-biological treatment (MBT) plants throughout several regions of Poland. This fraction is hereinafter referred to as OFMSW (organic fraction of municipal solid waste). Their properties are considered while using parameters such as: moisture, loss on ignition and organic carbon content, as well as moisture and loss on ignition of screen fractions &lt;10 mm and 10–20 mm that are found within. The main aim of this research was to test waste from 21 industrial installations, and to prove that ash content (fine fractions) in waste intended for MBT was about 1/3 of the mass of overall OFMSW mass. These quantities exceed the limits that were approved for the correct operation of MBT installations. The effect of their high content in MSW during the heating season is low moisture (from 25.4% to 58.3%) and the low loss on ignition (from 23.1% to 54.3% DM [dry matter]), which might even determine their inaptness in terms of biological treatment and incineration. The &lt;10 mm fraction contained on average 31.7 ± 7.5% of water and showed a loss on ignition of 29.8 ± 7.1% DM. These values for the 10–20 mm fraction were respectively: 36.6 ± 12.5% DM and 37.3 ± 8.8% DM, respectively.

An insight to municipal solid waste management of Varanasi city, India, and appraisal of vermicomposting as its efficient management approach

Varanasi, India's historic cultural capital, struggles with efficient waste management practices. This impacts environment and human well-being in terms of waste generation that is estimated around 550-650 TPD with a generation rate of 0.42kg capita-1day-1 (n = 117). The present study aims to explore and characterize wastes, current practices, ecological profiling, and phytotoxicity of an abandoned open dumping site, and vermicomposting of organic fraction of municipal solid waste (OFMSW) as sustainable waste management approach. Compositional analysis of waste indicates organic fraction (46.13%) as a major component along with a considerable amount of heavy metals. The calorific value and moisture content of municipal solid waste (MSW) was 2351.4calg-1 and 34.72%, respectively. Ecological profiling of the dumping site revealed that floral diversity and ecological species/indicators were negatively affected. Likewise, phytotoxicity results displayed a negative impact on germination and physiology of maize (Zea mays L.) plants grown on dumping site soil. Vermistabilization of OFMSW showed a significant increase in N (56.10-89.48%), P (33.93-82.87%), and K (25.55-50.42%) and a decrease in total organic carbon (15.15-24.81%). Similarly, C/N and C/P ratios decreased by 1.89-2.51 and 1.72-2.18 folds, respectively. A survey of stakeholders suggested that open dumping was the main practice adopted by Varanasi Municipal Corporation (VMC) during 2013-2015. Recently (2017-2018), VMC adopted different methods, such as door-to-door collection and source segregation for effective waste management. Waste characteristics and nutrient profile of the vermicompost explains that vermicomposting could be used for efficient waste management in Varanasi, further reducing the collection, transportation, and disposal costs of waste, which enables to close the loop and move towards a circular economy. Moreover, implications of existing waste management practices and possible management options need to be addressed scientifically. Therefore, this research outcome will help in designing a successful wastemanagement plan for Varanasi and other cities with similar waste characteristics.

In-situ measurement of temperature and alkali metal concentration in municipal solid waste incinerators using flame emission spectroscopy

In order to address slagging, fouling and high-temperature corrosion problems caused by alkali metals in Municipal Solid Waste (MSW), in-situ measurement of alkali metal in MSW incinerators is needed. The paper presents experimental measurements of temperatures and alkali metal concentrations in two MSW incinerators based on Flame Emission Spectroscopy (FES). Through the analysis of spontaneous emission spectra and a calibration procedure, the concentration of gas phase sodium (Na) and potassium (K), temperature and thermal radiation in the incinerator were in-situ measured by a portable spectral system simultaneously. Experimental results showed MSW composition has significant effect on the measured gaseous Na and K. Higher volatile content in MSW may enhance the alkali metal emission. Besides that, the released gaseous Na and K in the two incinerators are correlated with temperature in incinerators. The study provided a low cost and effective solution for in-situ measurement of temperature and alkali metal concentration in MSW incinerators.

Utilization of non-woven geotextile as insulation on bio-drying reactor

All Utilization of municipal solid waste into fuel requires a pre-treatment process to decrease the moisture content in the solid waste. Bio-drying is a drying method that utilizes microbiological activity of aerobic bacteria to increase the calorific value by decreasing the moisture content in municipal solid waste. The temperature formed in the bio-drying reactor maintained so that the drying process runs effectively by using good insulation. In this research use of nonwoven geotextile as insulation with 600 gsm based polyethylene terephthalate (PET). PET became from a recyclable plastic bottle waste that has low conductivity properties so it is expected to maintain the temperature conditions inside the bio-drying reactor. The results showed that this insulation can reduce moisture content was 51% to 18% and volatile solid loss 86% to 78% for 25 days drying process. Application of nonwoven geotextile insulation is expected to be a solution in the development of bio-drying so that the utilization of bio-drying as solid waste pre-treatment to refuse derived fuel (RDF) can be developed in Indonesia.

RELATING MAGNETIC PROPERTIES OF MUNICIPAL SOLID WASTE CONSTITUENTS TO IRON CONTENT – IMPLICATIONS FOR ENHANCED LANDFILL MINING

Ferrous metals are a main recyclable waste fraction in Enhanced Landfill Mining (ELFM) projects. However, prior to mining, the metal content of municipal solid waste (MSW) landfills is unknown. We investigate if the metal content of MSW landfills can be estimated by inverse modeling of geophysical measurements as the magnetic properties of the subsurface are particularly sensitive to ferromagnetic metal enrichments. We conducted magnetic total-field measurements on a MSW landfill in Austria and estimated the bulk magnetic susceptibility (MS) of the subsurface by inverse modelling. For validation of the subsurface MS values, 32 drill-core samples from multiple locations and depths within the landfill were obtained and manually sorted into 12 waste fractions including ferrous metals (2.3 +/- 1.4 wt.%, 1 sigma). To investigate if bulk MS could be accurately predicted from inverse modeling when the exact composition of the waste is known, the MS of iron and other expected waste fractions were investigated in laboratory analysis using reference samples from waste treatment plants and another ELFM project. Laboratory analyses partly yielded significantly larger MS values for waste materials than those given for virgin materials in literature. The bulk MS for each sample from the ELFM project was computed using a weighted mean with respect to the waste composition derived from manual sorting. The bulk MS derived from inverse modelling of the field data (0.06 to 0.11 SI) exceeded the bulk MS derived from the material composition of waste samples and the MS values of reference samples (0.01 to 0.05 SI).

Laboratory test investigations on soil water characteristic curve and air permeability of municipal solid waste.

The air permeability coefficient has a high correlation with the water content of municipal solid waste. In this study, continuous drying methodology using a tension meter was employed to construct the soil water characteristic curve of municipal solid waste (M-SWCC). The municipal solid waste air permeability test was conducted by a newly designed apparatus. The measured M-SWCC was well reproduced by the van Genuchten (V-G) model and was used to predict the parameters of typical points in M-SWCC, including saturated water content, field capacity, residual water content and water content at the inflection point. It was found that the M-SWCC was significantly influenced by void ratio. The final evaporation and test period of M-SWCC increase with the increase in void ratio of municipal solid waste. The evolution of air permeability coefficient with water content of municipal solid waste depicted three distinct characteristic stages. It was observed that the water contents that corresponded to the two cut-off points of the three stages were residual water content and water content at the inflection point, respectively. The air permeability coefficient of municipal solid waste decreased with the increase of the water content from zero to the residual water content. The air permeability coefficient was almost invariable when the water content increased from residual water content to the water content at the inflection point. When the water content of municipal solid waste exceeded the water content at the inflection point, the air permeability coefficient sharply decreased with the increase of water content.