Municipal Solid Waste Landfill Research Articles

Investigating Major Sources of Methane Emissions at US Landfills.

Airborne remote sensing observations were collected at 217 landfills across 17 states in the US in 2023. We used these observations to attribute emissions to major sources, including the landfill work face, where new waste is placed at the landfill and gas-control infrastructure. Methane emissions from the work face appeared to be more prevalent than gas-control infrastructure emissions, with 52 landfills exhibiting work face emissions out of the 115 observed landfills shown to be emitting in 2023. Landfills with work face emissions were often the highest emitters, especially sites with associated renewable natural gas facilities, and the total average site emissions from these landfills accounted for 79% of the observed emissions, indicating inefficient gas capture at these sites. Landfills with work face emissions also displayed the greatest disparity between observed emission rates and hourly emission rates that we estimated using annual emissions reported to the US EPA's Greenhouse Gas Reporting Program. Work face emissions present a major opportunity for methane mitigation: Observed emissions from work face emitting-landfills in this study were equivalent to 15% of US methane emissions from municipal solid waste landfills in 2022, as reported in the 2024 Greenhouse Gas Inventory, though these landfills accounted for only 4% of open sites in the US. As the 217 landfills in this study cover only 17% of open landfills in the US, the total mitigation potential is likely greater. Using remote sensing, we find that the largest contributor to observed methane emissions at US landfills is the landfill work face, an area of the landfill often left out of the required monitoring and traditional emissions accounting methods.

Anthropogenic and Natural Impacts on Surface Water Quality: The Consequences and Challenges at the Nexus of Waste Management Facilities, Industrial Zones, and Protected Areas

AbstractThe objective of this study was to evaluate the physicochemical characteristics of surface waters near an old landfill, to assess water quality using the Water Quality Index (WQI) and the Comprehensive Pollution Index (CPI), and to identify factors influencing surface water composition using multivariate statistical analysis. The analysis of temporal changes of 15 surface water parameters (pH, EC, Cl−, NH4+, SO42−, BOD5, CODCr, TOC, Zn, Cd, Pb, Cu, Cr, Hg, and PAH) was complemented by the investigation of surface water flow, ambient temperature, and precipitation. A twelve-year monitoring period was considered, focusing on monitoring sites located along a watercourse in the area of the Radiowo landfill (Poland). No significant correlations were found between precipitation and surface water quality parameters in the outflow direction. The results showed that the average WQI values ranged from 63.06 to 96.86, while the average CPI values ranged from 0.56 to 0.88, indicating good water quality or low pollution, respectively. The temperature had a greater influence on the physicochemical parameters than the precipitation, especially on the parameters of contamination by organic compound (correlations between temperature and BOD5, CODCr, and TOC of 0.40, 0.50, and 0.38, respectively). Significant correlations were observed between EC, Cl−, NH4, BOD5, CODCr, and TOC in the outflow direction of the landfill. In addition, surface water flow showed a significant moderate negative correlation with pH (r = -0.44) and a moderate positive correlation with Cu concentration (r = 0.47) downstream of the landfill. The analysis of surface water quality monitoring, coupled with the critical evaluation of global research, has made it possible to understand the variation in surface water quality and the factors that influence it. The study confirmed that given the complex nature of Municipal Solid Waste (MSW) landfills, understanding the dynamics and factors affecting water quality is essential for effective water protection and management and achieving the Sustainable Development Goals (SDGs).

Vegetation Density Mapping of Urban Solid Waste Landfill Coverage Using Vegetation Indexes Obtained with UAV

Objective: The objective of this study is to map the vegetation cover of a municipal solid waste landfill using high-resolution vegetation index images obtained with UAV, as a tool for geotechnical monitoring. Theoretical Framework: The theoretical framework describes the state of the art of vegetation indexes, starting from the first proposal of NVDI by Rouse et al. (1973), through to the NDWI by McFeeters (1996). Additionally, it presents the method of representing radiometric variables, considering that these indexes operate based on the ratio between spectral bands, which are displayed within intervals ranging from -1 to +1. Method: The study used a UAV equipped with MAPIR multispectral camera to capture images of the landfill. NDVI and NDWI indexes were applied to assess vegetation health and coverage. Field control points determined with GNSS-RTK, along with protogrametry software, ensured mapping accuracy, creating high-resolution orhomosaics for monitoring and determining vegetation indexes. Results and Discussion: The results indicate variation in vegetation cover, revealing areas of exposed soil ang vegetation at different stages of vigor, from senescence to full growth. The NDVI and NDWI indexes highlighted regions with water stress and soil exposure, demonstrating the effectiveness of the method in environmental and geotechnical monitoring. Conclusions: It is concluded that the use of UAVs and vegetation indexes are effective for monitoring vegetation health and landfill stability, enanbling the identification of erosion areas and the need for vegetation cover restoration.

A Fuzzy Spatial Multiple Criteria Analysis Methodology for Solid Waste Landfill Siting

The process of siting municipal solid waste landfills in Greece faces significant challenges due to land resource limitations, the country’s mountainous and water-permeable terrain, and strong public opposition. This study introduces a novel methodology for optimizing landfill sites on Lemnos Island in the North Aegean Sea using a Fuzzy Spatial Multiple Criteria Analysis (FSMCA) approach. By combining fuzzy sets theory, Geographic Information Systems (GIS), Analytic Hierarchy Process (AHP), spatial autocorrelation, spatial clustering and sensitivity analysis, this methodology addresses the uncertainties and complexities inherent in landfill siting. The decision problem is structured hierarchically into five levels to manage multiple criteria effectively. Criteria weights are determined using AHP, with discrete criteria graded according to Greek and EU guidelines, and continuous criteria evaluated through fuzzy sets theory. The region’s suitability is assessed using multiple criteria analysis, revealing that 9.7% of Lemnos Island is appropriate for landfill placement. Sensitivity analysis confirms the robustness of the methodology to changes in criteria weights. The case study demonstrates the practical application and benefits of FSMCA in a real-world scenario, underscoring its potential to improve sustainable waste management practices and inform policy making.

Hygienic aspects of ensuring chemical safety of using new health-saving technologies for the utilization of biogas at solid municipal waste landfills

Introduction. Environmental health issues are currently among the most important for the population of large administrative and industrial centers. Improving the quality of the environment and creating comfortable living conditions for humans using environmentally friendly methods is one of the current topical areas in environmental hygiene. Materials and methods. The assessment of the effectiveness and chemical safety of the application of a new technology for the collection, purification, neutralization, and disposal of landfill gas for the content of a wide range of organic compounds C5–C20 at a municipal solid waste landfill was carried out using a chromato-mass spectrometric method that allows identifying and quantifying with sensitivity at and below hygienic standards a wide range of organic compounds C5–C20 in air with an unknown composition of pollutants. Results. As a result of the operation of the new landfill gas purification system at the solid waste landfill, the total concentration of pollutants, including marginal and aromatic hydrocarbons, oxygen-containing compounds (alcohols, carboxylic acids), organic sulfur-containing compounds, and sulfur dioxide decreased. As a result of the operation of the new landfill gas purification technology, 100% purification from odourous dialkyl sulfides and nitrogen-containing compounds has been achieved. However, at the outlet of the system, compounds not detected at the inlet were identified, which can be considered as products of combustion and transformation of hydrocarbons that are part of landfill gas, the presence of which indicates to the use of an oxidative process in the process of its disposal. Limitations. The study is limited to the application of the method of investigation of organic compounds with the molecular formula C5–C20. Conclusion. For an adequate assessment of the quality and chemical safety to human health of health-saving technologies, an important condition is the use of physical-chemical studies that identify and quantify dozens of pollutants simultaneously, which makes it possible to take into account the multiple componentness of the chemical composition and the possibility of adverse side effects in the form of toxic transformation of products affecting humans in real environmental pollution conditions.

Suppression mechanism contributing to the low leaching rate of cesium from incineration bottom ash

After the Fukushima Daiichi nuclear accident, municipal solid waste (MSW) contaminated with radiocesium was generated. In Japan, approximately 80% of MSW by weight has been incinerated. As consequence, radiocesium was retained in incineration residue after the accident. Among the incineration residues, fly ash with high radioactivity was transported to an interim storage facility and special treatment has been carried out. While, bottom ash with radioactivity levels of <8000 Bq kg−1 wet has been directly deposited in conventional MSW landfills. The radiocesium leaching from bottom ash is low, but the reason for this low leaching remains unclear. In this study, leaching tests and microscopic observations of bottom ash containing stable Cs were conducted to investigate the mechanism making Cs leaching low. It is noted that the ash used was simulated ash created from combusting refuse derived fuel (RDF) to which stable Cs was added, not real radioactive ash. Based on pH dependence testing, the Cs leaching increased as the pH decreased. The amount of Cs leached in the neutral range was 2–4% mass of the total content. Electron probe microanalysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy confirmed that certain particles in bottom ash contain concentrated Cs. These particles were found to comprise aluminum, silicon, potassium, and oxygen at their core, surrounded by concentrated Cs. Raman microscopy suggested that these particles are microcline. Co-heating of microcline with Cs carbonate led to the condensation of Cs in a manner similar to particles observed in bottom ash, and Cs was captured in a glassy substance formed on the microcline surface, which reduced the leaching of Cs.

Characteristics and pollution indices of leachates from municipal solid waste landfills in Iranian metropolises and their implications for MSW management

Leachate from municipal solid waste landfills poses a significant threat to aquatic ecosystems due to poor management practices. This study evaluated thirty leachate samples from Iranian metropolises using the Leachate Pollution Index (LPI). Various parameters, including BOD₅, COD, TDS, pH, EC, heavy metals, turbidity, PAHs, phthalates, and humic acid, were analysed. The BOD₅ levels ranged from 350 to 20,000 mg/L, and the COD levels ranged from 2,000 to 90,000 mg/L. The TDS content varied between 14.7 and 67 g/L, while the turbidity ranged from 15 to 186 NTU. Heavy metals were present but within standard limits. The phthalate concentrations ranged from 6 to 150.8 mg/L, and the humic acid concentrations ranged from 135 to 2,200 mg/L. Naphthalene was the most frequent hydrocarbon detected. The LPIs were less than 30 for all the samples, with the highest in Ahvaz and the lowest in the treated samples from Tehran. This study highlights the presence of persistent organic and hazardous contaminants in Iran’s municipal landfills, emphasizing the need for effective leachate treatment and improved waste management practices. Enhanced final disposal methods, increased waste recovery, and improved solid residue separation are crucial for preventing further leachate production and environmental contamination.

Heat mitigation in basal compacted clay liners in municipal solid waste landfills.

In municipal solid waste (MSW) landfills, biodegradation of the organic MSW fraction results in elevated waste and basal liner temperatures which have the potential to cause the clay component of the basal liner to experience severe moisture loss over time and eventually undergo desiccation cracking. Cracking of the basal liner's clay component would result in an uncontrolled release of contaminants into the surrounding environment and ultimately give rise to a variety of major environmental concerns. Accordingly, this study examined the variation of temperature-moisture profiles along the depth of a compacted clay liner (CCL) exposed to different constant elevated waste temperatures (CETs) in the absence and presence of two heat reduction techniques, respectively. Rockwool insulation layers with varying thicknesses and galvanized steel cooling pipes with varying flowrates were introduced separately as the two heat reduction techniques. Introduction of both techniques led to a significant attenuation of the temperature rise and desiccation experienced by the CCL in the face of different CETs. An increase in rockwool thickness increments led to a progressive reduction of CCL temperature, while an increase in flow rate under turbulent condition did not have a significant influence on the temperature and desiccation reduction of the CCL. Nevertheless, the present study certainly highlights the potential of the two proposed heat reduction techniques to minimize desiccation and consequently increase the service life of CCLs exposed to different elevated temperatures in MSW landfills.

Effect of the spatial changes in engineering properties on municipal solid waste landfill slope stability

Effect of the spatial changes in engineering properties on municipal solid waste landfill slope stability

City-scale impacts of PFAS from normal and elevated temperature landfill leachates on wastewater treatment plant influent

The influence of elevated temperatures on PFAS leaching in municipal solid waste (MSW) landfills has not been well characterized in the published scientific literature. This study systematically examined the compositions and concentrations of per- and polyfluoroalkyl substances (PFAS) and precursors content in both normal temperature landfill and elevated temperature landfill (ETLF) leachates and compared to a municipal wastewater and to a WWTP influent with and without introduced leachates. The characterization of the samples involved the analysis of 71 PFAS target compounds before and after applying the total oxidizable precursor (TOP) assay, along with measuring fluorotelomer alcohols (FTOHs) and adsorbable organofluorine (AOF) levels. Summed PFAS concentrations in leachates were driven largely by fluorotelomer carboxylic acids (FTCAs), short-chain and ultrashort-chain perfluorinated carboxylic acids and sulfonic acids. Summed PFAS concentrations in ETLF leachate were significantly higher than in normal leachate for precursors and terminal PFAS products. TOP assay data demonstrated that ETLF leachate contained significantly higher concentrations of oxidizable PFAS precursors than normal leachate. PFAS profiles in leachates were distinct from municipal wastewater and from WWTP influent, suggesting diverse PFAS inputs to the WWTP. The presence of unknown precursors revealed by the TOP assay and AOF analyses highlights the complexity of PFAS sources impacting sewer networks, warranting further study to better characterize PFAS inputs to the WWTP on a city-wide scale.

Analysis of long-term MSW settlement based on field data measured at two closed landfills

Waste settlement characteristics vary depending on waste composition, physical properties, waste management operations, and time. In this study, the post-closure waste settlement behavior was analyzed using field data measured at two closed municipal solid waste landfills in Korea, for 23 and 5 years after landfill closure. The long-term waste settlement data was analyzed to derive a time-varying long-term compression ratio (CLT) that was consistent with modeled biodegradation processes. A statistical assessment of the field data was conducted to examine the relationship between CLT and several factors that may affect the observed settlements. The CLT of Landfill #1 and #2 was found to vary between the two landfills that had differences in the percentage of organic matter (B0), total unit weight (γwaste), and moisture content (w) due to changes in waste management policies.

Potential Use of Municipal Solid Waste Pile in Segawe Landfill (Tulungagung Regency, Indonesia) as Raw Material for Refuse Derived Fuel

The Segawe municipal solid waste (SW) landfill in Tulungagung Regency, Indonesia, has currently exceeded its capacity. This study aimed to determine the potential use of dumped SW at the landfill as raw material for the production of refuse derived fuel (RDF). Buried SW samples were collected at a passive zone of the landfill in six locations. The samples were sieved using 10 and 30 mm mesh sieves. A composition analysis was conducted following the ASTM D5231-92 method to sample fractions of greater than 30 mm size. The density was measured according to the weight and volume. The moisture and volatile matter contents were analyzed using the ASTM D2216-10 and D3175-07 methods, respectively. The calorific value was measured using a Parr C3000 bomb calorimeter following the ASTM D5865 method.The buried SW composition was dominated by a fraction size that was greater than 30 mm (79.4%). This fraction was dominantly composed of plastics (71.2%) and had average volatile matter and calorific values which met RDF criteria as a fuel. However, the ash and moisture contents exceeded the standards and, therefore, required appropriate treatments before their applications.

Phytocapping for Municipal Solid Waste Landfills: A Sustainable Approach

This paper reviews the historical developments in landfill technology and its drawbacks. It introduces phytocapping, in light of previous research, as a promising, eco-friendly and sustainable technology for municipal solid waste (MSW) landfill covers in order to reduce landfill gas and leachate generation. This paper highlights the challenges to successful phytocapping, such as selection criteria for appropriate plants and growth media, and the importance of new research into overcoming these challenges. It also presents a database of plants used in landfill phytocapping studies worldwide. In addition, the performance, economics, and sustainability of phytocapping technology are evaluated in comparison to ordinary MSW landfill methods.

Pollution Characteristics and Risk Assessment of Heavy Metals in the Soil of a Municipal Solid Waste Landfill Site

ABSTRACT With the excavation of landfill sites, the disposal and reduction of organic-rich soils with high proportions of heavy metals have become urgent issues. This study focuses on the pollution characteristics and ecological risks associated with heavy metals in the humus soil of a municipal solid waste (MSW) landfill. The results indicate that the concentrations of heavy metals in the humus soil followed the sequence of Cu > Zn > Cr > Pb > Ni > As > Cd > Hg, and Cu and Cd exhibited the highest exceedance multiples. Except for Cr, the concentrations of the heavy metals in the humus soil were higher than those in combustible components, with a strong Hg correlation. Heavy metal forms indicate varying degrees of mobility and stability; Cr, As, Hg, and Pb were stable, while Ni, Cd, Cu, and Zn showed higher mobility. The results of the principal component analysis reveal that heavy metals primarily originate from industrial and agricultural waste. Finally, the geoaccumulation index of the metals indicated that Cu, Zn, Cd, and Pb exhibited severe contamination. Most importantly, Cd posed the greatest environmental risk as it has the highest effective content, bioavailability, and mobility. This study provides a scientific foundation for mitigating heavy metal pollution in the humus soil of landfill sites.

Evaluation of greenhouse gas emission and reduction potential of high-food-waste-content municipal solid waste landfills: A case study of a landfill in the east of China

This study proposes a comprehensive evaluation method based on a two-stage model to assess greenhouse gas (GHG) emissions and reductions in high-food-waste-content (HFWC) municipal solid waste (MSW) landfills. The proposed method considers typical processes such as fugitive landfill gas (LFG), LFG collection, flaring, power generation, and leachate treatment. A case study of an HFWC MSW landfill in eastern China is considered to illustrate the evaluation. The findings revealed that the GHG emissions equivalent of the case landfill amounted to 21.23 million tons from 2007 to 2022, averaging 1.03 tons CO2-eq per ton of MSW. There was a potential underestimation of LFG generation at the landfill site during the initial stages, which led to delayed LFG collection and substantial fugitive LFG emissions. Additionally, the time distribution of GHG emissions from HFWC MSW was significantly different from that of low-food-waste-content (LFWC) MSW landfills, with peak emissions occurring much earlier. Owing to the rapid degradation characteristics of HFWC MSW, the cumulative LFG production of the landfill by 2022 (2 years after the final cover) was projected to reach 77 % of the total LFG potential. In contrast, it would take until 2030 for LFWC MSW landfills to reach this level. Furthermore, various scenarios were analyzed, in which if the rapid LFG generation characteristics of HFWC MSW are known in advance, and relevant facilities are constructed ahead of time, the collection efficiency can be improved from 31 % to over 78 %, resulting in less GHG emissions.

Electrical conductivity profiling for rapid contamination assessment in unsaturated zones: A case study of an MSW landfill

This study investigates the potential of using bulk soil electrical conductivity (ECbulk) to predict pore water conductivity (ECpw) for assessing the contamination in the unsaturated zone of an old municipal solid waste (MSW) landfill. ECbulk, ECpw, and water content were evaluated with depth at an old MSW landfill in Bhalswa, Delhi, using the Hydraulic Profiling Tool (HPT) and a dual tube soil sampling system. This data was also supplemented by a cone penetration test (CPTu) for high-resolution soil type identification. The correlation of ECbulk with ECpw was primarily influenced by volumetric water content and mineral conductivity with the latter being negligible at this site due to the high conductivity of the leachate. A reasonable linear correlation between normalized EC (ECbulk/ECpw) was observed with volumetric water content, except at low water contents. ECbulk and ECpw profiles with depth indicated attenuation of contaminants in clay layers, while sand layers exhibited constant profile with depth. ECpw was contributed by macro ions generally found in the leachate, including Na+, Mg2+, K+, Ca2+, NH4+, Cl−, SO42−, and HCO3−, as demonstrated by a strong correlation with their cumulative ionic strength. The results indicate that ECbulk profile can be used as a rapid semi-quantitative method for assessing contaminant migration in the unsaturated soil zone, supporting the remediation or control strategies at old landfills.

Analyzing MSW Landfill Failures: Stability and Reliability Evaluations from Five International Case Studies

This study investigates five cases of municipal solid waste (MSW) landfill slope failures in the USA, China, Sri Lanka, and Greece, with the aim of assessing the safety margins and reliability of these slopes. The stability and reliability of the landfill slopes were evaluated under both static and seismic loading conditions, using pre-failure geometries and geotechnical data, with analyses conducted in accordance with Eurocode 7, employing all three design approaches. Under static loading, the factors of safety were close to unity, and reliability indexes ranged from 1.0 to 2.8, both falling below the recommended values set by Eurocode. The landfill slopes failed to meet the stability criteria in Design Approaches 2 and 3, while in Design Approach 1, four out of five landfills met the criteria. Under seismic conditions, safety factors and reliability indexes were significantly lower than the prescribed criteria in all analyses. Sensitivity analyses revealed that in two cases, unit weight and friction angle were the dominant parameters, while cohesion was the dominant parameter in one case. The findings of this study underscore the importance of establishing minimum design requirements for MSW landfill slope stability to mitigate potential risks to public health and the environment.

Modeling the clogging process of leachate collection systems in municipal solid waste landfills: The role of temperature

The leachate collection system (LCS) is an important component of barrier systems in municipal solid waste (MSW) landfills. LCS Failure due to clogging could lead to leachate accumulation, potential soil and groundwater pollution and slope failure. LCS clogging is generally ascribed to particle deposition, biofilm growth, and calcium carbonate precipitation, while temperature strongly influences microbial activity and thus inevitably affects the clogging process of LCSs. However, the role of temperature in the process of clogging and leachate accumulation in LCSs remains unclear. The main objective of this study was to bridge this research gap by developing reasonable mathematical models and comprehensively analyzing this issue. The mathematical model involved leachate flow, solute migration, physical–chemical-biological clogging, and heat transfer processes. By conducting a series of numerical simulations, the temperature variation, clogging development, and corresponding leachate accumulation inside the system during long-term operation in both the geotextile and gravel layers were numerically analyzed and predicted. The results demonstrated that, in the gravel layer, due to the higher temperature, more thorough microbial substrate consumption led to higher production of carbonate ions and hence faster and more notable calcium carbonate precipitation. Overall, the bioactivity changes due to high temperatures could considerably accelerate the failure of LCS.

Evaluation of municipal solid waste characterization and landfill gas power plant electrical energy production efficiency during COVID-19 pandemic

Due to the COVID-19 pandemic, the amount and types of municipal solid waste (MSW) have dramatically changed. This study focuses on characterizing the MSWs in the regular waste storage facility (RWSF) in Izmir, Turkey, and determining the electrical energy that can be produced by the landfill gas power plant (LFGPP) established to convert the waste to energy (WtE). Therefore, firstly the MSWs were characterized. After, the amount of produced methane (CH4) gas was determined using Landfill Gas Emissions Modeling (LandGEM). The amount of generated electricity, the dependent variable in the LandGEM model, was most influenced by the quantity of MSW, garbage disposal processes, and maintenance times of gas generators, while other factors remained relatively weak. This situation has also been confirmed in the field. During the COVID-19 pandemic, the increase in MSW was 9.8% in 2020 and 10.3% in 2021. Kitchen waste containing the highest CH4, accounted for 38% of the MSW characterization. The amount of generated electricity in the LandGEM model was 237 GWh in 2020 and 245 GWh in 2021. While these values could be achieved by 11.25% in 2020 due to various system and field failures, they reached 79.73% in 2021 due to system and field improvements.

Evaluation of life cycle cost for the comparison of decentralized waste to composting and landfilling of municipal solid waste

BackgroundMunicipal solid waste (MSW) has increased dramatically in emerging economies like Bangladesh as a result of rapid urbanization and economic growth. Due to the high land requirements and nature of the waste, options of municipal waste management such as landfilling and waste-to-energy have proven to be expensive and inefficient. Previously, a pilot study on a waste-to-compost program in a decentralized facility was done in Dhaka to evaluate the effectiveness of municipal waste management.ObjectiveThe aim of this study was to analyze the life cycle costs (LCCs) of a waste-to-composting facility in Dhaka, Bangladesh. The objective was to ensure economical and effective management of MSW by comparing overall spending to the current and proposed waste management process.MethodologyIn order to evaluate the potential of the planned decentralized compost plant, LCC methods using UNEP/SETAC guidelines are used in the study. This includes an additional analysis of environmental and operational costs and benefits.ResultThe research found that the overall cost of the decentralized compost facility was $857,110, much less than the expenditures associated with landfilling and conventional composting methods in Dhaka.ConclusionThis study shows that a decentralized waste-to-compost plant may be a profitable option for dealing with municipal solid waste. Its potential to ease stress on municipal governments is highlighted by its much lower price tag. Insightful for policymakers and urban planners in emerging nations confronting comparable waste management difficulties, this research stresses the need to implement such creative, cost-effective approaches in quickly rising metropolitan cities.