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• Direct and indirect climate impacts of solid waste landfills in California were quantified. • Direct impacts were positive and high whereas indirect impacts were negative and low. • Cover characteristics including material type and areal extent control climate impacts. • Global warming potential time horizon significantly influences climate impact results. • Integration of direct and indirect impacts advances landfill climate mitigation strategies. Climate impacts of landfill gas emissions were investigated for 20- and 100-year time horizons to identify the effects of atmospheric lifetimes of short- and long-lived drivers. Direct and indirect climate impacts were determined for methane and 79 trace species. The impacts were quantified using global warming potential, GWP (direct and indirect); atmospheric degradation (direct); tropospheric ozone forming potential (indirect); secondary aerosol forming potential (indirect) and stratospheric ozone depleting potential (indirect). Effects of cover characteristics, landfill operational conditions, and season on emissions were assessed. Analysis was conducted at five operating municipal solid waste landfills in California, which collectively contained 13% of the waste in place in the state. Climate impacts were determined to be primarily due to direct emissions (99.5 to 115%) with indirect emissions contributing −15 to 0.5%. Methane emissions were 35 to 99% of the total emissions and the remainder mainly greenhouse gases (hydro)chlorofluorocarbons (up to 42% of total emissions) and nitrous oxide. Cover types affected emissions, where the highest emissions were generally from intermediate covers with the largest relative landfill surface areas. Landfill-specific direct emissions varied between 683 and 103,411 and between 381 and 37,925 Mg CO 2 -eq./yr for 20- and 100-yr time horizons, respectively. Total emissions (direct + indirect) were 680 to 103,600 (20-yr) and were 374 to 38,108 (100-yr) Mg CO 2 -eq./yr. Analysis time horizon significantly affected emissions. The 20-yr direct and total emissions were consistently higher than the 100-yr emissions by up to 2.5 times. Detailed analysis of time-dependent climate effects can inform strategies to mitigate climate change impacts of landfill gas emissions. [ABSTRACT FROM AUTHOR]

[Display omitted] The Sudokwon landfill (SL) in the Seoul metropolitan area, South Korea, is among the world's largest landfills, striving to curtail landfill gas (LFG) emissions and achieve carbon neutrality by 2050. Since 2005, the SL Management Corporation (SLC) has measured LFG emissions (i.e., methane (CH 4) and carbon dioxide (CO 2)) using a dynamic flux chamber proposed by the US EPA. However, uncertainty prevails in validating the reduction of LFG emissions due to the limited spatiotemporal data coverage. In 2020, an eddy covariance (EC) system was installed to enhance measurements, revealing highly fluctuating LFG emissions driven by waste layer LFG production, LFG collection, and atmospheric pressure changes. During the study period, the annual CH 4 emission increased slightly from 465.0 ± 4.2 to 485.5 ± 6.4 g C m−2, while that of CO 2 decreased by 2/3 (from 408.7 ± 16.5 to 270.6 ± 18.8 g C m−2), primarily due to the doubled CO 2 uptake by the vegetated topsoil. Our first long-term (March 2020 to February 2022) quasi-continuous monitoring using EC (with a gap-filling and partitioning technique based on Random Forest) emphasizes the difficulty of temporal upscaling of discontinuously observed surface emissions to quantify the LFG inventory and the need for continuous observations or suitable proxies (e.g., atmospheric CH 4 concentration). [ABSTRACT FROM AUTHOR]

[Display omitted] • PMOB is an economical solution to reduce landfill CH 4 emissions. • Both single- and two-phase flow models are used for calculating LUGM. • LUGM doesn't reflect gas flow rate into MOL. • A novel PMOB design is proposed with a trapezoidal MOL-GDL interface. • Trapezoidal MOL-GDL interface enhances total gas flow rate into MOL. Passive methane oxidation biosystems (PMOBs) are developed as an innovative and cost-effective solution to reduce methane (CH 4) emissions from municipal solid waste landfills. A PMOB consists of a methane oxidation layer (MOL) and an underlying gas distribution layer (GDL). The length of unrestricted gas migration (LUGM) has been recently proposed as the design criterion for PMOBs where the LUGM is calculated as the horizontal length along the MOL-GDL interface with the volumetric gas content (θ a) exceeding the threshold volumetric gas content (θ a,occ). This paper examined water and gas migration within three PMOBs with different MOL-GDL interfaces subject to precipitation and evaporation using verified numerical models. The results show that the use of a single-phase flow model underestimates the LUGM values of the PMOB for heavy precipitation events, and a two-phase flow model should be used to calculate both the LUGM and the total gas mass flow rate into the MOL when designing PMOBs. Both zig-zag and trapezoidal MOL-GDL interfaces can redistribute the gas mass flow rate at the MOL-GDL interface, while the trapezoidal MOL-GDL interface slightly outperforms the zig-zag MOL-GDL interface for enhancing the total gas mass flow rate into the MOL when comparing with the planar MOL-GDL interface. The zig-zag and trapezoidal MOL-GDL interfaces allow gas migration in the upper part of each PMOB segment even when the lower part of each PMOB segment was filled with water, and thus have a potential to minimize hotspot formation. [ABSTRACT FROM AUTHOR]

• Estimates of modeled CH 4 emission (E) data for 1,325 U.S. landfills were reviewed. • Operators use two methods to estimate E from landfills with a gas collection system. • First-order decay (FOD) method shows increasing emissions. • Collection efficiency assumption method shows decreasing emissions. • FOD method shows some agreement to remotely sensed national estimates. As part of its commitment to the United Nations Framework Convention on Climate Change, the U.S. annually develops a national estimate of methane emissions from municipal solid waste (MSW) landfills by aggregating activity data from each facility. Since 2010, the U.S. has reported a 20 % decrease in MSW landfill emissions despite a 21 % increase in tons disposed. Operator-submitted data were investigated to understand the causes of this decline. In the U.S., operators of landfills with a gas collection and control system (GCCS) calculate their facility's emissions via two separate approaches – (1) first-order decay (FOD) and (2) collection efficiency assumption (CEA) − and select either result to feed into the annual inventory. The FOD model predicts methane generation proportional to waste disposal and that approach calculated a 19 % increase in total methane generated from 2010 to 2022, whereas generation via the CEA approach decreased by 8.9 %. The amount of measured methane collected has increased 7.5 % for the same years. Discrepancies between the two models' generated methane, assumed gas collection efficiencies, and oxidized methane compound into substantive differences in national estimates. Operators more frequently select the CEA method, which results in decreased national estimates. If only the FOD method was used, U.S. MSW landfill emissions would be 1.3-1.7 times greater than current estimates which is similar to recent extrapolations from remote sensing campaigns in the U.S. Both models contain parameters with large inherent uncertainty. Without measurement methods that continuously quantify both point-source and diffuse emissions, an assessment of either equation's accuracy cannot be made. [ABSTRACT FROM AUTHOR]

• Demonstration of a whole-site flushing technique in an MSW landfill. • Use of bromide and water as tracers in landfill. • Verification of dual-porosity behaviour of MSW. • in situ field-scale estimates of block diffusion time. • Examination of different fill-and-draw flushing scenarios. A fill-and-draw flushing test on a landfill cell containing MSW waste was carried out to examine the operational viability of this method for accelerating the flushing of contaminants and landfill stabilisation. During the fill cycle, 800 m3 of water containing the tracer bromide was pumped into the base of a 0.44 ha landfill cell, resulting in the estimated saturation of 9,400 m3 of waste. Abstraction took place in two phases, during which 1,100 m3 of tracer/leachate was recovered. Samples of leachate were analysed for the tracer, electrical conductivity and indigenous solutes chloride and ammonia. Tracer recovery was between 63 and 72 % for bromide. An estimated 227 kg of ammonia and 575 kg of chloride were removed. Test data was used to calibrate a 1D, dual-porosity model involving advection in a mobile zone, and diffusion into 'blocks' of a less mobile zone. The model fitted well to the early time data, whereas later data appears to have been affected by recharge. The results of this trial demonstrate the possibilities of the 'fill-and-draw' concept using the basal leachate drainage system of landfills as a potential accelerated landfill remediation technique. However, modelling results suggest low contaminant removal efficiency. Including a pause between the fill and the draw cycles improves mass removal. [ABSTRACT FROM AUTHOR]

This study evaluates the efficacy of the Thiopaq bio-desulfurization system at the Daegu Bangcheon-ri Sanitary Landfill in Korea over 1 year focusing on operational insights and microbial dynamics. The system employs sulfur-oxidizing bacteria (SOBs) to convert hydrogen sulfide (H2S) in landfill gas (LFG) into elemental sulfur. Key findings include maintaining over 96% H2S removal efficiency despite operational challenges such as sulfur clogging and foam formation. Significant microbial community shifts were observed, with Thioalkalibacter halophilus remaining robust, Alkalilimnicola ehrlichii declining, and Halothiobacillus kellyi becoming more prominent, especially during new well installations with high thiol (methanethiol) concentrations. Scanning electron microscopy revealed distinct morphological characteristics of bio-sulfur under varying conditions contributing to process optimization. Our results underscore the necessity for continuous monitoring and adaptive management of microbial populations and system parameters to effectively handle fluctuating LFG compositions and operational conditions. This study provides substantial guidance for enhancing LFG quality and bio-sulfur production in large-scale landfills. [ABSTRACT FROM AUTHOR]

Brunei, similar to other nations, encounters difficulties in effectively managing solid waste, with 70% of the waste ending up in landfills, 2% through composting, and the remainder being disposed of through conventional methods. The current landfill site is anticipated to reach its maximum capacity in 2025. Energy recovery from waste is crucial for Brunei since it can improve waste management, mitigate environmental consequences, produce economic advantages, bolster energy security, and promote a circular economy. This study aims to identify the potential for energy recovery through landfill gas generated from solid waste disposal in Brunei Darussalam. The study finds that Brunei Darussalam can produce 129 thousand tonnes of CO2e/year landfill gas. Utilising gas to generate electricity of 367 GWh could save 1.6 million USD annually. In addition, it also identifies the strengths and weaknesses of the existing solid waste management in Brunei Darussalam. Furthermore, it formulates a waste management policy in Brunei Darussalam by identifying relevant stakeholders to overcome the weakness. Lastly, the framework for waste management is designed to consider short-, intermediate- and long-term goals and targets, with actions to be taken by respective stakeholders. [ABSTRACT FROM AUTHOR]

For the first time, a catalyst containing 5 wt. % Ni supported on a hydroxyapatite support (HAP) has been synthesized and evaluated in tri‐reforming of methane (TRM) for synthetic gas (syngas) production. Nickel nanoparticles could be easily formed on HAP surface by using the conventional incipient wetness impregnation technique. In TRM, under unfavorable reaction conditions from the thermodynamic point of view (e. g. medium reforming temperature of 700–800 °C, low steam‐to‐carbon ratio, etc.), this catalyst showed high methane conversion (up to 90 %), however, some deactivations took place. The latter could be explained by both the thermal sintering of nickel nanoparticles and the solid carbon formation. The impact of the main operational parameters has been studied. Increasing the reaction temperature, the molar ratios of oxygen‐to‐carbon and steam‐to‐carbon are favorable for the methane conversion and mostly for the stability of the catalyst. High methane conversion of ca. 90 % with a perfect catalytic stability during 300 hours‐on‐stream could be achieved at 800 °C and 1.4 bar, using a mixture containing low ratio of oxidant‐to‐carbon (molar ratio of CH4/CO2/H2O/O2/N2=1.0/0.67/0.9/0.1/0). These results offer the opportunity to further design an optimal Ni/HAP catalyst by improving metal‐support interaction and downsizing nickel nanoparticles. [ABSTRACT FROM AUTHOR]

An independent evaluation of methane emissions data from GHGSat, a private company that operates a constellation of small microsatellites flying Fabry‐Perot spectrometers operating at 1.6 µm, was performed. Data from multiple GHGSat commercial satellites, consisting of retrieved methane, diagnostics, and, where detected, plume and emissions information from roughly 250 scenes across Canada were analyzed. From these, 10 scenes contained methane plumes with a 2% detection rate for oil and gas scenes, and 10% for landfills. Methane precision was found to be 5%/2% on average for the C1/C2–C5 designs, with some variability due to scene albedo, terrain roughness, and airmass. Synthetic GHGSat plumes, generated using Lagrangian plume dispersion model and GHGSat characteristics, indicates typical detection limits of 240/180 kg/hr(C1/C2–C5), with a best case of roughly 100 kg/hr. Emissions and their uncertainties calculated using an alternative approach were in broad agreement with GHGSat‐reported emissions. Overall, the performance of the GHGSat C2 design (also used for C3 onward) for favorable‐viewing conditions was found to be largely consistent with company‐advertised performance. Plain Language Summary: We performed an independent evaluation of methane emissions data from GHGSat, a private company that owns and operates its own group of satellites, in order to evaluate the precision of their methane data products and compare these findings with that advertised. Roughly 250 GHGSat data scenes were acquired with 10 plumes detected, 2 for oil and gas and 8 for landfills. These, combined with advanced plume models, statistical analyses, and alternative data processing software, were used in the evaluation. It was found that the GHGSat‐reported detection limit—the quantity of methane release that was is the edge of detectability—of 100 kg/hr was possible, but only for ideal conditions. Ideal in this case means a surface that is quite reflective (at the wavelengths detected by the GHGSat sensors, roughly 1.6 μm) and flat near the source of the emissions. A detection limit of 180 kg/hr is more representative of average conditions. Key Points: GHGSat methane precision was found to be 1%–5%, varying with surface reflectance, terrain variability, and solar zenith angleGHGSat methane detection limit can be as low as 100 kg/hr under ideal conditions, but more typically is about 200 kg/hrGHGSat performance was found to be generally consistent with that reported by the company [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW) landfills are a significant source of methane (CH4) emissions in the United States, contributing to global warming. Current landfill gas (LFG) management methods, like the landfill cover system and LFG collection system, do not entirely prevent LFG release. Biocovers have the potential to reduce CH4 emissions through microbial oxidation. However, LFG also contains carbon dioxide (CO2) and trace hydrogen sulfide (H2S) depending on waste composition, temperature, moisture content, and age of waste. An innovative biogeochemical cover (BGCC) was developed to tackle these concerns. This cover comprises a biochar-based biocover layer overlaid with a basic oxygen furnace (BOF) steel slag layer. The biochar-based biocover layer oxidizes CH4 emissions, while the BOF slag layer reduces CO2 and H2S through carbonation and sulfidation reaction mechanisms. The BGCC system's field performance remains unexamined. Therefore, a large-scale tank setup simulating near-field conditions was developed to evaluate the BGCC system's ability to mitigate CH4, CO2, and H2S from LFG simultaneously. Synthetic LFG was passed through the BGCC in five distinct phases, each designed to simulate the varying gas compositions and flux rates typical of MSW landfill. Gas profiles along the depth were monitored during each phase, and gas removal efficiency was measured. After testing, biocover and BOF slag samples were extracted to analyze physico-chemical properties. Batch tests were also conducted on samples extracted from the biocover and BOF slag layers to determine potential CH4 oxidation rates and residual CO2 sequestration capacity. The results showed that the BGCC system's CH4 removal efficiency decreased with higher CH4 flux rates, achieving its highest removal (74.7–79.7%) at moderate influx rates (23.9–25.5 g CH4/m2-day) and reducing to its lowest removal (27.4%) at the highest influx rate (57.5 g CH4/m2-day). Complete H2S removal occurred during Phase 3 in the biocover layer of BGCC system. CH4 oxidation rates were highest near the upper (277.9 µg CH4/g-day) and lowest in the deeper region of the biocover layer. In the tank experiment, CO2 breakthrough occurred after 156 days due to drying of the BOF slag layer, with an average residual carbonation capacity of 46 gCO2/kg slag after moisture adjustment. Overall, the BGCC system effectively mitigated LFG emissions, including CH4, CO2, and H2S, at moderate flux rates, showing promise as a comprehensive solution for LFG management. [ABSTRACT FROM AUTHOR]

Advancements in satellite technology coupled with image processing, statistical tools and Artificial Intelligence (AI) algorithms, enable efficient, non-invasive, real-time monitoring and analysis of landfills. Landfills pose a severe environmental threat to the local ecosystem. Metropolitan cities in most developing countries usually have multiple landfills. Landfill Land surface temperature (LST) monitoring can help keep track of the changes in landfills, especially concerning waste management, land use, hotspot movement, fire prediction and the stability of the landfill. Monitoring these waste disposal sites through remote sensing data can provide real-time monitoring and analysis, supporting quick interventions when necessary. This research utilizes LANDSAT 8 satellite images for Mumbai, India. Using geospatial analysis, image processing and data processing, LST is derived for 576 LST data points. While landfill LST has a positive trend over time, but there are cyclical, seasonal and changes due to disruptive events. With landfill LST consistently remaining the highest over the years, in comparison to built-up, green and sea LSTs. A statistical analysis of the data reveals the overall significance of the model in ascertaining the increase in temperature due to the presence of landfills. Despite challenges such as large data libraries and variable environmental factors, this research emphasizes and contributes to satellite imagery's evolving potential for monitoring and assessing LSTs. [ABSTRACT FROM AUTHOR]

Landfills are widely employed as the primary means of solid waste disposal. However, this practice generates landfill gas (LFG) which contains methane (CH4), a potent greenhouse gas, as well as various volatile organic compounds and volatile inorganic compounds. These emissions from landfills contribute to approximately 25% of the total atmospheric CH4, indicating the imperative need to valorize or treat LFG prior to its release into the atmosphere. This review first aims to outline landfills, waste disposal and valorization, conventional gas treatment techniques commonly employed for LFG treatment, such as flares and thermal oxidation. Furthermore, it explores biotechnological approaches as more technically and economically feasible alternatives for mitigating LFG emissions, especially in the case of small and aged landfills where CH4 concentrations are often below 3% v/v. Finally, this review highlights biofilters as the most suitable biotechnological solution for LFG treatment and discusses several advantages and challenges associated with their implementation in the landfill environment. [ABSTRACT FROM AUTHOR]

Globally, food waste is a significant environmental, economic and social issue. Food waste in landfill creates the potent greenhouse gas, methane, contributing to climate change, with its management predominantly falling to local governments. Despite efforts by many countries, and extensive infrastructure and market development funding, food waste continues to be landfilled, with apparently similar councils taking diverse approaches. Using a mixed methods study design, data was firstly collected from a National online survey of Australian council-based waste management staff (n = 183), with descriptive and factor analysis of the survey data revealing a strong sense of structural empowerment (PCA.75 to.90) and a preference for sourcing information from networks (48%). These results informed a series of semi-structured interviews (n = 43) which, after thematic analysis, provided rich insights into the attitudinal and situational interpretations council-based waste managers bring to decisions around household food waste management. Framed by four pillars of Structural Empowerment, the findings suggest that waste manager's attitude is equally as important as support, resources, and knowledge and that, despite mandates and targets, individual motivational factors and organisational paradigms determined decision-making. Identified barriers included perceived capacity constraints, inadequate focus on actionable interventions, and fragmented, uninspiring, planning. This article provides important insights around 1) leveraging networks for knowledge dissemination, 2) fostering capacity-building initiatives, and 3) advocating for sustained engagement with food waste diversion within councils. This underscores the need for additional research into evolving council typologies and effectively engaging key stakeholders to achieve food waste diversion targets and address climate change impacts. [ABSTRACT FROM AUTHOR]

Long-term monitoring and treatment of landfill leachate (LFL) and landfill gas (LFG) is required until landfilled municipal solid waste (MSW) is sufficiently stabilized and post-closure care can be terminated. Monitoring data of methane (CH4) emissions in LFG from a marine landfill over 30 years were compared with the IPCC first order decay (FOD) model estimates. The observed changes in CH4 showed a similar attenuation trend to the estimates, but the observed CH4 emissions were only about 30% of the estimate over 30 years; LFL is considered to be another pathway for organic carbon to be released to the environment, but the total organic carbon in discharged LFL was only about 0.2% of CH4 carbon in LFG emission over the same period. The increase in the CO2/CH4 ratio in LFG over time suggests that the discrepancy between estimated and observed emissions is due to methane oxidation in the overlying soil, in addition to the high coefficient values used in the FOD model. Total organic carbon (TOC) in LFL discharged as effluent reached a maximum value in the early stages of the landfill and gradually decreased, but only to about one-third of the maximum value after more than 30 years and a decrease in the amount of effluent. As incineration of MSW is expected to reduce organic carbon and nitrogen, the CH4 reduction effect of incineration of business and household waste and sewage sludge was investigated using FOD model estimates. [ABSTRACT FROM AUTHOR]

Landfills are major emitters of greenhouse gases, especially methane (CH[sub 4]). To address this, the U.S. EPA promotes utilizing landfill gas (LFG) for renewable energy. Our study in Southeast Texas compared four LFG conversion strategies: flaring, electricity generation, renewable natural gas and methanol production. Scenario analysis was conducted to reveal the influence of market conditions and incentives on profitability. While electricity generation consistently yielded the highest returns, methanol production emerged as a close contender due to the strategic advantage of its proximity to the landfill site in this industrial zone. This study highlights the promising synergy between landfills and the hydrocarbon industry for sustainable development. [ABSTRACT FROM AUTHOR]

The Municipal Solid Waste Management (MSWM) system has been used as a unit of study to apply the Life Cycle Assessment (LCA) approach. Kanjur waste processing facility Mumbai, India was selected for technological performance assessment. The paper analyses multiple strategies for managing the MSW and the comparison of strategies is done to study impact on Global Warming Potential (GWP), Eutrophication Potential (GW) and Acidification potential (AP), which are the critical impact areas of MSW processing. The scenarios included were transportation, material recovery, direct landfill with the recovery of LFG, composting of the source-separated organic fraction with landfilling and biomining. Landfilling and the release of LFG (Landfill Gas), electricity generation from LFG, flaring of LFG were other assessed interventions. The scenarios were modelled using the CML impact characterisation method. The results highlight that sorting, biomining, composting, landfilling with energy recovery has the minimal impact on the environment compared to strategies where direct landfilling was considered. On a life cycle view, the transportation of waste to the processing site caused a significant global warming impact and is a hotspot, which can be considered for impact mitigation. Initiatives like RDF reuse, leachate recirculation, LFG recovery, biomining are other circular practices that lead to a significant reduction in GWP, EP and AP. [ABSTRACT FROM AUTHOR]

Due to the increased demand for energy resources and the continuous increase in population, the use of RES from biomass and waste is becoming increasingly popular. The work analyzed existing approaches to solving global environmental and social problems through the use of landfill gas generated at municipal solid waste (SMW) landfills, as well as further reforming of biogas into biohydrogen. Waste monitoring was also carried out on the territory of LR and St. Petersburg. It was found that more than 12 million m3 of SMW of hazard classes 1–5 are formed annually in the region. It has been shown that the majority of waste is biodegradable organic matter (about 20%). To increase the biogas potential of SMW landfills during degassing and create additional economic benefits, a system for blowing and irrigation of landfill masses with the addition of a substrate from residual biomass of Chlorella microalgae was proposed. It is proposed to improve the scheme for sorting and using organic waste through selective collection and separation from the total mass of waste at the site of generation. A waste flow diagram has been developed taking into account the material balance of SMW in LR and St. Petersburg. Using this scheme will avoid contamination of other recycled SMW components. In addition, the work proposes a scheme for the further use of biomethane obtained at SMW landfills. Using reforming, it is proposed to purify the resulting gas to biohydrogen. The production of biohydrogen from biogas is cost-effective and can become an alternative to petroleum products. This technology could become a key element in the production of environmentally friendly fuels and the reduction of harmful emissions into the atmosphere. [ABSTRACT FROM AUTHOR]

Emissions of greenhouse gases (GHG) from municipal solid waste (MSW) in North Macedonia are a serious issue for the environment and major efforts are needed to mitigate climate change. In order to determine the current situation with the GHG emissions in North Macedonia, several calculations were made and results and proposals for reduction of GHG emissions, related with waste, are presented in this paper. Municipal solid waste (MSW) management, primarily through landfilling, is a major contributor to GHG emissions in North Macedonia. The anaerobic decomposition of organic waste in landfills generates methane (CH4), a strong greenhouse gas with a high global warming potential, even 25 times more than carbon dioxide (CO2). Furthermore, open waste burning and inadequate waste management techniques lead to the release of CO2, nitrous oxide (N2O), and other pollutants. Despite efforts to mitigate GHG emissions from waste, challenges persist due to inadequate waste management infrastructure, limited waste reduction and recycling initiatives, and failure to implement regulatory frameworks. These challenges exacerbate the environmental impacts of waste management and hinder progress towards sustainable development goals. To tackle GHG emissions from waste in North Macedonia, a comprehensive approach is required that includes legislative interventions, technological advances, and public engagement techniques. Improving waste management infrastructure, promoting waste reduction and recycling, investing in waste-derived renewable energy, and enhancing regulatory enforcement are among the key recommendations. [ABSTRACT FROM AUTHOR]

This study investigates the process of long-term (bio)degradation of polyethylene (PE) in an old municipal waste landfill (MWL) and its implications for environmental and human health. Advanced techniques, such as ICP–ES/MS and IC–LC, were used to analyze heavy metals and anions/cations, demonstrating significant concentration deviations from control samples. The soil's chemical composition revealed numerous hazardous organic compounds, further indicating the migration of additives from PE to the soil. Toxicological assessments, including Phytotoxkit FTM, Microtox® bioassay, and Ostracodtoxkit®, demonstrated phytotoxicity, acute toxicity, and high mortality in living organisms (over 85% for Heterocypris Incongruens). An unusual concentration of contaminants in the MWL's middle layers, linked to Poland's economic changes during the 1980s and 1990s, suggests increased risks of pollutant migration, posing additional environmental and health threats. Moreover, the infiltration capability of microorganisms, including pathogens, into PE structures raises concerns about potential groundwater contamination through the landfill bottom. This research underscores the need for vigilant management and updated strategies to protect the environment and public health, particularly in older landfill sites. [ABSTRACT FROM AUTHOR]

Methanotrophy is a biological process that effectively reduces global methane emissions by utilizing microorganisms that can utilize methane as a source of energy under both oxic and anoxic conditions, using a variety of different electron acceptors. Methanotrophic microbes, which utilize methane as their primary source of carbon and energy, are microorganisms found in various environments, such as soil, sediments, freshwater, and marine ecosystems. These microbes play a significant role in the global carbon cycle by consuming methane, a potent greenhouse gas, and converting it into carbon dioxide, which is less harmful. However, methane is known to be the primary contributor to ozone formation and is considered a major greenhouse gas. Methane alone contributes to 30% of global warming; its emissions increased by over 32% over the last three decades and thus affect humans, animals, and vegetation adversely. There are different sources of methane emissions, like agricultural activities, wastewater management, landfills, coal mining, wetlands, and certain industrial processes. In view of the adverse effects of methane, urgent measures are required to reduce emissions. Methanotrophs have attracted attention as multifunctional bacteria with potential applications in biological methane mitigation and environmental bioremediation. Methanotrophs utilize methane as a carbon and energy source and play significant roles in biogeochemical cycles by oxidizing methane, which is coupled to the reduction of various electron acceptors. Methanotrophy, a natural process that converts methane into carbon dioxide, presents a promising solution to mitigate global methane emissions and reduce their impact on climate change. Nonetheless, additional research is necessary to enhance and expand these approaches for extensive use. In this review, we summarize the key sources of methane, mitigation strategies, microbial aspects, and the application of methanotrophs in global methane sinks with increasing anthropogenic methane emissions. [ABSTRACT FROM AUTHOR]

Low-permeability liners are required at the base of municipal solid waste (MSW) landfills to minimize leachate leakage and contaminant migration into groundwater. This paper uses a two-dimensional coupled groundwater flow and contaminant transport model to examine the performance of three types of low-permeability liners specified by the current Chinese landfill standard: (1) a compacted clay liner (CCL), (2) a geomembrane (GMB) overlying a CCL, and (3) a GMB overlying a geosynthetic clay liner (GCL) on a CCL. The model simulates leachate leaking and contaminant migrating over the entire base of the landfill for the CCL and through the holed GMB wrinkles for the GMB composite liners. The performance of each type of low-permeability liners was evaluated and compared in terms of leakage rate and peak impact of chloride on the aquifer. Based on liner cases and conditions examined in this paper, the results show that the three types of low-permeability liners are not equivalent for minimizing the leakage rate and chloride impact on the aquifer. The GMB + GCL + CCL performs the best among the three low-permeability liners, and is effective for limiting the peak chloride impact on the aquifer below the acceptable level in drinking water. [ABSTRACT FROM AUTHOR]

Understanding triggering mechanisms of slope failure is of great importance to the stability analysis and safety warning of waste landfill. This paper presents a centrifuge model test on slope failure induced by elevated gas pressure in wet landfill. The formation process of liquid level and gas pressure in the landfill is simulated by means of liquid and gas injections under a centrifugal acceleration of 66.7 g. The injected liquid contains surfactants, which allow it to generate foam in the waste pores when mixed with the injected gas. The pore gas and liquid pressures under two-phase flow condition are monitored separately to clarify the instability process. It is found that the continuous gas injection makes the pore gas pressure increase to peak values of 83.0 kPa–100.8 kPa, which are higher than the peak liquid pressures of 61.3 kPa–75.6 kPa. The formation of high gas pressure zone is attributed to the low gas permeability, which is affected by high liquid saturation as well as foam generation. The slope failure occurs when the pore gas pressure increases to the peak value and the corresponding shear strength decreases to the critical value. Although the gas injection raises the liquid level, the factor of safety of landfill slope will be overestimated if only considering the effect of liquid pressure. According to the response curves of displacement to gas pressure rise, the critical ratios of gas pressure to earth pressure are determined to be 0.74–0.84, which fall within the range of the prototype landfill. The difference between foam and air on pore pressure distribution is also calculated and discussed. [ABSTRACT FROM AUTHOR]

Paper mill sludge (PMS) is featured with a high content of cellulose and hemicellulose, and using its characteristics to make paperboard can achieve a high-value utilization of PMS, which has attracted growing interest. In this study, currently prevalent landfill, incineration technologies (generating heat and electricity by incineration), and three paperboard technologies (medium density fiberboard, pulp board, and corrugated paper) were evaluated and compared via life cycle assessment (LCA) and life cycle costing (LCC) methods. LCA results show that the PMS-to-pulp board outperforms others with an energy conservation and emission reduction (ECER) value of − 2.86 × 10−8, while the landfill exhibits the highest overall environmental impact with an ECER value of 4.80 × 10−9. LCC results reveal that the PMS-to-pulp board delivers the highest economic profit with $257.357, while the landfill is the lowest with $ − 35.63. The PMS paperboard technologies are more economically friendly than the incineration technologies due to additional electricity/steam consumption during the PMS pre-drying process in incineration. In addition, different scenarios were set up to explore national GHG emission reduction potential by increasing paperboard technologies application rate and reducing the proportion of landfill and incineration. The scenario analysis suggests that replacing 90% of landfill and incineration ratio with PMS paperboard technologies could tremendously improve the overall emission reduction performance with − 9.08 × 1010 kg CO2 eq. This result indicates that the PMS treatment technology transformation has a significant favorable impact on the achievement of the "carbon neutrality" target. [ABSTRACT FROM AUTHOR]

Atmospheric landfill gas emissions present serious problems when trying to counter the effects of global warming. The main constituent of landfill gas is methane, a more damaging greenhouse gas than CO2. European Union directives require the control and collection of landfill gases and promote energy recovery via combustion of the gas. A key challenge for combustion of landfill gas is the highly corrosive nature of the gas constituents which causes heightened maintenance and failure of applied engine systems. Conventional engines suffer from the effects of corrosion; however, stepped piston engine technology has yet to be considered for operational use at landfill sites. The engine has inherent advantages for such an application when compared with current conventional engines. The engine allows improved lubricating oil health compared to conventional engines and hence reduced oil use. This study discusses the challenges along with modelling of stepped piston and equivalent four-stroke engine solutions. [ABSTRACT FROM AUTHOR]

• VOCs components on the surface of large landfills were identified. • The NMHC of surrounding area was most affected by landfill in summer. • P + m-xylene was the key component that contributes to O 3 generation. • Ethylbenzenethe was the key component that contributes to SOA generation. Landfill disposal is a major approach of disposing municipal solid waste (MSW) in China. In order to explore the impact of volatile organic compounds (VOCs) generated by landfill on the air quality of regional environment, Jiangcungou landfill in Xi'an and its surrounding area were taken as a research object to analyze the spatial distribution and seasonal variation patterns of non-methane hydrocarbon (NMHC) and VOCs components through seasonal sampling of regional NMHC concentration and VOCs concentration (116 species). CALPUFF model was adopted to analyze the regional dispersion characteristics of NMHC on landfill. In addition, propylene equivalent concentration (PEC) and maximum incremental reactivity (MIR) methods were used to estimate O 3 formation potential of the landfill, while fraction aerosol coefficient (FAC) and SOA potential (SOAP) methods were used to estimate SOA formation potential of the landfill. It was indicated that, the component with the highest concentration of VOCs on the working surface and the surrounding area of landfill was p + m-xylene (41.0 μg/m3) and halohydrocarbon (111.2 μg/m3–156.3 μg/m3), respectively. The component with the greatest impact on the surrounding air was acetone, which accounts for 75 %–87 % of the corresponding substance concentration on the landfill. In summer, the surrounding area was affected most by NMHC from landfill, whose emissions contributed 9.5 mg/m3 to the surrounding area. The component making the largest contribution to O 3 formation was p + m-xylene (8 %–24 %), while ethylbenzene was the component making the largest contribution to SOA formation (20 %–24 %). [ABSTRACT FROM AUTHOR]

[Display omitted] • The void fraction (41.31%) formed by large-particle size gravel was rapidly reduced. • High rate of gas flow in the pipeline made landfill gas diluted rapidly. • A larger void fraction (44.62%) led to formation of a smaller anaerobic zone. The main disposal method for municipal solid waste (MSW), including the growing worldwide volumes of kitchen waste, involves transport to landfills. Because kitchen waste is mainly composed of organic matter and has a high moisture content, large amounts of leachate and landfill gas are generated when it is sent to landfills. Therefore, rapid waste stabilization is essential. In this study, four semi-aerobic bioreactors (named NS, SS, MS, and LS) were established with void fractions of 33.76%, 39.84%, 44.62%, and 41.31%, respectively. The results showed that the void fractions of landfill directly affected the gas flow path. When the landfill void fraction was small (e.g., NS), most airflow traveled directly through the pipeline and minimal airflow entered the waste layer. When the landfill void fraction was large (e.g., MS), air easily entered the waste layer and some air flowed into the gas vent with the landfill gas. As the reaction proceeded, the void fraction gradually decreased due to gravity-induced sedimentation. During the water addition experiment, the voids were occupied by water, leading to formation of an anaerobic area. Among the four bioreactors, only MS had negligible formation of an anaerobic zone in the center. Methane (CH 4) generation was detected only at the connection between the gas vent and the leachate collection pipe. A larger void fraction led to formation of a smaller anaerobic zone. The ratio of air flowing in pipeline was lowest in MS. These results indicated that a large void fraction promotes the decomposition of organic matter. [ABSTRACT FROM AUTHOR]

This research identifies the productivity of landfill gas actively captured at a municipal waste landfill site with a waste mass exceeding 1 million Mg from sectors in the operational and non-operational phases, considering meteorological conditions. Based on the analysis of landfill gas, including emissions and composition (CH4, CO2, O2, and other gases), the processes occurring demonstrate the impact of the decomposition of deposited waste on the activity of the deposit. With average monthly gas emissions exceeding 960,000 m3, the average content of CH4 (30–63%) and CO2 (18–42%) and the varied content of O2 (0.3–9.8%) in individual sectors of the landfill site were significant. The statistically significant relationship between CH4, CO2, and landfill gas emissions exhibited a noticeable decrease in methane content. Despite the abandonment of waste storage, a high correlation is present between the emission level and methane content (0.59) and carbon dioxide (0.50). In the operational part of the landfill, this relationship is also statistically significant but to a lesser extent; Spearman's R-value was 0.42 for methane and 0.36 for carbon dioxide. The operational and post-operational phases of the municipal waste landfill demonstrated a noticeable impact from the amount of precipitation, relative humidity, and air temperature, on landfill gas productivity. The generally progressive decline in the activity of the waste deposit, which reflects a decreasing trend in the methane content of approximately 2% annually in the total composition of landfill gas, as well as the share below 50%, indicates the need only to utilise landfill without producing energy. [ABSTRACT FROM AUTHOR]

Removing impurities that occur in landfill gas, from sulphur and silicon compounds, is crucial for the energetic use of biogas in a cogeneration unit for energy purposes. The aim of this study was to analyse the shaped activated carbon, examining its structure and elemental composition as part of the biogas purification. The qualitative study of the purified landfill gas performed in this study showed a significant overshoot of hydrogen sulphide at 304.1 ppm with respect to the gas engine manufacturer's requirements, while the calculated hydrogen sulphide reduction efficiency was 24.58%. Examination of the surface of the spent carbon and its pores with a scanning microscope revealed a high level of clotting by sulphur compounds, which prevents proper reduction of this compound and reduces the efficiency of the treatment plant. Replacement of the activated carbon bed with a new one showed a hydrogen sulphide value of 7.5 ppm in the purified gas and a calculated reduction efficiency of 97.9%. The results of the study confirmed that continuous monitoring of the quality of the purified gas is necessary to control the adsorption properties of the activated carbon and can be used for the operation of gas engines in cogeneration units. The landfill gas treatment method described in this paper constitutes an environmentally sustainable project within the meaning of the EU regulation on the establishment of a framework to promote and facilitate this type of investment in terms of its financing and operation. The topic of the work fits into three key areas of broad research and implementation activities. The first, technological, is the transition to a low-carbon, sustainable and resource-efficient closed-loop economy; the second, environmental, pollution prevention and control. The third area is economics and finance in terms of making financial products available designed to reduce climate change and reporting on these activities. [ABSTRACT FROM AUTHOR]

The study evaluates the generation and recovery capacity of methane at the Villavicencio Landfill in Colombia, using the LandGEM model. It shows a significant increase in methane generation, rising from about 1.5 million cubic meters in 2010 to over 8.5 million in 2020, indicating a growing urgency to implement effective mitigation measures. It was estimated that by the year 2042, the electrical energy production from methane could be 248.067 kW/day, capable of supplying about 43.705 homes monthly. Additionally, thermal energy generation would be 468.572 kWh/day, useful for industrial processes. Management scenarios were proposed, where, for example, operational optimization could increase electric production to 342.333 kW/day, benefiting more than 60.000 homes monthly. The conclusions highlight the direct correlation between the amount of waste and methane generation, and the significant potential for converting these emissions into energy, pointing towards regional energy self-sufficiency and sustainability. Methane recovery represents a valuable alternative to the dependence on fossil fuels and for the development of a circular economy. [ABSTRACT FROM AUTHOR]

The constant growth in global urban waste generation has led to an increasing need to address its management sustainably. Despite the proven effectiveness of converting this waste into energy in various countries, its implementation in Colombia is still in its early stages. In this study, a bibliometric analysis and systematic review of the literature was conducted to assess urban solid waste valorization technologies and their potential integration into biorefineries in the Colombian context. Among the identified technologies, incineration, gasification, pyrolysis, anaerobic digestion, and landfill gas recovery stand out. Anaerobic Digestion emerges as an attractive option due to its versatility. However, there is a recognized imperative to dynamically choose technologies, considering the diversity of contexts and specific conditions in Colombia. Additionally, gasification and pyrolysis appear as viable options, each with its own advantages and challenges, reflecting the complexity and variability in waste management. Concerning landfill gas recovery, its significance as an essential installation in controlled landfills is emphasized, dismissing its consideration as an independent alternative. While the literature suggests that incineration is perceived as less favorable in social, economic, and environmental terms, it is crucial to recognize the dynamics and specificity of each situation. The choice of technologies must be adaptive and guided by a contextual approach that considers the heterogeneity in waste composition, available infrastructure, and other factors that vary significantly from one scenario to another. This dynamic and adaptive approach is essential to address the complexity of urban waste management and find sustainable solutions in the Colombian context. [ABSTRACT FROM AUTHOR]

This article presents a methodology for evaluating the susceptibility of landfill areas to develop landslides by analyzing Synthetic Aperture Radar (SAR) satellite products. The deformation velocity of the landfills is computed through the Persistent Scatterer Method on SAR imagery. These data, combined with a deformation model based on the shallow water equations (SWE), form the foundation for a Monte Carlo experiment that extrapolates the current state of the landfill into the future. The results of this simulation are then employed to determine the probability of a landslide occurrence. In order to validate the methodology effectiveness, a case study is conducted on a landfill in Zaldibar, Spain, revealing its effectiveness in estimating the probability of landfill landslides. This innovative approach emerges as an asset in large landfill management, acting as a proactive tool for identifying high-risk sites and preventing potential landslides, ultimately safeguarding human life and the environment. By providing insights into landslide probabilities, this study enhances decision-making processes and facilitates the development of intervention strategies in the domain of landfill risk assessment and management. [ABSTRACT FROM AUTHOR]

Landfill leachate contains a significant amount of organic matter, making it a valuable source for CH4 production. However, due to its liquid form, the mono-digestion of leachate could result in a reduced CH4 yield per unit reactor volume. This necessitates its utilization in anaerobic digesters alongside solid waste streams. The objective of this study was to evaluate co-digestion performance of landfill leachate with different wastes using biomethane potential test and assess the optimum combination in terms of CH4 productivity. Modified Gompertz model was used for kinetic characterization. Experiments were held under mesophilic conditions and lasted for 30 days. Among mono-digestion of substrates, landfill leachate exhibited the highest CH4 productivity and yield: 83.17 mL/gVS.d and 793 ± 6.85 mL/gVS, respectively. Fish waste was found to have the lowest energy potential with 350 mL/gVS CH4 yield and 18.24 mL/gVS.d CH4 productivity. CH4 productivities for co-digestion cases ranged from 5.48 to 67.85 mL/gVS.d. Mixing landfill leachate and chicken manure with the same amount on wet weight basis yielded the highest CH4 productivity. On the other hand, inclusion of fish waste consistently resulted in decreased CH4 yield and productivity for all incubations, which suggests that fish waste may not be suitable as a co-substrate for landfill leachate in terms of CH4 production. Monitoring of chemical parameters revealed that buffering capacity of the system and free ammonia formation were the main parameters governing CH4 production. [ABSTRACT FROM AUTHOR]

Modeling with LandGEM offers a large field to quantify emissions from the decomposition of organic waste, consequently prediction of energy generated from gas emissions especially those of methane. Where, the simulation results makes it possible to define the reasons of malfunction concluded by comparing between the LandGEM simulation and the experimental methodology for estimation of methane gas emissions, whose offer a huge knowing, accuracy assessment, and detailed analysis to landfill site state in terms of the production of methane, the tightness, the progress of the anaerobic degradation, the existence of sulfur compound. This study accomplished in site the methane production at 80%, a tightness of 84% compared to the 100% given by LandGEM, and an hydrogen sulfide content which far exceed the recommended limit, cause of corrosion attacking especially the biogas compressor which provoke a complete shutdown to product the electrical energy. Unlike the LandGEM digital model, whose site must produce 3, 145.107 m³ of methane with 100% site tightness, a hydrogen sulfide content equivalent to 40 ppm, for a production of electrical energy equivalent to 10, 941.107 kWh according to the year 2022. To optimizing landfill gas performance, we forecast the installation of automatic analyzer sensors to anticipate of an alert for intervention, generated by accidental loss of methane in the air, infiltration of oxygen inside the lockers, disruption of the stability of the fermentation process, or existence of high sulfur contents in organic matter. [ABSTRACT FROM AUTHOR]

Open dump landfills are recognised as potential sources of heavy metal (HM) contamination. Their migration to the wider environment is largely controlled by their speciation; and in this study, results from sequential extraction, pH values and organic matter contents in soils around an open dump landfill and sediments in a leachate collection ditch were investigated in order to study the attenuation processes that lead to a decrease in HM mobility. The results revealed that Cu and Zn leached from the landfill were largely retained by sediments in the collection ditch and mostly bound to organic fraction. A simple mass balance suggested that, in comparison to other sources, HM accumulation in soils that resulted from the landfill was relatively low for Cu and relatively high for Zn. The concentrations observed were within safe limits according to the Thai standard for non-residential soil. This study showed that a leachate collection ditch plays an important role in minimising HM migration. Monitoring and further studies on fate and migration pathways of pollutants from open dump landfills, in particular to those underlain by different geologic settings to our study are needed to develop cost-effective measures to prevent/minimise the effect of landfill leachate and ensure that the environment surrounding landfill sites is safe. [ABSTRACT FROM AUTHOR]

Landfill leachate forms when waste-inherent water and percolated rainfall transfer are highly toxic, corrosive, acidic, and full of environmental pollutants. The release of leachate from municipal solid waste (MSW) landfill sites poses a severe hazard to human health and aquatic life. This study examined the impact of leachate from Delhi's Ghazipur landfill on the nearby groundwater quality. Analysis of leachate samples was done to determine various parameters such as total dissolved solids (TDS), hardness, alkalinity, electrical conductivity, pH, BOD5, COD, nitrate, sulphate, chloride and iron, and presence of coliform bacteria. Significant dissolved elements (22,690–34,525 mg/L) were observed in the samples, indicated by the high conductivity value (1156–1405 mho/cm). However, a stable pH range (6.90–7.80) of leachate samples was observed due to high alkalinity concentrations between 2123 and 3256 mg/L. The inverse distance weighing (IDW) interpolation tool from QGIS 3.22.7 developed spatial interpolated models for each parameter across the Ghazipur area. The IDW interpolated graphs of various parameters over the whole study area confirmed these contaminations. In addition, leachate and groundwater samples were physio-chemically analyzed, and temporal fluctuation in landfill waste has also been studied. The temporal fluctuation results showed that when heat is produced, transmitted, and lost throughout the waste system, the maximum temperature position fluctuates over time. The findings of this study highlight the critical importance of landfill management in reducing groundwater contamination from MSW leachate. [ABSTRACT FROM AUTHOR]

We quantify 2019 annual mean methane emissions in the contiguous US (CONUS) at 0.25° × 0.3125° resolution by inverse analysis of atmospheric methane columns measured by the Tropospheric Monitoring Instrument (TROPOMI). A gridded version of the US Environmental Protection Agency (EPA) Greenhouse Gas Emissions Inventory (GHGI) serves as the basis for the prior estimate for the inversion. We optimize emissions and quantify observing system information content for an eight-member inversion ensemble through analytical minimization of a Bayesian cost function. We achieve high resolution with a reduced-rank characterization of the observing system that optimally preserves information content. Our optimal (posterior) estimate of anthropogenic emissions in CONUS is 30.9 (30.0–31.8) Tg a -1 , where the values in parentheses give the spread of the ensemble. This is a 13 % increase from the 2023 GHGI estimate for CONUS in 2019. We find emissions for livestock of 10.4 (10.0–10.7) Tg a -1 , for oil and gas of 10.4 (10.1–10.7) Tg a -1 , for coal of 1.5 (1.2–1.9) Tg a -1 , for landfills of 6.9 (6.4–7.5) Tg a -1 , for wastewater of 0.6 (0.5–0.7), and for other anthropogenic sources of 1.1 (1.0–1.2) Tg a -1. The largest increase relative to the GHGI occurs for landfills (51 %), with smaller increases for oil and gas (12 %) and livestock (11 %). These three sectors are responsible for 89 % of posterior anthropogenic emissions in CONUS. The largest decrease (28 %) is for coal. We exploit the high resolution of our inversion to quantify emissions from 70 individual landfills, where we find emissions are on median 77 % larger than the values reported to the EPA's Greenhouse Gas Reporting Program (GHGRP), a key data source for the GHGI. We attribute this underestimate to overestimated recovery efficiencies at landfill gas facilities and to under-accounting of site-specific operational changes and leaks. We also quantify emissions for the 48 individual states in CONUS, which we compare to the GHGI's new state-level inventories and to independent state-produced inventories. Our posterior emissions are on average 27 % larger than the GHGI in the largest 10 methane-producing states, with the biggest upward adjustments in states with large oil and gas emissions, including Texas, New Mexico, Louisiana, and Oklahoma. We also calculate emissions for 95 geographically diverse urban areas in CONUS. Emissions for these urban areas total 6.0 (5.4–6.7) Tg a -1 and are on average 39 (27–52) % larger than a gridded version of the 2023 GHGI, which we attribute to underestimated landfill and gas distribution emissions. [ABSTRACT FROM AUTHOR]

Solid waste has surfaced as an eminent and critical concern of environmental and social significance on a global scale, and Ethiopia, a developing country with limited income, has also encountered unfavorable outcomes due to substandard waste management practices. When pinpointing a fitting landfill location in the town of Bule Hora, various ecological, economic, and societal aspects must be considered; these may result in discord and exacerbate a multifaceted and lengthy process. Hence, this research aims to identify prospective landfill sites within the town and utilize geospatial methods, such as Multi-Criteria Evaluation and Analytic Hierarchy Process, to accomplish its objectives. The utilization of geospatial technology and multi-criteria evaluation provides an efficient manner to simultaneously address all bottlenecks involved in the selection of an appropriate landfill location. Geospatial technology evaluates and manages environmental constraints, whereas multi-criteria assessment categorizes choices based on their desirability. Furthermore, by employing a restriction map adhering to established standards, seven landfill sites have successfully been identified within the town. The Land Suitability Index assesses site suitability based on ecological factors, while the Total Hauling Distance evaluates sites within an economic framework. AHP determines weightings through 25.4 pairwise comparisons, resulting in a consistency ratio of 1.95%. The cartographic analysis is conducted using ESRI ArcGIS version 10.8 software. The findings of this study reveal that 98.69% of the area under study is subject to restrictions. The study recommends the implementation of geospatial methods for identifying suitable landfill sites, which would aid in the decision-making process and prevent hasty decisions from triggering environmental degradation. Proper waste disposal would augment the quality of life for residents by diminishing health hazards. The study endeavors to serve as a reference for other developing countries in selecting appropriate landfill sites. Implications: The town of Bule Hora also faces the problem of waste disposal; there is no scientifically selected suitable landfill. Residents of the town of Bule Hora practice waste disposal in open fields, near settlements, water bodies, roads, agricultural land, and other places. The main sources of solid waste in the town are homes, shops, hotels, restaurants, open markets, hospitals, educational institutions, private clinics, etc. Water pollution can potentially lead to the spread of waterborne diseases. According to reports from the Bule Horas Health Department, many people are affected by water-related diseases every year. These open landfill systems with no regard for settlement, topography, geology, surface, or groundwater conditions are the consequences of these unsuitable habitats and health problems. To reduce these problems, this study plays an important role in determining the suitability of landfills for the town and proposing alternative measures that can minimize negative environmental impacts from waste. This study aims to apply geospatial-based technology to a multi-criteria assessment technique to select perfectly suitable landfill sites that are environmentally friendly, economically cost-effective, and socially responsible; examine the town's current waste management system; calculate the selected parameter weights for feature ranking; and delineate solid waste landfills. [ABSTRACT FROM AUTHOR]

The energy potential of municipal solid waste landfills receded into the background compared to more traditional sources of energy. Such possibilities as landfill degassing, as well as extraction of thermal energy from the depths of landfills, were little-researched, due to being kind of risky phenomena for their wide application. Currently, the energy system of Ukraine is under the risk as due to the military actions - objects of critical energy infrastructure have become the easy targets for the enemy. About 53 mln m3 of household waste were generated in Ukraine in 2021. Over 10 mln tons were buried at 6000 of landfills, total area of which accounts for 9000 hectares. The energy potential of these waste was used ineffective. Only 28 landfills of total have the degassing system established. The case of using landfill gas as an energy source lies between such challenges: the increasing amount of MSW, proper waste management and the energy crisis in Ukraine caused by the shellings. Landfill spreading throughout the country makes it possible to operate safely and reduce the risk of bringing any significant damage to such infrastructure. The study was focused on the Sumy City landfill, the potential of which is estimated as 36397 m3/t of solid waste. The degassing system was designed based on the methodology of State building regulations of Ukraine. Analysis of the efficiency of the system was done, including the potential energy output as a result of operation of such a system which comes paramount in dealing with the imperative of soaring amount of MSW, reducing greenhouse gas emissions and producing green, cheap energy. The negative impact of MSW landfills on the environment is beyond all dispute so it is crucial that their potential be used at full capacity. [ABSTRACT FROM AUTHOR]

This study presents a methodology to determine the appropriate location for effluent disposal in a low-flow river using numerical modelling, via a case study of a river located in Southern Brazil, considering disposal of landfill leachate with known characteristics. There are four key steps: 1) a principal component analysis (PCA) for a set of representative parameters; 2) a decision flowchart for proper water quality models; 3) a modified Water Quality Index (WQI) using the resulting concentrations and 4) simulation on 1D and 2D models and WQI calculation and evaluation. The PCA highlights eight relevant parameters: ammonia (NH3), chloride (Cl−), biochemical oxygen demand (BOD), total phosp horus, nitrite (NO2−), nitrate (NO3−), dissolved oxygen (DO) and total dissolved solids. Two models were considered suitable: HEC-RAS (1D) and SisBaHiA (2DH). After simulating the parameters in both models, a WQI was calculated for each location. Both HEC-RAS and SisBaHiA lead to the same effluent outfall location, showing that spatial discretisation does not affect the results. [ABSTRACT FROM AUTHOR]

Landfills are associated with significant environmental problems that pose serious concerns to the environment due to the continuous emission of methane and other greenhouse gases. This study uses the ZODM, FODM, MTM, and six simulations in the LandGEM-V-3.03 model to estimate and predict the methane emissions from the Rajbandh landfill in Khulna city. The predicted average emissions from 2000 to 2036 demonstrate remarkably close emissions (2.14–2.97 Gg/year) from FODM, MTM, and three LandGEM-V-3.03 simulations (site-specific SP, CAAA, and IC). This study compares the output and underlying assumptions of each model and suggests the FODM and LandGEM SP simulations can be suitable for estimating methane emissions in the conditions of Khulna. In addition, this study also investigated the feasibility of electricity generation using emitted methane at the landfill site. It reveals that the Rajbandh landfill holds the economically viable potential to establish a 1 MW power plant without subsidy. The total environmental lifetime benefits from this electricity generation project are estimated to reduce 0.563 MMTCO2-eq emissions. The outcome of this study may apply to other Bangladeshi landfills and improve waste management planning and energy security. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: The utilization of stabilization pond system for landfill leachate treatment is hindered by its requirement for expansive land areas and extended retention periods. Although the system effectively removes organic compounds, its ability to eliminate nutrients such as nitrogen and phosphorus is comparatively limited. Consequently, the leachate subjected to treatment often falls short of meeting the mandated standards for effluent quality. In response to this challenge, a research study was undertaken to investigate the potential of utilizing a consortium comprising microalgae and bacteria in the treatment of landfill leachate. METHODS: The microalgae, bacteria, and leachate utilized in this study were sourced from a leachate treatment facility located at the Aceh regional domestic waste management unit in Blang Bintang, Aceh Besar, Indonesia. The two glass photobioreactors were operated batchwise, where the first was provided with a combination of air and carbon dioxide, and the other was solely exposed to air. The pollutant removal efficacy in the leachate effluent was assessed through the measurements of chemical oxygen demand, ammonia, nitrate, nitrite, and phosphate concentrations. Subsequently, macroscopic identification of microalgae and bacteria species was also conducted. FINDINGS: Utilizing a consortium of microalgae and bacteria has demonstrated efficacy in treating leachate, resulting in a notable reduction of contaminants within the effluent. The symbiotic association between microalgae and bacteria in the context of leachate waste treatment is evident. The bacteria's metabolic actions result in carbon dioxide emission, which subsequently serves as a substrate for the photosynthetic activities of the microalgae. The microalgae facilitate the transfer of oxygen, produced through photosynthesis, to the bacteria to support their metabolic processes. Therefore, introducing exogenous carbon dioxide to the consortium yields minimal discernible effects, given that the bacteria adequately fulfill the carbon dioxide requirements of the microalgae. This discovery enhances the efficacy of leachate treatment techniques by leveraging the utilization of pre-existing mixed cultures of microalgae and bacteria found in leachate facilities. CONCLUSION: This study evaluated the microalgae-bacteria consortium's effectiveness in reducing leachate pollutants. The consortium exhibited a significant capability, achieving a 75 percent reduction in chemical oxygen demand and successfully eliminating a range of contaminants. Additionally, it demonstrated effective removal of nitrogen compounds such as ammonia, nitrate, and nitrite, with removal rates reaching 75 percent. Notably, the consortium showed a 99 percent removal rate for phosphate compounds. Even with the introduction of carbon dioxide, the pollutant removal remained consistently high, suggesting that the addition of carbon dioxide did not significantly influence the overall process. [ABSTRACT FROM AUTHOR]

A significant quantity of biologically produced sulfur (BPS) is generated as a by-product of chemical and biological desulfurization processes applied to landfill gas treatment. The beneficial upcycling of BPS has seen limited use in the environmental context. The effectiveness and underlying mechanism of BPS as an adsorbent for removing Hg2+ from both solution and wastewater were elucidated based on experiments encompassing surface characterization, adsorption isotherms, kinetics, and thermodynamics. The BPS exhibited remarkable efficacy in removing Hg2+ from solution, with the Langmuir model accurately describing the adsorption process and showing a maximum adsorption capacity of 244 mg g−1. Surface analysis through X-ray photoelectron spectroscopy and scanning electron microscopy revealed that Hg2+ complexed with sulfide on BPS surfaces, forming stable HgS. The adsorbed Hg was strongly retained in BPS, with less than 0.2% of the adsorbed Hg desorbed by strong acids. Adsorption kinetics followed the double-exponential first-order model, showing an initial rapid adsorption phase wherein 75% of the initial Hg2+ was removed within 5 min, followed by a slower adsorption rate. The thermodynamic parameters suggested that adsorption of Hg2+ by BPS was a spontaneous and endothermic process. Additionally, BPS effectively removed Hg2+ from wastewater, showing preference for Hg over other co-existing metals. These findings underscore the potential of BPS as an effective adsorbent for Hg2+ removal from wastewater. [ABSTRACT FROM AUTHOR]

Methane emissions from solid waste may represent a substantial fraction of the global anthropogenic budget, but few comprehensive studies exist to assess inventory assumptions. We quantified emissions at hundreds of large landfills across 18 states in the United States between 2016 and 2022 using airborne imaging spectrometers. Spanning 20% of open United States landfills, this represents the most systematic measurement-based study of methane point sources of the waste sector. We detected significant point source emissions at a majority (52%) of these sites, many with emissions persisting over multiple revisits (weeks to years). We compared these against independent contemporaneous in situ airborne observations at 15 landfills and established good agreement. Our findings indicate a need for long-term, synoptic-scale monitoring of landfill emissions in the context of climate change mitigation policy. [ABSTRACT FROM AUTHOR]

• Sustainable methane obtained by injection of liquified kitchen and food waste. • Ammonia gas emissions occurred mainly in rapid methane production phase. • Hydrogen sulfide gas emissions occurred in rapid and post-methane production phases. • Organic carbon in leachate decreased as injection round increased. • Salinity decreased during rapid methane production phase but increased thereafter. With continuous advancements in the zero-waste strategy in China, transportation of fresh municipal solid waste to landfills has ceased in most first-tier cities. Consequently, the production of landfill gas has sharply declined because the supply of organic matter has decreased, rendering power generation facilities idle. However, by incorporating liquefied kitchen and food waste (LKFW), sustainable methane production can be achieved while consuming organic wastewater. In this study, LKFW and water (as a control group) were periodically injected into high and low organic wastes, respectively. The biochemical characteristics of the resulting gas and leachate were analyzed. LKFW used in this research generated 19.5–37.6 L of methane per liter in the post-methane production phase, highlighting the effectiveness of LKFW injection in enhancing the methane-producing capacity of the system. The release of H 2 S was prominent during both the rapid and post-methane production phases, whereas that of NH 3 was prominent in the post-methane production phase. As injection continued, the concentrations of chemical oxygen demand, 5-d biological oxygen demand, total organic carbon, ammonia nitrogen, total nitrogen, and oil in the output leachate decreased and eventually reached levels comparable to those in the water injection cases. After nine rounds of injections, the biologically degradable matter of the two LKFW-injected wastes decreased by 8.2 % and 15.1 %, respectively. This study sheds light on determining the organic load, controlling odor, and assessing the biochemical characteristics of leachate during LKFW injection. [ABSTRACT FROM AUTHOR]

• Collection efficiency estimates are necessary for accurate emissions modeling. • Measured collection efficiency data categorized and compared with current defaults. • Cover type was statistically significant indicator of collection efficiency. • Results: 41% efficiency for daily cover, 69 % for intermediate, and 71 % for final. • New defaults greatly reduce discrepancy between modeled and measured estimates. Landfill methane emissions are commonly estimated using cover-type dependent default collection efficiency values, with a first-order decay model or measured gas collection. Current default collection efficiencies used in the United States were predominately derived from 4 studies conducted during or prior to 2007 that relied on flux chambers. Flux chambers are limited by small sample sizes, placement restrictions, and the inability to measure emissions from gas or leachate collection systems. Since 2007, over 14 new studies have been completed using more advanced technologies that allow for direct measurement of methane plumes from most or all of a landfill's surface. On average, these measurements are 2–3 times greater than emissions predicted by current models and collection efficiency defaults. In lieu of measuring emissions from all landfills, updating collection efficiency defaults can bring modeled emissions into better alignment with measurements. To this end, collection efficiency estimates derived from measured data were categorized into cover types and then adjusted to account for cases where whole plume measurement was an amalgamation of multiple cover types. The resultant adjusted default values were 41% for daily cover, 69% for intermediate cover, and 71% for final cover. Direct measurement of landfill methane emissions is preferrable to account for the full range of variables driving landfill emissions, including collection system design and operation. However, applying these updated defaults back into the landfill emission models eliminates underprediction of landfill emissions for the dataset reviewed, and would provide a more accurate estimate of landfill gas emissions where measurements are unavailable. [ABSTRACT FROM AUTHOR]

Currently, due to the insufficient resources of renewable natural gas, the development of renewable pathways to integrate into the natural gas-industry portfolio can reduce many concerns about the reserves depletion and the environmental crises. In the present article a structure-oriented framework for gas networks is developed to compare and prioritize different investment scenarios for renewable natural gas production projects. In this regard, different pathways to produce renewable natural gas through the waste-to-natural gas process were discussed and compared based on different waste feedstocks. To discuss and compare different pathways, a decision-making structure and framework under life cycle cost analysis (LCCA) and life cycle environmental analysis (LCEA) is employed to choose the appropriate pathway for the waste-to-natural gas process. The optimal pathway is identified through different multi-variable decision-making scenarios (under different geographical conditions, access to different feedstocks, and different interests of stakeholders). From the outcomes, under the neutral and Pro-economic scenarios, the renewable natural gas production pathway driven by landfill gas integrated with the pressure swing adsorption- biogas upgrading unit is the optimal and desirable option. While under an Eco-friendly scenario, the pathway driven by animal manure integrated with the pressure swing adsorption-upgrading unit is an optimal and desirable pathway. [Display omitted] [ABSTRACT FROM AUTHOR]

A two-phase liquid/gas flow numerical model has been used to investigate the presence of elevated pore water pressures in a 20-m-deep municipal solid wastes (MSW) landfill underlain by a fully drained leachate collection layer. Monitoring of leachate levels in the landfill using piezometers located at different discrete levels found water table type conditions to within 10 m of the surface and established a downward hydraulic gradient at an infiltration rate of ∼400 mm/year. Short-duration falling-head piezometer tests indicated landfill hydraulic conductivities (Kh) between 1×10−4 and 1×10−5 m/s , with a general reduction in K with depth. Several different hypotheses to explain the high pore water pressures in the landfill were investigated using a one-dimensional configuration of the landfill degradation and transport model LDAT. It was assumed that the unsaturated properties of the landfilled wastes can be bounded by two sets of van Genuchten parameters. Comparing the values of Kv required to create a match between observed and modeled leachate heads with the measured Kh values at the site led to a tentative conclusion that landfill-scale anisotropy could be as high as ∼1∶1,000. The introduction of a distributed landfill gas (LFG) source term into LDAT at a rate of 0.61 mLFG3 tw−1 year−1 , similar to the gassing rate at the site, increased the adopted saturated permeability relationship in LDAT by a factor of between ∼3 and ∼7.5 compared with a no-gassing scenario. Introducing even moderate gas generation rates (5.6 mLFG3 tw−1 year−1) into models simulating low infiltration rates of 50 mm/year can result in a significant depth of waste where pore water pressures are more than 1 kPa (10-cm water head). This results in apparent below-water-table type conditions because water will enter piezometers installed into such wastes, even though the gassing reduces the degree of saturation to below one. [ABSTRACT FROM AUTHOR]

The world is currently facing significant environmental challenges due to increasing urbanization and globalization. Human activities can produce greenhouse gases (GHGs) such as CO2 and CH4. One of the contributors to GHG generation is the open dumping of Municipal Solid Waste (MSW), particularly because much of the waste is organic. It undergoes anaerobic decomposition, leading to the formation of GHGs, particularly methane. However, CH4 has a high potential for energy generation, and if harnessed properly, it can be highly beneficial. This study aims to assess the total air pollutants emitted from the landfill gas (LFG), including methane (CH4), carbon dioxide (CO2), and nonmethane organic compounds (NMOC) at the Regional Piyungan landfill in D.I. Yogyakarta province. The study also projected the year when the production of these gaseous pollutants would peak and when they are expected to be exhausted. Additionally, the study aimed to identify the potential health problems and clinical codification caused by these gaseous pollutants. To achieve these objectives, the LandGEM 3.03 version of the model developed by USEPA was used for the period 2023-2071. Clinical coding used the 2019 version of the ICD-10 reference. The estimated values for total LFG were 1.648E+04 (2024) and 1.584E+04 (2025) Mg/year, while CH4 was estimated at 4.403E+03 (2024) and 4.230E+03 (2025) Mg/year. CO2 was estimated to be 1,208E+04 (2024) and 1,161E+04 (2025) Mg/year, and NMOC was projected at 2,839E+01 (2024) and 2,727E+01 (2025) Mg/year. Some of the toxic effects that can occur cause respiratory, visual, and mental disorders with a variety of clinical codes. [ABSTRACT FROM AUTHOR]