Active Landfill Research Articles

Enhancing the performance of biofilters with sorption ability for simultaneous purification of landfill gases using laterite soil-based substrate

Various harmful gas emissions are a major controversial issue globally, and open dumpsites have become a leading contributor to atmospheric pollution. The study aims to introduce a high-performance landfill gas purification substrate using laterite soil, an iron, and aluminum-rich, highly available soil type in tropical countries; the final suggested substrate contained uniformly mixed laterite soil and compost with a 4:1 fraction by volume. A self-design setup that can maintain moisture content and aerobic conditions was used with an active landfill gas collection system through the gas wells established on the Karadiyana landfill in Sri Lanka under a tropical climate. The elimination capacity of CH4, NH3, VOCs, and H2S were 202860 ± 51595, 91 ± 30, 75 ± 27, and 6 ± 3 mg m−3 h−1 with 91 ± 3, 96 ± 1, 93 ± 3 and 83 ± 4% of removal efficiencies respectively at a 9.4 min empty bed residence time (EBRT). Selected laterite soil acts as an adsorption material and provides a better bio-filtering substrate with compost due to its specific characteristics. The hybrid gas purification process, absorption, and biofiltration within the proposed material were the reasons for higher performance, and the setup may be successful under the industrial waste gas streams. Further investigation should be carried out to study the medium's effectiveness as the covering layer on the dump with the successful lowest thickness, regarding secondary pollutants, and industrial applicability under unique specific conditions.

Detection and long-term quantification of methane emissions from an active landfill

Abstract. Landfills are a significant source of fugitive methane (CH4) emissions, which should be precisely and regularly monitored to reduce and mitigate net greenhouse gas emissions. In this study, we present long-term, in situ, near-surface, mobile atmospheric CH4 mole fraction measurements (complemented by meteorological measurements from a fixed station) from 21 campaigns that cover approximately 4 years from September 2016 to December 2020. These campaigns were utilized to regularly quantify the total CH4 emissions from an active landfill in France. We use a simple atmospheric inversion approach based on a Gaussian plume dispersion model to derive CH4 emissions. Together with the measurements near the soil surface, mainly dedicated to the identification of sources within the landfill, measurements of CH4 made on the landfill perimeter (near-field) helped us to identify the main emission areas and to provide some qualitative insights about the rank of their contributions to total emissions from the landfill. The two main area sources correspond, respectively, to a covered waste sector with infrastructure with sporadic leakages (such as wells, tanks, pipes, etc.) and to the last active sector receiving waste during most of the measurement campaigns. However, we hardly managed to extract a signal representative of the overall landfill emissions from the near-field measurements, which limited our ability to derive robust estimates of the emissions when assimilating them in the atmospheric inversions. The analysis shows that the inversions based on the measurements from a remote road further away from the landfill (far-field) yielded reliable estimates of the total emissions but provided less information on the spatial variability of emissions within the landfill. This demonstrates the complementarity between the near- and far-field measurements. According to these inversions, the total CH4 emissions have a large temporal variability and range from ∼ 0.4 to ∼ 7 t CH4 d−1, with an average value of ∼ 2.1 t CH4 d−1. We find a weak negative correlation between these estimates of the CH4 emissions and atmospheric pressure for the active landfill. However, this weak emission–pressure relationship is based on a relatively small sample of reliable emission estimates with large sampling gaps. More frequent robust estimations are required to better understand this relationship for an active landfill.

Microplastic pollution from active and inactive landfill in Indonesia: Case study in Leuwigajah and Sarimukti Landfill

A landfill is the most common waste disposal in Indonesia, yet the implementation and operation of landfills are still far from optimal due to lack of funding and management failure. Moreover, landfill was operated as unmanaged open dumps. This situation could enhance the likelihood of plastics pollution through various transport of plastic waste from landfill sites, including microplastics release from leachate. This study was focused on the evidence of microplastic pollution originating from the landfill. Leachate sampling was conducted at two landfills, an inactive landfill called Leuwigajah Landfill, and an active landfill called Sarimukti Landfill. The characteristics of microplastics were analyzed through visual examination, particle density examination, and polymer investigation utilizing Fourier Transform Infrared Spectroscopy (FTIR). All three samples of active and inactive landfill leachate contains microplastic particles. The concentration ranges from 12.00 ± 5.29 to 56.33 ± 3.06 particles/liter. The most dominant polymers of plastic are Polypropylene (PP) and Polyester. Fiber shape is the highest percentage of founded microplastics. The results show the critical information of landfill likelihood as a source of microplastics.

Evaluating the performance of thermomechanically beneficiated fly ash blended mortar

This study explores the performance of beneficiated and reclaimed landfilled fly ashes (LFA) from three active landfills in Wyoming and Colorado. The LFAs that did not meet the physiochemical requirements of ASTM C618 underwent thermal and mechanical beneficiation processes to increase their fineness and reduce their carbon content. Subsequently, the performance of mortar samples incorporating these LFAs was thoroughly assessed in terms of compressive strength, electrical resistivity, resistance against alkali-silica reaction-induced expansion, water absorption, and chloride permeation. The results demonstrated that the beneficiation processes employed effectively improved the properties of the off-spec ashes, leading to all of the beneficiated ashes meeting the requirements set by ASTM C618. In most cases, the mortar specimens containing beneficated LFA exhibited comparable or even superior mechanical and durability performance compared to those containing ASTM C618-compliant fly ash. These findings highlight the potential of beneficiated LFAs as viable alternatives in concrete production, particularly in the face of the anticipated fly ash scarcity in the US and worldwide.

Advanced IoT Pressure Monitoring System for Real-Time Landfill Gas Management.

This research presents a novel stand-alone device for the autonomous measurement of gas pressure levels on an active landfill site, which enables the real-time monitoring of gas dynamics and supports the early detection of critical events. The developed device employs advanced sensing technologies and wireless communication capabilities, enabling remote data transmission and access via the Internet. Through extensive field experiments, we demonstrate the high sampling rate of the device and its ability to detect significant events related to gas generation dynamics in landfills, such as flare shutdowns or blockages that could lead to hazardous conditions. The validation of the device's performance against a high-end analytical system provides further evidence of its reliability and accuracy. The developed technology herein offers a cost-effective and scalable solution for environmental landfill gas monitoring and management. We expect that this research will contribute to the advancement of environmental monitoring technologies and facilitate better decision-making processes for sustainable waste management.

Reconciling a national methane emission inventory with in-situ measurements

Reconciling top-down and bottom-up country-level greenhouse gas emission estimates remains a key challenge in the MRV (Monitoring, Reporting, Verification) paradigm. Here we propose to independently quantify cumulative emissions from a significant number of methane (CH4) emitters at national level and derive robust constraints for the national inventory. Methane emissions in Cyprus, an insular country, stem primarily from waste and agricultural activities. We performed 24 intensive survey days of mobile measurements of CH4 from October 2020 to September 2021 at emission ‘hotspots’ in Cyprus accounting together for about 28 % of national CH4 emissions. The surveyed areas include a large active landfill (Koshi, 8 % of total emissions), a large closed landfill (Kotsiatis, 18 %), and a concentrated cattle farm area (Aradippou, 2 %). Emission rates for each site were estimated using repeated downwind transects and a Gaussian plume dispersion model. The calculated methane emissions from landfills of Koshi and Kotsiatis (25.9 ± 6.4 Gg yr−1) and enteric fermentation of cattle (10.4 ± 4.4 Gg yr−1) were about 129 % and 40 % larger, respectively than the bottom-up sectorial annual estimates used in the national UNFCCC inventory. The parametrization of the Gaussian plume model dominates the uncertainty in our method, with a typical 21 % uncertainty. Seasonal variations have little influence on the results. We show that using an ensemble of in situ measurements targeting representative methane emission hotspots with consistent temporal and spatial coverage can contribute to the monitoring and validation of national bottom-up emission inventories.

Considerations on the methane correction factor and fraction of methane parameters in the IPCC first-order decay model for active aeration landfills

Understanding the behavior of organic carbon in municipal solid waste landfills is a major challenge for estimating methane (CH4) emissions using the Intergovernmental Panel on Climate Change (IPCC) first-order decay (FOD) model. According to the IPCC guidelines, the default values of CH4 correction factor (MCF) and fraction of CH4 (F) for active aeration landfills are set as 0.4 and 0.5, respectively. However, whether it is reasonable to apply the default values of MCF and F to active aeration landfills is questionable. This study aims to estimate the MCF and develop a method to determine the F value for active aeration landfills. In this investigation, three landfill sites were operated as active aeration landfills to estimate the MCF and the F. The study results indicate that MCF values were lower than the default value of 0.4 provided in the IPCC guidelines under aerobic conditions with a CH4 concentration of less than 5%. According to the carbon balance analyses, there was a mismatch between the theoretical CH4/CO2 ratio based on the F default value of 0.5 and the measured CH4/CO2 ratio. Using the F calculation method proposed in this study, the theoretical CH4/CO2 ratio and the measured CH4/CO2 ratio was calculated equally. The F values during air injection ranged from 0.25 to 0.93 at three landfill sites, suggesting that adapting the F default value of 0.5 for active aeration landfills may lead to significant errors in the estimation of CH4 emissions using the IPCC FOD model.

Assessing moisture contributions from precipitation, waste, and leachate for active municipal solid waste landfills

Precipitation, evapotranspiration (ET), waste tonnage, landfill gas (LFG), and leachate data were aggregated from public sources to perform a 5–10 year water balance and estimate the contributions of three water sources (precipitation, incoming waste, and leachate recycling) for 36 active municipal solid waste (MSW) landfills in Ohio, USA. Uniquely, the water balance incorporated waste decomposition, using gas collection data to inform mass loss from biodegradation. Moisture contents of 20–30% for incoming waste indicate that entrained water is the largest source of landfill moisture. Infiltration of precipitation into the landfill after ET was the second largest source. Even at facilities where a majority of the leachate generated was recirculated, it did not significantly affect the moisture content in that year. Using the water balance approach, it appears leachate recirculation is unlikely to increase moisture content above 40% by mass, a regulatory threshold in the US, which would impose stricter air pollution control requirements. However, poor stormwater management could easily allow for “bioreactor” conditions to develop. The calculated landfill moisture content was significantly affected by the assumed runoff coefficient (CRO) parameter. CRO values below 20% and above 50% produced unrealistically high or low moisture contents, respectively. This approach can assist operators and regulators in understanding the contribution of different sources to a landfill's moisture profile and avoid future operational problems.

Breakthrough times for barrier systems at typical municipal solid waste landfills in China.

Landfill is the most common disposal method for municipal solid waste (MSW). Composite liners are widely used as bottom barriers in MSW landfills in China to minimize groundwater contamination with landfill leachate. However, little information is available on breakthrough times for bottom barrier systems used in landfills. In this study, breakthrough times for bottom barrier systems used in typical active MSW landfills in four Chinese cities (Hangzhou, Shanghai, Shenzhen, and Suzhou) were evaluated by numerically modelling chemical oxygen demand (COD) transport. The performances of the landfill bottom barrier systems were determined from the COD concentration of the leachate, the landfill operating period, and the leachate head. A leachate head of 0.3m is specified in the relevant regulations. Using a leachate head of 0.3m, the breakthrough times for the barrier systems in all of the four landfills were > 50years. However, using the actual leachate heads, the breakthrough time for the barrier system in the Hangzhou landfill was only 27years even though the barrier system was a compacted clay liner/geomembrane/geosynthetic clay composite liner. The results of this study provide reference data for designing and managing landfill barrier systems.

Quantification of methane and carbon dioxide emissions from an active landfill: study the effect of surface conditions on emissions

Quantification of methane and carbon dioxide emissions from an active landfill: study the effect of surface conditions on emissions

Assessment of Greenhouse Gas Emissions and Energetic Potential from Solid Waste Landfills in Jordan: A Comparative Modelling Analysis

Landfilling of solid waste has been and continues to be among the most common practices of solid waste disposal. This is particularly true for Jordan, where approximately 3.3 million tons of municipal solid waste (MSW) is annually generated, with 90% of the generated amount disposed into landfills. The main objective of this study is to estimate the quantities of landfill gas (LFG) generated from the solid waste disposal and its potential as a source of clean energy in Jordan using four different models, namely, GasSim 2.5, LandGEM, Afvalzorg, and Mexico Landfill Gas Model V2 (MLFGM V2). Furthermore, the greenhouse gas (GHG) mitigation potential of LFG projects was estimated. Currently, there are 18 active landfills that are distributed across the country. Based on screening criteria, the landfills were grouped into three categories: five landfills were considered for energy production, four were strong candidates for LFG collection and flaring, while the remaining nine landfills do not receive enough waste to be considered for either energy recovery or flaring. The total amount of LFG emissions was found to be 1.6 billion M3 of LFG, while the landfill energetic potential of the recovered LFG was estimated to be 34.8 MW. On the other hand, GHG mitigation potential was assessed between the years 2020 and 2030, which was found to be 18 million ton CO2 eq. The proposed LFG energy recovery projects will lead to increased biogas contribution to Jordan’s local renewable energy mix from a current level of 1% to 6%.

Characteristics Study of Daily Soil Cover in Pulau Burung Landfill, Penang

Municipal solid waste landfills are major sources of environmental pollution. This study evaluated heavy metal concentrations in soils around Pulau Burung Landfill, Penang, Malaysia, to determine the pollution potential of a landfill. Soil samples were collected at depths of 0–20 cm (top), 20–40 cm (center) and 40–60 cm (bottom) around the landfill and at a control site and characterized for various properties and concentrations of Lead (Pb) and Zinc (Zn). Samples of daily soil cover, collected from the same sites where soil samples were collected, were also analyzed for several of heavy metals analysis. The soils were silty sand, mostly acidic (4.45) with low organic matter content (0.41%) and cation exchange capacity (3.15-3.19 meq/100 g). Other basic physico-chemical and adsorption properties were conducted on soil indicated that soil alone is not effective to be used in the landfill to support the pollutant for a long time. Heavy metals concentrations (as background data) in the soils followed the order Iron (Fe) > Zinc (Zn) > Manganese (Mn) > Lead (Pb) > Arsenic (As) > Chromium (Cr) > Cadmium (Cd) > Copper (Cu) > Nickle (Ni) with samples from around the landfill having higher concentrations especially Iron, (Fe) and Zinc, (Zn). For soil profile contribution, heavy metal enrichment was highest at a depth of 40–60 cm. In short, soil alone cannot retain and minimize the migration of heavy metals in landfill based on the results of this study including removal efficiency test. Monitoring of environments around active landfills needs to be ongoing to mitigate negative impacts on humans and the environment.

Spatial Distribution of Salmonella in Soil near Municipal Waste Landfill Site

Due to the heterogeneous origin of municipal waste, different substrates support the growth of many microorganisms, including those hazardous to humans. In consequence, landfills collecting these refuses are regarded as serious sources of infectious material contaminating the environment. In this study, we aimed to assess how waste may be related to the presence of Salmonella spp. in soil within a landfill and its surroundings. The numbers of these pathogens were estimated in soil samples collected at 17 different stands established in the municipal waste landfill of Barycz (near Kraków, Poland) and the surrounding area. The analysis showed that in all soil samples, Salmonella spp. did not exceed 270 cfu g−1 in dry soil (i.e., the active landfill sector). Salmonella spp. was found in 57% of the tested soil samples in spring, 88% in summer, 45% in autumn, and was not detected in winter. A spatial distribution visualized by graphical maps allowed determination of the influence of the active sector on the surrounding areas. The graphical maps showed the impact of seasons on the spread of Salmonella spp. in the soil near the landfill. Detection and estimation of Salmonella spp. distribution in soil within the landfill area distinctly confirms the hazardous impact of collected wastes on hygienic characteristics of the soil.

Plastic Waste Degradation in Landfill Conditions: The Problem with Microplastics, and Their Direct and Indirect Environmental Effects.

As landfilling is a common method for utilizing plastic waste at its end-of-life, it is important to present knowledge about the environmental and technical complications encountered during plastic disposal, and the formation and spread of microplastics (MPs) from landfills, to better understand the direct and indirect effects of MPs on pollution. Plastic waste around active and former landfills remains a source of MPs. The landfill output consists of leachate and gases created by combined biological, chemical, and physical processes. Thus, small particles and/or fibers, including MPs, are transported to the surroundings by air and by leachate. In this study, a special focus was given to the potential for the migration and release of toxic substances as the aging of plastic debris leads to the release of harmful volatile organic compounds via oxidative photodegradation. MPs are generally seen as the key vehicles and accumulators of non-biodegradable pollutants. Because of their small size, MPs are quickly transported over long distances throughout their surroundings. With large specific surface areas, they have the ability to absorb pollutants, and plastic monomers and additives can be leached out of MPs; thus, they can act as both vectors and carriers of pollutants in the environment.

A comprehensive investigation of toxicity and pollution potential of municipal solid waste landfill leachate.

It is evident from the literature that research on the treatment of leachate generated from municipal solid waste (MSW) landfills has been a focus area of environmental management. However, the available information is discrete because most studies have reported only one or a couple of aspects of either closed or active MSW landfill leachate treatment. Hence, this investigation has focused on comprehensive attributes of both closed landfill leachate (CLL) and active landfill leachate (ALL), including generation, characterisation, and toxicity assessment to quantify and establish their pollution potential. The results indicated that CLL generation is higher (188.59 m3/d) than ALL (49.53 m3/d). The concentrations of principal physical, chemical, and biological constituents and concomitant leachate pollution index were higher in CLL (33.20) than in ALL (26.65). Furthermore, the germination indices of CLL (57.48) and ALL (79.14) and tail DNA damage of CLL (56.49%) and ALL (23.8%) ratified greater phytotoxicity and genotoxicity potential, respectively of CLL over ALL. The reasons for the variations in the generation, characteristics, and toxicity of CLL and ALL were discussed in detail. Evaluation of the commonly used landfill leachate treatment methods through the analytical hierarchy process confirmed that the activated sludge process and Fenton oxidation process are the most and least preferred treatment methods. The comprehensive investigation of CLL and ALL have established their pollution potential and the inevitable necessity for their treatment. The findings of this investigation will serve as a ready reference for researchers from academia and industry who work on the monitoring, treatment, and management of landfill leachate.

Dynamiczne badanie wydajności studni degazacyjnych jako narzędzie do zmniejszania emisji gazów cieplarnianych na składowiskach odpadów

The article was written as a continuation of the research on degassing wells in terms of their gas productivity in a landfill. Waste is one of the most serious threats to the environment. The term ‘waste’ means ‘any substance or object which the holder discards, he intends to get rid of, or which he has been required to get rid of’. The European Union, with the aim of ensuring a high quality of life and health of people through effective environmental protection, imposes on Poland very restrictive guidelines in the field of waste management. These guidelines include: waste prevention, preparation for re-use, recycling, other recovery methods, disposal. The waste goes to landfills, where it is collected. Landfills pose a very high threat to the natural environment because they emit pollutants into the atmosphere. The greatest threat is related to the organic matter contained in municipal waste, which during decomposition emits greenhouse gases such as CO2 and CH4. The amount of emitted gas can be reduced by equipping the landfill with a special installation for the production of landfill gas (biogas). Biogas is one of the alternative energy sources that can be used to produce electricity and heat. However, the installation itself is not enough, and the landfill must also be rationally managed to support biogas production. Within the mass of waste, optimal conditions should be created for the methanogenesis process to take place. Compacting or pouring waste into layers of earth may serve as examples. Both of these processes reduce the oxygen content in the stored material. However, the content of the organic fraction in the deposited waste has the most pronounced influence on the production of biogas. The article presents the results of research on the efficiency of degassing wells carried out in one of the active municipal landfills which was established in 2009. Five degassing wells located in different parts of the dump’s canopy were subjected to our measurements.

Some findings on the spatial and temporal distribution of methane emissions in landfills

The purpose of this article is to present some facts of interest for the quantification of gas emissions in active landfills obtained from a series of field campaigns in a case study landfill where spatial and temporal patterns of methane emissions were analyzed. Nine campaigns were carried out to measure diffuse surface methane emissions at an European municipal waste landfill in operation using the static flow chamber technique in different seasons over three years. Results obtained show a global annual diffuse flux of 733.26 t CH4/year for the year 2020. Certain points on the surface, where concentrations reached values above 1000 ppm, were observed during the campaigns. These points, called “hotspots”, represented only 10% of all the points measured but accounted for 73% of the total diffuse methane emissions (506 t CH4/year). Furthermore, localized emissions, such as those from landfill gas extraction wells, which were not connected to the general extraction network, were also analyzed. These localized emissions represent more than twice the total diffuse emissions measured on the surface (1500 t CH4/year). These results highlight the importance of identifying high emission points to design effective mitigation measures. Moreover, the influence of certain meteorological conditions such as atmospheric pressure, temperature or rainfall was also studied. A new particular effect has been detected regarding precipitation, which favors or hinders methane emissions depending on the volume accumulated during the previous weeks. Pressure was found to be the factor that most affects methane emission variations in the case studied, presenting a clear inverse correlation with the field data that was collected. This suggests the need to consider the meteorological fluctuations over time to calculate the field emission estimates. Correcting the annual estimation in the case studied by considering the atmospheric pressure fluctuations over the year led to a 14% change in the estimate, obtaining a final result of 836.73 t CH4/year for the total diffuse emissions.

Impact of thermal pre-treatment on anaerobic co-digestion of sewage sludge and landfill leachate

The complex microbial flocs with rigid cell walls and undigested organic matter in the domestic sewage sludge defy anaerobic digestion, especially hydrolysis, the rate-limiting step of anaerobic digestion. The anaerobic digestion of municipal solid waste landfill leachate is challenging because of its high refractory organics and ammoniacal nitrogen. However, if sewage sludge and landfill leachate are mixed in an optimal ratio and pre-treated, they can be anaerobically co-digested and clean bioenergy can be harnessed. Among the pre-treatment methods, thermal pre-treatment is preferred because it is simple and economical yet effective. In this investigation, sewage sludge from a domestic sewage treatment plant and landfill leachate from an active municipal solid waste landfill were mixed in the ratio of 75:25 and thermally pre-treated at 70 °C for 60 min. The pre-treated substrates were anaerobically digested at 37 ± 1 °C using fresh cow dung slurry as the inocula. The results of this experiment were compared with the control experiment in which substrates without pre-treatment were used. Though biogas production from the fresh substrates was higher during the initial days, it decreased after the seventh day. For the thermal pre-treated substrates, the biogas production was low during the first week, which started to increase from the tenth day until the end of the experiment. The cumulative biogas yields from untreated and thermal pre-treated reactors were 723.5 and 418 mL, respectively.

UAV-Based Landfill Land Cover Mapping: Optimizing Data Acquisition and Open-Source Processing Protocols

Earth observation technologies offer non-intrusive solutions for monitoring complex and risky sites, such as landfills. In particular, unmanned aerial vehicles (UAVs) offer the ability to acquire data at very high spatial resolution, with full control of the temporality required for the desired application. The versatility of UAVs, both in terms of flight characteristics and on-board sensors, makes it possible to generate relevant geodata for a wide range of landfill monitoring activities. This study aims to propose a robust tool and to provide data acquisition guidelines for the land cover mapping of complex sites using UAV multispectral imagery. For this purpose, the transferability of a state-of-the-art object-based image analysis open-source processing chain was assessed and its sensitivity to the segmentation approach, textural and contextual information, spectral and spatial resolution was tested over the landfill site of Hallembaye (Wallonia, Belgium). This study proposes a consistent open-source processing chain for the land cover mapping using UAV data with accuracies of at least 85%. It shows that low-cost red-green-blue standard sensors are sufficient to reach such accuracies and that spatial resolution of up to 10 cm can be adopted with limited impact on the performance of the processing chain. This study also results in the creation of a new operational service for the monitoring of the active landfill sites of Wallonia.

A Review on Mechanisms of Thermally Induced Volume Changes in Fine Soil

New geotechnical applications such as nuclear waste disposal, geothermal structure, thermally active landfills, and other structures dealing with temperature fluctuations in the short-term and long-term, have made it almost impossible to neglect the effect of temperature on the mechanical behavior of soils such as in conventional geotechnical designs. An important aspect in geotechnical engineering has always been the volumetric behavior that could be more critical in fine soils due to their complex nature. Therefore, a clear understanding on thermally induced volume changes in fine soils is essential in order to perform such thermal related geotechnical designs and to ensure safety and functionality during their lifetime. In this context, this paper presents a critical review on the current knowledge for thermally induced volumetric changes in fine soils as well as the effect of temperature on mechanical parameters. Thermal volume expansion and contraction occur in fine soils based on their stress history; however, some essential questions and discrepancies are still unresolved. The further assessment of proposed mechanisms is conducted in this paper that highlight the importance of microstructure and chemical interactions to be considered when studying thermal volume changes in fine soils.