Gas Collection Systems Research Articles

Assessing Greenhouse Gas Emissions and Methane Production During Post-Landfill Maintenance in Kish Island: A LandGEM Simulation Approach

Background: Municipal solid waste (MSW) landfills are significant contributors to the emission of greenhouse gases, particularly methane, during the breakdown of waste materials. Researchers have undertaken extensive investigations into quantifying methane emissions from landfills, utilizing various methodologies beyond reliance on the LandGEM model. Numerous studies have underscored the efficacy of this model in predicting methane generation and exploring its utility in activities such as energy generation and emission mitigation strategies. Objectives: Municipal solid waste landfills are vital contributors to greenhouse gas emissions, notably methane, during waste decomposition. Significant research has focused on estimating methane output from landfills, utilizing various approaches beyond the LandGEM model. Studies highlight the model's potential in assessing methane generation and its relevance to activities like energy generation and emission management. Methods: The LandGEM simulation model is employed to forecast future waste generation and provide valuable insights into the environmental consequences of landfill management on the island. By analyzing population data and waste generation statistics from 2023 to 2042, the study utilizes the LandGEM software to estimate methane emissions, incorporating site-specific data and waste composition analysis. Results: The findings reveal that 36% of the total waste on Kish Island consists of putrescible material, with food waste being a significant component. Over the study period, approximately 1,282,637 tons of waste are projected to be disposed of in the Kish landfill. The LandGEM model predicts the highest landfill gas emission in 2043, primarily methane, along with carbon dioxide and non-metallic organic compounds. The estimated quantities for these gases in 2043 are 5.415E+03, 1.486E+04, and 2.327E+02 metric tons, respectively. Conclusions: This research highlights the importance of tailored waste management strategies to mitigate environmental impacts and emphasizes the need for efficient gas collection systems. A proposed gas collection system combining vertical wells, horizontal trenches, and under-membrane pipes is discussed to enhance efficiency and reduce environmental risks. The study provides valuable insights into waste management and landfill gas emissions on Kish Island, underscoring the significance of accurate emission prediction and effective management to minimize environmental consequences and optimize the utilization of renewable energy resources.

ИССЛЕДОВАНИЕ СОСТАВА БИОГАЗА НА ПОЛИГОНЕ ТКО «СТРЕЛЕЦКОЕ»

The purpose of the work is to summarize data on the analysis of the composition of biogas produced at the Streletskoye MSW landfill (Belgorod region) from 2017 to the present in order to assess its average composition and its changes. The composition and yield of biogas was studied in an experimental line of three wells and in four gas collection systems with a total area of 1.75 hectares, built at the site in 2017–2020. According to the results of aeration, the methane content without taking into account leaks ranges from 35 to 70% and is constant for each gas collection field. The practice of operating gas collection systems shows the great importance of sealing the body of landfills to prevent atmospheric air suction. Monitoring of the natural release of landfill gas from the landfill body in 471 wells showed an uneven nature of gas formation at different points, so the installation of individual observation and working gas wells may not allow determining the average indicators for the landfill. Studies of the composition and yield of biogas over a long period of time have shown the stability of the indicators and their dependence only on the technical characteristics of the landfill site. Seasonality has little effect on methane output, so surveys for climatic conditions similar to the Belgorod region can be carried out at any time of the year. The conducted studies showed that GOST 59417-2021 does not allow for an effective determination of biogas potential. To solve this problem, an express survey method is proposed with the installation of temporary wells and determination of biogas parameters using portable equipment.

Mitigation of Fugitive Gas Emissions from Landfill Using Biochar-Amended Soil Cover and Its Geotechnical Characterization

Landfills with gas collection systems often struggle to capture fugitive emissions through the final soil cover, leading to significant environmental challenges. Considering recent major landfill fires in India, methane gas emissions have been identified as the primary cause. This research explores the potential of biochar-amended soil covers as an alternative solution to mitigate fugitive emissions. Various percentages of biochar were added to the soil collected from a landfill site in Vilholi, Maharashtra, India. Geotechnical testing assesses compaction characteristics, hydraulic conductivity, and shear strength. Amendment improves the compaction characteristics of soil cover. The decreased hydraulic conductivity with amendment indicates improved water retention. The interlocking between soil and biochar and the specific type of biochar influences the strength gained. The column setups containing different percentages of amended soil showed reduced emissions. The improved geotechnical properties and reduced fugitive emissions demonstrate the potential for biochar-amended soil covers to enhance landfills' stability.

Landfill gas collection efficiency: Categorization of data from existing in-situ measurements

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.

GREENHOUSE GAS EMISSIONS FROM MUNICIPAL WASTE DISPOSAL SITES AND MEASURES FOR ITS REDUCTION

Disposal of household waste at landfills and dumps leads to greenhouse gas emissions. Usually emissions are estimated based on the IPCC methodology, which takes into account the amount and composition of household waste as well as the climate conditions of the region. However, greenhouse gas emissions are significantly influenced by the technical and operational parameters of landfills and dumps. The Ukrainian landfill gas model, which is adapted to local conditions, allows these parameters to be taken into account. The objective of this study was the estimation of greenhouse gas emissions from certain classes of landfills and dumps, taking into account their specific parameters based on the Ukrainian landfill gas model, as well as the development of measures for its reduction. For this, landfills and dumps were classified by area, which indirectly characterizes their capacity and place of location. Based on the results of the classification, it was determined that out of more than 7,000 landfills and dumps in Ukraine, about 320 are classified as large sites. These sites occupy more than a third of the total area of landfills and dumps in Ukraine and contain up to 84% of disposed household waste. Large landfills and dumps are a priority for greenhouse gas emissions study. According to the results of greenhouse gas emissions study, their total amount is estimated to be 5,833.5 thousand tСО2. These amount 32.9% less than similar estimates according to the IPCC methodology, which is explained by the higher accuracy of the Ukrainian landfill gas model and its parameters. Of the total amount of greenhouse emissions, up to 40% can potentially be reduced by the continued development of landfill gas collection systems, which actually reduced about 10% greenhouse gas emission in 2021. This potential can be increased by half and the reduction of greenhouse gas emissions can potentially reach up to 60% of their total emissions from landfills and dumps. For this purpose, the rehabilitation of the landfills and dumps should be conducted along with the development of landfill gas collection systems. However, rehabilitation is a complex and expensive measure, and the rationale for its application may be the subject of further research.

Environmental assessment of landfill gas mitigation using biocover and gas collection with energy utilisation at aging landfills

A life cycle-based environmental assessment was conducted on the mitigation of landfill gas emissions, by implementing biocover and gas collection along with energy utilisation at aging landfills. Based on recent studies about gas generation at Danish landfills, the efficiency of the mitigation technologies involved and the composition of substituted energy production, 15 scenarios were modelled using the EASETECH life cycle assessment model, through which potential environmental impacts in the category “Climate change” were calculated. In all scenarios, biocover and gas collection systems with energy utilisation led to significant environmental improvements compared to the baseline scenario with no emission mitigation action. Scenarios representing biocovers with methane oxidation efficiencies between 70 and 90 % were environmentally superior in terms of climate change impact – in comparison to scenarios with 20–30 years of gas collection and energy utilisation (collection efficiencies between 40 and 80 %). Combining gas collection with energy utilisation and the subsequent installation of a biocover saw major improvements in comparison to where only gas collection and energy utilisation were in effect. Overall, it can be concluded that a biocover under the given assumptions is environmentally more appropriate than gas collection and utilisation at aging landfills, mainly due to methane emissions escaping through the landfill cover during and after the gas collection period playing a crucial role in the latter situation. Maintaining high methane oxidation efficiency for a biocover throughout the lifetime of a landfill is vital for reducing environmental impacts.

Surface emission determination of selected trace gases from an active municipal solid waste dumpsite under the surface physicochemical heterogeneity.

Karadiyana municipal solid waste (MSW) dumpsite in Colombo, Sri Lanka, has been in operation for over 30years and was evaluated for its surface Volatile Organic Compounds (VOCs), Ammonia (NH3), and Hydrogen sulfide (H2S) emissions. Based on the surface conditions and waste characters, the dump surface was divided into eight cells, and multiple samplings were done using static flux chamber methods. The study observed that the average flux rates of VOCs, H2S, and NH3 were 137.2±243.8, 6.63±15.9, and 14.2±16.2mgm-2h-1 throughout the dump site. The highest average VOCs and H2S flux rates (828.6, 24.3mgm-2h-1) were reported from new organic waste with a considerable fraction (62.5, 35.6%) from the total emission (61.0, 3.1 Kg d-1). Leachate-flowing trenches produced the highest NH3 flux rate (36.0mgm-2h-1), while the highest emission fraction (47.5%) from the total (12.0 Kg d-1) was reported on old mixed waste with vegetation. The moisture content of the organic waste layers is positively correlated with these trace gas flux rates, and the NH3 flux rates depend on the pH of the surface. Results showed that the age of the waste determines the trace gas emission rate, and leachate provides an ideal pathway for landfill trace gas migration to the atmosphere. Gas collection and purification systems are essential for the initial waste dumping area and leachate treatment system. The arrangement of a proper drainage system on the dump would reduce trace gas emissions.

Per- and polyfluoroalkyl substances (PFAS) distribution in landfill gas collection systems: leachate and gas condensate partitioning

While per- and polyfluoroalkyl substances (PFAS) have been reported extensively in municipal solid waste (MSW) landfill leachate,they have rarely been quantified in landfill gas or in discrete landfill liquids such as landfill gas condensate (LGC), and the potential for PFAS to partition to the condensate has not been reported. LGC and leachate collected from within gas wells known as gas well pump-out (GWP) from three MSW landfills underwent physical-chemical characterization and PFAS analysis to improve understanding of the conditions under which these liquids form and to illuminate PFAS behavior within landfills. LGC was observed to be clear liquid containing ammonia and alkalinity while GWP strongly resembled leachate – dark in color, high in chloride and ammonia. Notably, arsenic and antimony were found in concentrations exceeding regulatory thresholds by over two orders of magnitude in many LGC samples. LGC contained a lower average concentration of ΣPFAS (19,000 ng L) compared to GWP (56,000 ng L); however, LGC contained more diversity of PFAS, with 53 quantified compared to 44 in GWP. LGC contained proportionally more precursor PFAS than GWP, including more semi-volatile PFAS which are rarely measured in water matrices, such as fluorotelomer alcohols and perfluoroalkane sulfonamido ethanols. This study provides the first detailed comparison of these matrices to inform timely leachate management decisions.

A bio-hydro-chemical model for gas pressure development in municipal solid waste landfills

Prediction of gas pressure development within municipal solid waste (MSW) landfills is of great importance for the stability analysis and design of gas collection systems. This study presents a fully coupled bio-hydro-chemical model for the gas pressure development in landfills. The reduction of foam on the relative gas permeability and the variation of the intrinsic permeability with degradation degree are considered. The source terms in the governing equations of two-phase flow and solute transport are chosen from the biodegradation process of MSW. Both one-step landfilling and multi-step landfilling are calculated to compare the differences. It is found that the fast hydrolysis of fresh MSW produces most of the volatile fatty acids (VFAs) and leachate within the first 2 months. During multi-step landfilling, the VFA and leachate produced from fresh MSW in the top flow downward to the bottom, leading to high gas production and high leachate saturation in the deep. Meanwhile, the high concentration of VFA reduces the surface tension of the leachate, enabling it to generate foam and further reduce gas permeability. Owing to the high gas production and low gas permeability, the excess gas pressure is easily developed in the deep layer. The maximum gas pressure of multi-step landfilling is about 2·5 times that of one-step landfilling. Case studies of the laboratory column test and in situ borehole test verify the accuracy of the model in predicting the temporal and spatial distribution of gas pressure. For the slope failure induced by high gas pressure, the evolution of shear strength and stability during a 2 year landfilling period is calculated and discussed.

Landfill Emissions of Methane Inferred from Unmanned Aerial Vehicle and Mobile Ground Measurements

Municipal solid waste landfills are significant sources of atmospheric methane, the second most important greenhouse gas after carbon dioxide. Large emissions of methane from landfills contribute not only to global climate change, but also to local ozone formation due to the enhancement of radical chain lengths in atmospheric reactions of volatile organic compounds and nitrogen oxides. Several advanced techniques were deployed to measure methane emissions from two landfills in the Southeast Michigan ozone nonattainment area during the Michigan–Ontario Ozone Source Experiment (MOOSE). These techniques included mobile infrared cavity ringdown spectrometry, drone-mounted meteorological sensors and tunable diode laser spectrometry, estimation of total landfill emissions of methane based on flux plane measurements, and Gaussian plume inverse modeling of distributed methane emissions in the presence of complex landfill terrain. The total methane emissions measured at the two landfills were of the order of 500 kg/h, with an uncertainty of around 50%. The results indicate that both landfill active faces and leaking gas collection systems are important sources of methane emissions.

Design of gas collection systems: Issues and challenges.

The design of a gas collection system (GCS) for a landfill involves estimating several critical parameters, such as the radius of influence (ROI), suction pressures, number of wells and their spacing. One of the biggest challenges lies in the estimation of ROI for a particular landfill. In this study, the ROI for a Bagalur landfill is estimated for various possible gas generation rates. ROI for active and passive GCS is estimated with numerical modelling (two-dimensional) for all definitions of ROI at different suction pressures. An inverse correlation was observed between the values of various definitions of ROI at different gas generation rates. Justification for this behaviour is brought out by addressing the conceptual difference between these definitions. The number of wells along with their spacing was then calculated, and the efficiency of the design was assessed with three-dimensional modelling. Passive and active systems had average methane recovery rates of 84% and 88%, respectively, with an atmospheric methane flux ranging from 10-9 to 10-10 kg m-2 s-1. The high recovery rate and low methane flux indicate the effectiveness of the design. The values of the methane flow rate from the extraction well were validated with a theoretical method, suggesting the usability of the model for future investigations.

Assessment of Degree of Contamination of an Un-engineered Landfill Leachate Using Leachate Pollution Index (LPI)

The amount of waste generated each year is increasing. The un-engineered landfills used for waste disposal lack gas and leachate collection systems leading to pollution potential to groundwater if no action is taken to prevent it. In this study, leachate pollution index (LPI) is used to quantify leachate pollution potential of Al Amirat un engineered landfill in the Sultanate of Oman based on the actual concentration of leachate. Based on the results, it can be concluded that the LPI value of leachate is high (26.32-27.67) and treatment is needed before final discharge highlighting the importance of proper management and control of old landfills to avoid any unwanted impacts on the environment.

Analysis of Gas Collection Systems in the Fields of Uzbekistan

Annotation: Giant gas fields play an important role in the development of the world natural gas industry. The major gas producers have established their positions on the world arena with the support of their discovery and development of several or more giant gas fields. In Uzbekistan, special attention is paid to oil and gas production, which is one of the sources of economic development. Keywords: water vapor, liquid water, carbon monoxide, sulfuric acid H2S, nitrogen N2, and helium He, linear, light, ring collection system, the gas ejector, hydrocarbons

Efficiency of gas collection systems at Danish landfills and implications for regulations

Globally, landfills are an important source of anthropogenic methane emissions. Regulations require landfill gas be managed to reduce emissions, and some landfills have therefore installed gas collection systems to recover energy and mitigate methane emissions. However, the efficiency of such systems is seldom evaluated. This paper presents the gas collection efficiencies of 23 Danish landfills and suggests how these values could be used to regulate landfill methane emissions in Denmark. Methane emissions from all sites were measured using the tracer gas dispersion method, and gas collection efficiencies were calculated using the ratio of the methane collection rate to the sum of the collection and emission (and oxidation) rates. Gas collection efficiencies ranged between 13 and 86% with an average of 50% – a value lower than for Swedish (58%), UK (64%) and US (63%) landfills. Possible reasons for the inefficiency of gas collection systems in Denmark include shallow gas collection pipes, leakage from installations (e.g. leachate wells, gas engines), low gas recovery due to minimal gas production or a lack of gas collection in active waste cells. It is suggested to use gas collection efficiency to regulate landfills and help them reach a particular methane mitigation goal. Gas collection efficiency that falls below the target mitigation rate would in turn trigger actions to reduce landfill methane emissions. At sites where the quality of the collected gas is too low to operate a gas engine, the installed gas collection system could be retrofitted to a biocover system designed for methane oxidation.

Methane emissions from Icelandic landfills – A comparison between measured and modelled emissions

This study compares methane (CH4) emissions from five Icelandic landfills, quantified using tracer gas dispersion to modelled emission rates using the IPCC FOD model. The average CH4 emission rates measured from the investigated landfills were 475.4 kg CH4 h−1 (Álfsnes landfill), 32.5 kg CH4 h−1 (Fíflholt), 40.8 kg CH4 h−1 (Gufunes), 9.8 kg CH4 h−1 (Kirkjuferjuhjáleiga) and 78.4 kg CH4 h−1 (Stekkjarvík). At three of the landfills (Álfsnes, Fíflholt and Kirkjuferjuhjáleiga), the modelled emission was higher than the measured emission by factors ranging from 1.1 to 4.8, neglecting any CH4 oxidation in the cover soils. Even though CH4 oxidation might play a role at some of the investigated landfills, and thus reduce the gap between modelled and measured emissions, it is likely that the model overestimated CH4 generation due to uncertainties in input model parameters. Assuming that the measured emissions at the five landfills are representative of all the waste disposed in Iceland from 2007 to 2016, the measured emission should be extrapolated to 817 kg CH4 h−1, which is relatively close to the modelled national emission of 936 kg CH4 h−1 in 2017. This study showed that the application of the IPCC FOD model at national level is appropriate for estimating landfill CH4 emissions in Iceland. CH4 emissions from landfills in Iceland can be reduced by expanding or implementing gas collection or biocover systems for optimised microbial oxidation.

Amendment for increased methane production rate in municipal solid waste landfill gas collection systems

Optimization of methane production rate can potentially decrease the operational lifetime of the landfill site and assist with better management of methane harvesting from the landfill cells. Increased moisture content in landfill cells is known to increase the rate of methane production. Several natural biopolymers can sustain moisture content in a solid matrix while providing a scaffolding for microbial communities to grow. This research examined the effect of the biopolymer, produced by Rhizobium tropici, on bench-scale methane generation from municipal solid waste. The addition of the R. tropici biopolymer increased the rate of methane production from 27% to 78% when compared to the control study for low and high concentrations of biopolymer amendment, respectively. R. tropici biopolymer shortened the lag phase by up to six days over the control, depending on the level of biopolymer amendment added to the solid waste. The mechanism appears to be facilitating biofilm formation through the combination of increased moisture retention and surface modification of the solid waste. Incorporation of biopolymer amendment in the alternative daily cover activities at commercial landfills could provide a viable approach for full scale application.

Determination of the gas factor of oil at Western Siberia fields

The article presents the results of applying the method for determining gas factors at the wellhead of the support network of wells and separation sites of LUKOIL-Western Siberia LLC. The object is systems of oil separation and treatment, collection and transportation of gas from fields developed by LUKOIL-Western Siberia LLC. The aim is to measure the amount of gas produced together with oil, and specify gas factors by fields. The article describes and analyzes the existing oil treatment systems and gas collection and transportation systems. The tie-in points for field measurements of gas consumption have been determined. Instrumental field measurements of gas consumption in pipelines at all separation facilities and laboratory studies of properties and composition of gas were conducted. The relevance of the research is due to the increasing attention to the rational use, reduction of losses and an increase in the overall level of use of gas extracted from the subsoil

Utilization of landfill gas in emission trading from the finnish viewpoint

In this study the landfill gas utilization project case in the Volkhonka landfill in Russia ispresented. The carbon dioxide emissions into the atmosphere from landfills with and withoutlandfill gas collection systems are estimated and also emissions of certain fuels are calculated.According to the results of the study, the utilization project might be very profitable if thecircumstances are suitable.

Innovative Biogeochemical Cover to Mitigate Landfill Gas Emissions: Investigation of Controlling Parameters Based on Batch and Column Experiments

Municipal solid waste (MSW) landfills generate different gases mainly methane (CH4) and carbon dioxide (CO2) during the process of waste decomposition. Modern landfills are provided with gas collection systems, however, significant amount of landfill gas (LFG) escapes into the atmosphere, making landfills one of the largest anthropogenic sources of CH4 and CO2 emissions. Several researchers have investigated various alternative landfill cover systems, such as biocovers, in order to mitigate CH4 transport across landfill covers by enhancing microbial CH4 oxidation. In recent years, biochar as an organic amendment has shown promise in enhanced microbial oxidation due to its inert/stable chemical nature, high surface area, high internal porosity, and high moisture holding capacity. However, in all these efforts, little regard is given to the CO2 that still escapes into the atmosphere in undesirable amounts. The current study introduces the concept of biogeochemical cover, which uses steel slag in conjunction with biochar-amended soil to mitigate fugitive emissions from a landfill. The current study compares the CO2 sequestration potential of steel slag, mainly basic oxygen furnace (BOF) slag under various environmental conditions that may prevail in the landfill cover. BOF slag shows significant CO2 sequestration potential under variable conditions including moisture, temperature, gas flow conditions, and BOF slag type and particle size. The results suggest that the use of BOF slag could be a cost effective and green solution to the problems of fugitive LFG emissions.

IMPROVMENT THE MATHEMATICAL MODEL FOR THE HYDRATES FORMATION CALCULATING IN THE GAS GATHERING NETWORK

Background Most gas fields are characterized by complex and branched systems for collecting and inter-field gas transportation. It should be noted that the main characteristics of gas fields are well cluster location and an extensive plume system from wells to the integrated gas treatment unit (GTU) for transportation, as well as the complex network structure of the inter-field collector. Such systems form a complex hierarchical structure, in which field information has a high degree of inaccuracy, and often there are a large number of errors in the measurements of technological parameters, such as measurements of flow, pressure and temperature. In some nodes of the gas gathering network, these data are not displayed at all or the corresponding parameters are not measured due to the lack of instrumentation. All this leads to increased consumption of chemical reagent methanol. Aims and Objectives To improve gas collection systems and reduce the consumption of chemical reagents during operation, it is necessary to analyze existing mathematical models and, based on this analysis, create a more sophisticated mathematical model of calculation that takes into account the optimal number of factors affecting the formation of hydrates in field systems. Especially this problem is relevant in the conditions of operation of wells at negative ambient temperatures, that is, in the winter period or for the fields of the Far North. Results A completely new mathematical model has been developed that allows to diagnose the formation of hydrates in the plumes of the gas gathering network prior to the integrated gas treatment unit. A formula is proposed for calculating the temperature in gas pipelines, which reflects two independent (physically meaningful) parameters that take into account the presence of a thermal boundary layer and the temperature variation along the length of the pipeline. A flowchart of the proposed mathematical model has been developed, which can be easily realized and obtained a system for diagnosing and preventing the formation of hydrates for the control units of the GTU.