Landfill Gas Treatment Research Articles

Exploring the potential of biofiltration for mitigating harmful gaseous emissions from small or old landfills: a review.

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.

Technical and Economic Aspects of Environmentally Sustainable Investment in Terms of the EU Taxonomy

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.

Mechanistic Evidence for Hg Removal from Wastewater by Biologically Produced Sulfur.

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.

Analysis of the Efficiency of Landfill Gas Treatment for Power Generation in a Cogeneration System in Terms of the European Green Deal

Climate change and environmental degradation pose a threat to Europe and the world. The mechanism that will address these challenges is the European Green Deal, which envisions transforming the EU into a modern, resourceful, economical and competitive economy, aiming for zero greenhouse gas emissions. Landfill gas generated in a landfill waste deposit poses a threat to the environment and people. In this aspect, its capture, treatment and safe neutralization or use for energy purposes are important. Treatment of landfill gas, which is the fuel for gas engines in cogeneration units, is crucial for their proper operation and the quantity and quality of electricity and heat generated. The purpose of this study was to perform research to determine the hydrogen sulfide content of landfill gas and the actual efficiency of hydrogen sulfide removal from the gas using activated carbon. The tests performed constitute the basis for the reliable operation of gas engines in cogeneration installations and are dedicated mainly to the operators of these installations. Accordingly, three measurement campaigns were carried out, each with 42 measurements, the first for the “raw” gas obtained directly from the landfill, the second for the gas before entering the carbon filter and the third after its treatment. In addition, surface analysis was performed, and the elemental composition of the “fresh” molded activated carbon constituting the filter material was determined using a scanning electron microscope with an EDS system. The results showed a high elemental content of carbon in the test sample at 92.78%, while the efficiency of hydrogen sulfide removal from landfill gas by activated carbon, calculated from the measurements, was 97.05%. The obtained test results confirmed the validity of using impregnated activated carbon to remove hydrogen sulfide from landfill gas and its high adsorption efficiency, which can consequently result in reliable operation of the gas engine in the cogeneration unit and ultimately fit in with the objectives of the European Green Deal. The research results are an incentive for operators of cogeneration installations to systematically examine the quality of landfill gas and the efficiency of biogas purification devices.

GHG Emissions in the Current and Future MSW Management System in Zvornik, Bosnia and Herzegovina

Each and every step in the process of municipal solid waste (MSW) management generates the greenhouse gases (GHG). Therefore, it is imperative to focus on MSW from the source to the final waste disposal in order to decrease the negative impact on the environment. This study aims to calculate the GHG emissions at the present moment (Status Quo) for waste management as well as on the improved MSW management that should be implemented in this local community by 2027 (Scenario 2027). To visualize waste streams in these two scenarios, the STAN 2.5 software was used, and for the calculation of GHG emissions in the City of Zvornik, the IWM-2 software was used. The MSW management Status Quo is basically characterized by the collection communal of waste and its deposition on the landfill without a degasification system and landfill gas treatment. The guidelines and recommendations for MSW management improvement, Scenario 2027 propose the establishment of separate collections of secondary raw materials and biodegradable waste, and improved collection and treatment of landfill gas at the landfill site. The implementation of these measures would result in a reduction of approximately 40% in GHG emissions compared to the Status Quo. The most significant impact would be realized in the environment due to the collection and treatment of landfill.

Insights on volatile metals in landfill gas as determined from advanced treatment media

This study analyzed spent activated carbon (AC) from a landfill gas (LFG) treatment system for an expanded suite of lesser studied volatile metals, revealing elevated levels of As and Sb in the LFG, exceeding those previously reported, with minimum average concentrations of 640 µg m−3 and 590 µg m−3, respectively. The annual release of As and Sb through landfill gas was found to be significant, surpassing leachate emissions by an order of magnitude. Extrapolating these findings to all US landfills suggests that the release of As and Sb through landfill gas could be a major, previously overlooked source of these metals in global emission estimates, underscoring the need to include them when developing future inventories. The spent AC was further found to exceed US toxicity limits established for As, classifying it as hazardous waste under US regulations. However, findings suggest that the AC scrubber employed at the landfill effectively prevented substantial releases of As and Sb. This research emphasizes that landfill gas is a primary contributor to environmental release of As and Sb from landfills, even more so than leachate, highlighting the significance of implementing effective LFG treatment measures to mitigate the release of volatile metal emissions.

Variations of trace metals in combustion chamber deposit in landfill gas engine a long period of time

The combustion chamber deposit (CCD) is a major problem for the gas engines that formed accumulating of the metal oxides during the oxidation of trace compounds in the landfill gas (LFG). Therefore, the LFG was purified with activated carbon (AC) before in use to reduce deposit formation in gas engines. The AC treatment demonstrated the high removal capacity by reducing to below 1 % of the mass ratios of Si and Ca in the deposit. Unfortunately, the AC treatment caused the formation of black deposit in the intercooler that was analyzed by EDS and XRD. First time in this study, the variation of the elements of the CCD was comparatively investigated over a long period of time in 2010 and in 2019 without -AC treatment of LFG. The variation of the concentrations of C, Ca, N, S, Sb, Si- and Sn in the CCD were confirmed by the analysis with ICP-OES and SEM-EDS for 9-year period. It was determined with EDS analysis that while Sb and Sn were relatively low, C and N were high based on 2010. It has been determined that there is a proportional change depending on the time of the elements forming in the deposit.

Current Status and Trend of Landfill Technology -- Quantitative Analysis of Landfill Profiles Based on Histcite

Analyzing the development in China’s landfill technology research ranges from 1997 to 2020 at the aspects of chronological distribution, high-yield journals, high-yield research institutions and keyword hotspot through Histcite, which sets landfill relevant studies in Web of Science as statistical samples. The result indicates: 1) The engineering application of landfill has declined, but the interest in landfill academic research has increased per year. 2) Although China’s landfill technology is globally highly researched, the depth and recognition of research need to be further improved from the facets of cited times. 3) Landfill articles published in JOURNAL OF HAZARDOUS MATERIALS have the highest impact factor and better recognition. 4) Tongji University is the critical institute of landfill technology research. 5) The research hotspots in recent 24 years are leachate treatment methods, leachate composition analysis, landfill gas treatment and oxidation repair technology, etc.

Methods of landfill gas treatment in landfills in integrated prevention system

The article focuses on the issue of landfill gas management in landfills, which are within the scope of Act No. 76/2002 Coll., on integrated prevention. Although landfilling as a way of disposing of municipal waste is in decline, the subsequent care of landfills will continue for another decade after their closure, and landfill gas must be captured even then. The article summarizes information on the method of landfill gas management obtained through the information system of integrated prevention as well as the rules for landfill gas management according to the valid Czech technical standards. According to data obtained from the public database of the integrated prevention system, 136 relevant landfills were identified. The application of a cogeneration has the largest share in the way of landfill gas management. If a cogeneration unit is installed at the landfill, it is in most cases operated by a company other than the landfill operator. It was also found that the region with the lowest population density has the largest number of landfills with low capacity. Due to the fact that the production of landfill gas decreases over time, it is possible that there will be changes in the way landfill gas is handled at individual landfills.

Methods of landfill gas treatment in landfills in integrated prevention system

The article focuses on the issue of landfill gas management in landfills, which are within the scope of Act No. 76/2002 Coll., on integrated prevention. Although landfilling as a way of disposing of municipal waste is in decline, the subsequent care of landfills will continue for another decade after their closure, and landfill gas must be captured even then. The article summarizes information on the method of landfill gas management obtained through the information system of integrated prevention as well as the rules for landfill gas management according to the valid Czech technical standards. According to data obtained from the public database of the integrated prevention system, 136 relevant landfills were identified. The application of a cogeneration has the largest share in the way of landfill gas management. If a cogeneration unit is installed at the landfill, it is in most cases operated by a company other than the landfill operator. It was also found that the region with the lowest population density has the largest number of landfills with low capacity. Due to the fact that the production of landfill gas decreases over time, it is possible that there will be changes in the way landfill gas is handled at individual landfills.

Climate action and food security: Strategies to reduce GHG emissions from food loss and waste in emerging economies

Peru struggles to upgrade its waste management, with landfilling only just overtaking open dumpsters as the main disposal method. Despite the benefits of this transition, including reduced environmental impacts to water and soil, previous studies demonstrated that greenhouse gas (GHG) emissions may increase if adequate levels of technological sophistication are not implemented. Considering that 58% of municipal solid waste (MSW) is organic, it seems plausible that a relevant portion of emissions can be linked directly to food loss and waste (FLW) management. This study aims to determine the GHG emissions mitigation potential in FLW compared to the current baseline scenario in 24 Peruvian cities, by modelling alternative technologies to treat organic MSW. Life cycle modelling was performed using the waste-LCA software EASETECH. Five treatment scenarios were modelled: i) open dumping; ii) landfilling with no gas treatment; iii) landfilling with landfill gas treatment; iv) landfilling with energy recovery; and, v) anaerobic digestion. GHG emissions of FLW generation proved to be substantially higher than those for FLW treatment. However, if sophisticated technologies are implemented in FLW treatment, an annual reduction of up to 1.56 Mt CO2eq could be attained. Moreover, despite the health and environmental benefits of a transition to optimized diets, in which, for example, meat consumption is reduced and vegetables are boosted, an important increase in FLW and, therefore, an increase in GHG emissions in the treatment phase is shown. However, if certain technologies, such as energy recovery or anaerobic digestion, were implemented, most carbon losses would be avoided.

Perm National Research Polytechnic Assessment of the Landfill Gas Treatment System at the Kuchino MSW Landfill

The problems of landfill gas collection and treatment at municipal solid waste landfills are considered. The analysis of the main methods of landfill gas treatment and use is carried out. The characteristic of the gas collection system used at the Kuchino MSW landfill is presented. Installation of a landfill gas treatment system on a flare at the stage of landfill closing will reduce methane emissions by 65 % in comparison with a landfill not equipped with such a system, and the fee for negative impact on environmental objects will decrease by 30 %. Based on the analysis of monitoring studies of landfill biogas emissions from the Kuchino MSW landfill, a decrease in the concentration of pollutants in the landfill gas after its treatment to the MPC level and below was established.

Simultaneous mitigation of methane and odors in a biowindow using a pipe network

In this study, a biowindow with a piped gas collection network is proposed as an area-efficient landfill gas treatment system. A 9-m2 biowindow was constructed for treating landfill gas collected from an area of 450 m2 in a sanitary landfill, and its performance was evaluated for 224 days. The methane removal efficiency was 59–100% at 146.3–675.1 g-CH4 m−2 d−1. Odorous compounds were also removed by the biowindow, with a complex odor intensity removal rate of 93–100%. In particular, the removal efficiency for hydrogen sulfide and methanethiol, major contributors to the complex odor intensity, was 97% and 91%, respectively. Metagenomic analysis showed that the dominant bacterial genera shifted from Acinetobacter and Pseudomonas to Methylobacter and Methylocaldum due to the high concentration of methane. A high bacterial diversity was maintained, which may have contributed to the robust performance of the biowindow against environmental fluctuations. At 1/50th of the size of conventional biocovers, the proposed biowindow can greatly reduce the required installation area and represents a competitive method for the simultaneous treatment of methane and odor in landfills.

Transitioning from open dumpsters to landfilling in Peru: Environmental benefits and challenges from a life-cycle perspective

The Peruvian waste management sector is steadily transitioning from a mostly informal and underdeveloped system based on the use of open dumpsters to a landfill-based system. The environmental consequences of these policies must be evaluated with environmental management tools such as Life Cycle Assessment (LCA). Therefore, the main goal of the study is to analyze the life-cycle environmental performance of waste disposition in three different landfills located in three distinct geographical areas of Peru: i) the hyper-arid coast; ii) the Andean highlands; and, iii) the Amazon Rainforest. With this aim in mind, a comparative analysis is provided regarding the waste treatment process as compared to other landfill technologies (i.e., biogas combustion or energy recovery) and open dumpsters. The modelling of these systems was performed with the EASETECH waste LCA tool, including a sensitivity analysis in terms of waste composition and waste decay rates. Results show that landfill gas (LFG) treatment reduces greenhouse gas (GHG) emissions considerably. However, these remain higher in the Amazon as compared to the Andean Highlands (+105%) and the hyper-arid coast (+17%). Most of the decomposition in the Amazon basin occurs within 5 years after disposition (80%) due to heat and humidity, whereas in the other regions values were below 55%. LFG treatment or recovery is necessary for these emissions to be lower than in open dumpsters. The implementation of these technologies would strengthen the country's action plan regarding the Paris Agreement in the waste sector. In other impact categories, the transitioning from dumpsters to landfills is most visible in the soil and water compartments.

Application of biochar for acid gas removal: experimental and statistical analysis using CO2.

Acid gases such as carbon dioxide and hydrogen sulfide are common contaminants in oil and gas operations, landfill gases, and exhaust stacks from power plants. While there are processes currently used to treat these effluents (e.g., amine absorption and adsorption using zeolite), many of these processes require high energy, space, and hazardous chemicals. Removal using biochar derived from the fast pyrolysis of forestry residues represents a more sustainable option. In this study, adsorption using CO2 as a surrogate for acid gases was investigated using various biochars produced from fast pyrolysis of sawmill residues. Response surface methodology was used to determine operating conditions for maximum adsorption and assess interaction of the adsorption parameters, i.e., temperature, inlet feed flow rate, and CO2 concentration, on biochar adsorption capacity. The Freundlich isotherm best represented the equilibrium adsorption, and the kinetic model was pseudo first-order. Thermodynamic analysis indicated the adsorption process was spontaneous and exothermic. The biochar had better adsorption capacity relative to commercial zeolite. Our results suggested that biochar could be used as a sustainable and cost-effective option for contaminant removal from acid gases produced in landfill gas treatment, fossil fuel extraction, and/or combustion.

GLOBAL DEVELOPMENT OF GREENHOUSE GAS EMISSIONS IN THE WASTE MANAGEMENT SECTOR

The Member States of the United Nations Framework Convention on Climate Change are required to periodically publish their national inventories of anthropogenic emissions in National Inventory Reports. The data used in this paper was extracted from these reports and applied to generate a study of the development of greenhouse gas emissions in the waste management sector. The results show a reduction of greenhouse gas emissions for developed contries/regions from 1990 to 2016 due to improved collection and treatment of landfill gas, a shift from landfilling to biological and thermal treatment, as well as a shift to separate waste collection and treatment. The developing countries and regions show another development of greenhouse gas emissions. On the one hand, their greenhouse gas emissions from the waste sector strongly increased due to higher generation of waste. And on the other hand, they increased due in most cases to unorganized and technically insufficent disposal of mixed waste on dumpsites along with better observation of disposal sites and therefore better registration of emissions. Nevertheless, the per capita emissions in developed countries/regions are with approx. 500 kg CO₂-eq./a much higher than for developing and emerging countries/regions, which just emit around 100 kg CO₂-eq./a.

Treatment of landfill gas with low methane content by biocover systems

Landfills are significant sources of anthropogenic atmospheric methane (CH4), which contributes to climate change. Large amounts of CH4 are emitted from landfills in dilute form due to mixing with air in leachate collection systems, or during lateral migration away from landfills. The objective of this study was to investigate the CH4 oxidation efficiency of a compost material subject to LFG diluted with atmospheric air resulting in CH4 concentrations of 5–10% v/v. CH4 oxidation rates and carbon dioxide (CO2) production were measured through batch and dynamic column experiments where two laboratory scale biofilters were constructed. The columns were run at increasing flow rates. Column gas concentration profiles for each of five flow campaigns were compared to each other. This showed that oxygen (O2) was present through the entire column and elevated CO2 concentrations throughout the biofilters were found. Moreover, the oxidation process tended to be centred in the lower parts of both columns. It was observed that the biofilters performed better once they had adapted to the increasing loads of CH4. In both columns, the maximum removal rate of CH4 was found to be 98–100%. Using CH4 mass balances the maximum oxidation rate was 238 g CH4 m−2 d−1 in Column 1 and 483 g CH4 m−2 d−1 in Column 2 (equal to the load). None of the biofilters reached their maximum CH4 oxidation capacity, hence they could have been exposed to a larger CH4 load. It was found that the retention time in the columns was not a factor limiting the oxidation process. High O2 consumption and carbon mass balances underlined the strong microbial activity in the biofilters and it was not suspected that the methane oxidising bacteria were O2 limited. The results of this study suggest that biofilters have great potential for reducing CH4 in diluted LFG.

Environmental factors influencing landfill gas biofiltration: Lab scale study on methanotrophic bacteria growth

ABSTRACTThe post-management of landfills represents an important challenge for landfill gas treatment. Traditional systems (energy recovery, flares, etc.) present technical problems in treating flow with low methane (CH4) concentrations. The objective of this study was to isolate methanotrophic bacteria from a field-scale biofilter in order to study the bacteria in laboratories and evaluate the environmental factors that mostly influence Microbial Aerobic Methane Oxidation (MAMO). The soil considered was sampled from the biofilter located in the landfill of Venosa (Basilicata Region, Italy) and it was mainly composed of wood chips and compost. The results showed that methanotrophic microorganisms are mainly characterized by a slow growth and a significant sensitivity to CH4 levels. Temperature and nitrogen (N) also have a very important role on their development. On the basis of the results, biofilters for biological CH4 oxidation can be considered a viable alternative to mitigate CH4 emissions from landfills.

Treatment of landfill waste, leachate and landfill gas: A review

This review aims at the treatment of the entire landfill, including the waste mass and the harmful emissions: leachate and landfill gas. Different landfill treatments (aerobic, anaerobic and semi-aerobic bioreactor landfills, dry-tomb landfills), leachate treatments (anaerobic and aerobic treatments, anammox, adsorption, chemical oxidation, coagulation/flocculation and membrane processes) and landfill gas treatments (flaring, adsorption, absorption, permeation and cryogenic treatments) are reviewed. Available information and the gaps present in current knowledge is summarized. The most significant areas to expand are landfill waste treatments, which in recent years has begun to grow but there is an opportunity for much more. Another area to explore is the treatment of landfill gas, a very large field to which not much effort has been put forth. This review is to compare different treatment methods and give direction to future research.

Using multivariate regression modeling for sampling and predicting chemical characteristics of mixed waste in old landfills

Municipal solid waste landfills pose a threat on environment and human health, especially old landfills which lack facilities for collection and treatment of landfill gas and leachate. Consequently, missing information about emission flows prevent site-specific environmental risk assessments. To overcome this gap, the combination of waste sampling and analysis with statistical modeling is one option for estimating present and future emission potentials. Optimizing the tradeoff between investigation costs and reliable results requires knowledge about both: the number of samples to be taken and variables to be analyzed.This article aims to identify the optimized number of waste samples and variables in order to predict a larger set of variables. Therefore, we introduce a multivariate linear regression model and tested the applicability by usage of two case studies. Landfill A was used to set up and calibrate the model based on 50 waste samples and twelve variables. The calibrated model was applied to Landfill B including 36 waste samples and twelve variables with four predictor variables.The case study results are twofold: first, the reliable and accurate prediction of the twelve variables can be achieved with the knowledge of four predictor variables (Loi, EC, pH and Cl). For the second Landfill B, only ten full measurements would be needed for a reliable prediction of most response variables. The four predictor variables would exhibit comparably low analytical costs in comparison to the full set of measurements. This cost reduction could be used to increase the number of samples yielding an improved understanding of the spatial waste heterogeneity in landfills.Concluding, the future application of the developed model potentially improves the reliability of predicted emission potentials. The model could become a standard screening tool for old landfills if its applicability and reliability would be tested in additional case studies.