Landfill Gas Generation Research Articles

Stability Analyses of Municipal Solid Waste Landfills with Decomposition

A bioreactor landfill is operated to enhance refuse decomposition, gas production, and waste stabilization. Some of the potential advantages of bioreactor include rapid stabilization of waste, increased landfill gas generation, gain in landfill space, enhanced leachate treatment, and reduced post closure maintenance period. Due to the accelerated decomposition and settlement of solid waste, bioreactor landfills are gaining popularity as an alternative to the conventional Subtitle D landfills. However, the addition of leachate to accelerate the decomposition changes the physical and engineering characteristic of waste and therefore affects the geotechnical characteristics of waste mass. The changes in the physical and mechanical characteristics of solid waste with time and decomposition are expected to affect the shear strength of waste mass. The objective of this paper is to analyze the stability of solid waste slopes within the bioreactor landfills, as a function of time and decomposition. The finite element program PLAXIS is used for numerical modeling of bioreactor landfills. Stability analysis of bioreactor landfills was also performed using limit equilibrium program STABL. Finally the results from finite element program PLAXIS and limit equilibrium program STABL are compared. GSTABL predicted a factor of safety of more than 1 in all the cases analyzed, whereas PLAXIS predicted a factor of safety of less than 1 at advanced stages for a slope of 2:1. However, the interface failures between solid waste and landfill liners have not been considered in this paper.

Modified landfill gas generation rate model of first-order kinetics and two-stage reaction

This investigation was carried out to establish a new domestic landfill gas (LFG) generation rate model that takes into account the impact of leachate recirculation. The first-order kinetics and two-stage reaction (FKTSR) model of the LFG generation rate includes mechanisms of the nutrient balance for biochemical reaction in two main stages. In this study, the FKTSR model was modified by the introduction of the outflow function and the organic acid conversion coefficient in order to represent the in-situ condition of nutrient loss through leachate. Laboratory experiments were carried out to simulate the impact of leachate recirculation and verify the modified FKTSR model. The model calibration was then calculated by using the experimental data. The results suggested that the new model was in line with the experimental data. The main parameters of the modified FKTSR model, including the LFG production potential (L0), the reaction rate constant in the first stage (K1), and the reaction rate constant in the second stage (K2) of 64.746 L, 0.202 d−1, and 0.338 d−1, respectively, were comparable to the old ones of 42.069 L, 0.231 d−1, and 0.231 d−1. The new model is better able to explain the mechanisms involved in LFG generation.

Estimates of CO<SUB align=right>2 emissions reduction and potential power generation from biogas at Mare Chicose landfill

In this study, the annual generation of Landfill Gas (LFG) and methane using the Scholl-Canyon model have been predicted for 1998-2030 for five scenarios of landfill management at the Mare Chicose landfill in Mauritius. Using the Approved Large-Scale Methodology AM003 and Approved Baseline Methodology AM0010 of the Approved Methodologies for CDM activities, the carbon dioxide (CO2) emissions reduction and electricity generation capacities for three CO2 emissions intensities from flaring of methane have been estimated for 2008-2030. The total LFG generation has amounted to 319.8-2371.2 Mm³ for 1998-2030. At 50% (v/v), methane content and 60% recovery, the maximum LFG generation and recoverable volume of methane amounted to 1869.5 and 560.9 Mm³ for 2008-2030, respectively. This corresponded to an emissions reduction of up to 421,657.3tCO2e. Potential power generations have been found to vary from 44.6-937 GWhour for the three emissions intensities.

Landfill gas generation after mechanical biological treatment of municipal solid waste. Estimation of gas generation rate constants

Mechanical biological treatment (MBT) of residual municipal solid waste (RMSW) was investigated with respect to landfill gas generation. Mechanically treated RMSW was sampled at a full-scale plant and aerobically stabilized for 8 and 15 weeks. Anaerobic tests were performed on the aerobically treated waste (MBTW) in order to estimate the gas generation rate constants (k,y(-1)), the potential gas generation capacity (L(o), Nl/kg) and the amount of gasifiable organic carbon. Experimental results show how MBT allowed for a reduction of the non-methanogenic phase and of the landfill gas generation potential by, respectively, 67% and 83% (8 weeks treatment), 82% and 91% (15 weeks treatment), compared to the raw waste. The amount of gasified organic carbon after 8 weeks and 15 weeks of treatment was equal to 11.01+/-1.25kgC/t(MBTW) and 4.54+/-0.87kgC/t(MBTW), respectively, that is 81% and 93% less than the amount gasified from the raw waste. The values of gas generation rate constants obtained for MBTW anaerobic degradation (0.0347-0.0803y(-1)) resemble those usually reported for the slowly and moderately degradable fractions of raw MSW. Simulations performed using a prediction model support the hypothesis that due to the low production rate, gas production from MBTW landfills is well-suited to a passive management strategy.

Modelling the landfill process using GasSim2

The prediction of landfill gas generation is an important exercise for both operators and regulators of landfill sites. The GasSim2 model, developed for this purpose by Golder Associates (UK) Ltd on behalf of the Environment Agency, is used to predict gas generation and subsequent emissions to air and land in order to assess whether emissions exceed acceptable limits. A number of other models for the prediction of landfill processes exist, and they have evolved significantly over the last decade. In order to compare individual models' strengths and weaknesses and therefore enable further development, a formal framework was designed by researchers at Southampton University. A challenge was set to modellers to predict the performance of a laboratory experiment on biodegradable waste. The data provided, including waste composition, cellulose and hemicellulose content, leachate recirculation and experimental layout, were manipulated to fit into GasSim2. A number of difficulties were experienced in modelling, including scaling the laboratory experiment to the required scale of the model, categorisation of the waste stream and the length of the model timestep. Model results indicate a potential for gas production of 17·7–47·6 m3/t dry waste per year initially, decreasing over time.

Permeability of Municipal Solid Waste in Bioreactor Landfill with Degradation

Bioreactor landfills are operated for rapid stabilization of waste, increased landfill gas generation for cost-effective energy recovery, gain in landfill space, enhanced leachate treatment, and reduced post closure maintenance period. The fundamental process of waste stabilization in bioreactor landfill is recirculation of generated leachate back into the landfills. This creates a favorable environment for rapid microbial decomposition of the biodegradable solid waste. In order to better estimate the generated leachate and design of leachate recirculation system, clear understanding of the permeability of the Municipal Solid Waste (MSW) with degradation and the factors influencing the permeability is necessary. The objective of the paper is to determine the changes in hydraulic properties of MSW in bioreactor landfill with time and decomposition. Four small-scale bioreactor landfills were built in laboratory and samples were prepared to represent each phase of decomposition. Then, the changes in hydraulic properties of MSW in bioreactor landfill with time and decomposition were determined. A series of constant head permeability tests were performed on the samples generated in laboratory scale bioreactor landfills to determine variation of permeability of MSW with degradation. The test results indicated that the permeability of MSW in bioreactor landfills decreases with decomposition. Based on the test results, the permeability of MSW at the first phase of degradation was estimated as 0.0088 cm/s at density 700 kg/m3. However, with degradation, permeability decreased to 0.0013 cm/s at the same density, for MSW at Phase IV.

Feasibility of Landfill Gas as a Liquefied Natural Gas Fuel Source for Refuse Trucks

The purpose of this paper is to develop a methodology to evaluate the feasibility of using landfill gas (LFG) as a liquefied natural gas (LNG) fuel source for heavy-duty refuse trucks operating on landfills. Using LFG as a vehicle fuel can make the landfills more self-sustaining, reduce their dependence on fossil fuels, and reduce emissions and greenhouse gases. Acrion Technologies Inc. in association with Mack Trucks Inc. developed a technology to generate LNG from LFG using the CO2 WASH process. A successful application of this process was performed at the Eco Complex in Burlington County, PA. During this application two LNG refuse trucks were operated for 600 hr each using LNG produced from gases from the landfill. The methodology developed in this paper can evaluate the feasibility of three LFG options: doing nothing, electricity generation, and producing LNG to fuel refuse trucks. The methodology involved the modeling of several components: LFG generation, energy recovery processes, fleet operations, economic feasibility, and decision-making. The economic feasibility considers factors such as capital, maintenance, operational, and fuel costs, emissions and tax benefits, and the sale of products such as surplus LNG and food-grade carbon dioxide (CO2). Texas was used as a case study. The 96 landfills in Texas were prioritized and 17 landfills were identified that showed potential for converting LFG to LNG for use as a refuse truck fuel. The methodology was applied to a pilot landfill in El Paso, TX. The analysis showed that converting LFG to LNG to fuel refuse trucks proved to be the most feasible option and that the methodology can be applied for any landfill that considers this option.

Methane emissions from MSW landfill with sandy soil covers under leachate recirculation and subsurface irrigation

CH 4 emissions and leachate disposal are recognized as the two major concerns in municipal solid waste (MSW) landfills. Recently, leachate recirculation was attempted to accelerate land-filled waste biodegradation and thus enhanced landfill gas generation. Leachate irrigation was also conducted for volume reduction effectively. Nevertheless, the impacts of leachate recirculation and irrigation on landfill CH 4 emissions have not been previously reported. A field investigation of landfill CH 4 emissions was conducted on selected sandy soil cover with leachate recirculation and subsurface irrigation based on whole year around measurement. The average CH 4 fluxes were 311±903, 207±516, and 565±1460 CH 4 m −2 h −1 from site A without leachate recirculation and subsurface irrigation, lift B2 with leachate subsurface irrigation, and lift B1 with both leachate recirculation and subsurface irrigation, respectively. Both gas recovery and cover soil oxidation minimized CH 4 emissions efficiently, while the later might be more pronounced when the location was more than 5 m away from gas recovery well. After covered by additional clay soil layer, CH 4 fluxes dropped by approximately 35 times in the following three seasons compared to the previous three seasons in lift B2. The diurnal peaks of CH 4 fluxes occurred mostly followed with air or soil temperature in the daytimes. The measured CH 4 fluxes were much lower than those of documented data from the landfills, indicating that the influences of leachate recirculation and subsurface irrigation on landfill CH 4 emissions might be minimized with the help of a well-designed sandy soil cover. Landfill cover composed of two soil layers (clay soil underneath and sandy soil above) is suggested as a low-cost and effective alternative to minimize CH 4 emissions.

Discussion of “Landfill Settlement with Decomposition and Gas Generation” by Ertan Durmusoglu, M. Yavuz Corapcioglu, and Kagan Tuncay

In their paper, the authors show that with a municipal solid waste landfill modeled to represent balances of deformation stresses, naturally occurring short-term and long-term site settlement may be better characterized than with the past empirical or theoretical models that have generally assumed a rigid landfill skeleton. The authors propose a one-dimensional site model with a deformable matrix that combines time-varying stresses, caused by selfand imposed-weight, collapse and rearrangement of particles, decomposition and buoyant effects due to gas generation, and movement and liquid flows through the matrix. The latter is said to delay ultimate settlement rates. The authors point out that previous studies have incurred significant and unexamined estimation errors through indirect assumption of a rigid landfill skeleton, even when considering gas and liquid generation and flows. They however agree with previous investigators Bleiker et al. 1995; Wall and Zeiss 1995; Park and Lee 1997; Machado et al. 2002; Park et al. 2002; Hossain et al. 2003; Marques et al. 2003 , that total settlement may be characterized according to the conventional soil mechanics approach pioneered by Sowers 1973 and Edil et al. 1990 . This approach involves settlement with short-term or primary stage of compression that results from wasted self-weight and applied load, followed by dissipation of gas and liquid from voids in the system, and an extended period of secondary compression that is the result of particle rearrangement and slippage, and long-term microbially induced enzymatic decomposition. They note that gas generation rates patterned on secondary compression or settlement rates, which can continue for decades, account for most of the settlement, and have considerable engineering importance relative to landfill site reuses. One important innovation of this model is a possible first consideration of all phases as deformable, making their landfill representation more amenable to modeling as a completely viscoelastic system viscoelastic Maxwell bodies attached to compressible Hookean springs , per Edil et al. 1990 and Wall and Zeiss 1992 . In development of their model, for purposes of simplicity in use of landfill gas generation rates, the authors have followed the approach used by Findikakis and Leckie 1979 and Hossain et al. 2003 , who characterized landfill refuse according to biodegradability into three or more fractions, with specific first-order decomposition and methane gas yield rates. The authors have correctly noted that this is an oversimplification. They have also adopted the pioneering Emcon Associates 1980 general sto-

Landfilling of pretreated municipal solid waste by natural convection of air and its effects

The problems of leachate treatment and landfill gas (LFG) emissions are increasing gradually. Reducing the hazard before emplacement, pretreatment of municipal solid waste (MSW) prior to landfilling has become very important for the conventional landfill. In this study, pretreated mixed un-shredded MSW by the natural convection of air was employed to assess the aerobic pretreatment suitability. To study the effects of pretreated waste on landfill behavior, landfill simulation reactor (LSR) was developed at laboratory scale; pretreated MSW was placed in it. In a LSR, the behavior of aerobically pretreated waste disposal on a landfill was simulated. The LSR was operated for more than 9 months. The LSR operating phases were analyzed together with the consolidation of the leachate and gas production. The leachate collected was analyzed for pH, BOD (biochemical oxygen demand), COD (chemical oxygen demand), NH3-N and trace metals. The gas collected was analyzed for CH4 and CO2. The COD and BOD values were reduced to 1850 mg/L and 235 mg/L respectively within 5 months respectively. The maximum landfill gas (LFG) generation was observed about 60 m3 per ton dry matter (DM) of MSW. This work demonstrates that pretreatment is significantly effective in reducing the landfill emissions that is LFG; and leachate quality was improved in terms of COD and BOD.

Modelling of environmental impacts of solid waste landfilling within the life-cycle analysis program EASEWASTE

A new computer-based life-cycle assessment model (EASEWASTE) has been developed to evaluate resource and environmental consequences of solid waste management systems. This paper describes the landfilling sub-model used in the life-cycle assessment program EASEWASTE, and examines some of the implications of this sub-model. All quantities and concentrations of leachate and landfill gas can be modified by the user in order to bring them in agreement with the actual landfill that is assessed by the model. All emissions, except the generation of landfill gas, are process specific. The landfill gas generation is calculated on the basis of organic matter in the landfilled waste. A landfill assessment example is provided. For this example, the normalised environmental effects of landfill gas on global warming and photochemical smog are much greater than the environmental effects for landfill leachate or for landfill construction. A sensitivity analysis for this example indicates that the overall environmental impact is sensitive to the gas collection efficiency and the use of the gas, but not to the amount of leachate generated, or the amount of soil or liner material used in construction. The landfill model can be used for evaluating different technologies with different liners, gas and leachate collection efficiencies, and to compare the environmental consequences of landfilling with alternative waste treatment options such as incineration or anaerobic digestion.

A Sustainable Approach to the Remediation of the Payatas Disposal Facility in Metro Manila, Philippines

AbstractThe municipal solid waste management crisis facing the Payatas disposal facility in Metro Manila, Philippines underscores the urgent need for sustainable solutions to address leachate contamination, the geotechnical instability of the dumpsite, landfill gas generation and the safety and health of facility workers and residents. A team of environmental engineers selected the site as a design project for the Mondialogo Worldwide Engineering Award and identified the following engineering solutions suitable for the remediation of the dumpsite: slope reinforcement anchors, soil-bentonite vertical impermeable barriers, an impermeable dumpsite cap, a perimeter drainage system, a leachate recirculation system, a facultative lagoon and constructed wetland system, a methane gas collection and power generation system, and a materials recovery facility. The proposed management system and financial remediation strategy requires the local government to spearhead the programme with funding to be derived from international loans and grants. It is recommended that the energy recovery component of the project be funded under the clean development mechanism, in which the certified emissions reductions (CERs) generated may be used to offset the capital outlay for the retrofitting of the engineering solutions and continuance of the remediation programme. The proposed remediation programme addresses the Millennium Development Goals set by the Philippine government relating to protection of the environment, improvement of health and sanitation, and the enhancement of energy services and community income sharing gained from surplus CERs.

Approach of technical decision-making by element flow analysis and Monte-Carlo simulation of municipal solid waste stream

This paper deals with the procedure and methodology which can be used to select the optimal treatment and disposal technology of municipal solid waste (MSW), and to provide practical and effective technical support to policy-making, on the basis of study on solid waste management status and development trend in China and abroad. Focusing on various treatment and disposal technologies and processes of MSW, this study established a Monte-Carlo mathematical model of cost minimization for MSW handling subjected to environmental constraints. A new method of element stream (such as C, H, O, N, S) analysis in combination with economic stream analysis of MSW was developed. By following the streams of different treatment processes consisting of various techniques from generation, separation, transfer, transport, treatment, recycling and disposal of the wastes, the element constitution as well as its economic distribution in terms of possibility functions was identified. Every technique step was evaluated economically. The Mont-Carlo method was then conducted for model calibration. Sensitivity analysis was also carried out to identify the most sensitive factors. Model calibration indicated that landfill with power generation of landfill gas was economically the optimal technology at the present stage under the condition of more than 58% of C, H, O, N, S going to landfill. Whether or not to generate electricity was the most sensitive factor. If landfilling cost increases, MSW separation treatment was recommended by screening first followed with incinerating partially and composting partially with residue landfilling. The possibility of incineration model selection as the optimal technology was affected by the city scale. For big cities and metropolitans with large MSW generation, possibility for constructing large-scale incineration facilities increases, whereas, for middle and small cities, the effectiveness of incinerating waste decreases.

Pilot-scale experiment on anaerobic bioreactor landfills in China

Developing countries have begun to investigate bioreactor landfills for municipal solid waste management. This paper describes the impacts of leachate recirculation and recirculation loadings on waste stabilization, landfill gas (LFG) generation and leachate characteristics. Four simulated anaerobic columns, R1–R4, were each filled with about 30 tons of waste and recirculated weekly with 1.6, 0.8 and 0.2 m 3 leachate and 0.1 m 3 tap water. The results indicated that the chemical oxygen demand (COD) half-time of leachate from R1 was about 180 days, which was 8–14 weeks shorter than that of R2–R4. A large amount of LFG was first produced in R1, and its generation rate was positively correlated to the COD or volatile fatty acid concentrations of influent leachates after the 30th week. By the 50th week of recirculation, the waste in R1 was more stabilized, with 931.2 kg COD or 175.6 kg total organic carbon released and with the highest landfill gas production. However, this contributed mainly to washout by leachate, which also resulted in the reduction of LFG generation potential and accumulation of ammonia and/or phosphorus in the early stage. Therefore, the regimes of leachate recirculation should be adjusted to the phases of waste stabilization to enhance efficiency of energy recovery. Integrated with the strategy of in situ leachate management, extra pre-treatment or post-treatment methods to remove the nutrients are recommended.

Brownfields and health risks—air dispersion modeling and health risk assessment at landfill redevelopment sites

Redevelopment of landfill sites in the New Jersey-New York metropolitan area for recreational (golf courses), commercial, and even residential purposes seems to be gaining acceptance among municipal planners and developers. Landfill gas generation, which includes methane and potentially toxic nonmethane compounds usually continues long after closure of the landfill exercise phase. It is therefore prudent to evaluate potential health risks associated with exposure to gas emissions before redevelopment of the landfill sites as recreational, commercial, and, especially, residential properties. Unacceptably high health risks would call for risk management measures such as limiting the development to commercial/recreational rather than residential uses, stringent gas control mechanisms, interior air filtration, etc. A methodology is presented for applying existing models to estimate residual landfill hazardous compounds emissions and to quantify associated health risks. Besides the toxic gas constituents of landfill emissions, other risk-related issues concerning buried waste, landfill leachate, and explosive gases were qualitatively evaluated. Five contiguously located landfill sites in New Jersey intended for residential and recreational redevelopment were used to exemplify the approach.

Numerical model to predict settlements coupled with landfill gas pressure in bioreactor landfills

Landfills settle due to its weight and biodegradation of waste. Biodegradation-induced settlement is a direct result of rearrangement of waste skeleton in response to the conversion of waste mass into landfill gases. Traditionally, the compressibility index based on settlement of clays is used to explain the settlement of waste. Literature review showed that there are limited research attempts of landfill settlement predictions by coupling with landfill gas generation and transport. This research describes a model which couples settlement in a bioreactor landfill with the generation and subsequent upward movement of landfill gases. The mass balance of the landfill gas was used to link settlement and gas pressures. In the absence of a closed-formed analytical solution, a computer program was developed to numerically predict the settlements and gas pressures in a bioreactor landfill using landfill geometry and waste properties. Explicitly computed settlement values were then used to predict the pressure profile implicitly. To test the mathematical formulations, a numerical exercise was performed using a single-cell hypothetical bioreactor landfill. The numerical simulation produced satisfactory trends of the settlement and the landfill gas pressure profiles.

Passive drainage and biofiltration of landfill gas: Australian field trial

In Australia a significant number of landfill waste disposal sites do not incorporate measures for the collection and treatment of landfill gas. This includes many old/former landfill sites, rural landfill sites, non-putrescible solid waste and inert waste landfill sites, where landfill gas generation is low and it is not commercially viable to extract and beneficially utilize the landfill gas. Previous research has demonstrated that biofiltration has the potential to degrade methane in landfill gas, however, the microbial processes can be affected by many local conditions and factors including moisture content, temperature, nutrient supply, including the availability of oxygen and methane, and the movement of gas (oxygen and methane) to/from the micro-organisms. A field scale trial is being undertaken at a landfill site in Sydney, Australia, to investigate passive drainage and biofiltration of landfill gas as a means of managing landfill gas emissions at low to moderate gas generation landfill sites. The design and construction of the trial is described and the experimental results will provide in-depth knowledge on the application of passive gas drainage and landfill gas biofiltration under Sydney (Australian) conditions, including the performance of recycled materials for the management of landfill gas emissions.

Energy Potential of Municipal Solid Wastes

In this article, energy recovery from municipal solid wastes is examined. The fuel characteristics of solid waste components as well as the landfill gas (LFG) yield are reviewed. The energy potential of solid wastes of Izmir (third biggest city of Turkey) is then estimated. The heating value is calculated at about 3,500–5,500 kJ/kg, particularly in urban places, whereas it is 6,000–7,000 kJ/kg for industrial and commercial establishments. LFG generation is predicted from the data taken from the Harmandali landfill area. As a result, energy generation from LFG is shown to be environmentally beneficial and an economic alternative.

Stochastic Model for Landfill Gas Transport and Energy Recovery

Predicting the amount of landfill gas (LFG) that will be recovered at a sanitary landfill is generally associated with a high level of uncertainty, which is primarily due to the uncertainty in the definition of the parameters that control the LFG generation rate and LFG transport. To quantify these uncertainties, a three-dimensional stochastic model for the generation and transport of LFG is proposed. Using Monte Carlo simulations, multiple realizations of key input parameters are generated. For each realization, LFG transport is simulated and then used to evaluate probabilistically the rates and efficiency of energy recovery. For demonstration, the stochastic model is applied to the Kemerburgaz landfill in Istanbul, Turkey. Uncertainty in the definition of three key parameters, namely: the LFG production rate, the waste gas permeability and the soil cover gas permeability were accounted for. Modeling results suggest that the collection system is sufficient to capture most of the generated gas, but that uncertainty in the factors controlling LFG production is the main source of uncertainty in the amount of energy that will be recovered.

Strategies for the municipal solid waste sector to assist Canada in meeting its Kyoto Protocol commitments

The Government of Canada has ratified the Kyoto Protocol, committing to a 6% reduction in greenhouse gas (GHG) emissions from 1990 levels during the commitment period of 2008–2012. To attain this target, emission reductions throughout many sectors must be achieved. The waste sector can assist Canada in reducing GHG emissions to meet its commitments under the Kyoto Protocol. In 2001, the waste sector generated 24.8 megatonnes (Mt) of carbon dioxide equivalent (CO2e) from landfill gas (LFG) generation, wastewater treatment, and incineration. Emissions from the transportation of solid waste were not considered, and are seen to be small. Several strategies for reducing GHG emissions from solid waste are analyzed. Source reduction decreases the amount of material being generated, thus reducing from the source any emissions that might be related to the life cycle of the material. Recycling can reduce GHG emissions by reducing the amount of virgin material being processed, avoiding life cycle emissions. Landfill gas collection for energy recovery can reduce methane (CH4) emissions from organic wastes in landfills, and the Government of Canada's Climate Change Plan has considered this strategy. Anaerobic digestion converts some of the organic matter in the municipal solid waste (MSW) to both CH4 and carbon dioxide (CO2), where the CH4 can be used to generate power, while composting converts some of the organic fraction to CO2. Both of these processes produce a soil conditioner as their residue. Waste incineration reduces MSW volume and can generate power, displacing generation from fossil fuels. An integrated approach, considering these techniques where appropriate, can succeed in reducing emissions from the solid waste sector. Policy choices such as extended producer responsibility, minimum recycled content laws, and LFG capture criteria would increase the impact of solid waste management on GHG emissions. Key words: climate change, Kyoto Protocol, municipal solid waste, source reduction, recycling, landfill gas capture, anaerobic digestion.